Cogprints: No conditions. Results ordered -Date, Title. 2018-01-17T14:24:38ZEPrintshttp://cogprints.org/images/sitelogo.gifhttp://cogprints.org/2006-10-28Z2011-03-11T08:56:42Zhttp://cogprints.org/id/eprint/5242This item is in the repository with the URL: http://cogprints.org/id/eprint/52422006-10-28ZEarly Outcomes of Out-of-Hospital Cardiac Arrest after Early Defibrillation: a 24 Months Retrospective Analysis
Introduction: Cardiovascular disease remains the most common cause of death in the United States and most other Western nations. Among these deaths, sudden, out-of-hospital cardiac arrest claims approximately 1000 lives each day in the United States alone. Most of these cardiac arrests are due to ventricular fibrillation. Though highly reversible with the rapid application of a defibrillator, ventricular fibrillation is otherwise fatal within minutes, even when cardiopulmonary resuscitation is provided immediately. The overall survival rate in the United States is estimated to be less than 5 percent. Recent developments in automated-external-defibrillator technology have provided a means of increasing the rate of prompt defibrillation after out-of-hospital cardiac arrest. After minimal training, nonmedical personnel (e.g., flight attendants and casino workers) are also able to use defibrillators in the workplace, with lifesaving effects. Nonetheless, such programs have involved designated personnel whose job description includes assisting persons who have had sudden cardiac arrest. Data are still lacking on the success of programs in which automated external defibrillators have been installed in public places to be used by persons who have no specific training or duty to act.
Materials and Methods: All patients who had an out-of-hospital cardiac arrest between January 2003 and December 2004 and who received early defibrillation for ventricular fibrillation were included. We conducted a 24 months retrospective population-based analysis of the outcome in our population.
Results: Over a 24 month period, 446 people had non–traumatic cardiac arrest, and in all of them it was observed to be ventricular fibrillation. In a very few cases, the defibrillator operators were good Samaritans, acting voluntarily. Eighty-nine patients (about 19%) with ventricular fibrillation were successfully resuscitated, including eighteen who regained consciousness before hospital admission.
Conclusion: Automated external defibrillators deployed in readily accessible, well-marked areas, are really very effective in assisting patients with cardiac arrest. However, it's quite true that, in the cases of survivors, most of our users had good prior training in the use of these devices.
Paolo TerranovaPaolo ValliSimonetta Dell'OrtoEnrico Maria Greco2006-10-28Z2011-03-11T08:56:41Zhttp://cogprints.org/id/eprint/5240This item is in the repository with the URL: http://cogprints.org/id/eprint/52402006-10-28ZRemote Monitoring of Implantable Cardioverter Defibrillator
The rate of implantable cardioverter defibrillator (ICD) implantation has gone up as primary and secondary prevention trials have relatively consistently shown significant improvement in mortality and morbidity. Most patients with ICDs are followed routinely at intervals ranging from 3 to 6 months. Many patients require additional non-scheduled visits to investigate symptoms that may or may not relate to their cardiac disease or device. Appropriate and inappropriate therapies of implantable cardioverter defibrillators have a major impact on morbidity and quality of life in ICD recipients. Remote monitoring systems can substitute for routine follow-up visits and/ or deliver continuous diagnostic and device status information. Remote monitoring of ICDs can decrease the need for many patient visits and, thereby, probably reduce expense.
Dwight W ReynoldsN JayaprasadJohnson Francis2006-10-28Z2011-03-11T08:56:38Zhttp://cogprints.org/id/eprint/5210This item is in the repository with the URL: http://cogprints.org/id/eprint/52102006-10-28ZDiastolic And Systolic Right Ventricular Dysfunction Precedes Left Ventricular Dysfunction In Patients Paced From Right Ventricular Apex Background: Cardiac dysfunction after right ventricular (RV) apical pacing is well known but its extent, time frame of appearance and individual effect on left ventricular (LV), RV systolic and diastolic parameters has not evaluated in a systematic fashion.
Methods: Patients with symptomatic bradycardia and ACC-AHA Class I indication for permanent pacemaker implantation (PPI) were implanted a single chamber (VVI) pacemaker. They were followed prospectively by echocardiographic examination which was done at baseline, 1 week, 1 month and 6 months after implantation. Parameters observed were chamber dimensions (M-line), chamber volumes, cardiac output (modified Simpson's method), systolic functions (ejection fraction, pre-ejection period, ejection time and ratio) and diastolic functions( isovolumic relaxation time & deceleration time) of left and right heart.
Results: Forty eight consecutive patients (mean age 65.6±11.8 yrs, 66.7% males, mean EF 61.82±10.36%) implanted a VVI pacemaker were enrolled in this study. The first significant change to appear in cardiac function after VVI pacing was in diastolic properties of RV as shown by increase in RV isovolumic relaxation time (IVRT) from 65.89±15.93 to 76.58±17.00 ms,(p<0.001) at 1week and RV deceleration time (DT) from 133.84±38.13 to 153.09±31.41 ms, (p=0.02) at 1 month. Increase in RV internal dimension (RVID) from 1.26±0.41 to 1.44±0.44, (p<0.05) was also noticed at 1 week. The LV diastolic parameters were significantly altered after 1 month with increase in LV-IVRT from 92.36±21.47 to 117.24±27.21ms, (p<0.001) and increase in LV DT from 147.56±31.84 to 189.27±28.49ms,(p<0.01). This was followed by LV systolic abnormality which appeared at 6 months with an increase in LVPEP from 100.33±14.43 to 118.41±21.34ms, (p<0.001) and increase in LVPEP/LVET ratio from 0.34±0.46 to 0.44±0.10, (p<0.001)]. The reduction in LV EF was manifested at 6 months falling from 61.82±10.36% to52.52±12.11%, (p<0.05) without any significant change in the resting cardiac output.
Conclusion: The present study shows that dysfunction of right ventricle is the first abnormality that occurs in VVI paced patients, which manifests by 1 week followed by LV dysfunction which starts appearing by 1 month and the diastolic dysfunctions precede the systolic dysfunction in both ventricles.
Dwivedi SKSandeep BansalAniket PuriMakharia MKNarain VSSaran RKHasan MPuri VK2006-10-28Z2011-03-11T08:56:41Zhttp://cogprints.org/id/eprint/5239This item is in the repository with the URL: http://cogprints.org/id/eprint/52392006-10-28ZInfra-His Block in a Normal Heart
A 55 year old man with history of palpitation was referred for electrophysiologic study. Baseline ECG, physical examination and transthoracic echocardiographic study were normal. Electrophysiologic study revealed normal AH and HV intervals. Pacing of right atrium with a cycle length of 300 msec showed 2:1 AV block. AH interval was 252 msec and the block was infra-his (Figure 1). With continual of right atrial pacing, one to one AV conduction with increasing AH interval to 282 msec and QRS widening (LBBB pattern) were being observed. HV intervals during 2:1 block and during 1:1 AV conduction were normal. What is the mechanism? Is it an abnormal finding in this patient?
Mohammad AlastiAbolfath AlizadehAmirfarjam FazelifarMohammad Ali Sadr-Ameli2006-10-28Z2011-03-11T08:56:39Zhttp://cogprints.org/id/eprint/5237This item is in the repository with the URL: http://cogprints.org/id/eprint/52372006-10-28ZQuality of Life in Patients with Implantable Cardioverter Defibrillators
Background: The implantable cardioverter defibrillator (ICD) is a life saving device for individuals with life threatening ventricular arrhythmias. There is no doubt that it is a cost effective therapy in various congenital and acquired arrhythmogenic disorders. Nevertheless, shock delivery may be painful and frightening which causes psychological distress and deterioration of perceived quality of life.
Methods: A systematic meta-analysis on studies reporting quality of life in patients implanted with ICDs was done using professional databases. Related articles and references of the relevant articles were also searched for suitable studies.
Results: Thirty studies with a total of 3412 patients on implantable defibrillators were identified. Five of them were large randomised studies with a total of 1680 patients, while 25 were non-randomised studies. Medical Outcome Study 36-item Short Form health survey (SF - 36) was the most common instrument used for assessment of quality of life. Only one of the 5 major randomised trial reported worsening of quality of life after implantation of a defibrillator. In the subgroup of patients receiving shocks, three out of the five trials reported worsening of quality of life.
Summary: Most of the randomised studies showed either neutral or better quality of life in patients on implantable defibrillators. In the subset of patients receiving shocks, worsening of quality of life was found in most randomised studies. Therefore, activation of antitachycardia pacing should be performed in every ICD-patient in order to miminze painful shocks and consequent deterioration of quality of life.
Johnson FrancisBeena JohnsonMichael Niehaus2006-10-28Z2011-03-11T08:56:38Zhttp://cogprints.org/id/eprint/5211This item is in the repository with the URL: http://cogprints.org/id/eprint/52112006-10-28ZSingle-chamber Versus Dual-chamber Implantable Cardioverter Defibrillators: Do We Need Physiologic Pacing in The Course?
Background: Many patients with ICD receive different antiarrhythmic drugs (e.g. sotalol, amiodarone, β-blockers) because of ventricular or atrial tachycardias. These drugs can cause AV-block or chronotropic incompetence resulting in a higher percentage of ventricular pacing.
Methods: We analyzed in a retrospective study the impact of DDD(R) versus VVI(R) mode on subjective (NYHA classification) and objective parameters [brain natriuretic peptide (BNP), 6 minute walk test, echocardiography] in 12 of 120 patients (age 60.2 ± 11.2 years; 10 males, 2 females) who needed an upgrading of a single to a dual chamber ICD. The ICD had to be upgraded because of chronotropic incompetence in all patients with signs of progressing heart failure. Data were collected in VVI(R)-pacing and after 6 and 12 months in DDD(R)-pacing with a long AV-interval and AV hysteresis to reduce ventricular pacing.
Results: The 6 minute walk test (392.4 ± 91.4 vs. 324.6 ± 93.3 m, P < 0.001), NYHA-classification (1.4 ± 0.3 vs. 2.6 ± 0.8, P < 0.0001), BNP (234.1 ± 73.5 vs. 410.4 ± 297.0 pg/ml, P < 0.001), left ventricular ejection fraction (49.8 ± 9.6 vs. 36.5 ± 10.9 %, P < 0.0001) and A-wave (73.6 ± 13.7 vs. 41.0 ± 14.0 cm/sec, P < 0.0001) improved with DDD(R)-pacing after 12 months. The ventricular pacing decreased (84.2 ± 18.1 vs. 1.1 ± 1.7 %, P < 0.0001) after 12 months by DDD(R)-pacing with long AV-interval (220.0 ± 10.4 ms) and AV hysteresis.
Conclusion: Our data show a superiority of DDD(R) mode versus VVI(R) mode regarding subjective and objective parameters as NYHA-classification, BNP, 6 minute walk test, left ventricular ejection fraction and left ventricular endsystolic volume after 12 months. The improvements seem to depend on the reduction of ventricular pacing with advanced atrial contraction. But only a small number of patients needed the upgradation.
Marco BudeusThomas BuckHeinrich WienekeRaimund ErbelStefan Sack2006-10-28Z2011-03-11T08:56:42Zhttp://cogprints.org/id/eprint/5241This item is in the repository with the URL: http://cogprints.org/id/eprint/52412006-10-28ZStable Atrial Sensing on Long-Term Follow Up of VDD Pacemakers
Background:
The hemodynamic advantages of maintaining AV synchrony through AV synchronous pacing are widely known as compared to single chamber pacing. DDD pacemaker implantation entails higher cost and is technically more challenging than the VDD pacemaker.
Methods:
Seventy one patients underwent VDD lead (Biotronik GmbH, St. Jude Medical and Medtronic Inc.) implantation at KEM hospital, Mumbai during a period of 3 years through subclavian, axillary and cephalic routes for degenerative, post-surgical or congenital high grade atrioventricular or complete heart block. They were followed up regularly for ventricular threshold and P wave amplitude of the floating atrial dipole.
Results:
Follow up data of almost 95% of patients is available for a period of 15.8 ± 6.7 months. P wave amplitude at implant was 2.1 ± 0.7mV and at follow up 1.1 ± 0.6mV with mean ventricular threshold of <0.5V at implant and <1V at follow-up.
Conclusion:
Implantation of a single lead VDD pacemaker is possible in all patients with symptomatic AV block and intact sinus node function without any technical complications. P wave sensing is reliable and consistent with floating atrial lead at an average follow up of 15.8 months, providing an excellent alternative to DDD pacemaker implantation.
Ashok ShahJairam AithalDhiraj NarulaPrafulla Kerkar2006-10-05Z2011-03-11T08:56:22Zhttp://cogprints.org/id/eprint/4808This item is in the repository with the URL: http://cogprints.org/id/eprint/48082006-10-05ZSudden Cardiac Death in Athletes - What Can be Done?Sudden death in athletes is a rare event but brings with it an impact that goes beyond sport. There are many causes of sudden death during exercise. While the responsibility of preventing or treating them lays with us physicians, preparticipation screening is largely ineffective and impractical. Definitive, large scale prospective research is required in order to design the most cost-effective system for screening of athletes. In the meanwhile rapid access to defibrillators by trained personnel remains the best possible approach to abort sudden death.
Joydeep Ghosh2006-10-28Z2011-03-11T08:56:41Zhttp://cogprints.org/id/eprint/5238This item is in the repository with the URL: http://cogprints.org/id/eprint/52382006-10-28ZTransient unexpected improvement of AV conduction: What is the mechanism?
This ECG was recorded from a 93 year old patient with a previously documented third degree AV block and an underlying LBBB. The twelve lead ECG demonstrates sinus bradycardia at a rate of 52 beats per minute, a PR interval of 230 milliseconds, and a left bundle branch block (Figure 1). In figure 2, a rhythm strip of leads V1, II and V5 shows sinus rhythm with AV block. Note that only P waves in the T wave of the paced beat are conducted. The non-conducted P waves are followed by ventricular paced beats at an escape interval of 1200 milliseconds. Meir FriedmanPaul Schweitzer2006-04-01Z2011-03-11T08:56:22Zhttp://cogprints.org/id/eprint/4803This item is in the repository with the URL: http://cogprints.org/id/eprint/48032006-04-01ZAn Approach to Catheter Ablation of Cavotricuspid Isthmus Dependent Atrial Flutter Much of our understanding of the mechanisms of macro re-entrant atrial tachycardia comes from study of cavotricuspid isthmus (CTI) dependent atrial flutter. In the majority of cases, the diagnosis can be made from simple analysis of the surface ECG. Endocardial mapping during tachycardia allows confirmation of the macro re-entrant circuit within the right atrium while, at the same time, permitting curative catheter ablation targeting the critical isthmus of tissue located between the tricuspid annulus and the inferior vena cava. The procedure is short, safe and by demonstration of an electrophysiological endpoint - bidirectional conduction block across the CTI - is associated with an excellent outcome following ablation. It is now fair to say that catheter ablation should be considered as a first line therapy for patients with documented CTI-dependent atrial flutter.Mark D O’NeillPierre JaïsAnders JönssonYoshihide TakahashiFrédéric SacherMélèze HociniPrashanthan SandersThomas RostockMartin RotterJacques ClémentyMichel Haïssaguerre2006-04-01Z2011-03-11T08:56:22Zhttp://cogprints.org/id/eprint/4800This item is in the repository with the URL: http://cogprints.org/id/eprint/48002006-04-01ZComplications and Mortality of Single Versus Dual Chamber Implantable Cardioverter Defibrillators Background: The implantable cardioverter defibrillators (ICDs) are increasingly being used as a treatment modality for life threatening tachyarrhythmia. The purpose of this study was to compare the frequency of complications and mortality between single-chamber and dual-chamber ICD implantation in Shahid Rajaie cardiovascular center.
Methods and results: Between January 2000 and December 2004, 234 patients received ICD by a percutaneous transvenous approach and were followed for 33 ± 23 months. The cumulative incidence of complications was 9.4% over the follow-up period. There was no significant difference in overall complication rate between single chamber (VR) and dual chamber (DR) ICD groups in the follow-up period (P= 0.11). The risk of complications did not have any statistically significant difference in secondary versus primary prevention groups (P=0.06). The complications were not associated with the severity of left ventricular systolic dysfunction (P=0.16).The frequency of lead-related complications was higher in dual chamber ICDs in comparison with single chamber ICDs (P=0.02). There was no significant difference in mortality between different sex groups (P=0.37), different indications for ICD implantation (P=0.43) or between VR and DR ICD groups (P= 0.55). Predictors of mortality were NYHA class III or more (P<0.001), age >65 years (P=0.011) and LVEF<30% (P<0.001). The mortality in patients with CAD and DCM were significantly higher than those with other structural heart diseases (P=0.001).
Conclusions: Close monitoring of patients during the first 2 month after ICD implantation is recommended because the majority of complications occur early after the procedure.
Ataallah BagherzadehZahra EmkanjooMajid HaghjooMaryam Moshkani FarahaniAbolfath AlizadehMohammad Ali Sadr-Ameli2006-04-01Z2011-03-11T08:56:22Zhttp://cogprints.org/id/eprint/4807This item is in the repository with the URL: http://cogprints.org/id/eprint/48072006-04-01ZConcealed Malfunction of The Temporary PacemakerThe 12-lead ECG shows sequential atrial and ventricular pacing (Figure 1A). A tracing, obtained simultaneously during pacemaker interrogation, disclosed pacemaker functioning as VDD mode (Figure 1B). The careful examination of this pacemaker tracing showed that there is a pacing stimulus before each P wave (compatible with DDD mode). This paradox can only be explained by displacement of the temporary pacing lead to right atrium and right atrial stimulation by temporary pacemaker. In this setting, each temporary pacemaker-induced atrial depolarization is tracked by the right atrial lead of the permanent pacemaker as intrinsic P wave. Fluoroscopic study confirmed this explanation (Figure 2). The displaced temporary pacing lead was seen near the lateral right atrial wall. Temporary pacemaker lead had been inserted before replacement of permanent pacemaker. Mohammad AlastiMajid HaghjooAbolfath AlizadehMohammad Ali Sadr-Ameli2006-04-01Z2011-03-11T08:56:22Zhttp://cogprints.org/id/eprint/4804This item is in the repository with the URL: http://cogprints.org/id/eprint/48042006-04-01ZElectrophysiological Mechanisms of Atrial FlutterAtrial flutter (AFL) is a common arrhythmia in clinical practice. Several experimental models such as tricuspid regurgitation model, tricuspid ring model, sterile pericarditis model and atrial crush injury model have provided important information about reentrant circuit and can test the effect of antiarrhythmic drugs. Human atrial flutter has typical and atypical forms. Typical atrial flutter rotates around tricuspid annulus and uses the crista terminalis and sometimes sinus venosa as the boundary. The IVC-tricuspid isthmus is a slow conduction zone and the target of radiofrequency ablation. Atypical atrial flutter may arise from the right or left atrium. Right atrial flutter includes upper loop reentry, free wall reentry and figure of eight reentry. Left atrial flutter includes mitral annular atrial flutter, pulmonary vein-related atrial flutter and left septal atrial flutter. Radiofrequency ablation of the isthmus between the boundaries can eliminate these arrhythmias.
Ching- Tai TaiShin-Ann Chen2006-04-01Z2011-03-11T08:56:19Zhttp://cogprints.org/id/eprint/4689This item is in the repository with the URL: http://cogprints.org/id/eprint/46892006-04-01ZEndocardial Pacemaker Implantation in Neonates and Infants Transvenous pacemaker lead implantation is the preferred method of pacing in adult patients. Lead performance and longevity are superior and the implantation approach can be performed under local anaesthetic with a very low morbidity. In children, and especially in neonates and infants, the epicardial route was traditionally chosen until the advent of smaller generators and lead implantation techniques that allowed growth of the child without lead displacement. Endocardial implantation is not universally accepted, however, as there is an incidence of venous occlusion of the smaller veins of neonates and infants with concerns for loss of venous access in the future. Growing experience with lower profile leads, however, reveals that endocardial pacing too can be performed with low morbidity and good long-term results in neonates and infants.Canan AyabakanEric Rosenthal2006-04-01Z2011-03-11T08:56:22Zhttp://cogprints.org/id/eprint/4806This item is in the repository with the URL: http://cogprints.org/id/eprint/48062006-04-01ZExercise-induced left septal fascicular block: an expression of severe myocardial ischemiaThe electrocardiogram (ECG) criteria for the left septal fascicular block (LSFB) are not universally accepted and many other denominations can be seen in literature: focal septal block, septal focal block, left septal fascicular block, left anterior septal block, septal fascicular conduction disorder of the left branch, left septal Purkinje network block, left septal subdivision block of the left bundle branch, anterior conduction delay, left median hemiblock, left medial subdivision block of the left bundle branch, middle fascicle block, block of the anteromedial division of the left bundle branch of His, and anteromedial divisional block. During exercise stress test, fascicular blocks (left anterior and posterior) seem to indicate severe coronary artery narrowing of left main coronary or proximal left anterior descending artery disease1 and transient exercise-induced left septal fascicular block has been reported a few times2,3.
54-year-old male, with a history of essential arterial systemic hypertension, primary hyperlipidemia and six-month typical chest pain during exercise (Class II – Canadian Cardiovascular Society) underwent an exercise stress test. During the exercise stress test, ECG demonstrated abrupt prominent anterior forces, an increase in R wave amplitude from V1 to V4, extreme left axis deviation and minor ST segment depression in DII, DIII and aVF (Figure 1). The post-exercise period showed progressive return of the QRS axis in both frontal and horizontal planes and the ST depression worsened by 1 mm. Coronary angiogram (Figure 2A) showed a critical proximal left anterior descending artery lesion. An exercise stress test done three months after coronary artery bypass surgery grafting was normal (Figure 2B).
Augusto Hiroshi UchidaPaulo Jorge MoffaAndrés Ricardo Pérez Riera Beatriz Moreira Ayub Ferreira2006-04-01Z2011-03-11T08:56:22Zhttp://cogprints.org/id/eprint/4805This item is in the repository with the URL: http://cogprints.org/id/eprint/48052006-04-01ZGene Therapy in Cardiac Arrhythmias
Gene therapy has progressed from a dream to a bedside reality in quite a few human diseases. From its first application in adenosine deaminase deficiency, through the years, its application has evolved to vascular angiogenesis and cardiac arrhythmias. Gene based biological pacemakers using viral vectors or mesenchymal cells tested in animal models hold much promise. Induction of pacemaker activity within the left bundle branch can provide stable heart rates. Genetic modification of the AV node mimicking beta blockade can be therapeutic in the management of atrial fibrillation. G protein overexpression to modify the AV node also is experimental. Modification and expression of potassium channel genes altering the delayed rectifier potassium currents may permit better management of congenital long QT syndromes. Arrhythmias in a failing heart are due to abnormal calcium cycling. Potential targets for genetic modulation include the sarcoplasmic reticulum calcium pump, calsequestrin and sodium calcium exchanger.Lastly the ethical concerns need to be addressed.S.V PraveenJohnson FrancisK Venugopal2006-04-01Z2011-03-11T08:56:22Zhttp://cogprints.org/id/eprint/4799This item is in the repository with the URL: http://cogprints.org/id/eprint/47992006-04-01ZPacemaker Prevention Therapy in Drug–refractory Paroxysmal Atrial Fibrillation: Reliability of Diagnostics and Effectiveness of Prevention Pacing Therapy in Vitatron™ Selection® deviceIntroduction. Atrial fibrillation (AF), the most common and rising disorder of cardiac rhythm, is quite difficult to control and/or to treat. Non pharmacological therapies for AF may involve the use of dedicated pacing algorithms to detect and prevent atrial arrhythmia that could be a trigger for AF onset. Selection 900E/AF2.0 Vitatron DDDRP pacemaker (1) keeps an atrial arrhythmia diary thus providing detailed onset reports of arrhythmias of interest, (2) provides us data about the number of premature atrial contractions (PACs) and (3) plots heart rate in the 5 minutes preceding the detection of an atrial arrhythmia. Moreover, this device applies four dedicated pacing therapies to reduce the incidence of atrial arrhythmia and AF events.
Aim of the Study. To analyze the reliability to record atrial arrhythmias and evaluate effectiveness of its AF preventive pacing therapies.
Material and Methods. We enrolled 15 patients (9 males and 6 females, mean age of 71±5 years, NYHA class I–II), with a DDDRP pacemaker implanted for a “bradycardia–tachycardia” syndrome, with advanced atrioventricular conduction disturbances. We compared the number and duration of AF episodes’ stored in the device with a contemporaneous 24h Holter monitoring. After that, we switched on the atrial arrhythmias detecting algorithms, starting from an atrial rate over 180 beats per minute for at least 6 ventricular cycles, and ending with at least 10 ventricular cycles in sinus rhythm. Thereafter, in order to evaluate the possible reduction in PACs number and in number and duration of AF episodes, we tailored all the four pacing preventive algorithms. Patients were followed for 24±8 months (from 20 to 32 months).
Results. All 59 atrial arrhythmia episodes occurred in the first part of this trial, were correctly recorded by both systems, with a correlation coefficient (r) of 0.96. During the follow–up, we observed a significant reduction not only in PACs number (from 83±12/day to 2.3±0.8/day) but also in AF episodes (from 46±7/day to 0.12±0.03/day) and AF burden (from 93%±6% to 0.3%±0.06%). An increase in atrial pacing percentages (from 3%±0.5% to 97%±3%) was also contemporaneously observed.
Conclusion. In this pacemaker, detection of atrial arrhythmia episodes is highly reliable, thus making available an appropriate monitoring of heart rhythm, mainly suitable in AF asymptomatic patients. Moreover, the significant reduction of atrial arrhythmia episodes indicates that this might represent a suitable therapeutic option for an effective preventive therapy of AF in paced brady–tachy patients.
Paolo TerranovaPaolo ValliPeppino TerranovaSimonetta Dell’OrtoEnrico Maria Greco2006-04-01Z2011-03-11T08:56:22Zhttp://cogprints.org/id/eprint/4802This item is in the repository with the URL: http://cogprints.org/id/eprint/48022006-04-01ZThe Postural Tachycardia Syndrome (POTS): Pathophysiology, Diagnosis & Management
Postural tachycardia syndrome (POTS), characterized by orthostatic tachycardia in the absence of orthostatic hypotension, has been the focus of increasing clinical interest over the last 15 years 1. Patients with POTS complain of symptoms of tachycardia, exercise intolerance, lightheadedness, extreme fatigue, headache and mental clouding. Patients with POTS demonstrate a heart rate increase of ≥30 bpm with prolonged standing (5-30 minutes), often have high levels of upright plasma norepinephrine (reflecting sympathetic nervous system activation), and many patients have a low blood volume. POTS can be associated with a high degree of functional disability. Therapies aimed at correcting the hypovolemia and the autonomic imbalance may help relieve the severity of the symptoms. This review outlines the present understanding of the pathophysiology, diagnosis, and management of POTS.
Satish R Raj2006-01-06Z2011-03-11T08:56:17Zhttp://cogprints.org/id/eprint/4676This item is in the repository with the URL: http://cogprints.org/id/eprint/46762006-01-06ZAndersen-Tawil SyndromeAndersen-Tawil syndrome (ATS) is a rare condition consisting of ventricular arrhythmias, periodic paralysis, and dysmorphic features. In 2001, mutations in KCNJ2, which encodes the α subunit of the potassium channel Kir2.1, were identified in patients with ATS. To date, KCNJ2 is the only gene implicated in ATS, accounting for approximately 60% of cases. ATS is a unique channelopathy, and represents the first link between cardiac and skeletal muscle excitability. The arrhythmias observed in ATS are distinctive; patients may be asymptomatic, or minimally symptomatic despite a high arrhythmia burden with frequent ventricular ectopy and bidirectional ventricular tachycardia. However, patients remain at risk for life-threatening arrhythmias, including torsades de pointes and ventricular fibrillation, albeit less commonly than observed in other genetic arrhythmia syndromes. The characteristic heterogeneity at both the genotypic and phenotypic levels contribute to the continued difficulties with appropriate diagnosis, risk stratification, and effective therapy. The initial recognition of a syndromic association of clinically diverse symptoms, and the subsequent identification of the underlying molecular genetic basis of ATS has enhanced both clinical care, and our understanding of the critical function of Kir2.1 on skeletal muscle excitability and cardiac action potentialAndrew H SmithFrank A FishPrince J Kannankeril2006-01-06Z2011-03-11T08:56:19Zhttp://cogprints.org/id/eprint/4687This item is in the repository with the URL: http://cogprints.org/id/eprint/46872006-01-06ZCardiac Arrhythmia and Geomagnetic Activity Background: The purpose of this paper is a review of a number of studies considering links between life threatening cardiac arrhythmias, sudden cardiac death (SCD) and the level of environmental physical activity factors like geomagnetic activity (GMA) and opposite them cosmic ray and high energy proton flux. This is a part of studies in the field named Clinical Cosmobiology.
Methods: Temporal distribution of cardiac arrhythmias and SCD daily and monthly were compared to the level of GMA, space proton flux, cosmic ray activity according to neutron activity (impulse/min) on the earth's surface. The cosmophysical data was obtained from the cosmic science institutions in the USA, Russia and Finland (cosmic ray data, partially).
Results: As it follows from the results of the quoted studies there is an inverse relationship between the frequency of cardiac arrhythmic events and SCD and the level of daily GMA.
Conclusions: Now studies are in progress considering the role of neutron (cosmic ray) activity in the natural history of the mentioned events. According to the various studies, we can presume that the GMA has some protective effect on cardiac arrhythmias and SCD.
E Stoupel2006-01-06Z2011-03-11T08:56:19Zhttp://cogprints.org/id/eprint/4688This item is in the repository with the URL: http://cogprints.org/id/eprint/46882006-01-06ZChanging QRS Morphology: What is the mechanism? ECG in sinus rhythm with ventricular preexcitation and changing QRS morphology was seen that was initially interpreted as the multiple accessory pathway from elsewhere. (Figure 1A).
The following mechanisms are potentially involved in the electrogenesis of changing QRS morphology in WPW syndrome: 1) multiple accessory pathways1; 2) simultaneous occurrence of aberrant atrioventricular conduction with accessory pathway conduction 2; 3) ventricular fusion of preexcited sinus impulse with ectopic impulse.
Electrophysiologic study showed short PR (75 ms) interval with wide QRS (152 ms) and negative HV (-12 ms) interval. No change in delta wave polarity was observed during HRA and CS pacing. In full preexcitation, no breakthrough was seen in the CS. During incremental ventricular pacing, atrial breakthrough site is initially recorded on the HRA catheter and then changed to distal pole of CS catheter with progressive decrease in pacing cycle length. During ventricular pacing at cycle length of 500 ms (S1), earliest atrial activity is recorded on HRA catheter.
Changing QRS could not be explained by presence of multiple APs because only right-sided AP had bidirectional conduction and no distal CS breakthrough was seen simultaneous with changing QRS morphology. The possibility of aberrant conduction is excluded by presence of negative HV interval in the beats with differing QRS morphology. No sinus cycle length variation before and after the beats with different morphologies are against the occurrence of functional LBBB. The prematurity of ventricular electrogram in His recording catheter with variable HV (H-electrogram is recorded after V-electrogram in second beat and before V-electrogram in third beat) and fixed V-RB intervals (interval from ventricular electrogram in His to the RB potential) are compatible with ventricular fusion of preexcited sinus impulse with ectopic ventricular impulse originating from parahissian area (explaining LBBB and inferior axis morphology of the beats with changing QRS) but not from the His bundle or RBB itself (because H-electrogram and RB potential is recorded after V-electrogram in the second beat with greater degree of ventricular fusion)(Figure 1B). Majid HaghjooArash AryaMohammad Reza DehghaniMohammad Ali Sadr-Ameli2006-01-06Z2011-03-11T08:56:19Zhttp://cogprints.org/id/eprint/4686This item is in the repository with the URL: http://cogprints.org/id/eprint/46862006-01-06ZLeft Ventricular Pacing In Patients With Congestive Heart Failure Cardiac resynchronisation therapy (CRT) using biventricular (BIV) pacing has proved its effectiveness to correct myocardial asynchrony and improve clinical status of patients with severe congestive heart failure (CHF) and widened QRS. Despite a different effect on left ventricular electrical dispersion, left univentricular (LV) pacing is able to achieve the same mechanical synchronisation as BIV pacing in experimental studies and in humans. This results in clinical benefits of LV pacing at mid-term follow-up, with significant improvement in functional class, quality of life and exercise tolerance at the same extent as those observed with BIV stimulation in non randomised studies. Furthermore these benefits are obtained at lesser costs and with conventional dual-chamber devices. However, LV pacing has to be compared to BIV pacing in randomised trials before being definitely considered as a cost-effective alternative to BIV pacing.
Yves EtienneFatemi MarjanehBlanc Jean-Jacques2006-01-06Z2011-03-11T08:56:17Zhttp://cogprints.org/id/eprint/4674This item is in the repository with the URL: http://cogprints.org/id/eprint/46742006-01-06ZP Wave Dispersion is Increased in Pulmonary StenosisAim: The right atrium pressure load is increased in pulmonary stenosis (PS) that is a congenital anomaly and this changes the electrophysiological characteristics of the atria. However, there is not enough data on the issue of P wave dispersion (PWD) in PS.
Methods: Forty- two patients diagnosed as having valvular PS with echocardiography and 33 completely healthy individuals as the control group were included in the study. P wave duration, p wave maximum (p max) and p minimum (p min) were calculated from resting electrocariography (ECG) obtained at the rate of 50 mm/sec. P wave dispersion was derived by subtracting p min from p max. The mean pressure gradient (MPG) at the pulmonary valve, structure of the valve and diameters of the right and left atria were measured with echocardiography. The data from two groups were compared with the Mann-Whitney U test and correlation analysis was performed with the Pearson correlation technique.
Results: There wasn’t any statistically significance in the comparison of age, left atrial diameter and p min between two groups. While the MPG at the pulmonary valve was 43.11 ± 18.8 mmHg in PS patients, it was 8.4 ± 4.5 mmHg in the control group. While p max was 107.1 ± 11.5 in PS group, it was 98.2 ± 5.1 in control group (p=0.01), PWD was 40.4 ± 1.2 in PS group, and 27.2 ± 9.3 in the control group (p=0.01)Moreover, while the diameter of the right atrium in PS group was greater than that of the control group, (38.7 ± 3.9 vs 30.2 ± 2.5, p=0.02). We detected a correlation between PWD and pressure gradient in regression analysis.
Conclusion: P wave dispersion and p max are increased in PS. While PWD was correlated with the pressure gradient that is the degree of narrowing, it was not correlated with the diameters of the right and left atria.
Namik OzmenBekir Sitki CebeciEjder KardesogluTurgay CelikMehmet DincturkErgun Demiralp2006-01-06Z2011-03-11T08:56:17Zhttp://cogprints.org/id/eprint/4675This item is in the repository with the URL: http://cogprints.org/id/eprint/46752006-01-06ZPharmacological cardioversion for atrial fibrillation and flutter*Atrial fibrillation is the commonest cardiac dysrhythmia. It is associated with significant morbidity and mortality. There are two approaches to the management of atrial fibrillation: controlling the ventricular rate or converting to sinus rhythm in the expectation that this would abolish its adverse effects.
The objective of this review was to assess the effects of pharmacological cardioversion of atrial fibrillation in adults on the annual risk of stroke, peripheral embolism, and mortality.
We made a thorough search for existing evidence in the following databases: the Cochrane Controlled Trials Register (Issue 3, 2002), MEDLINE (2000 to 2002), EMBASE (1998 to 2002), CINAHL (1982 to 2002), Web of Science (1981 to 2002). We also handsearched the following journals: Circulation (1997 to 2002), Heart (1997 to 2002), European Heart Journal (1997-2002), Journal of the American College of Cardiology (1997-2002) and selected abstracts published on the web site of the North American Society of Pacing and Electrophysiology (2001, 2002). We selected trials based on the following criteria: randomised controlled trials or controlled clinical trials of pharmacological cardioversion versus rate control in adults (>18 years) with acute, paroxysmal or sustained atrial fibrillation or atrial flutter, of any duration and of any aetiology.
We identified two completed studies AFFIRM (n=4060) and PIAF (n=252). We found no difference in mortality between rhythm control and rate control - relative risk 1.14 (95% confidence interval 1.00 to 1.31). Both studies show significantly higher rates of hospitalisation and adverse events in the rhythm control group and no difference in quality of life between the two treatment groups. In AFFIRM there was a similar incidence of ischaemic stroke, bleeding and systemic embolism in the two groups. Certain malignant dysrhythmias were significantly more likely to occur in the rhythm control group. There were similar scores of cognitive assessment in both groups. In PIAF, cardioverted patients enjoyed an improved exercise tolerance but there was no overall benefit in terms of symptom control or quality of life.
There is no evidence that pharmacological cardioversion of atrial fibrillation to sinus rhythm is superior to rate control. Rhythm control is associated with more adverse effects and increased hospitalisation. It does not reduce the risk of stroke. These conclusions cannot be generalised to all people with atrial fibrillation as most of the patients included in these studies were relatively older (>60 years) with significant cardiovascular risk factors.
J CordinaG Mead2006-01-06Z2011-03-11T08:56:17Zhttp://cogprints.org/id/eprint/4673This item is in the repository with the URL: http://cogprints.org/id/eprint/46732006-01-06ZPredictors of appropriate ICD therapy in patients with implantable cardioverter-defibrillatorBackground: Understanding the predictors of appropriate implantable cardioverter defibrillator (ICD) therapy could help to better identify candidates for ICD implantation.
Methods: One hundred and sixty two patients with ICD (111 with coronary artery disease [CAD] and 51 with dilated cardiomyopathy [DCM]) were included in the study. Clinical, electrocardiographic, and ICD stored data and electrograms were collected.
Results: During mean follow up of 15±11 months 54 patients (33%) received ≥ 1 appropriate ICD therapy (AICDT). We used binary logistic regression analysis with forward selection method to find the potential predictors of appropriate ICD therapy after device implantation. Male gender (odds ratio [OR] = 2.76, 95% confidence interval [CI] = 1.1 – 7.1, P=0.021), DCM as underlying heart disease (OR = 4.2, 95% CI = 1.9 – 9.5, P=0.001), and QRS width > 100 ms (OR = 2.58, 95% CI = 1.2 – 5.4, P=0.010) were correlated with increased likelihood of AICDT during the follow up period. In subgroup analysis of the patients with CAD and DCM, QRS duration > 100 ms was correlated with the probability of ≥ 1 AICDT. In our patients indication of ICD implantation (primary versus secondary prevention) did not influence probability of ≥ 1 AICDT (adjusted OR = 1.66, 95% CI = 0.7 – 4.0, Mantel-Haenszel P value P=0.355.)
Conclusion: QRS width could be used as an additional simple risk stratifier beyond EF to identify potential candidates who would benefit more from ICD implantation. This may have practical implications for patient selection especially in developing countries. Indication of ICD implantation (primary versus secondary prevention) did not affect the probability of ≥ 1 AICDT during the follow up period.
Mohammad Reza DehghaniArash AryaMajid HaghjooEmkanjoo ZahraAlasti MohammadKazemi BabakMohammad Hosein NikooMohammad Ali Sadr-Ameli2006-01-06Z2011-03-11T08:56:15Zhttp://cogprints.org/id/eprint/4672This item is in the repository with the URL: http://cogprints.org/id/eprint/46722006-01-06ZShort- and long-term experience in pulmonary vein segmental ostial ablation for paroxysmal atrial fibrillation*Introduction: Segmental ostial pulmonary vein isolation (PVI) is considered a potentially curative therapeutic approach in the treatment of paroxysmal atrial fibrillation (PAF). There is only limited data available on the long-term effect of this procedure.
Methods: Patients (Pts) underwent a regular clinical follow up visit at 3, 6 and 24 months after PVI. Clinical success was classified as complete (i.e. no arrhythmia recurrences, no antiarrhythmic drug), partial (i.e. no/only few recurrences, on drug) or as a failure (no benefit). The clinical responder rate (CRR) was determined by combining complete and partial success.
Results: 117 patients (96 male, 21 female), aged 51±11 years (range 25 to 73) underwent a total of 166 procedures (1.4/patient) in 2-4 pulmonary veins (PV). 115 patients (98%) had AF, 2 patients presented with regular PV atrial tachycardia. ,109/115 patients. exhibited PAF as the primary arrhythmia (versus persistent AF). A total of 113 patients with PVI in the years 2001 to 2003 were evaluated for their CRR after 6 (3) months. A single intervention was carried out in 63 patients (55.8%), two interventions were performed in 45 patients (39.8%) and three interventions in 5 patients (4.4%). The clinical response demonstrated a complete success of 52% (59 patients), a partial success of 26% (29 patients) and a failure rate of 22% (25 patients), leading to a CRR of 78% (88 patients). Ostial PVI in all 4 PVs exhibited a tendency towards higher curative success rates (54% versus 44% in patients with 3 PVs ablated for the 6 month follow up). Long-term clinical outcome was evaluated in 39 patients with an ablation attempt at 3 PVs only (excluding the right inferior PV in our early experience) and a mean clinical follow up of 21±6 months. At this point in time the success rate was 41% (complete, 16 patients) and 21% (partial, 8 patients), respectively, adding up to a CRR of 62% (24 patients). In total, 20 patients (17.1%) had either a single or 2 (3 patients, 2.6%) complications independent of the number of procedures performed with PV stenosis as the leading cause (7.7%).
Conclusion: The CRR of patients with medical refractory PAF in our patient cohort is 78% at the 6 month follow up. PV stenosis is the main cause for procedure-related complications. Ablation of all 4 PV exhibits a tendency towards higher complete success rates despite equal CRR. Calculation of the clinical response after a mid- to long-term follow of 21±6 months in those patients with an ostial PVI in only 3 pulmonary veins (sparing the right inferior PV) shows a further reduction to 62%, exclusively caused by a drop in patients with a former partial success. To evaluate the long-term clinical benefit of segmental ostial PVI in comparison with other ablation techniques, more extended follow up periods are mandatory, including a larger study cohort and a detailed description of procedural parameters.
H PürerfellnerJ AichingerM MartinekH.J NesserJ Janssen2005-11-12Z2011-03-11T08:56:08Zhttp://cogprints.org/id/eprint/4455This item is in the repository with the URL: http://cogprints.org/id/eprint/44552005-11-12ZAblation Surgery for Atrial Fibrillation: "Freeze it or Buzz it; Just do it and Cure it"Patients in normal sinus rhythm have lesser stroke rate, better functional class and quality of life than those in atrial fibrillation. Adding a surgical procedure to cure atrial fibrillation in patients needing correction of structural heart disease has been shown to be a safe option, which benefits the majority in restoration of sinus rhythm. Age is no bar to implement this option. The same does not hold true for lone atrial fibrillation. The affirm trial has shown that there is need for improved treatment strategies for patients in atrial fibrillation, although young patients were not represented in sizable proportion. There is need to develop curative treatment for patients with lone atrial fibrillation. And there are technological advances in the form of ablative energy sources and hardware for applying these with minimal invasion. “Between tomorrow’s dream and yesterday’s regret is today’s opportunity”. Let’s make the best of it!AM Patwardhan2005-11-12Z2011-03-11T08:56:13Zhttp://cogprints.org/id/eprint/4598This item is in the repository with the URL: http://cogprints.org/id/eprint/45982005-11-12ZArrhythmias After Tetralogy of Fallot Repair
Tetralogy of Fallot is the most common cyanotic congenital heart disease, with a good outcome after total surgical correction. In spite of a low perioperative mortality and a good quality of life, late sudden death remains a significant clinical problem, mainly related to episodes of sustained ventricular tachycardia and ventricular fibrillation. Fibro-fatty substitution around infundibular resection, intraventricular septal scar, and patchy myocardial fibrosis, may provide anatomical substrates of abnormal depolarization and repolarization causing reentrant ventricular arrhythmias.
Several non-invasive indices based on classical examination such as ECG, signal-averaging ECG, and echocardiography have been proposed to identify patients at high risk of sudden death, with hopeful results. In the last years other more sophisticated invasive and non-invasive tools, such as heart rate variability, electroanatomic mapping and cardiac magnetic resonance added a relevant contribution to risk stratification.
Even if each method per se is affected by some limitations, a comprehensive multifactorial clinical and investigative examination can provide an accurate risk evaluation for every patientAntonio Franco FolinoLuciano Daliento2005-11-12Z2011-03-11T08:56:13Zhttp://cogprints.org/id/eprint/4597This item is in the repository with the URL: http://cogprints.org/id/eprint/45972005-11-12ZAtrial Fibrillation and Hyperthyroidism
Atrial fibrillation occurs in 10 – 15% of patients with hyperthyroidism. Low serum thyrotropin concentration is an independent risk factor for atrial fibrillation. Thyroid hormone contributes to arrythmogenic activity by altering the electrophysiological characteristics of atrial myocytes by shortening the action potential duration, enhancing automaticity and triggered activity in the pulmonary vein cardio myocytes. Hyperthyroidism results in excess mortality from increased incidence of circulatory diseases and dysrhythmias. Incidence of cerebral embolism is more in hyperthyroid patients with atrial fibrillation, especially in the elderly and anti-coagulation is indicated in them. Treatment of hyperthyroidism results in conversion to sinus rhythm in up to two-third of patients. Beta-blockers reduce left ventricular hypertrophy and atrial and ventricular arrhythmias in patients with hyperthyroidism. Treatment of sub clinical hyperthyroidism is controversial. Optimizing dose of thyroxine treatment in those with replacement therapy and beta-blockers is useful in exogenous subclinical hyperthyroidism.
N JayaprasadJohnson Francis2005-11-12Z2011-03-11T08:56:12Zhttp://cogprints.org/id/eprint/4593This item is in the repository with the URL: http://cogprints.org/id/eprint/45932005-11-12ZAtrial fibrillation and its determinants after radiofrequency ablation of chronic common atrial flutter
Aim. Atrial fibrillation (AFib) is a major clinical issue and its occurrence is the main problem after catheter ablation of atrial flutter. The long-term occurrence of AFib after common atrial flutter ablation is still matter of debate as it may influence the therapeutic approach. So, the aim of our study was to analyze the determinants and the time course of AFib after radiofrequency catheter ablation of chronic common atrial flutter.
Methods and Results. 89 consecutive patients (67.5 ± 12.0 yrs) underwent RF ablation of chronic common atrial flutter. 38.2 % had previous history of paroxysmal AFib. 51% had no underlying structural heart disease. Over a mean follow-up of 38 ± 13 months, the occurrence rate of AFib progressively increased up to 32.9% at the end of follow-up. The median occurrence time for AFib was 8 months. AFib occurrence was significantly associated with previous AFib history (P=0.01) but not with the presence of underlying heart disease (P=n.s.). Of particular interest, in our study, AFib never occurred in patients without previous AFib history. Palpitations after chronic common atrial flutter ablation was mostly related to AFib.
Conclusion. In conclusion, after chronic common atrial flutter ablation, AFib incidence progressively increased over the follow-up in all patients. Patients with prior AFib history appeared to be a very high risk group. In these patients, closer monitoring is mandatory and the persistent risk of AFib recurrences may justify prolonged anticoagulation policy.
Stéphane CadeShahine SedighianAgustin BortoneRichard GervasoniJean Christophe MaciaFlorence LeclercqRobert GrolleauJean Luc Pasquié2005-11-12Z2011-03-11T08:56:12Zhttp://cogprints.org/id/eprint/4594This item is in the repository with the URL: http://cogprints.org/id/eprint/45942005-11-12ZInfluence of Atrioventricular Nodal Reentrant Tachycardia Ablation on Right to Left Inter-atrial ConductionBackground: Radiofrequency (RF) catheter ablation is the procedure of choice for the potential cure of atrioventricular nodal reentrant tachycardia (AVNRT) with high success rates. We hypothesed that as a result of the close proximity of Koch’s triangle and low inter-atrial septal fibers, the RF ablation applied at this region may result in prolongation of inter-atrial conduction time (IACT).
Methods: RF ablation of AVNRT was performed by conventional technique. IACT was measured before and 20 minutes after RF ablation during sinus rhythm. Number of ablations given and duration of ablation were noted.
Results: The study group was consisted of 48 patients (36 [75%] female, 12 [25%] male, mean age 43.4 ± 14. 5 years). RF ablation was successful in all patients. Mean RF time was 4. 0 ± 3. 3 minutes and mean number of RF was 11. 9 ± 9, 8. The mean IACT was 70.1 ± 9.0 ms before ablation and 84.9 ± 12.7 ms after ablation, which demonstrated a significant prolongation (p<0.001). The prolongation of IACT was very well correlated with the number of (r=0.897, p<0.001) and duration of RF (r=0.779; p<0.001).
Conclusions: RF ablation of AVNRT results in prolongation of IACT. The degree of prolongation is associated with the duration and number of RF ablations given. The relationship between this conduction delay and late arrhythmogenesis need to be evaluated.
Abdurrahman EksikAhmet AkyolTugrul NorgazIzzet Erdinler2005-11-12Z2011-03-11T08:56:12Zhttp://cogprints.org/id/eprint/4592This item is in the repository with the URL: http://cogprints.org/id/eprint/45922005-11-12ZPattern of initiation of monomorphic ventricular tachycardia in recorded intracardiac electrograms
Background: By analyzing stored intracardiac electrograms during spontaneous monomorphic ventricular tachycardia (VT), we examined the patterns of the VT initiation in a group of patients with implantable cardioverter defibrillators (ICDs).
Methods: Stored electrograms (EGMs) were monomorphic VTs and at least 5 beats before the initiation and after the termination of VT were analyzed. Cycle length, sinus rate, and the prematurity index for each episode were noted.
Results: We studied 182 episodes of VT among 50 patients with ICDs. VPC-induced (extrasystolic initiation) episode was the most frequent pattern (106; 58%) followed by 76 episodes (42%) in sudden-onset group. Among the VPC-induced group, VPCs in 85 episodes (80%) were different in morphology from subsequent VT. Sudden-onset episodes had longer cycle lengths (377±30ms) in comparison with the VPC-induced ones (349±29ms; P= 0.001). Sinus rate before VT was faster in the sudden-onset compared to that in VPC-induced one (599±227ms versus 664±213ms; P=0.005). Both of these episodes responded similarly to ICD tiered therapy. There was no statistically significant difference in coupling interval, prematurity index, underlying heart disease, ejection fraction, and antiarrhythmic drug usage between two groups (P=NS).
Conclusions: Dissimilarities between VT initiation patterns could not be explained by differences in electrical (coupling interval, and prematurity index) or clinical (heart disease, ejection fraction, and antiarrhythmic drug) variables among the patients. There is no association between pattern of VT initiation and the success rate of electrical therapy.
Majid HaghjooArash AryaMohammad Ali Sadr-Ameli2005-11-12Z2011-03-11T08:56:08Zhttp://cogprints.org/id/eprint/4456This item is in the repository with the URL: http://cogprints.org/id/eprint/44562005-11-12ZPermanent atrial fibrillation ablation surgery in patients with advanced age
Background: Even if permanent atrial fibrillation (pAF) is a frequent concomitant problem in patients undergoing open heart surgery and particularly in those with advanced age, data of pAF ablation surgery in older aged patients are scarce. This study was performed to assess early and late results of combined open heart surgery and pAF ablation procedures in patients with advanced aged, compared to young patients.
Material and Methods: A selective group of 126 patients (Group A: age ≥70 [76.4±4.8] years, n=70; Group B: age <70 [62.0±6.2] years: n=56) with pAF (≥6 months) underwent either monopolar (Group A, B: n=51 vs. n=44) or bipolar (Group A, B: n=19 vs. n=12) radiofrequency (RF) ablation procedures concomitant to open heart surgery. Regular follow-up was performed 3 to 36 months after surgery to assess survival, New York Heart Association (NYHA) class and conversion rate to stable sinus rhythm (SR).
Results: Early mortality (<30 days) was 2.9% in Group A (Group B: 0%), cumulative survival at long-term follow up was 0.78 vs. 0.98 (p=0.03) and NYHA-class improved significantly in both groups, particularly in cases with stable SR. At 12-months follow-up 73% of Group A patients were in stable SR (Group B 78%).
Conclusions: Concomitant mono- and bipolar RF ablation surgery represents a safe option to cure pAF during open heart surgery with a very low risk, even in patients with advanced age.
Stephan GeidelMichael LassJörg Ostermeyer2005-11-12Z2011-03-11T08:56:13Zhttp://cogprints.org/id/eprint/4596This item is in the repository with the URL: http://cogprints.org/id/eprint/45962005-11-12ZRate-Control or Rhythm-Contol: Where do we stand?
Atrial fibrillation is the most common sustained rhythm disturbance and its prevalence is increasing worldwide due to the progressive aging of the population. Current guidelines clearly depict the gold standard management of acute symptomatic atrial fibrillation but the best-long term approach for first or recurrent atrial fibrillation is still debated with regard to quality of life, risk of new hospitalizations, and possible disabling complications, such as thromboembolic stroke, major bleeds and death. Some authors propose that regaining sinus rhythm in all cases, thus re-establishing a physiologic cardiac function not requiring a prolonged antithrombotic therapy, avoids the threat of intracranial or extracranial haemorrhages due to Vitamin K antagonists or aspirin. On the contrary, advocates of a rate control approach with an accurate antithrombotic prophylaxis propose that such a strategy may avoid the risk of cardiovascular and non cardiovascular side effects related to antiarrhythmic drugs. This review aims to explore the state of our knowledge in order to summarize evidences and issues that need to be furthermore clarified.
Testa LTrotta GDello Russo ACasella MPelargonio GAndreotti FBellocci F2005-11-12Z2011-03-11T08:56:12Zhttp://cogprints.org/id/eprint/4595This item is in the repository with the URL: http://cogprints.org/id/eprint/45952005-11-12ZThe Role of Biphasic Shocks for Transthoracic Cardioversion of Atrial Fibrillation
The modern generation of transthoracic defibrillators now employ impedance compensated biphasic waveforms. These new devices are superior to those with monophasic waveforms and practice is currently switching to biphasic defibrillators for the treatment of both ventricular and atrial fibrillation. However, there is no universal guideline for the use of biphasic defibrillators in direct current cardioversion of atrial fibrillation. This article reviews the use of biphasic defibrillation waveforms for transthoracic cardioversion of atrial fibrillation. Simon J WalshBen M GloverAA Jennifer Adgey2005-07-13Z2011-03-11T08:56:07Zhttp://cogprints.org/id/eprint/4446This item is in the repository with the URL: http://cogprints.org/id/eprint/44462005-07-13ZAutomatic Mode Switching in Atrial FibrillationAutomatic mode switching (AMS) algorithms were designed to prevent tracking of atrial tachyarrhythmias (ATA) or other rapidly occurring signals sensed by atrial channels, thereby reducing the adverse hemodynamic and symptomatic consequences of a rapid ventricular response. The inclusion of an AMS function in most dual chamber pacemaker now provides optimal management of atrial arrhythmias and allows the benefit of atrioventricular synchrony to be extended to a population with existing atrial fibrillation. Appropriate AMS depends on several parameters: a) the programmed parameters; b) the characteristics of the arrhythmia; c) the characteristics of the AMS algorithm. Three qualifying aspects constitute an AMS algorithm: onset, AMS response, and resynchronization. Since AMS programs also provide data on the time of onset and duration of AMS episodes, AMS data may be interpreted as a surrogate marker of ATAs recurrence. Recently, stored electrograms corresponding to episodes of ATAs have been introduced, thus clarifying the accuracy of AMS in detecting ATAs Clinically this information may be used to assess the efficacy of an antiarrhythmic intervention or the risk of thromboembolic events, and it may serve as a valuable research tool for evaluating the natural history and burden of ATAs.
Stabile GiuseppeSimone Antonio DeRomano Enrico2005-07-13Z2011-03-11T08:56:07Zhttp://cogprints.org/id/eprint/4453This item is in the repository with the URL: http://cogprints.org/id/eprint/44532005-07-13ZEffects of Endocardial Microwave Energy Ablation
Until recently the treatment of atrial fibrillation (AF) consisted primarily of palliation, mostly in the form of pharmacological intervention. However because of recent advances in nonpharmacologic therapies, the current expectation of patients and referring physicians is that AF will be cured, rather than palliated. In recent years there has been a rapid expansion in the availability and variety of energy sources and devices for ablation. One of these energies, microwave, has been applied clinically only in the last few years, and may be a promising technique that is potentially capable of treating a wide range of ventricular and supraventricular arrhythmias. The purpose of this study was to review microwave energy ablation in surgical treatment of AF with special interest in histology and ultrastructure of lesions produced by this endocardial ablation procedure.
Climent VicenteHurlé AquilinoHo Siew YenSánchez-Quintana Damián2005-07-13Z2011-03-11T08:56:08Zhttp://cogprints.org/id/eprint/4454This item is in the repository with the URL: http://cogprints.org/id/eprint/44542005-07-13ZIdiopathic Submitral Left Ventricular Aneurysm: an Unusual Substrate for Ventricular Tachycardia in Caucasians
Annular submitral aneurysms have been rarely reported in Caucasians. They are typically diagnosed in non-white adults who present with severe mitral regurgitation, heart failure, systemic embolism, ventricular arrhythmias, and sudden cardiac death. In this article, we describe the case of a white woman, presenting with ventricular tachycardia, who had a large submitral left ventricular aneurysm diagnosed incidentally during coronary angiography.
Kazemi BabakArya ArashHaghjoo MajidSadr-Ameli Mohammad Ali2005-08-11Z2011-03-11T08:56:08Zhttp://cogprints.org/id/eprint/4487This item is in the repository with the URL: http://cogprints.org/id/eprint/44872005-08-11ZImpact of a Right Ventricular Impedance Sensor on the Cardiovascular Responses to Exercise in Pacemaker Dependent PatientsBackground. The evaluation of the heart rate (HR) response to exercise is important for the assessment of the rate response algorithm of sensor-controlled pacemakers. This study examined the effects of a right ventricular impedance sensor driven pacemaker on the cardiovascular responses to incremental exercise in pacemaker dependent patients.
Methods. Twelve patients (70.5 ± 9.5 years; 5 Females: 7 Males) implanted with an Inos2+ closed loop stimulation (CLS) pacemaker were compared to 12 healthy age and sex matched controls (70.6 ± 4.8 years). All subjects performed the chronotropic assessment exercise protocol (CAEP). Variables of interest included HR, cardiac output (Q), oxygen uptake (Vo2) and blood pressure (BP). Data were analyzed at rest, throughout exercise and during recovery. Furthermore, patient chronotropic responses were compared to a reference chronotropic response slope for aerobic exercise.
Results. There were no differences between groups for HR or Q. response throughout exercise. At peak exercise, V.o2 (mL.kg-1.min-1) was higher for the controls (p < 0.05). The patient chronotropic response slope was comparable to the CAEP reference slope from rest to both the anaerobic threshold (AT) and peak exercise. During recovery, no differences were observed between the groups for any parameters or for the HR decay slopes.
Conclusions. Up to the anaerobic threshold, the right ventricular impedance sensor driven pacemaker delivered a pacing rate that contributed to an overall cardiovascular response similar to that observed in healthy age matched subjects.
Cook LinneaTomczak CoreyBusse EdwardHiroshi TadaTsang JohnWojcik WladyslawHaennel Robert2005-07-13Z2011-03-11T08:56:07Zhttp://cogprints.org/id/eprint/4450This item is in the repository with the URL: http://cogprints.org/id/eprint/44502005-07-13ZMagnetic Resonance Imaging in patients with ICDs and Pacemakers
Magnetic resonance (MR) imaging has unparalleled soft-tissue imaging capabilities. The presence of devices such as pacemakers and implantable cardioverter/defibrillators (ICDs), however, is historically considered a contraindication to MR imaging. These devices are now smaller, with less magnetic material and improved electromagnetic interference protection. This review summarizes the potential hazards of the device-MR environment interaction, and presents updated information regarding in-vivo and in-vitro experiments. Recent reports on patients with implantable pacemakers and ICDs who underwent MR scan shows that under certain conditions patients with these implanted systems may benefit from this imaging modality. The data presented suggests that certain modern pacemaker and ICD systems may indeed be MR safe. This may have major clinical implications on current imaging practice.
Nair PrashantRoguin Ariel2005-07-13Z2011-03-11T08:56:07Zhttp://cogprints.org/id/eprint/4452This item is in the repository with the URL: http://cogprints.org/id/eprint/44522005-07-13ZMethods of Assessment and Clinical Relevance of QT Dynamics
The dependence on heart rate of the QT interval has been investigated for many years and several mathematical formulae have been proposed to describe the QT interval/heart rate (or QT interval/RR interval) relationship. While the most popular is Bazett’s formula, it overcorrects the QT interval at high heart rates and under-corrects it at slow heart rates. This formulae and many others similar ones, do not accurately describe the natural behaviour of the QT interval. The QT interval/RR interval relationship is generally described as QT dynamics. In recent years, several methods of its assessment have been proposed, the most popular of which is linear regression. An increased steepness of the linear QT/RR slope correlates with the risk of arrhythmic death following myocardial infarction. It has also been demonstrated that the QT interval adapts to heart rate changes with a delay (QT hysteresis) and that QT dynamics parameters vary over time. New methods of QT dynamics assessment that take into account these phenomena have been proposed. Using these methods, changes in QT dynamics have been observed in patients with advanced heart failure, and during morning hours in patients with ischemic heart disease and history of cardiac arrest. The assessment of QT dynamics is a new and promising tool for identifying patients at increased risk of arrhythmic events and for studying the effect of drugs on ventricular repolarisation.
Sredniawa BeataMusialik-Lydka AgataJarski PiotrSliwinska AnnaKalarus Zbigniew2005-07-13Z2011-03-11T08:56:07Zhttp://cogprints.org/id/eprint/4451This item is in the repository with the URL: http://cogprints.org/id/eprint/44512005-07-13ZNon-Linear Heart Rate Variability and Risk Stratification in Cardiovascular Disease
Traditional time and frequency domain heart rate variability (HRV) have cardiac patients at risk of mortality post-myocardial infarction. More recently, non linear HRV has been applied to risk stratification of cardiac patients. In this review we describe studies of non linear HRV and outcome in cardiac patients. We have included studies that used the three most common non-linear indices: power law slope, the short term fractal scaling exponent and measures based on Poincaré plots. We suggest that a combination of traditional and non-linear HRV may be optimal for risk stratification. Considerations in using non linear HRV in a clinical setting are described.
Stein Phyllis KReddy Anand2005-07-09Z2011-03-11T08:56:07Zhttp://cogprints.org/id/eprint/4447This item is in the repository with the URL: http://cogprints.org/id/eprint/44472005-07-09ZTechniques for Identification of Left Ventricular Asynchrony for Cardiac Resynchronization Therapy in Heart Failure The most recent treatment option of medically refractory heart failure includes cardiac resynchronization therapy (CRT) by biventricular pacing in selected patients in NYHA functional class III or IV heart failure. The widely used marker to indicate left ventricular (LV) asynchrony has been the surface ECG, but seems not to be a sufficient marker of the mechanical events within the LV and prediction of clinical response. This review presents an overview of techniques for identification of left ventricular intra- and interventricular asynchrony. Both manuscripts for electrical and mechanical asynchrony are reviewed, partly predicting response to CRT. In summary there is still no gold standard for assessment of LV asynchrony for CRT, but both traditional and new echocardiographic methods have shown asynchronous LV contraction in heart failure patients, and resynchronized LV contraction during CRT and should be implemented as additional methods for selecting patients to CRT.
Schuster PeterFaerestrand Svein2005-06-26Z2011-03-11T08:56:06Zhttp://cogprints.org/id/eprint/4418This item is in the repository with the URL: http://cogprints.org/id/eprint/44182005-06-26ZTissue Tracking Imaging for Identifying the Origin of Idiopathic Ventricular Arrhythmias: A New Role of Cardiac Ultrasound in ElectrophysiologySeveral strategies for mapping ventricular outflow tract tachycardia have been reported as useful indices for differentiating between those originating from the right and the left side. Recently, tissue tracking imaging (TTI) has been demonstrated as a novel non-invasive modality for identifying the origin of outflow tract tachycardias. Tissue tracking imaging is an ultrasonographic technique that measures the myocardial motion amplitude towards the transducer in each region during systole, identifying regional myocardial displacement on the basis of myocardial velocities using color Doppler myocardial imaging principles. In this technique, the origin of the arrhythmia could be recognized as the site where the earliest color-coded signal (ECCS) appeared on the myocardium at the onset of the systole. In preliminary studies this modality was found to be useful in differentiating out flow tract ventricular tachycardias. ECCS was always found below or at the level of the pulmonary valve in all arrhythmias which could be ablated from the right ventricular outflow tract, while in those where the origin was above the pulmonary valve could be ablated from the left sinus of valsalva. These results indicate that TTI can provide detailed and accurate information on the arrhythmia origin of OT-VT and may be useful for differentiating between an OT-VT originating from the LV epicardium remote from the LSV and that from the LSV. Newer advances in echocardiographic technologies like high resolution, high frame rate real time three dimensional echocardiography with speckle tracking may further improve the precise localization of arrhythmias in the future.
Sunil Roy TNVikram SankarJohnson FrancisHiroshi Tada2005-08-11Z2011-03-11T08:56:08Zhttp://cogprints.org/id/eprint/4486This item is in the repository with the URL: http://cogprints.org/id/eprint/44862005-08-11ZTissue Tracking Imaging for Identifying the Origin of Idiopathic Ventricular Arrhythmias: A New Role of Cardiac Ultrasound in ElectrophysiologySeveral strategies for mapping ventricular outflow tract tachycardia have been reported as useful indices for differentiating between those originating from the right and the left side. Recently, tissue tracking imaging (TTI) has been demonstrated as a novel non-invasive modality for identifying the origin of outflow tract tachycardias. Tissue tracking imaging is an ultrasonographic technique that measures the myocardial motion amplitude towards the transducer in each region during systole, identifying regional myocardial displacement on the basis of myocardial velocities using color Doppler myocardial imaging principles. In this technique, the origin of the arrhythmia could be recognized as the site where the earliest color-coded signal (ECCS) appeared on the myocardium at the onset of the systole. In preliminary studies this modality was found to be useful in differentiating out flow tract ventricular tachycardias. ECCS was always found below or at the level of the pulmonary valve in all arrhythmias which could be ablated from the right ventricular outflow tract, while in those where the origin was above the pulmonary valve could be ablated from the left sinus of valsalva. These results indicate that TTI can provide detailed and accurate information on the arrhythmia origin of OT-VT and may be useful for differentiating between an OT-VT originating from the LV epicardium remote from the LSV and that from the LSV. Newer advances in echocardiographic technologies like high resolution, high frame rate real time three dimensional echocardiography with speckle tracking may further improve the precise localization of arrhythmias in the future.
Sunil Roy TNVikram SankarJohnson FrancisHiroshi Tada2005-04-16Z2011-03-11T08:55:57Zhttp://cogprints.org/id/eprint/4224This item is in the repository with the URL: http://cogprints.org/id/eprint/42242005-04-16ZBrugada-type Electrocardiographic Pattern Induced by Fever
ST-segment elevation in Brugada syndrome is caused by a shift in the ionic current balance and the creation of a voltage gradient between the epicardium and the endocardium. This ionic mechanism have been shown to be temperature dependent. We describe a 33-year-old man who presented with fever with the dynamic electrocardiographic changes similar to the Brugada syndrome. These electrocardiographic anomalies disappeared when the temperature returned to normal.
Ozcan OzekeDursun ArasBilal GeyikBulent DeveciTimur Selcuk2005-04-16Z2011-03-11T08:55:56Zhttp://cogprints.org/id/eprint/4218This item is in the repository with the URL: http://cogprints.org/id/eprint/42182005-04-16ZBundle Branch Reentrant Ventricular Tachycardia
Bundle branch reentrant (BBR) tachycardia is an uncommon form of ventricular tachycardia (VT) incorporating both bundle branches into the reentry circuit. The arrhythmia is usually seen in patients with an acquired heart disease and significant conduction system impairment, although patients with structurally normal heart have been described. Surface ECG in sinus rhythm (SR) characteristically shows intraventricular conduction defects. Patients typically present with presyncope, syncope or sudden death because of VT with fast rates frequently above 200 beats per minute. The QRS morphology during VT is a typical bundle branch block pattern, usually left bundle branch block, and may be identical to that in SR. Prolonged His-ventricular (H-V) interval in SR is found in the majority of patients with BBR VT, although some patients may have the H-V interval within normal limits. The diagnosis of BBR VT is based on electrophysiological findings and pacing maneuvers that prove participation of the His- Purkinje system in the tachycardia mechanism. Radiofrequency catheter ablation of a bundle branch can cure BBR VT and is currently regarded as the first line therapy. The technique of choice is ablation of the right bundle. The reported incidence of clinically significant conduction system impairment requiring implantation of a permanent pacemaker varies from 0% to 30%. Long-term outcome depends on the underlying cardiac disease. Patients with poor systolic left ventricular function are at risk of sudden death or death from progressive heart failure despite successful BBR VT ablation and should be considered for an implantable cardiovertor-defibrillator. Alexander MazurJairo KusniecBoris Strasberg2005-04-16Z2011-03-11T08:55:57Zhttp://cogprints.org/id/eprint/4225This item is in the repository with the URL: http://cogprints.org/id/eprint/42252005-04-16ZCoexistence of Atrioventricular Nodal Reentrant Tachycardia and Idiopathic Left Ventricular Outflow-Tract Tachycardia
Double tachycardia is a relatively rare condition. We describe a 21 year old woman with history of frequent palpitations. In one of these episodes, she had wide complex tachycardia with right bundle branch and inferior axis morphology. A typical atrioventricular nodal tachycardia was induced during electrophysiologic study, aimed at induction of clinically documented tachycardia. Initially no ventricular tachycardia was inducible. After successful ablation of slow pathway, a wide complex tachycardia was induced by programmed stimulation from right ventricular outflow tract. Mapping localized the focus of tachycardia in left ventricular outflow tract and successfully ablated via retrograde aortic approach. During 7 month's follow-up, she has been symptom free with no recurrence. This work describes successful ablation of rare combination of typical atrioventricular nodal tachycardia and left ventricular outflow tract tachycardia in the same patient during one session.
Majid HaghjooArash AryaMohammadreza DehghaniZahra EmkanjooAmirfarjam FazelifarAlireza HeidariMohammadAli Sadr-Ameli2005-04-16Z2011-03-11T08:55:56Zhttp://cogprints.org/id/eprint/4222This item is in the repository with the URL: http://cogprints.org/id/eprint/42222005-04-16ZIdiopathic Epicardial Ventricular Arrhythmias: Diagnosis and Ablation Technique from the Aortic Sinus of Valsalva
Idiopathic outflow tract arrhythmias (ventricular tachycardias or symptomatic premature ventricular contractions; OT-VT/PVCs) can originate from the left ventricular (LV) epicardium (Epi-VT/PVCs), and radiofrequency (RF) energy applications from the aortic sinus of Valsalva can eliminate Epi-VT/PVCs in selected patients.
Among the various ECG findings, the R-wave duration index and R/S amplitude index in leads V1 or V2 are useful for identifying Epi-VT/PVCs, and the Q-wave ratio of leads aVL to aVR and S-wave amplitude in lead V1 are useful for differentiating between an Epi-VT/PVC originating from the LV epicardium remote from the left sinus of Valsalva (LSV) and that from the LSV. Tissue tracking imaging is a promising modality for identifying the origin of OT-VT/PVCs and for differentiating between an Epi-VT/PVC originating from the LV epicardium remote from the LSV and that from the LSV.
If the origin of the Epi-VT/PVC is identified within the LSV, coronary and aortic angiography should be performed to assess the anatomic relationships between the Epi-VT/PVC origin and coronary arteries and aortic valve before the RF energy delivery. To avoid potential complications, RF ablation should be performed at the LSV using a maximum power of 35 watts and maximum temperature of 55°C. Epicardial mapping through the coronary venous system and the presence of potentials recorded from the ablation site within the LSV and their changes before and after the RF energy applications may be useful for diagnosing Epi-VT/PVCs or predicting a successful catheter ablation from the LSV.
Hiroshi Tada2005-04-16Z2011-03-11T08:55:56Zhttp://cogprints.org/id/eprint/4221This item is in the repository with the URL: http://cogprints.org/id/eprint/42212005-04-16ZMay Fever Trigger Ventricular Fibrillation?The clinical precipitants of ventricular fibrillation (VF) remain poorly understood. Clinical factors such as hypoxemia, acidosis or electrolyte imbalance, drug-related toxicity, autonomic nervous system disorders as well as viral myocarditis have been proposed to be associated with sudden cardiac death particularly in patients with structural heart disease. However, In the Brugada syndrome, concurrent febrile illness has been reported to unmask the electrocardiographic features of the Brugada syndrome and be associated with an increased propensity for VF. More recently, a febrile illnesses of infectious etiology was associated to polymorphic ventricular tachycardia or VF in patients with normal hearts and without known repolarization abnormality. In this review we detail this phenomenon and its putative mechanisms. Jean Luc Pasquié2005-04-16Z2011-03-11T08:55:56Zhttp://cogprints.org/id/eprint/4215This item is in the repository with the URL: http://cogprints.org/id/eprint/42152005-04-16ZNaxos Disease Since 1995, according to the World Health Organisation’s classification of cardiomyopathies, Naxos disease has been considered as the recessive form of arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C).1 It is a stereotype association of ARVD/C with a cutaneous phenotype, characterised by woolly hair and palmoplantar keratoderma.2 Epidemiology Naxos disease was first reported in 1986 by Protonotarios et al in patients originating from the Hellenic island of Naxos.2,3 Apart from Naxos, cases have also been reported from other Hellenic islands, as well as from Turkey, Israel and Saudi Arabia.4 The prevalence of the disease in Hellenic islands reaches 1:1000. A variety of Naxos disease presenting at a younger age with more pronounced left ventricular involvement has been described in families from India and Ecuador (Carvajal syndrome).Nikos ProtonotariosAdalena Tsatsopoulou2005-04-16Z2011-03-11T08:55:56Zhttp://cogprints.org/id/eprint/4220This item is in the repository with the URL: http://cogprints.org/id/eprint/42202005-04-16ZRisk Stratification for Sudden Cardiac Death In Patients With Non-ischemic Dilated Cardiomyopathy
Non ischemic dilated cardiomyopathy (NIDCM) is a disorder of myocardium. It has varying etiologies. Albeit the varying etiologies of this heart muscle disorder, it presents with symptoms of heart failure, and rarely as sudden cardiac death (SCD). Manifestations of this disorder are in many ways similar to its counterpart, ischemic dilated cardiomyopathy (IDCM). A proportion of patients with NIDCM carries a grave prognosis and is prone to sudden cardiac death from sustained ventricular arrhythmias. Identification of this subgroup of patients who carry the risk of sudden cardiac death despite adequate medical management is a challenge .Yet another method is a blanket treatment of patients with this disorder with anti arrhythmic medications or anti tachyarrhythmia devices like implantable cardioverter defibrillators (ICD). However this modality of treatment could be a costly exercise even for affluent economies. In this review we try to analyze the existing data of risk stratification of NIDCM and its clinical implications in practice.
Karthik ShekhaJoydeep GhoshDeepak ThekkoottYisachar Greenberg2005-04-16Z2011-03-11T08:55:56Zhttp://cogprints.org/id/eprint/4217This item is in the repository with the URL: http://cogprints.org/id/eprint/42172005-04-16ZRole of Catheter Ablation in Arrhythmogenic Right Ventricular Dysplasia
Arrhythmogenic right ventricular dysplasia/cardiomyopathy is a disorder characterized by frequent ventricular tachycardia originating from the right ventricle and fibro-fatty replacement of right ventricular myocardium. Though the disorder was originally described during surgical ablation of refractory ventricular tachycardia, catheter ablation of tachycardia is one of the options for patients not responding to anti arrhythmic agents. Direct current fulguration was used in the initial phase followed by radiofrequency catheter ablation. In the present day scenario, all patients with risk for sudden cardiac death should receive an implantable cardioverter defibrillator. Radiofrequency catheter ablation remarkably reduces the frequency of defibrillator therapies. Direct current fulguration can still be considered in cases when radiofrequency ablation fails, though it requires higher expertise, general anesthesia and carries a higher morbidity. Newer mapping techniques have helped in identification of the site of ablation. In general, the success rate of ablation in arrhythmogenic right ventricular dysplasia is less than in other forms of right ventricular tachycardias like right ventricular outflow tract tachycardia.Johnson FrancisGuy Fontaine2005-04-16Z2011-03-11T08:55:56Zhttp://cogprints.org/id/eprint/4214This item is in the repository with the URL: http://cogprints.org/id/eprint/42142005-04-16ZRole of Implantable Cardioverter Defibrillators in the Treatment of Hypertrophic Cardiomyopathy
Hypertrophic cardiomyopathy (HCM) is an important cardiovascular disease with sudden cardiac death as the most devastating presentation. Implantable cardioverter defibrillators (ICD) are the optimal therapy for prevention of sudden death from ventricular tachycardia or fibrillation of any cause. While there is no controversy with implanting ICDs in patients who have already survived a cardiac arrest, identifying high-risk patients for primary prevention in this disease remains a challenge. Implanting ICDs in patients with HCM is an important clinical consideration since many individuals could achieve normal or near-normal lifespans with this protection.
Joydeep GhoshJohnson FrancisBarry J. Maron2005-04-16Z2011-03-11T08:55:56Zhttp://cogprints.org/id/eprint/4219This item is in the repository with the URL: http://cogprints.org/id/eprint/42192005-04-16ZVentricular Tachycardia in the Absence of Structural Heart Disease In up to 10% of patients who present with ventricular tachycardia (VT), obvious structural heart disease is not identified. In such patients, causes of ventricular arrhythmia include right ventricular outflow tract (RVOT) VT, extrasystoles, idiopathic left ventricular tachycardia (ILVT), idiopathic propranolol-sensitive VT (IPVT), catecholaminergic polymorphic VT (CPVT), Brugada syndrome, and long QT syndrome (LQTS). RVOT VT, ILVT, and IPVT are referred to as idiopathic VT and generally do not have a familial basis. RVOT VT and ILVT are monomorphic, whereas IPVT may be monomorphic or polymorphic. The idiopathic VTs are classified by the ventricle of origin, the response to pharmacologic agents, catecholamine dependence, and the specific morphologic features of the arrhythmia. CPVT, Brugada syndrome, and LQTS are inherited ion channelopathies. CPVT may present as bidirectional VT, polymorphic VT, or catecholaminergic ventricular fibrillation. Syncope and sudden death in Brugada syndrome are usually due to polymorphic VT. The characteristic arrhythmia of LQTS is torsades de pointes. Overall, patients with idiopathic VT have a better prognosis than do patients with ventricular arrhythmias and structural heart disease. Initial treatment approach is pharmacologic and radiofrequency ablation is curative in most patients. However, radiofrequency ablation is not useful in the management of inherited ion channelopathies. Prognosis for patients with VT secondary to ion channelopathies is variable. High-risk patients (recurrent syncope and sudden cardiac death survivors) with inherited ion channelopathies benefit from implantable cardioverter-defibrillator placement. This paper reviews the mechanism, clinical presentation, and management of VT in the absence of structural heart disease.
Komandoor SrivathsanSteven J LesterChristopher P AppletonLuis R P ScottThomas M Munger2005-05-02Z2011-03-11T08:56:02Zhttp://cogprints.org/id/eprint/4329This item is in the repository with the URL: http://cogprints.org/id/eprint/43292005-05-02ZArrhythmia Diagnosis Following an ICD ShockA 60 year male presents to the emergency room following a shock from his implanted cardioverter defibrillator. He had just risen from bed that morning and experienced mild dizziness prior to the shock.
He has a history of hypertension, and had undergone coronary bypass surgery 3 years previously. Six months following surgery, he developed spontaneous rapid sustained monomorphic ventricular tachycardia associated with syncope. Therapy with amiodarone was complicated by acute pneumonitis requring steroids and cessation of amiodarone therapy. He was implanted with a Ventritex Model V 145 single chamber ICD. A recent echocardiogram had shown inferior and posterior left ventricular hypokinesis with an ejection fraction of 35%. Left atrium measured 4.4 cm. His medications included metoprolol 25 mg bid, lisinopril 5mg bid, hydrochlorthiazide 25 mg qd, atrovostatin 10 mg qd, and aspirin 325 mg qd. Physical examination revealed normal jugular venous pressure, sinus rhythm with a heart rate of 84 bpm, BP 140/85, a soft pansystolic murmur at the apex, and clear lung fields.
Roy M. John2006-01-06Z2011-03-11T08:56:13Zhttp://cogprints.org/id/eprint/4599This item is in the repository with the URL: http://cogprints.org/id/eprint/45992006-01-06ZBiological PacemakersGenetically engineered pacemakers could be a possible alternative to implantable electronic devices for the treatment of bradyarrhythmias. The strategies include upregulation of beta adrenergic receptors, conversion of myocytes into pacemaker cells and stem cell therapy. Pacemaker activity in adult ventricular myocytes is normally repressed by the inward rectifier potassium current (IK1). The IK1 current is encoded by the Kir2 gene family. Use of a negative construct that suppresses current when expressed with wild-type Kir2.1 is an experimental approach for genesis of genetic pacemaker. hyperpolarisation activated cyclic nucleotide gated (HCN) channels which generate If current, the pacemaker current of heart can be delivered to heart by using stem cell therapy approach and viral vectors. The unresolved issues include longevity and stability of pacemaker genes, limitations involved in adenoviral and stem cell therapy and creation of genetic pacemakers which can compete with the electronic units.
Rajesh GJohnson Francis2005-04-14Z2011-03-11T08:55:53Zhttp://cogprints.org/id/eprint/4174This item is in the repository with the URL: http://cogprints.org/id/eprint/41742005-04-14ZCatheter Ablation of Tachyarrhythmias in Small Children
An estimated 80,000-100,000 radiofrequency ablation (RFA) procedures are performed in the United States each year.1 Approximately 1% of these are performed on pediatric patients at centers that contribute data to the Pediatric Radiofrequency Registry.2 Previous reports from this registry have demonstrated that RFA can safely and effectively be performed in pediatric patients.3,4 However, patients weighing less than 15 kg have been identified as being at greater risk for complications.3,4 Consequently, there has been great reluctance to perform RFA in small children such that children weighing less than 15 kg only represent approximately 6% of the pediatric RFA experience2 despite the fact that this age group carries the highest incidence of tachycardia, particularly supraventricular tachycardia (SVT).5 Factors other than the risk of complications contribute to the lower incidence of RFA in this group, including the natural history of the most common tachycardias (SVT), technical issues with RFA in small hearts, and the potential unknown long-term effects of RF applications in the maturing myocardium. Conversely, there are several reasons why ablation may be desirable in small children, including greater difficulties with medical management,6,7,8 the higher risk for hemodynamic compromise during tachycardia in infants with congenital heart disease (CHD), and the inability of these small children to effectively communicate their symptoms thereby making it more likely that their symptoms may go unnoticed until the children become more seriously ill. Before ultimately deciding that catheter ablation is indicated in small children, one must consider which tachycardias are likely to be ablated, the clinical presentation of these tachycardias, alternatives to ablation, the relative potential for success or complications, and modifications of the procedure that might reduce the risk of ablation in this group. Andrew D. Blaufox2005-04-13Z2011-03-11T08:55:53Zhttp://cogprints.org/id/eprint/4170This item is in the repository with the URL: http://cogprints.org/id/eprint/41702005-04-13ZCryothermal Energy Ablation Of Cardiac Arrhythmias 2005: State Of The ArtAt the time of antiarrhythmic surgery, cryothermal energy application by a hand-held probe was used to complement dissections and resections and permanently abolish the arrhythmogenic substrate. Over the last decade, significant engineering advances allowed percutaneous cryoablation based on catheters, apparently not very different from standard radiofrequency ablation catheters. Cryothermal energy has peculiar characteristics. In fact, it allows testing in a reversible way the effects of energy application at higher temperature, before producing a permanent lesion at –75°C. Moreover, slow formation of the lesion allows timely discontinuation of the application, as soon as inadvertent modifications of normal atrioventricular conduction are observed during ablation in the proximity of atrioventricular node and His bundle, avoiding its permanent damage. Over the last years, percutaneous cryothermal ablation has been widely used for a variety of cardiac arrhythmias. From the data gathered, it is unlikely that cryoablation will replace standard ablation in unselected cases. Nevertheless, for the above mentioned peculiarities, cryothermal ablation has proved very effective and safe for ablation of arrhythmogenic substrates close to the normal conduction pathways, becoming the first choice method to ablate anteroseptal and midseptal accessory pathways. It can be also the best treatment for ablation of the slow pathway to abolish atrioventricular node reentrant tachycardia in pediatrics or when particular anatomy of the Koch’s triangle is observed. Cryothermal ablation of the pulmonary veins for atrial fibrillation, although longer than radiofrequency ablation, is not associated with pulmonary vein stenosis and is expected to be less thrombogenic; new catheter designs for cryothermal ablation of this challenging arrhythmia are to be tested to assess their efficacy and clinical usefulness.
Roberto De Ponti2005-04-14Z2011-03-11T08:55:53Zhttp://cogprints.org/id/eprint/4171This item is in the repository with the URL: http://cogprints.org/id/eprint/41712005-04-14ZElectrical Storms in Brugada Syndrome: Review of Pharmacologic and Ablative Therapeutic Options
Electrical storm occurring in a patient with the Brugada syndrome is an exceptional but malignant and potentially lethal event. Efficient therapeutic solutions should be known and urgently applied because of the inability of usual antiarrhythmic means in preventing multiple recurrences of ventricular arrhythmias. Isoproterenol should be immediately infused while oral quinidine should be further administrated when isoproterenol is not effective. In case of failure of these therapeutic options, ablation of the triggering ventricular ectopies should be attempted
P MauryM HociniM Haïssaguerre2005-04-14Z2011-03-11T08:55:53Zhttp://cogprints.org/id/eprint/4173This item is in the repository with the URL: http://cogprints.org/id/eprint/41732005-04-14ZElectrophysiological Mechanisms of Ventricular Fibrillation Induction
Ventricular fibrillation (VF) is known as a main responsible cause of sudden cardiac death which claims thousands of lives each year. Although the mechanism of VF induction has been investigated for over a century, its definite mechanism is still unclear. In the past few decades, the development of new advance technologies has helped investigators to understand how the strong stimulus or the shock induces VF. New hypotheses have been proposed to explain the mechanism of VF induction. This article reviews most commonly proposed hypotheses that are believed to be the mechanism of VF induction. Nipon ChattipakornKirkwit ShinlapawittayatornSiriporn Chattipakorn2005-04-14Z2011-03-11T08:55:53Zhttp://cogprints.org/id/eprint/4176This item is in the repository with the URL: http://cogprints.org/id/eprint/41762005-04-14ZMultiple Arrhythmogenic Substrate for Tachycardia in a Patient with Frequent PalpitationsWe report a 26-year-old woman with frequent episodes of palpitation and dizziness. Resting electrocardiography showed no evidence of ventricular preexcitation. During electrophysiologic study, a concealed right posteroseptal accessory pathway was detected and orthodromic atrioventricular reentrant tachycardia incorporating this pathway as a retrograde limb was reproducibly induced. After successful ablation of right posteroseptal accessory pathway, another tachycardia was induced using a concealed right posterolateral accessory pathway in tachycardia circuit. After loss of retrograde conduction of second accessory pathway with radiofrequency ablation, dual atrioventricular nodal physiology was detected and typical atrioventricular nodal reentrant tachycardia was repeatedly induced. Slow pathway ablation was done successfully. Finally sustained self-terminating atrial tachycardia was induced under isoproterenol infusion but no attempt was made for ablation. During 8-month follow-up, no recurrence of symptoms attributable to tachycardia was observed.
Majid HaghjooArash AryaMohammadreza DehghaniZahra EmkanjooAmirfarjam FazelifarMohammadAli Sadr-Ameli2005-04-14Z2011-03-11T08:55:53Zhttp://cogprints.org/id/eprint/4172This item is in the repository with the URL: http://cogprints.org/id/eprint/41722005-04-14ZPacemapping Pacemapping (PM) is an electrophysiologic technique designed to help locating tachycardia sources by stimulating at different endocardial sites in order to reproduce the clinical tachycardia characteristics. A recorded electrocardiogram (ECG) during the clinical tachycardia has been conventionally used as reference. Yet, endocardial activation pattern during tachycardia may be utilized as well to guide the procedure. In focal tachycardia ablation, PM guide has consistently provided remarkable outcomes1, while outcomes in reentrant tachycardia ablation are less favourableMauricio MorenoNicasio Perez-CastellanoJulian Villacastín2005-04-13Z2011-03-11T08:55:53Zhttp://cogprints.org/id/eprint/4163This item is in the repository with the URL: http://cogprints.org/id/eprint/41632005-04-13ZRole of Biatrial Pacing in Prevention of Atrial Fibrillation after Coronary Artery Bypass SurgeryBackground: Atrial fibrillation (AF) after coronary artery bypass graft surgery (CABG) constitutes the most common sustained arrhythmia and results in prolonged hospitalization. The purpose of this study was to assess simultaneous right and left atrial pacing as prophylaxis for postoperative atrial fibrillation.
Methods and Results: From July 2003 to May 2004, 120 patients without structural heart disease and who underwent CABG were randomly classified into one of the following 3 groups: biatrial pacing (BAP), left atrial pacing (LAP), and no pacing (control). Atrial pacing was performed for 4 days. Post-CABG AF was significantly reduced in BAP group compared to single-site and control group (BAP, 17.5%; LAP, 30%; control, 45%; p=0.02). The mean length of hospital stay was significantly reduced in BAP group. Hospital charges were not significantly different between three groups. The mean length of hospital stay was most significantly reduced in BAP group (6.1±1.2 versus 9.0±4.1 days in the control groups; p=0.002, and 8.7±1.3 days in LAP groups; p=0.01). The mean length of stay in the intensive care unit was also significantly reduced in the BAP group (2.8±0.7 versus 4.6±4.5 days in control group; p=0.04, and 4.2±3.2 days in LAP group; p=0.01).
Conclusions: Simultaneous right and left atrial pacing is well tolerated and is more effective in preventing post-CABG AF than single-site pacing, and, results in a shortened hospital stay. Identifying patients at risk for developing postoperative AF and using this prophylactic method may be the optimal effective strategy.
Massoud EslamiHamid S. MirkhaniMehdi SanatkarHomeira BayatRoya SattarzadehMahmood Mirhoseini2005-04-13Z2011-03-11T08:55:53Zhttp://cogprints.org/id/eprint/4164This item is in the repository with the URL: http://cogprints.org/id/eprint/41642005-04-13ZTo Pace Or Not To Pace! – Prevention Of Atrial Fibrillation After Coronary Artery Bypass SurgeryAtrial fibrillation (AF) is a very undesirable, but unfortunately a common arrhythmia following coronary artery bypass graft (CABG) surgery, occurring in up to 40% of patients. There is an increase in hospital stay and adds to the overall cost of the surgery. Atrial fibrillation occurrence may identify a subset of patients with reduced survival. Prevention of AF therefore would have a significant positive impact on patients undergoing CABG surgery. Based on the mechanism of postoperative AF, it seems likely that overcoming the slow atrial conduction with reduction in the dispersion of atrial refractoriness and suppression of the atrial ectopy should prevent AF. With these considerations atrial overdrive pacing to prevent post CABG AF has been evaluated with a number of randomized, controlled trials.Amit Vora2005-04-14Z2011-03-11T08:55:53Zhttp://cogprints.org/id/eprint/4175This item is in the repository with the URL: http://cogprints.org/id/eprint/41752005-04-14ZU wave: an Important Noninvasive Electrocardiographic Diagnostic MarkerStudy of U waves exemplifies important clinical role of noninvasive electrocardiography in modern cardiology. Present article highlights significance of U waves with a clinical case and also summarizes in brief the history of the same.
Girish MPMohit Dayal GuptaSaibal MukhopadhyayJamal YusufSunil Roy TNVijay Trehan2005-04-13Z2011-03-11T08:55:54Zhttp://cogprints.org/id/eprint/4189This item is in the repository with the URL: http://cogprints.org/id/eprint/41892005-04-13ZArrhythmia Diagnosis Following An ICD ShockA 70 year old male underwent placement of a Medtronic Marquis DR ICD following syncope. He has coronary artery disease and severe LV dysfunction and was inducible for rapid hemodynamically unstable ventricular tachycardia at intracardiac electrophysiological study prior to implantation of the ICD. Three weeks later, he presents with an ICD shock. He had been drinking excessive amounts of alcohol and experienced lightheadedness prior to experiencing the ICD shock. A ventricular arrhythmia is appropriately converted by the ICD shock Roy M John2005-04-14Z2011-03-11T08:55:53Zhttp://cogprints.org/id/eprint/4182This item is in the repository with the URL: http://cogprints.org/id/eprint/41822005-04-14ZArrhythmogenicity of the Coronary Sinus
The coronary sinus (CS) is the cardiac venous system that begins at its ostium in the right atrium and ends at the origin of the great cardiac vein. The major tributaries of the CS include the great cardiac vein (anterior cardiac vein), the left obtuse marginal vein, the posterior (or inferior) left ventricular vein, the middle cardiac vein, and the right coronary vein. In addition, atrial veins and, notably, the vein of Marshall (or oblique left atrial vein) also enter the coronary sinus. From the perspective of electrophysiologists, the CS represents an anatomical structure of particular interest. First, it provides access to epicardial atrioventricular pathways and arrhythmogenic foci of both atrial6 and ventricular arrhythmia. Second, it represents by itself a potential source of atrial arrhythmia. The arrhythmogenic potential of the thoracic veins in general has been recognised since the 1970s. Atrial arrhythmias can originate in the pulmonary veins, the superior vena cava, and the CS. Indeed, biatrial flutter,left atrial tachycardia, and atrial fibrillation, involving the distal CS have been well described. There is now evidence that the CS apart from participating in arrhythmia circuits, such as in the slow-slow form of atrioventricular nodal reentrant tachycardia and atrioventricular reentrant tachycardia due to accessory pathways,may itself be a source of apparently atrial arrhythmia. In patients with paroxysmal atrial fibrillation apparently originating from the left superior or inferior pulmonary vein, detailed epicardial mapping through the distal coronary sinus might identify epicardial location of the arrhythmogenic focus. Therefore, the search for foci of abnormal automaticity within the CS should be part of the electrophysiologic evaluation of left atrial arrhythmias.Demosthenes G Katritsis2005-04-14Z2011-03-11T08:55:53Zhttp://cogprints.org/id/eprint/4183This item is in the repository with the URL: http://cogprints.org/id/eprint/41832005-04-14ZFetal Tachyarrhythmia - Part II: TreatmentThe decision to initiate pharmacological intervention in case of fetal tachycardia depends on several factors and must be weighed against possible maternal and/or fetal adverse effects inherent to the use of antiarrhythmics. First, the seriousness of the fetal condition must be recognized. Many studies have shown that in case of fetal tachycardia, there is a significant predisposition to congestive heart failure and subsequent development of fetal hydrops and even sudden cardiac death1,2,3 Secondly, predictors of congestive heart failure have been suggested in several studies, such as the percentage of time that the tachycardia is present, the gestational age at which the tachycardia occurs4, the ventricular rate5 and the site of origin of the tachycardia6. However, the sensitivity of these predictors is low and they are therefore clinically not very useful. In addition, hemodynamic compromise may occur in less than 24 - 48 hours as has been shown in the fetal lamb7 and in tachycardic fetuses8,9. On the other hand, spontaneous resolution of the tachycardia has also been described10. Thirdly, transplacental management of fetuses with tricuspid regurgitation11, congestive heart failure or fetal hydrops is difficult12,13, probably as a result of limited transplacental transfer of the antiarrhythmic drug14,15. In case of fetal hydrops, conversion rates are decreased and time to conversion is increased13. Treatment of sustained fetal tachycardia is therefore to be preferred above expectant management, although some centers oppose this regimen and suggest that in cases with (intermittent) fetal SVT not complicated by congestive heart failure or fetal hydrops, conservative management and close surveillance might be a reasonable alternative16,17,18. Martijn A OudijkGerard HA VisserErik J Meijboom2005-04-14Z2011-03-11T08:55:53Zhttp://cogprints.org/id/eprint/4178This item is in the repository with the URL: http://cogprints.org/id/eprint/41782005-04-14ZIssues in QT interval measurement The QT interval, apart from clinical implications is crucial for safety assessment of new drugs under development. A QTc prolongation of even 10 msec in a study group is a warning signal for a new drug.
There are various issues involved in the measurement of the QT interval especially regarding the ending of the T wave and different morphological pattern of T-U complex. The other issue is significant spontaneous variability in the QT interval, resulting in spurious QT prolongation and unnecessary concern.
To minimize all these confounding factors, all clinical trials for assessing QT interval prolongation should be randomized and double blinded with appropriate control groups including placebo. ECG measurements should be done by trained readers with electronic calipers at ECG core Lab. ECGs should be compared with multiple baseline values with multiple, time-matched on-treatment values.
Pallavi LanjewarVaishali PathakYash Lokhandwala2005-04-14Z2011-03-11T08:55:54Zhttp://cogprints.org/id/eprint/4184This item is in the repository with the URL: http://cogprints.org/id/eprint/41842005-04-14ZNew Concepts in Pacemaker Syndrome
After implantation of a permanent pacemaker, patients may experience severe symptoms of dyspnea, palpitations, malaise, and syncope resulting from pacemaker syndrome. Although pacemaker syndrome is most often ascribed to the loss of atrioventricular (A-V) synchrony, more recent data may also implicate left ventricular dysynchrony caused by right ventricular pacing. Previous studies have not shown reductions in mortality or stroke with rate-modulated dual-chamber (DDDR) pacing as compared to ventricular-based (VVI) pacing. The benefits in A-V sequential pacing with the DDDR mode are likely mitigated by the interventricular (V-V) dysynchrony imposed by the high percentage of ventricular pacing commonly seen in the DDDR mode. Programming DDDR pacemakers to encourage intrinsic A-V conduction and reduce right ventricular pacing will likely decrease heart failure and pacemaker syndrome. Studies are currently ongoing to address these questions.
Michael D FarmerMark NA III EstesMark S Link2005-04-13Z2011-03-11T08:55:54Zhttp://cogprints.org/id/eprint/4188This item is in the repository with the URL: http://cogprints.org/id/eprint/41882005-04-13ZRadiofrequency Catheter Ablation of Atrioventricular Nodal Reentrant Tachycardia: It Is Not Always As It Is Expected
Observation of Coincident arrhythmias is not uncommon but the co-existence of idiopathic verapamil sensitive left ventricular tachycardia (ILVT) with other arrhythmias is very rare. We hereby presented a 30 year old male patient with a history of frequent episodes of palpitations and sustained narrow complex tachycardia. During electrophysiologic study two arrhythmias, one with narrow complexes which was shown to be typical atrioventricular nodal re-entrant tachycardia and the other with wide QRS complexes and right bundle branch block and left axis morphology, compatible with ILVT, were inducible. Radiofrequency catheter ablation of both arrhythmias was done at two consecutive sessions. The patient has remained asymptomatic without antiarrhythmic therapy for the past six months.
Arash AryaMajid HaghjooZahra EmkanjooAlireza HeydariMohammad Ali Sadr-Ameli2005-04-13Z2011-03-11T08:55:54Zhttp://cogprints.org/id/eprint/4186This item is in the repository with the URL: http://cogprints.org/id/eprint/41862005-04-13ZA Rare, Late Complication after Automated Implantable Cardioverter-Defibrillator PlacementThis article describes an interesting case of automated implantable cardioverter defibrillator (AICD) extrusion fifteen months after implantation. The case report is followed by a discussion of the causes and treatment of skin erosion following pacemaker/AICD insertion.
Michael ShapiroSam HanonPaul Schweitzer2005-04-14Z2011-03-11T08:55:53Zhttp://cogprints.org/id/eprint/4180This item is in the repository with the URL: http://cogprints.org/id/eprint/41802005-04-14ZShort-term Heart Rate Turbulence Analysis Versus Variability and Baroreceptor Sensitivity in Patients With Dilated Cardiomyopathy
New methods for the analysis of arrhythmias and their hemodynamic consequences have been applied in risk stratification, in particular to patients after myocardial infarction. This study investigates the suitability of short-term heart rate turbulence (HRT) analysis in comparison to heart rate and blood pressure variability as well as baroreceptor sensitivity analyses to characterise the regulatory differences between patients with dilated cardiomyopathy (DCM) and healthy controls. In this study, 30 minutes data of non-invasive continuous blood pressure and ECGs of 37 DCM patients and 167 controls measured under standard resting conditions were analysed. The results show highly significant differences between DCM patients and controls in heart rate and blood pressure variability as well as in baroreceptor sensitivity parameters. Applying a combined heart rate-blood pressure trigger, ventricular premature beats were detected in 24.3% (9) of the DCM patients and 11.3% (19) of the controls. This fact demonstrates the limited applicability of short-term HRT analyses. However, the HRT parameters showed significant differences in this subgroup with ventricular premature beats (turbulence onset: DCM: 1.80±2.72, controls: - 4.34±3.10, p<0.001; turbulence slope: DCM: 6.75±5.50, controls: 21.30±17.72, p=0.021). Considering all (including HRT) parameters in the subgroup with ventricular beats, a discrimination rate between DCM patients and controls of 88.0% was obtained (max. 6 parameters). The corresponding value obtained for the total group was 86.3% (without HRT parameters). Comparable classification rates and high correlations between heart rate turbulence and variability and baroreflex parameters point to a more universal applicability of the latter methods.
Hagen MalbergRobert BauernschmittUdo MeyerfeldtAlexander SchirdewanNiels Wessel2005-04-14Z2011-03-11T08:55:54Zhttp://cogprints.org/id/eprint/4185This item is in the repository with the URL: http://cogprints.org/id/eprint/41852005-04-14ZTrends in Cardiac Pacemaker Batteries
Batteries used in Implantable cardiac pacemakers-present unique challenges to their developers and manufacturers in terms of high levels of safety and reliability. In addition, the batteries must have longevity to avoid frequent replacements. Technological advances in leads/electrodes have reduced energy requirements by two orders of magnitude. Micro-electronics advances sharply reduce internal current drain concurrently decreasing size and increasing functionality, reliability, and longevity. It is reported that about 600,000 pacemakers are implanted each year worldwide and the total number of people with various types of implanted pacemaker has already crossed 3 million. A cardiac pacemaker uses half of its battery power for cardiac stimulation and the other half for housekeeping tasks such as monitoring and data logging. The first implanted cardiac pacemaker used nickel-cadmium rechargeable battery, later on zinc-mercury battery was developed and used which lasted for over 2 years. Lithium iodine battery invented and used by Wilson Greatbatch and his team in 1972 made the real impact to implantable cardiac pacemakers. This battery lasts for about 10 years and even today is the power source for many manufacturers of cardiac pacemakers. This paper briefly reviews various developments of battery technologies since the inception of cardiac pacemaker and presents the alternative to lithium iodine battery for the near future.
Venkateswara Sarma MallelaV IlankumaranSrinivasa N Rao2005-04-13Z2011-03-11T08:55:54Zhttp://cogprints.org/id/eprint/4192This item is in the repository with the URL: http://cogprints.org/id/eprint/41922005-04-13ZThe Automatic External Cardioverter-Defibrillator
In-hospital cardiac arrest remains a major problem but new technologies allowing fully automatic external defibrillation are available. These technologies allow the concept of “external therapeutic monitoring” of lethal arrhythmias. Since early defibrillation improves outcome by decreasing morbidity and mortality, the use of this device should improve the outcome of in-hospital cardiac arrest victims. Furthermore, the use of these devices could allow safe monitoring and treatment of patients at risk of cardiac arrest who not necessarily must be in conventional monitoring units (Intensive or Coronary Care Units) saving costs with a more meaningful use of resources. The capability to provide early defibrillation within any patient-care areas should be considered as an obligation (“standard of care”) of the modern hospital.
Antoni Martínez-RubioGonzalo Barón-Esquivias2005-04-13Z2011-03-11T08:55:54Zhttp://cogprints.org/id/eprint/4191This item is in the repository with the URL: http://cogprints.org/id/eprint/41912005-04-13ZFetal Tachyarrhythmia - Part I: Diagnosis Fetal tachycardia, first recognized in 1930 by Hyman et al1, is a condition occurring in approximately 0.4-0.6% of all pregnancies2. A subset of these cases with more sustained periods of tachycardia is clinically relevant. The necessity of therapeutic intervention in this condition is still a matter of discussion focused on the natural history of the disease. The spectrum of opinions varies from non-intervention3,4,5 based on a number of cases in which the tachycardia subsided spontaneously6, to aggressive pharmacotherapeutic intervention7,8 based on reports of deterioration of the fetal condition ultimately ending in significant neurological morbidity9,10,11, or fetal demise12,13,14. Prenatal treatment through indirect, maternally administered drug therapy seems to be the preference of most centers15,16,17,18,19,20,21. This matter will be discussed further in Fetal Tachyarrhythmia, Part II, Treatment. Martijn A OudijkGerard HA VisserErik J Meijboom2005-04-13Z2011-03-11T08:55:54Zhttp://cogprints.org/id/eprint/4195This item is in the repository with the URL: http://cogprints.org/id/eprint/41952005-04-13ZFigure-8 Tachycardia Confined to the Anterior Wall of the Left AtriumIncisional atrial tachycardias have been described most frequently in patients with previous corrective surgery for congenital heart defects and mitral valve disease. Less information is available on atrial tachycardias appearing late after isolated aortic valve surgery. We report the case of a patient who developed a left figure-8 tachycardia after undergoing aortic valve replacement. During electrophysiologic study the entire cycle length of the tachycardia was mapped within a low voltage area confined to the left anterior atrial wall. However, during ablation a transmural lesion could not be attained. The mapping and ablation strategy along with the mechanism of the tachycardia are discussed.
Ioan LiubaAnders JönssonHåkan Walfridsson2005-04-13Z2011-03-11T08:55:55Zhttp://cogprints.org/id/eprint/4197This item is in the repository with the URL: http://cogprints.org/id/eprint/41972005-04-13ZFirst International Symposium on Long QT Syndrome through the Internet, April 2004
With the First Virtual Symposium on Long QT Syndrome already finished; which was held over the month of April, 2004 as an educational activity of the International Society for Holter and Noninvasive Electrocardiology (ISHNE), and completely through the Internet; we, the Presidents of the Scientific and Steering Committees, Sergio Dubner, Edgardo Schapachnik and Andrés Ricardo Pérez Riera, are wondering gladly surprised, which may have been the main causes of such a huge success as we have reached, and the enormous interest arisen. Just to have an idea of the dimension achieved, data obtained from http://www.a9.com (an Amazon.com site) or with the traditional search engine Google, prove that the first reply when you request information about long QT Syndrome is the access site of the Symposium. We believe that the response to this question may be summarized in one word: REALIZATION. The best definition for success is realization. The huge motivation in each one of us made the difference. We worked with a cohesive group, like a team, aware of the unparalleled and great opportunity Prof. Arthur Moss had initially assigned to Sergio Dubner and Edgardo Schapachnik, an invitation that the latter extended to Andrés Ricardo Pérez Riera. Sergio DubnerEdgardo SchapachnikAndrés Ricardo Pérez Riera2005-04-13Z2011-03-11T08:55:54Zhttp://cogprints.org/id/eprint/4193This item is in the repository with the URL: http://cogprints.org/id/eprint/41932005-04-13ZFrequency Analysis of Atrial Fibrillation From the Surface ElectrocardiogramAtrial fibrillation (AF) is the most common arrhythmia encountered in clinical practice. Neither the natural history of AF nor its response to therapy are sufficiently predictable by clinical and echocardiographic parameters.
Atrial fibrillatory frequency (or rate) can reliably be assessed from the surface electrocardiogram (ECG) using digital signal processing (filtering, subtraction of averaged QRST complexes, and power spectral analysis) and shows large inter-individual variability. This measurement correlates well with intraatrial cycle length, a parameter which appears to have primary importance in AF domestication and response to therapy. AF with a low fibrillatory rate is more likely to terminate spontaneously, and responds better to antiarrhythmic drugs or cardioversion while high rate AF is more often persistent and refractory to therapy.
In conclusion, frequency analysis of AF seems to be useful for non-invasive assessment of electrical remodeling in AF and may subsequently be helpful for guiding AF therapy.
Daniela HusserMartin StridhLeif SornmoBertil OlssonAndreas Bollmann2005-04-13Z2011-03-11T08:55:54Zhttp://cogprints.org/id/eprint/4190This item is in the repository with the URL: http://cogprints.org/id/eprint/41902005-04-13ZIdiopathic Fascicular Ventricular Tachycardia
Idiopathic fascicular ventricular tachycardia is an important cardiac arrhythmia with specific electrocardiographic features and therapeutic options. It is characterized by relatively narrow QRS complex and right bundle branch block pattern. The QRS axis depends on which fascicle is involved in the re-entry. Left axis deviation is noted with left posterior fascicular tachycardia and right axis deviation with left anterior fascicular tachycardia. A left septal fascicular tachycardia with normal axis has also been described. Fascicular tachycardia is usually seen in individuals without structural heart disease. Response to verapamil is an important feature of fascicular tachycardia. Rare instances of termination with intravenous adenosine have also been noted. A presystolic or diastolic potential preceding the QRS, presumed to originate from the Purkinje fibers can be recorded during sinus rhythm and ventricular tachycardia in many patients with fascicular tachycardia. This potential (P potential) has been used as a guide to catheter ablation. Prompt recognition of fascicular tachycardia especially in the emergency department is very important. It is one of the eminently ablatable ventricular tachycardias. Primary ablation has been reported to have a higher success, lesser procedure time and fluoroscopy time.
Johnson FrancisVenugopal KKhadar SASudhayakumar NAnoop K Gupta2005-04-12Z2011-03-11T08:55:54Zhttp://cogprints.org/id/eprint/4194This item is in the repository with the URL: http://cogprints.org/id/eprint/41942005-04-12ZSensors for Rate Responsive Pacing
Advances in pacemaker technology in the 1980s have generated a wide variety of complex multiprogrammable pacemakers and pacing modes. The aim of the present review is to address the different rate responsive pacing modalities presently available in respect to physiological situations and pathological conditions. Rate adaptive pacing has been shown to improve exercise capacity in patients with chronotropic incompetence. A number of activity and metabolic sensors have been proposed and used for rate control. However, all sensors used to optimize pacing rate metabolic demands show typical limitations. To overcome these weaknesses the use of two sensors has been proposed. Indeed an unspecific but fast reacting sensor is combined with a more specific but slower metabolic one. Clinical studies have demonstrated that this methodology is suitable to reproduce normal sinus behavior during different types and loads of exercise. Sensor combinations require adequate sensor blending and cross checking possibly controlled by automatic algorithms for sensors optimization and simplicity of programming. Assessment and possibly deactivation of some automatic functions should be also possible to maximize benefits from the dual sensor system in particular conditions. This is of special relevance in patient whose myocardial contractility is limited such as in subjects with implantable defibrillators and biventricular pacemakers. The concept of closed loop pacing, implementing a negative feedback relating pacing rate and the control signal, will provide new opportunities to optimize dual-sensors system and deserves further investigation. The integration of rate adaptive pacing into defibrillators is the natural consequence of technical evolution.
Simonetta Dell’OrtoPaolo ValliEnrico Maria Greco2005-04-13Z2011-03-11T08:55:54Zhttp://cogprints.org/id/eprint/4196This item is in the repository with the URL: http://cogprints.org/id/eprint/41962005-04-13ZAn Unusual Tachycardia
The following article presents an unusual case of atrial tachycardia, initially misdiagnosed due to a lack of clear P waves. The diagnosis was eventually confirmed using the atrial electrogram from the patient’s pacemaker.
Sam HanonMichael ShapiroPaul Schweitzer2005-04-17Z2011-03-11T08:55:57Zhttp://cogprints.org/id/eprint/4230This item is in the repository with the URL: http://cogprints.org/id/eprint/42302005-04-17ZAutomatic Capture Verification in Pacemakers (Autocapture) – Utility and Problems
The concept of a closed – loop feedback system, that would automatically assess pacing threshold and self -adjust pacing output to ensure consistent myocardial capture, has many appeals. Enhancing patient safety in cases of an unexpected rise in threshold, reduced current drain, hence prolonging battery longevity and reducing the amount of physician intervention required are just some of the advantages. Autocapture (AC) is a proprietary algorithm developed by St Jude Medical CRMD, Sylmar, CA, USA, (SJM) that was the first to commercially provide these automatic functions in a single chamber pacemaker (Microny and Regency), and subsequently in a dual chamber pacemaker (Affinity, Entity and Identity family of pacemakers). This article reviews the conditions necessary for AC verification and performance and the problems encountered in clinical practice. Ruth Kam2005-04-13Z2011-03-11T08:55:55Zhttp://cogprints.org/id/eprint/4198This item is in the repository with the URL: http://cogprints.org/id/eprint/41982005-04-13ZCongenital Short QT Syndrome
Long QT intervals in the ECG have long been associated with sudden cardiac death. The congenital long QT syndrome was first described in individuals with structurally normal hearts in 1957.1 Little was known about the significance of a short QT interval. In 1993, after analyzing 6693 consecutive Holter recordings Algra et al concluded that an increased risk of sudden death was present not only in patients with long QT interval, but also in patients with short QT interval (<400 ms).2 Because this was a retrospective analysis, further evaluation of the data was not possible. It was not until 2000 that a short-QT syndrome (SQTS) was proposed as a new inherited clinical syndrome by Gussak et al.3 The initial report was of two siblings and their mother all of whom displayed persistently short QT interval. The youngest was a 17 year old female presenting with several episodes of paroxysmal atrial fibrillation requiring electrical cardioversion.3 Her QT interval measured 280 msec at a heart rate of 69. Her 21 year old brother displayed a QT interval of 272 msec at a heart rate of 58, whereas the 51 year old mother showed a QT of 260 msec at a heart rate of 74. The authors also noted similar ECG findings in another unrelated 37 year old patient associated with sudden cardiac death. Charles AntzelevitchJohnson Francis2005-04-17Z2011-03-11T08:55:57Zhttp://cogprints.org/id/eprint/4232This item is in the repository with the URL: http://cogprints.org/id/eprint/42322005-04-17ZCurrent concepts on ventricular fibrillation: A Vicious Circle of Cardiomyocyte Calcium Overload in the Initiation, Maintenance, and Termination of Ventricular Fibrillation
Based on recent experimental studies, this review article introduces the novel concept that cardiomyocyte Ca2+ and ventricular fibrillation (VF) are mutually related, forming a self-maintaining vicious circle in the initiation, maintenance, and termination of VF. On the one hand, elevated myocyte Ca2+ can cause delayed afterdepolarizations, triggered activity, and consequently life-threatening ventricular tachyarrhythmias in various pathological conditions such as digitalis toxicity, myocardial ischemia, or heart failure. On the other hand, VF itself directly and rapidly causes progressive myocyte Ca2+ overload that maintains VF and renders termination of VF increasingly difficult. Accordingly, energy levels for successful electrical defibrillation (defibrillation thresholds) increase as both VF and Ca2+ overload progress. Furthermore, VF-induced myocyte Ca2+ overload can promote re-induction of VF after defibrillation and/or postfibrillatory myocardial dysfunction (postresuscitation stunning) due to reduced myofilament Ca2+ responsiveness. The probability of these adverse events is best reduced by early detection and rapid termination of VF to prevent or limit Ca2+ overload. Early additional therapy targeting transsarcolemmal Ca2+ entry, particularly during the first 2 min of VF, may partially prevent myocyte Ca2+ overload and thus, increase the likelihood of successful defibrillation as well as prevent postfibrillatory myocardial dysfunction.
Christian E. Zaugg2005-04-17Z2011-03-11T08:55:57Zhttp://cogprints.org/id/eprint/4233This item is in the repository with the URL: http://cogprints.org/id/eprint/42332005-04-17ZInteresting Electrophysiological Findings in a Patient With Coincidental Right Ventricular Outflow Tract and Atrioventricular Nodal Reentrant Tachycardia
Tachycardia induced tachycardias are not common in clinical practice, and it is believed that most cases of double tachycardia are coincidental. The existence of two different tachycardias in the same patient almost always poses problems in the electrophysiology laboratory. However, in rare instances, the emergence of a second tachycardia can actually provide invaluable information about the first one. In this report, we describe a 30-year-old woman who presented with palpitations. Electrophysiological study revealed that atrial programmed stimulation at baseline induced right ventricular outflow tract (RVOT) tachycardia and supraventricular tachycardia. The study also showed that each of the tachycardias was able to induce the other. A short run of RVOT tachycardia during supraventricular tachycardia was able to entrain the latter. This finding provided important information about the nature of the supraventricular tachycardia, which proved to be atrioventricular nodal reentrant tachycardia. Both of these tachycardias were successfully ablated, and the patient’s palpitations disappeared.
Bülent OzinBahar PiratHaldun Müderrisoglu2005-04-17Z2011-03-11T08:55:57Zhttp://cogprints.org/id/eprint/4229This item is in the repository with the URL: http://cogprints.org/id/eprint/42292005-04-17ZRadiofrequency Ablation for Post Infarction Ventricular Tachycardia
Radiofrequency ablation has an important role in the management of post infarction ventricular tachycardia. The mapping and ablation of ventricular tachycardia (VT) is complex and technically challenging. In the era of implantable cardioverter defibrillators, the role of radiofrequency ablation is most commonly reserved as an adjunctive treatment for patients with frequent, symptomatic episodes of ventricular tachycardia. In this setting the procedure has a success rate of around 70-80% and a low complication rate. With improved ability to predict recurrent VT and improvements in mapping and ablation techniques and technologies, the role of radiofrequency ablation should expand further.
David O’DonnellVoltaire Nadurata2005-04-17Z2011-03-11T08:55:57Zhttp://cogprints.org/id/eprint/4231This item is in the repository with the URL: http://cogprints.org/id/eprint/42312005-04-17ZThe role of Psychological Factors in the Aetiology and Treatment of Vasovagal SyncopeSyncope is a sudden transient loss of consciousness with loss of postural tone, followed by spontaneous recovery1. Around 30 percent of the general population have one syncopal event in their lifetime, with 3% having recurrent episodes2. Vasovagal syncope (VVS) is an exaggerated tendency towards the common faint that accounts for up to 29% of syncope3 and affects all age groups. VVS is characterised by profound hypotension with or without bradycardia. Those with VVS are at risk of injury during episodes and the long term implications of recurrent episodes of hypotension are unclear1. The underlying pathophysiology of VVS is uncertain and current treatments involve salt and fluid replacement and maintenance of blood pressure using mineralocorticoids or alpha agonists1. These treatments are largely symptomatic and may be associated with side effects that make their use in younger age groups inappropriateJennifer GracieChristine BakerMark H. FreestonJulia L. Newton2005-04-17Z2011-03-11T08:55:57Zhttp://cogprints.org/id/eprint/4240This item is in the repository with the URL: http://cogprints.org/id/eprint/42402005-04-17ZArrhythmia Diagnosis Following an ICD Shock A 70 year old male with coronary artery disease, severe left ventricular dysfunction (LVEF 20%), first degree AV block and underlying QRS of 154 msec underwent upgrade of an existing dual chamber ICD system with a Medtronic Insync Model 7272. The device was programmed to provide atrial synchronized biventricular pacing in the DDD mode. He experienced significant improvement in heart failure symptoms following cardiac resynchronization therapy. His ICD was programmed for single zone detection in the VF zone at 182 bpm with first shock therapy of 24J. Pacing was programmed in the DDD mode with lower rate limit of 70 and upper rate limit of 120ppm.
Roy M John2005-04-17Z2011-03-11T08:55:57Zhttp://cogprints.org/id/eprint/4239This item is in the repository with the URL: http://cogprints.org/id/eprint/42392005-04-17ZA Case of Atrial Fibrillation from Cyclosporine ToxicityWe describe the unusual occurrence of atrial fibrillation immediately after a seizure in a young patient with cyclosporine toxicity. The new onset atrial fibrillation was triggered by high levels of cyclosporine and possibly facilitated by the electrolyte imbalances post seizure and the presence of underlying mild left atrial enlargement.
Pramod SanghiMasood Ahmad2005-04-17Z2011-03-11T08:55:57Zhttp://cogprints.org/id/eprint/4228This item is in the repository with the URL: http://cogprints.org/id/eprint/42282005-04-17ZDevices for Prevention of Atrial TachyarrhythmiasAtrial fibrillation (AF) is the most frequent sustained cardiac arrhythmia in clinical practice and, although its importance has been underestimated even in recent years, we are now becoming aware of its clinical transcendence1,2,3. The classical treatment is pharmacological, but its efficacy is limited and it does have side effects4,5. Therefore, in recent years, there has been an increasing interest in other types of non-pharmacological treatments6,7. Physiologic cardiac pacing has proven to be more effective than VVI mode pacing to prevent the occurrence of AF during the follow-up of patients who have had a permanent pacemaker implanted 8,9,10. There are currently different lines of research that use different atrial pacing techniques to prevent and treat episodes of paroxysmal atrial fibrillation11,12. Techniques of multi-site pacing in the right atrium or both atria, new atrial pacing sites, prevention algorithms for paroxysmal atrial fibrillation episodes, and even high-frequency atrial tachyarrhythmia termination algorithms have all been proposed. In this article, we will try to synthesize the grounds for and findings of the different lines of research currently being developed. Ignacio Fernández LozanoJorge ToqueroJosé Antonio Fernández DíazBogdan IonescuVanesa MoñivasPilar OrtizBeatriz Fuertes2005-04-17Z2011-03-11T08:55:57Zhttp://cogprints.org/id/eprint/4238This item is in the repository with the URL: http://cogprints.org/id/eprint/42382005-04-17ZOsborn Waves: History and SignificanceThe Osborn wave is a deflection with a dome or hump configuration occurring at the R-ST junction (J point) on the ECG (Fig. 1). In the historical view, different names have been used for this wave in the medical literature, such as “camel-hump sign”, “late delta wave”, “hathook junction”, “hypothermic wave”, “J point wave”, “K wave”, “H wave” and “current of injury”.1 Although there is no definite consensus about terminology of this wave, either “Osborn wave” or “J wave” are the most commonly used names for this wave in the current clinical and experimental cardiology. The Osborn wave can be generally observed in hypothermic patients,1,2,3,4 however, other conditions have been reported to cause Osborn waves, such as hypercalcemia,5 brain injury,6 subarachnoid hemorrhage,7 cardiopulmonary arrest from oversedation,8 vasospastic angina,9 or idiopathic ventricular fibrillation.10,11,12 Our knowledge about the link between the Osborn waves and cardiac arrhythmias remains sparse and the arrhythmogenic potential of the Osborn waves is not fully understood. In this paper, we present a historic review of Osborn waves and discuss their clinical significance in the various clinical settings.
Mitsunori MaruyamaYoshinori KobayashiEitaroh KodaniYoshiyuki HirayamaHirotsugu AtarashiTakao KatohTeruo Takano2005-04-17Z2011-03-11T08:55:57Zhttp://cogprints.org/id/eprint/4234This item is in the repository with the URL: http://cogprints.org/id/eprint/42342005-04-17ZRe-use of Explanted DDD Pacemakers as VDD- Clinical Utility and Cost Effectiveness Re-use of DDD pulse generators explanted from patients died of unrelated causes is associated with an additional cost of two transvenous leads if implanted as DDD itself, and high rate of infection according to some studies. We studied the clinical and economical aspects of reutilization of explanted DDD pacemakers programmed to VDD mode. Out of 28 patients who received VDD pacemaker during the period, October 2000- September 2001 in the Department of Cardiology, PGIMER, Chandigarh, 5 poor patients were implanted with explanted DDD pulse generators programmed to VDD mode. Each implantation was planned and carried out according to a standard protocol. The age ranged from 45 to 75 (mean-61) years. The indications for pacing were complete heart block (4) and second degree AV block (1). The clinical profile, costs and complications, if any were noted and followed up at regular intervals. The results were compared with patients who received new DDD pulse generators during this period. The additional cost for the atrial lead was not required in these patients. None of these patients had any local site infection. Compared to the two-lead system, the single lead system provided more rapid implantation and minimized complications associated with placement of an atrial lead. The explanted DDD pacemaker can be safely reused as VDD mode with same efficacy in selected patient population. This is associated with lower cost and complications compared to reimplantation as DDD itself.
KKN NamboodiriYP SharmaHK BaliA Grover2005-04-17Z2011-03-11T08:55:57Zhttp://cogprints.org/id/eprint/4235This item is in the repository with the URL: http://cogprints.org/id/eprint/42352005-04-17ZRefurbishing Pacemakers: A Viable ApproachCardiologists implant permanent pacemakers widely for indications like sick sinus syndrome and complete heart block. The guidelines for such implantations are well established1. However, in developing countries like India, all patients who need pacemakers do not receive them because of financial constraints. Even when such patients get a pacemaker, it is often a more affordable VVI pacemaker rather than the costly DDD pacemaker. The lack of a health insurance scheme and improper social support programs prevent the more widespread implantation of appropriate pacemakers.
However, in the developed countries and in affluent pockets of developing countries like India, the pacemaker implantation rates are quite high. Often permanent pacemakers are implanted in the very old and people with predicted brief longevities, due to medico-legal and other social reasons. There are quite a few instances when pacemakers are explanted within a year or even within a few months. This is often due to the unfortunate death of the patient due to unrelated causes. Such pacemakers have battery lives, which are near normal. These can be explanted from the dead patient after taking consent from the relatives and “refurbished” for use in another needy patient. Refurbishing involves proper re-sterilization, checking of battery life, pacing mode and other parameters and re-labelling with the current parameters including predicted battery life. These refurbished pacemakers are a suitable alternative for the financially ‘no option’ group of patients who otherwise would not afford a pacemaker. These can last nearly as long as the original pacemakers. Even pulse generators whose shelf lives have expired can also be resterilised and used gainfully for the economically deprived.
Anilkumar RBalachander J2005-04-17Z2011-03-11T08:55:57Zhttp://cogprints.org/id/eprint/4236This item is in the repository with the URL: http://cogprints.org/id/eprint/42362005-04-17ZRole of pharmacotherapy in Brugada syndrome In patients who undergo aborted sudden cardiac death or syncope of unknown origin (symptomatic Brugada syndrome), no one argues that the implantation of an ICD is the first-line therapy regardless of the findings of the EP study. For those patients, drug therapy plays not a contradictory but a complimentary role to the ICD by reducing the number of ICD shock deliveries. Prevention of VF contributes to the improvement in the quality of life of the patients by avoiding uncomfortable ICD shock deliveries.
As mentioned above, Belhassen et al. 11, performed EP-guided medical therapy in 34 patients with idiopathic VF, in 5 of whom the criterion of Brugada syndrome were fulfilled, and reported excellent long-term results. Although medical therapy requires markers that can accurately predict the preventive effect of VF over a long-term period, there, however, seems to be no reliable marker. An EP study is usually used to examine the preventive effects of antiarrhythmic agents on sustained ventricular tachycardia in patients with structural heart disease, whereas the prognostic value of the EP study in predicting life-threatening events in Brugada syndrome is still controversial. Brugada et al., 3 suggested that among the asymptomatic patients, the inducibility of VT during the EP study might be a prognostic marker of risk. Studies by Priori et al., 22 and Kanda et al., 23 failed to find an association between the inducibility and recurrence of VT/VF in patients with Brugada syndrome regardless of whether it was symptomatic or asymptomatic. As Belhassen suggested 13, the difference might be due to the VF induction protocol in the EP study, in which Belhassen et al., used a stimulus current intensity of five times the diastolic threshold along with the use of repetition of double and triple extrastimulation at the shortest coupling intervals that resulted in ventricular capture. Further appropriate clinical trials are needed to clarify this issue.
In patients with asymptomatic Brugada syndrome who are family members of symptomatic Brugada syndrome patients, the same strategy as that for the symptomatic Brugada syndrome patients should be considered 2,3,4. In another asymptomatic-patient group in whom an ECG that discloses the Brugada sign is performed for routine reasons such as a workup prior to surgery or sport license or screening for insurance, risk stratification to find the patients at high risk is needed because in most cases these patients have a benign prognosis3,22,23. Antzelevitch et al. 4, recommended that all asymptomatic patients with the Brugada sign should undergo an EP study for risk stratification, and, if inducible, an ICD should be implanted since Brugada et al.3, reported that an overall 8% life-threatening event rate was found in initially asymptomatic patients. Belhassen et al.,13 suggested that EP study-guided quinidine therapy might become an alternative to ICD therapy for prophylaxis of arrhythmic events in these patients. Further appropriate clinical trials are needed.Takeshi Tsuchiya2005-04-20Z2011-03-11T08:55:58Zhttp://cogprints.org/id/eprint/4242This item is in the repository with the URL: http://cogprints.org/id/eprint/42422005-04-20ZOptical Mapping Of Cardiac ArrhythmiasThe concept of mapping rhythmic activation of the heart dates back to the beginning of last century, with initial descriptions of reentry in turtle hearts1, to the first systematic mapping of sinus rhythm and then atrial flutter by Lewis et al2. Barker et al3 were the first to map the human heart. Initial mapping was primarily performed using single probes to record activation in different regions of the heart. The 1960’s and 70’s saw the development of computerized mapping of the human heart, e.g. in the cure of Wolf-Parkinson-White syndrome as well as in the study of Langendorff preparations4. In fact, most of the recent advances in cardiac mapping have focused on improvements in multisite recordings within the heart, with the ability to simultaneous record electrical activation from several hundreds of sites having contributed significantly to our understanding of atrial and ventricular arrhythmias.
Despite these recent advances, multisite contact mapping suffers from several limitations, including the technical problems associated with amplification, gains, sampling rates, signal-to-noise ratio, and the inability to see signals during high-voltage shocks. In addition, an intrinsic limitation of current mapping techniques is their inability to provide information about repolarization characteristics of electrically active cells, thereby limiting our ability to study entire action potentials. In fact, intracellular microelectrode recordings are still considered the gold standard for the study of action potential characteristics in whole tissue. Microelectrode techniques are limited however, by an inability to record action potentials from several sites simultaneously, thereby precluding their use in high-density activation mapping.
In part due to the above-mentioned limitations, the last few years have seen the development and use of voltage-sensitive dyes as a means to map not only activation, but repolarization as well. Voltage-sensitive dyes, when excited, provide an optical signal that mimics an action potential and thus allows the visualization of both activation and recovery processes in any region under view. This allows one to precisely evaluate the propagation of a wave of excitation and to measure its wavelength visually.
Optical mapping techniques use imaging devices such as a photodiode array or a charge-coupled device video camera with the heart being illuminated and either continuously or spatially scanned. The basis for these techniques is the use of voltage-sensitive dyes that bind to or interact with cell membranes.
Rishi AroraMithilesh K DasDouglas P ZipesJianyi Wu2005-04-20Z2011-03-11T08:55:58Zhttp://cogprints.org/id/eprint/4251This item is in the repository with the URL: http://cogprints.org/id/eprint/42512005-04-20ZBrugada Disease: Chronology Of Discovery And Paternity.
Preliminary Observations And Historical Aspects The Brugada disease, the last clinico-cardiologic entity described in the 20th century, initially called right bundle branch block syndrome with ST segment elevation from V1 to V2 or V3 and sudden cardiac death, is genetically determined in a dominant autosomal mode, and it affects the alpha subunit of the Na+ channel by alteration of chromosome 3 and mutation in the SCN5A gene.
In clinical diagnosis the mentioned electrocardiographic pattern in a patient without structural heart disease and positivity in pharmacological tests are considered major criteria. As minor criteria, the following are considered: positive family history, presence of syncope with unknown origin, documented episode of VT/VF, inducibility in electrophysiologic study and positivity of genetic study.
The long-standing technology of ECG, with more than a century of existence, remains as the supplementary method with highest value in diagnosis, and currently new electrocardiographic criteria are suggested, which indicate high risk of VF.
Natural history indicates a somber diagnosis in symptomatic patients with a high index of arrhythmic SCD secondary to very fast polymorphic ventricular tachycardia bursts, which degenerate into VF. Asymptomatic individuals with only a Brugada-type electrocardiographic pattern have a low risk. The prognosis seems to depend more on clinical facts, since a positive electrophysiologic study has an accuracy of just around 50%.
We propose that this entity should be promoted to the category of disease, since it has a characteristic set of signs and symptoms, and an identified genetic defect.
Andrés Ricardo Pérez RieraEdgardo SchapachnikCelso Ferreira2005-04-20Z2011-03-11T08:55:58Zhttp://cogprints.org/id/eprint/4246This item is in the repository with the URL: http://cogprints.org/id/eprint/42462005-04-20ZCatheter Ablation for Atrial FibrillationAtrial fibrillation (AF), the most common arrhythmia in adults, affects 1 in 25 people over the age of 60 years and 1 in 10 over the age of 80 years.1 There is considerable morbidity, mortality and economic burden associated with AF, all of which will increase with the expanding elderly population. Until recently, pharmacologic therapy with AV nodal blocking agents, antiarrhythmics and anticoagulation were the mainstay of therapy. Although electrical cardioversion is associated with a high immediate success rate, most patients have recurrences of AF with only 23% remaining in sinus rhythm one year after cardioversion.2 Antiarrhythmic agents have been shown to improve sinus maintenance, but these medications have variable success and are associated with many potentially serious side effects. In addition, the recently published AFFIRM trial suggests that a pharmacological rhythm control strategy has no benefit in terms of mortality or morbidity over a rate control and anticoagulation strategy.3 Over the last few years, there has been a great deal of enthusiasm regarding catheter based ablation strategies aimed at curing AF.
Andre J GauriBradley P Knight2005-04-20Z2011-03-11T08:55:58Zhttp://cogprints.org/id/eprint/4241This item is in the repository with the URL: http://cogprints.org/id/eprint/42412005-04-20ZThe fallacies of QT correctionNot to correct QT, but how to, that is the question”. The QT interval is a reflection of the action potential in the cardiac cells. Homogenous or heterogenous changes in the action potential duration lead to alteration of QT interval (in addition to morphological changes of T & U waves) 1. Such changes can be due to change in heart rate & autonomic tone. They can also be markers of abnormal repolarization, depolarization or both as a result of electrolyte disturbances, cardiac diseases, drugs and congenital long QT syndromes 2.
Repolarization disorders are responsible for life threatening arrhythmias like torsades de pointes2. The purpose of heart rate correction is to obtain a standardized value that would have been measured in the same subject if the heart rate was 60 beats per minute (QTc). Thus this QTc value will now become independent of the heart rate and measure replarization changes. It will thus be a surrogate marker of the risk of torsade de pointes.
The concept of QTc appeared in 1920, when Bazett introduced his square root formula 3. This formula obtained from data on 39 young men has been questioned because it overcorrects QT at fast heart rate and undercorrects at low heart rate (4). Thus at slow heart rate, which is one of the predisposing factors of torsade initiation, Bazett correction can easily mask substantial QT prolongation by under correcting. This can hide the proarrhythmic toxicity of drugs slowing heart rate. An alternative, cube root correction of Fridericia, corrects better than Bazett but again is not reliable at fast heart rates. Compared to these non linear correction formulae, linear regression correction obtained from large population data, like the Framingham heart study linear correction are still better 4.
Yash LokhandwalaToal SC2005-04-20Z2011-03-11T08:55:58Zhttp://cogprints.org/id/eprint/4243This item is in the repository with the URL: http://cogprints.org/id/eprint/42432005-04-20ZGenetic basis and pathogenesis of Familial WPW Syndrome
The Wolff-Parkinson-White (WPW) syndrome has been a known clinical entity for over fifty years. In 1967 Durrer et al postulated WPW syndrome was due to an accessory pathway, bypassing the AV node, from the atria to the ventricles1. This was later confirmed by epicardial mapping. WPW is the second most common cause of paroxysmal supraventricular tachycardias in the western world and the most common cause in China2. WPW syndrome has a prevalence of 1.5 to 3.1 per 1000 persons in western countries3,4,5 . Patients with the WPW syndrome may present with palpitations, presyncope, syncope, or sudden cardiac death (SCD). In some patients the first and only manifestation of the disease is SCD. This is more likely to occur in the setting of atrial fibrillation with a rapid ventricular response.
Electrocardiographic findings of WPW syndrome consist of preexcitation manifested by a shortened PR interval (<120 msec), a widened QRS (>100 msec) a delta wave (abnormal initial QRS vector) and supraventricular tachycardia. The EKG finding of preexcitation is a result of early ventricular depolarization through the accessory pathway. SVT can occur with retrograde or antigrade conduction through the accessory pathway forming the basis of the so-called “macro-reentrant” arrhythmia model 6. Rapid conduction through the accessory pathway in the setting of atrial fibrillation markedly increases the risk of SCD7.
We recently identified the gene responsible for familial Wolff-Parkinson-White 8. The gene (PRKAG2) which encodes for a protein AMPK (AMP- activated protein kinase) was identified as the causal gene. Missense (single nucleotide change) mutations in this gene were identified in families with WPW. Six such mutations have been identified. Along with preexcitation the affected families had conduction abnormalities (AV block) and cardiac hypertrophy.
Jasvinder SidhuRobert Roberts2005-04-20Z2011-03-11T08:55:58Zhttp://cogprints.org/id/eprint/4254This item is in the repository with the URL: http://cogprints.org/id/eprint/42542005-04-20ZIntra-atrial Re-entrant Tachycardia with Wenckebach PeriodicityA 15-year-old girl, previously asymptomatic for palpitations, underwent a successful atrial septal defect (ASD) device closure. Twelve weeks after the procedure, the patient was admitted complaining of dyspnoea on effort and palpitations. The twelve-lead ECG showed a narrow QRS tachycardia with slight heart rate irregularity, with a mean HR of 170bpm. P waves were not clearly identified with a suspicious of negative P-waves in II, III and aVF leads. No clear relationship could be observed between the suspected P waves and QRS complexes Berardo SarubbiPasquale VergaraMichele D’AltoFrancesco SessaRaffaele Calabrò2005-04-20Z2011-03-11T08:55:58Zhttp://cogprints.org/id/eprint/4255This item is in the repository with the URL: http://cogprints.org/id/eprint/42552005-04-20ZLatest Updates In EP
Side effects of antiarrhythmic drug (AAD) therapy -- not inefficacy -- are responsible for the inability of rhythm control to maintain long-term sinus rhythm, according to an analysis from the Rate Control vs. Electrical Cardioversion (RACE) study.1
Presenting the data at the European Society of Cardiology 2003 Congress (Vienna, Austria), Eduard H. Hoekstra, MD, University Hospital (Groningen, The Netherlands) on behalf of the RACE investigators reported that long-term maintenance of sinus rhythm was significantly reduced by the side effects of sotalol and amiodarone and the discontinuation amiodarone, but not by clinical characteristics. They suggested that the high incidence of side effects from the drugs is responsible for the failure of rhythm control to show superiority over rate control for the treatment of atrial fibrillation (AF), as reported in several large randomized trials. The current analysis was designed to determine the actual number of AAD side effects, their clinical characteristics, and relation of the side-effects to the failure of long-term maintenance of sinus rhythm in the 266 patients with AF (</= 6 months) randomized to the rhythm control arm of the RACE study. Patients enrolled in the study had persistent AF despite previous electrical cardioversion. Baseline clinical characteristics were "typical" of a patient population with persistent AF; 91% of rhythm patients presented with >/= 1 risk factor for stroke.2
Indranill Basu Ray2005-04-20Z2011-03-11T08:55:58Zhttp://cogprints.org/id/eprint/4253This item is in the repository with the URL: http://cogprints.org/id/eprint/42532005-04-20ZNearly Fatal Torsade de Pointes with SotalolA 75-year-old woman with paroxysmal atrial fibrillation (AF) experienced recurrent seizures at home. Holter monitoring (each line 50 sec) showed repetitive runs of torsade de pointes (TdP), degenerating into ventricular fibrillation and ventricular tachycardia (VT). Abrupt asytole heralded end of electrical activity and life. Amazingly, 6 min after cardiac arrest a slow ventricular escape rhythm arose spontaneously without resuscitation. At baseline, repolarisation was markedly prolonged (QTc>660 msec) and ventricular bigeminy triggered short bursts of TdP after „long-short” sequences. No hypokalemia or renal dysfunction was present. Following intensive treatment (sedation, magnesium iv, acceleration of heart rate) the patient recovered without neurological deficit. Except left ventricular hypertrophy and incomplete left bundle branch block the results of angiography, electrophysiological study and ajmaline test were normal. There was no family history of sudden death. Months ago a cardioversion attempt with ibutilide triggered polymorphic VT. Therapy with metoprolol (95 mg/day) was discontinued due to poor efficacy of rhythm control. Thus, sotalol (240 mg/day) was initiated in-hospital without signs of QT prolongation within 4 days (QT 416, QTc 432 msec). However, two weeks later the patient presented with an “idiosyncratic” proarrhythmic response to sotalol (IKr-blocking drug) and a life-threatening arrhythmia.1 There is growing evidence that drug-induced long QT syndrome (LQTS) may be due to "silent" mutations on LQT genes.2,3 Although not proven by molecular analysis, our case seems to resemble a subclinical, inherited form of LQTS that makes the patient vulnerable to the QT-prolonging effects of a variety of cardiac and noncardiac drugs. The concept of “repolarization reserve” suggests that any factor that impairs the repolarizing currents renders TdP very likely when IKr-blocking drugs are used. Avoiding torsadogenic drugs should basically prevent recurrence of TdP. However, an implantable cardioverter-defibrillator was placed for safety reasons.4 During a follow-up of more than two years a few non-sustained episodes occurred, the longest, a short-coupled polymorphic VT lasted for 25 beats resulting in a diverted shock..
Bernhard StrohmerChristiana SchernthanerMaximilian Pichler2005-04-20Z2011-03-11T08:55:58Zhttp://cogprints.org/id/eprint/4249This item is in the repository with the URL: http://cogprints.org/id/eprint/42492005-04-20ZPacemaker Lead Displacement: Mechanisms And Management Pacemaker lead displacements can be defined as any other pacemaker position change, whether the functionality of the pacemaker is affected or not. However, only those displacements that provoke a malfunction in the pacing system are clinically relevant. Chronologically speaking, there are early displacements, which occur within the first six weeks after implantation, and late displacements, after this period of time1. Early displacements are more frequent than late displacements and they usually affect atrial leads. The incidence of early displacements is 1% in VVI pacemakers and 5.2% in DDD pacemakers (3.8% of the cases affecting atrial leads and 1.4% ventricular leads). Acceptable displacement rates should probably be less than 1 percent for ventricular leads and no more than 2 to 3 percent for atrial leads. These values are higher in biventricular pacing devices, related to coronary sinus lead displacement. Early lead displacements are the most frequent cause of reintervention, involving atrial leads in the majority of cases. After the first six weeks, late displacements are remarkable and they can rarely be related to a specific event2.
Beatriz FuertesJorge ToqueroRamón Arroyo-EspligueroIgnacio F Lozano2005-04-20Z2011-03-11T08:55:58Zhttp://cogprints.org/id/eprint/4248This item is in the repository with the URL: http://cogprints.org/id/eprint/42482005-04-20ZRole of Atrial Fibrillation Threshold Evaluation on Guiding TreatmentAtrial fibrillation could be induced reproducibly by 50Hz rapid stimulation which was given through systolic and early diastolic phase of atrial excitation. Duration of atrial fibrillation induced in this way was roughly dependent on the current amplitude of the stimulation. The minimum current that could induce long-lasting atrial fibrillation (30sec in the clinical setting, 2sec in the rabbit or rat model) was defined as atrial fibrillation threshold (AFT). AFT was larger in patients who had history of atrial fibrillation than those who did not. Anti-arrhythmic drugs raised AFT by various degrees both in experimental and clinical cases. Long-term efficacy of a drug could be predicted in a patient, measuring how much the drug increased AFT (cut-off point = 5mA increase). AFT is a useful marker to evaluate atrial vulnerability and to guide pharmacological treatment of atrial fibrillation.
Takeshi Shirayama2005-04-20Z2011-03-11T08:55:58Zhttp://cogprints.org/id/eprint/4252This item is in the repository with the URL: http://cogprints.org/id/eprint/42522005-04-20ZSelecting Dual Chamber or Single Chamber Implantable Defibrillators: What is the Golden Rule?
During the last years, the implantation rate of dual chamber defibrillators (ICD) significantly increased worldwide. In 1999, the proportion of dual chamber ICD implants reached 30% in Europe and 50% in U.S.A.1. According to manufacturer data, in Italy, the ratio between implanted single chamber and dual chamber units decreased from 1.97 in 1999 to 1.86 in 2000 and 1.50 in 2001. Technological progress, demonstration of reliability and clinical efficacy of the new devices, combined with their smaller size, contributed to their wide acceptance. Nowadays, the matter to be debated is if all the patients in whom the atrium can be sensed and paced should receive a dual chamber ICD or if device selection should be individually evaluated according to different clinical profiles. As a matter of fact, criteria to identify the patients who may benefit more from dual chamber ICD have not been already defined. The theoretical advantages of dual chamber ICD include: improved discrimination between supraventricular and ventricular tachycardias, optimal treatment of symptomatic bradycardias (pre-existing, drug-induced or late developing), hemodynamic and antiarrhythmic benefits.
Massimo SantiniRenato Ricci2005-04-13Z2011-03-11T08:55:53Zhttp://cogprints.org/id/eprint/4166This item is in the repository with the URL: http://cogprints.org/id/eprint/41662005-04-13ZTilt Table Test: State of The ArtVasovagal syncope is the most frequent form of syncope of unknown aetiology. Since 1986, the tilt-table test has become an important tool in the diagnosis of vasovagal syncope. Before this test was introduced, several patients were submitted to a multitude of tests although most of them did little more than waste of resources. The similarity between clinical and induced vasovagal syncope during the test shows its value. The tilt-table test yields a range of positive results from 60% to 70%, with a specificity greater than 85%. The results are also highly reproducible (data similar to provocation diagnostic tests such as the treadmill test) when drug-based protocols are used. This, with the absence of serious complications and very small number of side effects, makes probably the nitroglycerine protocol as the actually most recommended test for clinical practice.Gonzalo Barón-EsquiviasAntoni Martínez-Rubio2005-04-20Z2011-03-11T08:55:58Zhttp://cogprints.org/id/eprint/4250This item is in the repository with the URL: http://cogprints.org/id/eprint/42502005-04-20ZTilt Table Test: State of The Art The loss of consciousness has been a subject of wonder and uncertainty in humans, and for this reason it has been the object of medical investigation since the beginning of time. Even actually, it is certainly an unresolved clinical problem. Many centuries ago, complicated exorcisms and remedies were used on these unfortunate patients, who upon regaining consciousness would find themselves soaked in miraculous liquids, ingesting curative potions, and often on the way to be burned accused of being possessed. In the seventeen century, physicians began to relate loss of consciousness and haemodinamic changes. William Harvey was perhaps the first to describe a circulatory response (vasovagal reaction) during a phlebotomy in the year 1628: “...Yet it fear or any other cause, or something do intervene through passion of the mind, so that the heart do beat more faintly, the blood will be no means pass through but drop after drop…”1. During the nineteenth century, loss of consciousness was the object of studies and research, and the vagally mediated cardioinhibition, as a primary cause, was noted by Foster who proposed that profound bradycardia diminished cerebral perfusion to a level inadequate to maintain consciousness2. At this time, it was reported the first use of the tilt-table test3. Commonly referred to as fainting or loss of consciousness, from last century the preferred medical term is syncope, which itself is derived from the Greek term “syncoptein” meaning “to cut short”. Syncope is defined as the sudden loss of consciousness and postural tone with spontaneous recovery. In 1907, Gowers was the first person to use the term vasovagal syncope4. In 1918 was published the work in which Cotton and Lewis described for the first time the clinical characteristics that are still used today to recognize the syncopal reaction5. However, it was not till 1932 when Lewis described this reaction as being characterized by a combination of bradycardia, hypotension, and syncope, and he coined the term vasovagal syncope for the first time6.
Gonzalo Barón-EsquiviasAntoni Martínez-Rubio2005-04-20Z2011-03-11T08:55:58Zhttp://cogprints.org/id/eprint/4245This item is in the repository with the URL: http://cogprints.org/id/eprint/42452005-04-20ZTransesophageal pacing : a versatile diagnostic and therapeutic toolTransesophageal atrial pacing is feasible because of the proximity between the oesophagus and the posterior aspect of the atria1. Atrial pacing is possible through the oesophagus in almost all patients and can yield important information in many arrhythmias where single site atrial pacing is of value. It is a cheap procedure. There is no need for X Rays or cathlab.
Technical considerations
Transesophageal pacing and recording is done using specialized or non specialized catheters. There are two different lead types: 1) the pill electrode, connected to a flexible wire, that the patient swallows with water. This pill electrode necessitates patient collaboration. 2) a flexible catheter that can even be used in comatose or intubated patients.
The pacing lead, in our cases a bipolar flexible catheter, is introduced into the oesophagus via the nares after local nose anesthesia with xylocaine spray. Sometimes throat anesthesia with the same spray is also performed. Xylocaine gel is used to lubricate the lead and the lead is introduced with guidewires in it in order to increase its stiffness. It is positioned into the oesophagus in order to record the posterior paraseptal atrial electrogram. There is a relationship between the site of maximal atrial amplitude and the lowest atrial pacing threshold. The optimal atrial pacing site is usually found around 40 cm from the nares. Bipolar or unipolar recordings can be made.
Thierry VerbeetJosé CastroPierre Decoodt2005-04-24Z2011-03-11T08:55:59Zhttp://cogprints.org/id/eprint/4279This item is in the repository with the URL: http://cogprints.org/id/eprint/42792005-04-24ZArrhythmogenic Right Ventricular Cardiomyopathy/DysplasiaArrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is characterized by the patchy replacement of myocardium by fatty or fibrofatty tissue. These changes lead to structural abnormalities including right ventricular enlargement and wall motion abnormalities that can be detected by echocardiography, angiography, and cine MRI. ARVC/D is a genetically heterogeneous disorder, since it has been linked to several chromosomal loci. Myocarditis may also be a contributing etiological factor. Patients are typically diagnosed during adolescence or young adulthood. Presenting symptoms are generally related to ventricular arrhythmias. Concern for the risk of sudden cardiac death may lead to the implantation of an intracardiac defibrillator. An ongoing multicenter international registry should further our understanding of this disease.
Julia H. IndikFrank I. Marcus2005-04-20Z2011-03-11T08:55:58Zhttp://cogprints.org/id/eprint/4256This item is in the repository with the URL: http://cogprints.org/id/eprint/42562005-04-20ZBrugada-Like Electrocardiographic Pattern The Brugada syndrome is characterized by a ST-segment elevation in the right precordial leads associated with right bundle branch block (RBBB) pattern and a propensity for life-threatening ventricular arrhythmias in the absence of structural heart disease.1 Mutations in a cardiac sodium channel gene have been linked to this syndrome2.
The mechanism underlying the RBBB and ST-segment elevation in right precordial leads in patients with the Brugada syndrome is thought to be an outward shift of the ionic currents during early repolarization causing a marked accentuation of the action potential notch in right ventricular epicardial but not endocardial cells. The outward shift of current ultimately leads to loss of the action potential dome causing marked abbreviation of the action potential in the right ventricular epicardial cells.3, 4,Johnson FrancisCharles Antzelevitch2005-04-24Z2011-03-11T08:55:59Zhttp://cogprints.org/id/eprint/4282This item is in the repository with the URL: http://cogprints.org/id/eprint/42822005-04-24ZBrugada-like Precordial ST Elevation on ECG by Anterior Mediastinal Infective Mass LesionSeveral causes are known to induce the right precordial ST elevation mimicking Brugada syndrome. Right ventricular outflow area is assumed to be responsible for such ECG changes. We experienced a case of anterior mediastinal infective mass lesion with a Brugada-like ECG.
A 52-year-old female, who has pulmonary stenosis and recurrent episodes of right ventricular heart failure, complained of high fever, abdominal discomfort, and edema. On physical examination, jugular vein dilation, hepatomegaly, and facial and leg edema were noted. Leucocytosis was also noted on blood examination. An ECG showed right ventricular hypertrophy, incomplete right bundle branch block pattern and marked ST elevation on precordial leads mimicking Brugada syndrome. Magnetic resonance imaging revealed an abnormal mass shadow located on the anterior mediastinum and compressing the right ventricle (Figure 1A). Trans-thoracic echocardiography also showed the high echogenic mass lesion at the anterior side of right ventricle and the vicinity of pulmonary valve. After treatment with antibiotics, the mass lesion gradually shrunk. Concomitantly, the ST elevation disappeared with improvement of inflammatory markers (Figure 1B). The symptoms suggesting right ventricular failure were also ameliorated. The mechanism of Brugada-like ST elevation in this patient was considered to be compression, by the abnormal infective mass, of the right ventricular outflow tract with/without focal pericardial inflammation.Yuji NakazatoTakayasu OhmuraIssei ShimadaHiroyuki Daida2005-04-24Z2011-03-11T08:55:59Zhttp://cogprints.org/id/eprint/4277This item is in the repository with the URL: http://cogprints.org/id/eprint/42772005-04-24ZCardiac Resynchroniztion Therapy In Heart Failure: Recent Advances And New InsightsNewer non-pharmacological therapies for heart failure are being evaluated for patients of congestive heart failure (CHF). Mechanical support with left ventricular assist devices and heart transplantation are reserved for the minority of patients who have severely decompensated heart failure1. Despite these therapeutic advances, it is generally accepted that current therapies do not adequately address the clinical need of patients with heart failure, and additional strategies are being developed. Cardiac resynchronization therapy (CRT) is a new modality that involves synchronization of ventricular contraction and has shown a lot of promise in managing symptomatic patients of CHF who are on optimal medical therapy and have interventricular conduction delay (IVCD). It has improved exercise tolerance and NYHA functional class in such patients in sinus rhythm and a recent meta-analysis has also shown mortality benefits in CHF. Recently benefits of CRT have also been observed in CHF patients who do not have wide QRS complexes on electrocardiogram (EKG). It has also been shown to benefit drug refractory angina in CHF. Recent studies have also focused on the combined use of CRT and implantable cardioverter defibrillator (ICD) and it has shown encouraging results. Our aim in this descriptive review is to define practice guidelines and to improve clinicians' knowledge of the available published clinical evidence, concentrating on few randomized controlled trials. V BhatiaR BhatiaS DhindsaA Virk2005-04-24Z2011-03-11T08:55:59Zhttp://cogprints.org/id/eprint/4278This item is in the repository with the URL: http://cogprints.org/id/eprint/42782005-04-24ZCongenital Junctional Ectopic Tachycardia: Presentation And OutcomeJunctional ectopic tachycardia (JET) is a rare type of supraventricular arrhythmia. Even if its management has improved in recent years, it remains a great challenge for the cardiologist. Two are the possible clinical presentations of this arrhythmia: as a primary idiopathic disorder during infancy, configuring the so called “congenital” JET, or more often as a transient phenomenon immediately after surgery for congenital heart disease, giving rise to the “post-operative” variety.
The congenital form, firstly described as a distinct entity by Coumel et al. in 19761, usually occurs in the first six months of life presenting as a persistent sustained form, lasting up to 90% of the time. Its clinical presentation may be dramatic, being associated in up to 60% of cases with cardiomegaly and/or heart failure.
Congenital JET is hampered by high mortality. Secondary dilated cardiomyopathy, ventricular fibrillation and sudden cardiac death have also been reported 2,3.
Berardo SarubbiPasquale VergaraMichele D’AltoRaffaele Calabrò2005-04-24Z2011-03-11T08:55:59Zhttp://cogprints.org/id/eprint/4281This item is in the repository with the URL: http://cogprints.org/id/eprint/42812005-04-24ZDo All Children with Congenital Complete Atrioventricular Block Require Permanent Pacing ?
With an incidence of 1 in 20’000 live born infants1, congenital complete atrioventricular block (CCAVB) is a rare disease. The aetiology is not completely understood. However, CCAVB may be isolated or combined with congenital heart diseases in up to 53% of affected individuals2. Isolated CCAVB is in up to 98% of the children associated with positive autoimmune antibodies in the maternal serum (anti-Ro/SS-A and anti-LA/SS-B)3,4. Interestingly, these antibodies are not specifically directed against the conduction system but also against normal myocardial cells and may cause myocarditis5,6. Affection of the conduction system can occur at different levels7. Histologically, the atrioventricular node tissue may be replaced by fibrous fatty tissue with variable involvement of the distal conduction system8.
The onset of clinical symptoms in patients with CCAVB is already antenatally in up to 28%9, but can also occur only later in life. This is due to a variable degree of heart block and heart rate. Most of the symptoms are related to the slow heart rate: hydrops foetalis, heart failure of the neonate, exercise intolerance of the child. Longer pauses may cause praesyncope, syncope (classical Adams Stokes attacks) or even sudden cardiac death. Whether or not Cardiomegaly is mainly the result of a chronic compensatory increased stroke volume secondary to the slow heart rate is somewhat controversial10. Cardiomegaly may also be a distinct disease in a subgroup of patients because it does not necessarily resolve with pacemaker (PM) therapy11,12. Morbidity and mortality of CCAVB do not seem to correlate with antibody status or associated cardiac lesions13,14. There are case reports, that fetal CCAVB can be improved with steroids15. Rarely, CCAVB resolves spontaneously16,17,18,19. In most patients, the degree of conduction abnormality will either persist or worsen over time.
Christian BalmerUrs Bauersfeld2005-04-24Z2011-03-11T08:55:58Zhttp://cogprints.org/id/eprint/4260This item is in the repository with the URL: http://cogprints.org/id/eprint/42602005-04-24ZFactors Influencing Lesion Formation during Radiofrequency Catheter Ablation
In radiofrequency (RF) ablation, the heating of cardiac tissue is mainly resistive. RF current heats cardiac tissue and in turn the catheter electrode is being heated. Consequently, the catheter tip temperature is always lower - or ideally equal - than the superficial tissue temperature. The lesion size is influenced by many parameters such as delivered RF power, electrode length, electrode orientation, blood flow and tissue contact. This review describes the influence of these different parameters on lesion formation and provides recommendations for different catheter types on selectable parameters such as target temperatures, power limits and RF durations.
Olaf J. Eick2005-04-20Z2011-03-11T08:55:58Zhttp://cogprints.org/id/eprint/4258This item is in the repository with the URL: http://cogprints.org/id/eprint/42582005-04-20ZThe Lead Extractor's Toolbox: A Review Of Current Endovascular Pacemaker And ICD Lead Extraction Techniques
Recently introduced pacemaker leads float freely within the veins and myocardium. Later on, fibrous encapsulation of the lead develops 1. These adhesions not only occur at the lead tip but are commonly found anywhere along the whole length of the lead at sites where the lead is in contact with the vein or the myocardium 1,2,3,4. These adhesions hamper lead removal as tight scar tissue can withhold the leads during traction. This not only occurs at the level of the flings and tines of passive fixation leads but at any level of the lead body, especially at sites of unequal diameter for example electrodes and defibrillator coils. Further the lead tip is often larger than the lead body due to the fixation mechanism and adhering scar tissue and can become impacted on withdrawal in the narrow canal provided by the fibrous envelope.
Force applied to leads is limited by the tensile strength of the insulation and conductor coils of the leads. They may severe with forceful traction, and denuded indwelling lead fragments have a higher incidence of thrombo-fibrotic complications and may maintain infection 5,6,7,8. Force is also limited by the impact of traction on the veins and myocardium. Unopposed traction can lead to invagination of the myocardium, myocardial rupture, arrhythmia, hypotension or avulsion of a tricuspid valve leaflet 9,10,11,12,13.
Therefore, additional tools have been developed to assist in freeing the lead body from the adhesions as well as the lead tip from the myocardium, to prevent laceration of the myocardium and to provide enough room for the lead to be withdrawn whilst preventing disintegration of the lead. We describe the technical aspects of current endovascular techniques, the results, the complications and shortly discuss the indications.
FA Bracke2005-04-24Z2011-03-11T08:55:59Zhttp://cogprints.org/id/eprint/4280This item is in the repository with the URL: http://cogprints.org/id/eprint/42802005-04-24ZLeft Septal Fascicular Block: Myth Or Reality?
Anatomic studies have shown that the left bundle branch divides into three fascicles in most humans. Changes in the 12 lead ECG (electrocardiogram) due to conduction abnormalities of the left anterior fascicle and left posterior fascicle are now part of the standard repertoire of electrocardiographic interpretation. There are no standard criteria for detecting conduction defects involving the third left fascicle, the septal or median fascicle, and the very existence of such defects is still a matter of controversy. The purposes of this article are to review the available evidence on this subject, suggest electrocardiographic criteria for its recognition, and present examples which illustrate that left septal fascicular block does indeed exist as a specific entity. Left septal fascicular block is a polymorphic conduction defect which may explain some previously inadequately understood electrocardiographic abnormalities.
Rex N. MacAlpin2005-04-24Z2011-03-11T08:55:58Zhttp://cogprints.org/id/eprint/4259This item is in the repository with the URL: http://cogprints.org/id/eprint/42592005-04-24ZSinoatrial Reentry Tachycardia: A ReviewThe concept of reentry within the sinus node is by no means new. In their 1943 report, Barker and co-workers postulated that “…a circus rhythm could be accommodated in auricular muscle and in one of the specialized nodes at known rates of conduction and with cycle lengths such as occur in paroxysmal tachycardia” 1. Lack of invasive electrophysiology at that time and subsequent failure to appreciate the heterogeneity of supraventricular arrhythmias, left their astute observation in the realm of conjecture. It was not until 1968 that Han, Malozzi and Moe finally demonstrated the existence of sinoatrial echoes 2. In a superfused isolated rabbit right atrial preparation, they examined the response to premature extrastimuli with an 18 electrode grid at the sinus node and surrounding atrial tissue. They found that critically timed extrastimuli led to early re-excitation of the atrium, supposedly due to sinoatrial reentry. Sequential microelectrode measurements of sinus node and atrial transmembrane potentials were performed in an attempt to provide a temporal and anatomical map of the observed phenomenon. Based on findings, the authors concluded that sinoatrial reciprocation was caused by entrance block at one site, slow conduction within the node with disparate refractoriness, and re-excitation of the atrium at the original area of entrance block. They went on to suggest that repetition of this phenomenon may conceivably form the basis for clinically relevant tachycardia. In vivo confirmation of sinoatrial echoes was inferred from work by Childers 3 and Paulay 4. In the former study, programmed electrical stimulation was performed in dogs. Three responses to premature atrial stimuli were noted: complete interpolation (i.e. the subsequent sinus complex was on time), incomplete interpolation (i.e. the subsequent beat was delayed), and sinus echo. In the latter, the first post-extrastimulus complex was electrocardiographically the same as sinus, but earlier than expected. The authors attributed this to sinoatrial reentry, and went on to describe each of the three responses to premature atrial beats in a 70-year-old man in an elegant electrocardiographic deduction of underlying mechanisms. An in vivo canine model was also employed in the report by Paulay et al. While confirming Childers’ findings, Paulay offered two additional pieces of evidence implicating the sinus node/perinodal area: firstly, timing of the echo was independent of stimulation site (they performed pacing at the sinus node, Bachmann’s bundle, right and left atrial appendages and low atrial septum), and secondly echoes were eliminated by crushing the sinus node. As has long been the case for AV nodal reentry tachycardia, it is apparent that considerable discussion also revolves around the issue of whether sinoatrial echoes do or do not involve perinodal atrial tissue as well as the sinus node itself. In 1979, Allessie and Bonke published work suggesting confinement of the re-entrant circuit to the node per se 5. The experimental set-up was similar to earlier work by Han 2, with the significant difference that resolution of the measuring electrodes was superior: 32 unipolar surface atrial electrograms were recorded during initiation of sinoatrial echoes as opposed to the 18 used by Han. In addition, up to 130 transmembrane sinus node potentials were recorded sequentially in cases of sustained reciprocation. These detailed observations led to the conclusion that sinus node reentry was confined to a circuitous pathway in an extremely small area (1-2mm) with low conduction velocities (2.5cm/s) within the node itself. It is of note that the same authors pointed out the inability to induce sustained arrhythmia in this model, and later concluded that sinoatrial reentry tachycardia (SART) may not be feasible without border zone atrial tissue. Given the limitations inherent to in vivo study in man, it may be fair to continue to use “sinus node reentry” and “sinoatrial reentry” synonymously for the time being. In the wake of in vivo studies in dogs, and reports of sinus node reentry in man by Paulay 6 and Childers 3, Narula first described sustained SART in two patients in 1974 7. Out of 300 patients undergoing electrophysiologic study, he observed sinus node reentry beats in 20, and sustained tachycardia in two. The criteria for the diagnosis of SART proposed by Narula are still valid: 1. atrial activation and P-wave morphology are the same or highly similar to sinus rhythm, with activation from high to low right atrium, 2. the arrhythmia is inducible with atrial extrastimuli at specific coupling intervals, independent of AV nodal conduction intervals and site of stimulation, and 3. the arrhythmia can be terminated by atrial stimuli. SART is thus, by definition, a paroxysmal arrhythmia.
TA SimmersN Sreeram2005-04-20Z2011-03-11T08:55:58Zhttp://cogprints.org/id/eprint/4257This item is in the repository with the URL: http://cogprints.org/id/eprint/42572005-04-20ZSurgical treatment of permanent atrial fibrillation during cardiac surgery using monopolar and bipolar radiofrequency ablationObjective: Permanent atrial fibrillation (pAF) is a serious problem in cardiac surgery: An incidence of 3.5% among all patients scheduled for open heart surgery, 9.8% in heart valve cases and 45.6% among patients with severe rheumatic mitral valve (MV) disease was observed in our institution. Our experience with radiofrequency (RF) ablation procedures to treat pAF in these cases is reported.
Methods: Since February 2001 monopolar endocardial RF ablation procedures creating two encircling isolation lesions around the left and the right pulmonary veins (LPVs, RPVs) and a connection line between both were performed in patients with pAF concomitant to heart valve surgery. Since March 2003 bipolar RF ablation was used as an adjunct to CABG surgery. Amiodarone was given for 3 months after surgery.
Results: Sixtytwo patients with pAF underwent surgical ablation procedures and primary valve (mitral: n=45; aortic: n=13; aortic+mitral: n=1; LA-diameter 55.6±7.3 mm) or CABG surgery (n=3). Follow-up was performed at 3, 6, 9, 12, 18 and 24 months; 75% had stable sinus rhythm (SR) at late follow-up. Almost 90% of the patients with a preoperative LA-diameter of <56mm had SR.
Conclusion: Isolation of the PVs using RF ablation procedures in combination with amiodarone therapy represents a safe and efficient option to cure pAF in patients undergoing open heart surgery.
Stephan GeidelJörg OstermeyerMichael LassSigrid BoczorKarl-Heinz Kuck2005-05-02Z2011-03-11T08:56:01Zhttp://cogprints.org/id/eprint/4288This item is in the repository with the URL: http://cogprints.org/id/eprint/42882005-05-02ZAtrial Remodeling: Evolving ConceptsThe term "Electrophysiological remodeling" defines the changes of atrial electrophysiologic properties taking place in atrial myocites during atrial fibrillation and/or following periods of sustained atrial fibrillation (AF).
Early research was prompted by clinical observations: many patients were seen to get through increasingly frequent and longer paroxisms of AF to persistent AF, until chronic AF eventually ensued, without significant changes of underlying heart disease.
Mauro BiffiGiuseppe Boriani2005-05-02Z2011-03-11T08:56:00Zhttp://cogprints.org/id/eprint/4287This item is in the repository with the URL: http://cogprints.org/id/eprint/42872005-05-02ZThe Effects Of Right Ventricular Apical Pacing On Left Ventricular Function
Stimulation Of The Right Ventricular Apex: Should It Still Be The Gold Standard?
Current pacing practice is undergoing continuous and substantial changes. Initially pacing had an exclusively palliative role, since it was reserved for patients developing complete heart block or severe symptomatic bradycardia. With the appearance of novel pacing indications such as pacing for heart failure and atrial fibrillation, the effect of pacing site on cardiac function has become a critically important issue and a subject for consideration. It seems that the classical pacing site in the right ventricular apex is no longer the gold standard because of possible disadvantageous effects on cardiac function. The aim of this review article is to discuss the effect of right ventricular apical pacing on cardiac function including cellular and hemodynamic changes. We also aim to discuss the role of alternative pacing sites in the light of cardiac function.
T Szili-TorokA Thornton2005-05-02Z2011-03-11T08:56:00Zhttp://cogprints.org/id/eprint/4284This item is in the repository with the URL: http://cogprints.org/id/eprint/42842005-05-02ZMahaim Fibre Tachycardia: Recognition and Management
Dr. Gallagher et al1 wrote 22 years ago that "the role of Mahaim fibers in the genesis of cardiac arrhythmias in man has been controversial since they were first described " in the late 30's by Dr. Ivan Mahaim2. The very early reports were strictly anatomical studies2,3,4,5,6. This histopathologic quest did not end yet. Mahaim fibers were supposed to be accessory connections taking off from the His bundle and fascicles (FV-fasciculoventricular) to the right ventricle or from the atrioventricular node (NV-nodoventricular fibers) to the right ventricle. Anderson et al7 proposed 2 varieties of NV fibers, one that arises from the transitional zone and the other which inserted from the deep, compact nodal portion of the AV junction. In his pioneering work HJJ Wellens paved the road for clinical electrophysiological investigation. He was the first to study a patient with accessory pathway with decremental properties and long conduction times assuming its relationship with the fibers described long ago by "Mahaim", as reported in his doctoral thesis8 in 1971. The term nodofascicular (NF) was applied when the retrograde His bundle potential preceded the ventricular deflection, while nodoventricular pathway would be appropriate when the retrograde His bundle deflection followed the ventricular potential. It took some years to electrophysiologists realize the conceptual mismatch among the "Mahaim" physiology and structure described by Mahaim et al. An important observation was done in 1978 by Becker et al5 who found an accessory node associated with a bundle of specialized fibers measuring 1 cm and coursing through the right ventricle, mimicking a second AV conduction system located on the lateral tricuspid annulus. However, that did not change the mainstream concept of NV fibers. During the early 80's many centers started to refer patients with drug refractory tachycardias to surgical treatment. According to the current concepts at that time targeting the A-V node would be the logic strategy for curative treatment of patients with NV/NF fibers. Some courageous electrophysiologists used a new technique consisting of high-energy catheter ablation of the A-V node to treat a patient with "Mahaim" fiber, which yielded complete AV block and persistent preexcitation9. The turning point came in 1988 at the University Hospital of Western Ontario, Canada, when Klein, Guiraudon et al10 had decided to extensively freeze the A-V node and upper His bundle region of a 29 year old man and they soon realized that preexcitation did not go away. It became clear for them that his accessory pathway was not linked whatsoever to the A-V node. The next patient was luckier, and had kept intact his A-V node, while his "Mahaim fibers" were successfully severed after ice mapping produced a consistent zone of reversible block in the accessory pathway at the right lateral aspect of the tricuspid annulus. Klein's manuscript was received on August 24, 1987, and published the next year on JACC. Two months later (October 20, 1987) Circulation received a manuscript from Tchou P et al11 entitled "Atriofascicular connection or a nodoventricular fiber? Electrophysiologic elucidation of the pathway and associated reentrant circuit". From a single case report we were taught how simple it is to make sure that such pathways arise from the atrium. In recent years catheter ablation techniques have shed more light on the subject. Discrete "Mahaim" potentials that are considered surrogates of pseudo-Mahaim tissue depolarization, are used as an effective target for ablation12,13. A number of pharmacologic14 and histologic data5,6,15,16, electrophysiologic maneuvers and observations during radiofrequency catheter ablation like heat induced "Mahaim" automaticity19,20 are regarded as evidences of either an ectopic A-V node or remnants of the specialized A-V ring tissue. The NV/NF fibers are now considered a rare item but there are some convincing reports21 of narrow and regular QRS tachycardias with ventriculoatrial dissociation. The last variety which is known as fasciculoventricular pathway22 seems to play no role in clinical tachycardias but as long as it is very often associated with bypass tracts they should be correctly recognized and not targeted for ablation, avoiding unnecessary damage to the A-V node-His bundle conduction system.Eduardo Back Sternick2005-05-02Z2011-03-11T08:56:01Zhttp://cogprints.org/id/eprint/4289This item is in the repository with the URL: http://cogprints.org/id/eprint/42892005-05-02ZPacing for the Suppression of Paroxysmal Atrial Fibrillation in an 87-year-old Patient
Background: Sinus node dysfunction, atrioventricular (AV) block and atrial fibrillation (AF) are associated with advanced age. Required therapy commonly includes pacemaker implantation.
Methods: We report the course of therapy for an 87-year-old with symptomatic sinus node dysfunction and paroxysmal atrial fibrillation who was intolerant of drug therapy.
Results: The patient received a pacemaker for treatment of sick sinus syndrome. She continued to have symptomatic episodes of AF and was intolerant of pharmacologic therapy despite adequate rate support provided by the pacemaker. The AF suppression algorithm in the pacemaker was enabled, resulting in the elimination all AF episodes effectively eliminating the need for antiarrhythmic medication. If this continues to stabilize her atrium, withdrawal of anticoagulation therapy is anticipated.
Conclusions: The clinical presentation of sinus node dysfunction and related conduction abnormalities is common in the elderly. Pharmacologic management is often a challenge in the presence of the advanced age and concomitant disease processes. In individuals who have paroxysmal atrial fibrillation or are likely to develop this and who need a pacemaker for standard indications, the availability of an AF Suppression™ algorithm may facilitate their management without needed to use medications or being able to utilize lower doses of those medications. Paul A. LevineRobin WachsnerAdel El-Bialy2005-05-02Z2011-03-11T08:56:00Zhttp://cogprints.org/id/eprint/4285This item is in the repository with the URL: http://cogprints.org/id/eprint/42852005-05-02ZPreventing Sudden Death And The Use Of Prophylactic Implanted DefibrillatorsImplanted defibrillators have become mainstream therapy for the prevention of sudden cardiac death from ventricular tachyarrhythmias. A decade of studies has confirmed the superiority of ICDs over antiarrhythmic drug therapy in prolonging the life of patients with a prior history of sustained VT or VF.
More recent studies have compared ICD therapy to drugs or no antiarrhythmic therapy as ‘primary prophylaxis’ in patients considered at high risk for sudden death or with prior MIs. In selected patients, ICDs lead to important relative and absolute reductions in mortality in patients with no prior history of sustained VT or VF. Clinicians need to carefully consider these studies in their management of patients with CAD and severe LV dysfunction.Indranill Basu Ray2005-04-24Z2011-03-11T08:56:00Zhttp://cogprints.org/id/eprint/4283This item is in the repository with the URL: http://cogprints.org/id/eprint/42832005-04-24ZSuppression of Paroxysmal Atrial Fibrillation by Pacing Atrial Fibrillation (AF) affects approximately five million people world- wide. The incidence of AF increases with aging and more common in males.1 Atrial fibrillation is the most common cardiogenic cause of stroke and exacerbates heart failure. Despite the prevalence of AF, it is still one of the most difficult arrhythmia to treat.2 The management option of AF ranges from pharmacological therapy, catheter based ablation and surgery. However, non-traditional uses of pacemaker therapy have been reported in recent past.
Pacing therapies for AF are specific to the nature of the patient’s AF. 3,4 Pharmacological management alone is the typical initial course of action. In AF cases where rapid ventricular rates cannot be controlled by pharmacological therapy, ventricular pacing therapy may be combined with radiofrequency catheter ablation of AV node. 5
Anoop K. Gupta2005-05-02Z2011-03-11T08:56:00Zhttp://cogprints.org/id/eprint/4286This item is in the repository with the URL: http://cogprints.org/id/eprint/42862005-05-02ZT Wave Alternans And Ventricular Tachyarrhythmia Risk Stratification: A ReviewSudden cardiac death (SCD) is one of the leading causes of mortality in industrialized countries. Thus, identifying patients at high risk of SCD is an important goal. T wave alternans (TWA) is a new method for identifying patients with lethal ventricular tachyarrhythmias, and is dependent on heart rate. The maximal predictive accuracy is achieved at heart rates between 100 and 120 bpm, so that TWA is usually measured during exercise, phamacological stress, or atrial pacing. It has been shown that TWA has high sensitivity and negative predictive value for predicting SCD after myocardial infarction and is also useful for predicting SCD in patients with nonischemic cardiomyopathy. Although the implantable cardioverter defibrillator (ICD) is now the primary therapy for preventing SCD, it is difficult to identify those patients who are susceptible to lethal ventricular tachyarrhythmias for primary prevention. In the prediction of SCD, TWA can be used as a screening test of appropriate patients for further electrophysiological examination and therapy.
Masahiko TakagiJunichi Yoshikawa2005-05-02Z2011-03-11T08:56:01Zhttp://cogprints.org/id/eprint/4295This item is in the repository with the URL: http://cogprints.org/id/eprint/42952005-05-02ZExcerpts from Electrophysiology Sessions at the European Society of Cardiology Congress 2002 - BerlinAdministration of adenosine triphosphate (ATP) in sinus rhythm identifies dual atrioventricular node physiology (DAVNP) in 75% of patients with inducible slow / fast AV nodal reentrant tachycardia (AVNRT). The incidence of DAVNP following termination of AVNRT with ATP is unknown. Incremental doses of ATP (10-60mg) were administered, first in sinus rhythm and then during tachycardia induced at electrophysiologic study, to 84 patients with inducible AVNRT and to 18 control patients with inducible AV reentrant tachycardia (AVRT) and no electrophysiologic evidence of DAVNP. Study end-points were the occurrence of DAVNP or > 2nd degree AV block following administration of ATP in sinus rhythm and tachycardia termination following administration of ATP during tachycardia. Of the 82 patients with AVNRT who completed the study, 62 (75.6%) exhibited DAVNP following administration of 17.1 + 9.4 mg ATP in sinus rhythm, while 30 (36.5%) exhibited DAVNP at the termination of AVNRT following administration of 10.6 + 2.4 mg ATP. The occurrence of DAVNP following the administration of 10 mg ATP in sinus rhythm.was a good predictor (62%) of its occurrence after termination of AVNRT with ATP. The dose of ATP had a strong correlation between the presence of DAVNP following AVNRT termination and the ATP doses needed for tachycardia termination. Of the 18 control patients, none had DAVNP at ATP test during sinus rhythm but 1 (5.5%) showed slight (60 msec) PR jump after termination of AVRT with ATP. In conclusion, DAVNP is present in a relatively high proportion (36.5%) of patients following termination of AVNRT with ATP but is much less frequent (5.5%) in control patients. Thus, findings at termination of tachycardia by ATP may be useful in the noninvasive diagnosis of the mechanism of a paroxysmal supraventricular tachycardia. Ashish Nabar2005-05-02Z2011-03-11T08:56:01Zhttp://cogprints.org/id/eprint/4292This item is in the repository with the URL: http://cogprints.org/id/eprint/42922005-05-02ZHeart Rate Turbulence: a ReviewHeart rate turbulence (HRT) is a recently coined phrase that describes the short term fluctuation in sinus cycle length that follows a ventricular premature complex (VPC). Its proven clinical significance lies in its ability to predict mortality and sudden cardiac death following myocardial infarction, although small studies suggest that it is also applicable to many other cardiac diseases. This review will attempt to summarize the literature to date, and to speculate on possible mechanisms. Because HRT is a new field, there are only a handful of full length papers on it. In order to present the full breadth of the research being carried out, the information provided here is based on conference abstracts as well as peer reviewed articles, and readers should keep this in mind. Most of the literature cited here, and downloadable HRT calculation programs (in C++) are available on the website www.h-r-t.org. Mari A. Watanabe2005-05-02Z2011-03-11T08:56:01Zhttp://cogprints.org/id/eprint/4294This item is in the repository with the URL: http://cogprints.org/id/eprint/42942005-05-02ZHeart Rate Variability Analysis in General Medicine
Autonomic nervous system plays an integral role in homeostasis. Autonomic modulation can frequently be altered in patients with cardiac disorders as well as in patients with other critical illnesses or injuries. Assessment of heart rate variability is based on analysis of consecutive normal R-R intervals and may provide quantitative information on the modulation of cardiac vagal and sympathetic nerve input. The hypothesis that depressed heart rate variability may occur over a broad range of illness and injury, and may inversely correlated with disease severity and outcome has been tested in various clinical settings over the last decade. This article reviews recent literature concerning the potential clinical implications and limitations of heart rate variability assessment in general medicine.Yi GangMarek Malik2005-05-02Z2011-03-11T08:56:01Zhttp://cogprints.org/id/eprint/4291This item is in the repository with the URL: http://cogprints.org/id/eprint/42912005-05-02ZIncidence of Dual AV Node Physiology Following Termination of AV Nodal Reentrant Tachycardia by Adenosine-5'-Triphosphate: A Comparison with Drug Administration in Sinus RhythmAdministration of adenosine triphosphate (ATP) in sinus rhythm identifies dual atrioventricular node physiology (DAVNP) in 75% of patients with inducible slow / fast AV nodal reentrant tachycardia (AVNRT). The incidence of DAVNP following termination of AVNRT with ATP is unknown. Incremental doses of ATP (10-60mg) were administered, first in sinus rhythm and then during tachycardia induced at electrophysiologic study, to 84 patients with inducible AVNRT and to 18 control patients with inducible AV reentrant tachycardia (AVRT) and no electrophysiologic evidence of DAVNP. Study end-points were the occurrence of DAVNP or > 2nd degree AV block following administration of ATP in sinus rhythm and tachycardia termination following administration of ATP during tachycardia. Of the 82 patients with AVNRT who completed the study, 62 (75.6%) exhibited DAVNP following administration of 17.1 + 9.4 mg ATP in sinus rhythm, while 30 (36.5%) exhibited DAVNP at the termination of AVNRT following administration of 10.6 + 2.4 mg ATP. The occurrence of DAVNP following the administration of 10 mg ATP in sinus rhythm.was a good predictor (62%) of its occurrence after termination of AVNRT with ATP. The dose of ATP had a strong correlation between the presence of DAVNP following AVNRT termination and the ATP doses needed for tachycardia termination. Of the 18 control patients, none had DAVNP at ATP test during sinus rhythm but 1 (5.5%) showed slight (60 msec) PR jump after termination of AVRT with ATP. In conclusion, DAVNP is present in a relatively high proportion (36.5%) of patients following termination of AVNRT with ATP but is much less frequent (5.5%) in control patients. Thus, findings at termination of tachycardia by ATP may be useful in the noninvasive diagnosis of the mechanism of a paroxysmal supraventricular tachycardia. Bernard BelhassenRoman FishSami ViskinAharon GlickMichael GliksonMichael Eldar2005-05-02Z2011-03-11T08:56:01Zhttp://cogprints.org/id/eprint/4297This item is in the repository with the URL: http://cogprints.org/id/eprint/42972005-05-02ZReuse of Occluded Veins During Permanent Pacemaker Lead Extraction: A New Indication for Femoral Lead Extraction Objectives: This study examined the utility of a novel technique for reuse of thrombosed veins when extracting permanent pacemaker leads via a femoral vein approach.
Background: Although lead extraction permanent pacemaker using a femoral approach has advantages over the subclavian approach, it cannot be used to provide access for a new lead using currently employed techniques. This is important because up to 23% of patients have occluded veins after permanent pacemaker implantation.
Methods: The pacemaker lead to be extracted was released from the generator and retaining sutures at the implantation site. The lead was then grabbed from below using a needle-eye-snare or basket. The lead was then cut short and a drag through technique performed where a guide wire was pushed into the gap between the insulation and the coil. This guide wire was then drawn into the right atrium as the lead was pulled down from below. This guide wire was then used to introduce a sheath through which a replacement lead could be inserted.
Results: A total of 34 consecutive patients (21 male, aged 63±14 years, mean±SD) had 57 (1.7/patient) leads extracted. Fourteen patients required implantation of a new system and were suitable for immediate lead replacement using the drag through technique. All leads were successfully extracted, with 5 partial successes (9.1% of leads). The drag-through technique was successful in all, including 4 with subclavian vein occlusion. Procedure and fluoroscopy times, including the time required for implantation of a new system, were 143±65 mins and 31±23 mins respectively. There were no complications and hospital stay was 1.6±1.2 days for patients undergoing the drag-through procedure.
Conclusion: The drag-through technique can be successfully used to provide access in order to replace pacemaker leads removed using a femoral approach.Andrew D StaniforthRichard J Schilling2005-05-02Z2011-03-11T08:56:01Zhttp://cogprints.org/id/eprint/4290This item is in the repository with the URL: http://cogprints.org/id/eprint/42902005-05-02ZRole of Adenosine/ATP Test in Supraventricular Tachycardia
The successful treatment of paroxysmal supraventricular tachycardia with adenosine 5` triphosphate (ATP) was initially reported by Somlo1 in 1955. Sharma et al2 noted the value of intravenous ATP in the diagnosis and management of wide QRS complex tachycardia. ATP in incremental doses has been used for the non-invasive diagnosis of concealed accessory pathways3.
Non-invasive diagnosis of dual AV node physiology (DAVNP) in patients with AV nodal reentrant tachycardia by administration of ATP or adenosine has been reported by different authors4,5. Though many of the studies were using incremental dosage, single dose tests with ATP6 and adenosine7 have also been useful in the diagnosis of DAVNP. The test is useful in sinus rhythm to establish the presence of DAVNP. DAVNP is considered to be present when at least one of the following events occur following ATP injection: 1) PR interval increases or decreases by >50 ms in 2 consecutive sinus beats; 2) an AV nodal echo beat is observed; 3) AVNRT develops. In this issue of the Journal, Belhassen et al8 report that DAVNP is present in a relatively high proportion (36.5%) of patients following termination of AVNRT with ATP but is much less frequent (5.5%) in control patients. In addition, they show that the occurrence of DAVNP following the administration of ATP in sinus rhythm is a good predictor of its occurrence after termination of AVNRT with ATP. Thus, findings at termination of tachycardia by ATP may be useful in the noninvasive diagnosis of the mechanism of a paroxysmal supraventricular tachycardia.Johnson Francis2005-05-02Z2011-03-11T08:56:01Zhttp://cogprints.org/id/eprint/4293This item is in the repository with the URL: http://cogprints.org/id/eprint/42932005-05-02ZSpecial Problems Of Pacing In ChildrenThe number of children suffering from congenital or acquired rhythm disorders, and therefore being pacemaker dependent, is very small. This is one of the reasons why a special hardware has never been developed for this cohort.
Pacemaker implantation into children does not differ substantially from operations in adults. But there are several important points which have to be fulfilled in these small patients in order to guarantee a complication free function. As most of these children remain pacemaker dependent a lifetime, it is of tremendous importance to minimize all revisions regarding the implanted systems and to enable our small patients a high and therefore nearly normal quality of life.
Pros and cons of different surgical approaches, implantation sites and the problem of growth after pacemaker implantation in children are considered.Herwig AntretterJoshua ColvinUlli SchweigmannHerbert HanglerDaniel HöferKarin DunstJosef MargreiterGuenther Laufer2005-05-02Z2011-03-11T08:56:01Zhttp://cogprints.org/id/eprint/4301This item is in the repository with the URL: http://cogprints.org/id/eprint/43012005-05-02ZApproach to the Evaluation and Management of Wide Complex TachycardiasWide complex tachycardia (WCT) refers to a cardiac rhythm of more than 100 beats per minute with a QRS duration of 120 ms or more on the surface electrocardiogram (ECG). It often presents a diagnostic dilemma for the physician particularly in determining its site of origin, which can be ventricular or supraventricular. In one series, only 32% of clinicians correctly diagnosed ventricular tachycardia (VT) in patients who presented with WCT1. Prompt diagnosis of the etiology of WCT is, however, essential since immediate care is frequently required. Diagnostic and therapeutic errors can produce poor outcome especially when ventricular tachycardia is not recognized.2,3
WCT that is grossly irregular typically represents atrial fibrillation with aberrant conduction or preexcitation. If its rate exceeds 200 beats per minute, the likelihood of atrial fibrillation with conduction over an accessory pathway should be entertained. In this article, we will discuss the approach to the evaluation and management of regular WCT.
Patrick LamSamir Saba2005-05-02Z2011-03-11T08:56:01Zhttp://cogprints.org/id/eprint/4304This item is in the repository with the URL: http://cogprints.org/id/eprint/43042005-05-02ZElectromagnetic Interference in Implantable Rhythm Devices: CommentThis is a short comment on the editorial on Electromagnetic Interference in Implantable Rhythm Devices - The Indian Scenario in the July-September issue of the journal.1 Regarding the statement: "Systems working at 0.5 Tesla are available in the country so that it may be considered in such situations..." , though the author conveys his point, it gives reader a feeling that 0.5 Tesla magnetic resonance imaging (MRI) units are advantageous. In fact for every other diagnostic purpose we would like to have higher Tesla MRI units. The 0.5 Tesla unit is inferior compared to higher Tesla systems. The cry of Eastern European countries in a conference held in November 2001 at Antwerpen by the European Working Group on Management in Radiology (EWGMR), was that they have only 0.5 Tesla magnets and so they can not do this , that , no functional MRI , no stroke imaging etc etc... But a western European reader can get confused. I do not think there will be a single system working at 0.5 Tesla in countries like Germany.
P.V. Ramachandran2005-05-02Z2011-03-11T08:56:01Zhttp://cogprints.org/id/eprint/4303This item is in the repository with the URL: http://cogprints.org/id/eprint/43032005-05-02ZElectrophysiological evaluation of Wolff-Parkinson-White SyndromeSudden death might complicate the follow-up of symptomatic patients with the Wolff-Parkinson-White syndrome (WPW) and might be the first event in patients with asymptomatic WPW. The risk of sudden death is increased in some clinical situations. Generally, the noninvasive studies are unable to predict the risk of sudden death correctly . The electrophysiological study is the best means to detect the risk of sudden death and to evaluate the nature of symptoms. Methods used to define the prognosis of WPW are well-defined. At first the maximal rate of conduction through the accessory pathway is evaluated; programmed atrial stimulation using 1 and 2 extrastimuli delivered at different cycle lengths is then used to determine the accessory pathway refractory period and to induce a supraventricular tachycardia. These methods should be performed in the control state and repeated in adrenergic situations either during exercise test or more simply during a perfusion of small doses of isoproterenol. The induction of an atrial fibrillation with rapid conduction through the accessory pathway (> 240/min in control state, > 300/min after isoproterenol) is the sign of a form of WPW at risk of sudden death.
Béatrice Brembilla-Perrot2005-05-02Z2011-03-11T08:56:01Zhttp://cogprints.org/id/eprint/4296This item is in the repository with the URL: http://cogprints.org/id/eprint/42962005-05-02ZLead Extraction: "Drag Through" TechniqueThe goal of extraction techniques of chronic pacemaker and defibrillator leads is to present an approach that is successful in extracting all leads and minimizes or eliminates complications. To extract a chronically implanted intravascular device, the device must be separated from the encapsulating inflammatory tissue. Three ablation techniques are currently used: mechanical, laser and electrosurgical.Anoop K. Gupta2005-05-02Z2011-03-11T08:56:01Zhttp://cogprints.org/id/eprint/4302This item is in the repository with the URL: http://cogprints.org/id/eprint/43022005-05-02ZThe Long QT SyndromeThe Long QT syndrome (LQTS) can be inherited or acquired and is of particular interest and concern at present. Patients with LQTS are predisposed to the ventricular tachyarrhythmia torsade de pointes (TdP) which causes syncope and sudden death. Inherited LQTS is the prototype of the “primary cardiac arrhythmias” or “cardiac ion channelopathies”. The study of inherited LQTS has provided enormous insight into the molecular basis of cardiac electrophysiology and arrhythmogenesis in general. Drug induced LQTS is the most common cause of acquired LQTS, and is a pressing public health issue. Considerable attention has been focussed on this form of LQTS following the withdrawal from the USA market of a number of prescription medications, including terfenedine in 2000 and cisapride in 2001. This review will discuss both forms, but with more emphasis on inherited LQTS.
G. Michael Vincent2005-05-02Z2011-03-11T08:56:01Zhttp://cogprints.org/id/eprint/4300This item is in the repository with the URL: http://cogprints.org/id/eprint/43002005-05-02ZPacing for Vasovagal SyncopeVasovagal syncope is a common condition, usually associated with a benign prognosis. Most sufferers experience only occasional symptoms, and can be treated with reassurance and lifestyle advice. However, a minority of patients are debilitated by frequent fainting that can infringe on daily living, or even mimic sudden death. This has been termed "malignant" vasovagal syncope because of the associated falls and physical injury. In these cases, a more interventional approach may be appropriate.
Pharmacological measures have been the mainstay of treatment for recurrent vasovagal syncope: beta-blockers (e.g. atenolol), serotonin reuptake inhibitors (e.g. paroxetine), certain vasoconstricting drugs (e.g. midodrine) and fluid retaining agents (e.g. fludrocortisone) have been of particular interest. However, there is only mixed support from randomised controlled trials for the efficacy of these agents in preventing vasovagal syncope. 1,2,3
In the last few years, cardiac pacing has been advocated for the treatment of some forms of vasovagal syncope. This article reviews the literature and discusses the indications for pacing in vasovagal syncope.
Nevin T WijesekeraArvinder S Kurbaan2005-05-02Z2011-03-11T08:56:01Zhttp://cogprints.org/id/eprint/4298This item is in the repository with the URL: http://cogprints.org/id/eprint/42982005-05-02ZTachycardiomyopathy
Sustained chronic tachyarrhythmias often cause a deterioration of cardiac function known as tachycardia-induced cardiomyopathy or tachycardiomyopathy.1 It has been recognized that the tachycardiomyopathy occurs in experimental models2 and also in patients with supraventricular or ventricular tachycarrhythmias.3,4,5,6 Generally, cardiac function will recover if drug or catheter ablation therapy is successfully performed. Phillips and Levine7 initially presented this concept in 1949 for the relationship between rapid atrial fibrillation and reversible left ventricular (LV) failure. However, it might be difficult to define its cause and effect relationship when cardiomyopathy and tachycardia are identified simultaneously. The reversibility of LV dysfunction may often be variable and the precise mechanisms of the pathophysiological features of this phenomenon should be elucidated. Although excellent and comprehensive review articles by Fenelon G, et al.8 and Shinbane JS et al 9 regarding these topics have already been published, I will firstly present a typical case and then review the basic and clinical characteristics of tachycardiomyopathy in this article. Yuji Nakazato2005-05-02Z2011-03-11T08:56:01Zhttp://cogprints.org/id/eprint/4309This item is in the repository with the URL: http://cogprints.org/id/eprint/43092005-05-02ZAblation Of Atrial Flutter:Block (Isthmus Conduction) Or Not A Block, That Is The Question?
It is important to identify residual slow conduction and minimize the chance of resumption of conduction after right atrial isthmus ablation to reduce the chance of recurrence of atrial flutter (AFL). The aim of this article is to discuss the best possible way of confirming a bi-directional isthmus conduction (BIC) block after ablation of an isthmus-dependent AFL. A combination of activation and double potential mapping seems to be the most practical way of acutely confirming the BIC block.
Ashish Nabar2005-05-02Z2011-03-11T08:56:02Zhttp://cogprints.org/id/eprint/4310This item is in the repository with the URL: http://cogprints.org/id/eprint/43102005-05-02ZArrhythmia Diagnosis Following an ICD Shock: Part II
A 70 year old male with history of coronary artery bypass surgery and depressed left ventricular ejection fraction of 30% presented with hemodynamically unstable sustained monomorphic ventricular tachycardia 5 years previously. He underwent implantation of a single chamber ICD. Six months ago, he experienced multiple ICD shocks for ventricular tachycardia and was placed on amiodarone, the maintenance dose of which was increased to 400 mg daily for arrhythmia recurrence. Two months ago, his ICD was upgraded to provide atrial synchronized biventricular pacing for progressive heart failure symptoms and marked sinus bradycardia. His underlying QRS duration was 160 msec. A Medtronic Attain OTW 4193 lead was placed in the posterolateral LV branch of the coronary sinus. This lead was connected in parallel via a bipolar connector with an existing Medtronic Sprint 6945 ICD lead in the right ventricle to the ventricular IS-1 port of an GEM III DR 7275 dual chamber ICD. Adequate atrial synchronized biventricular pacing was obtained in the DDDR mode. ICD detection was programmed for fast VT from 171 to 200 bpm and for VF above 200 bpm.Roy M. John2005-05-02Z2011-03-11T08:56:01Zhttp://cogprints.org/id/eprint/4305This item is in the repository with the URL: http://cogprints.org/id/eprint/43052005-05-02ZElectromagnetic Interference in Implantable Rhythm Devices - The Indian Scenario Implantable rhythm device (IRD) is the generic name for the group of implantable devices used for diagnosis and treatment of cardiac arrhythmias. Devices in this category include cardiac pacemakers, implantable cardioverter defibrillators and implantable loop recorders. Since these devices have complex microelectronic circuitry and use electromagnetic waves for communication, they are susceptible to interference from extraneous sources of electromagnetic radiation and magnetic energy. Electromagnetic interference (EMI) is generally not a major problem outside of the hospital environment. The most important interactions occur when a patient is subjected to medical procedures such as magnetic resonance imaging (MRI), electrocautery and radiation therapy. Two articles in this issue of the journal discusses various aspects of EMI on IRD1,2 . Together these articles provide a good review of the various sources of EMI and their interaction with IRD for the treating physician.Johnson Francis2005-05-02Z2011-03-11T08:56:01Zhttp://cogprints.org/id/eprint/4308This item is in the repository with the URL: http://cogprints.org/id/eprint/43082005-05-02ZElectromagnetic Interference in Patients with Implanted Cardioverter-Defibrillators and Implantable Loop RecordersModern life exposes us all to an ever-increasing number of potential sources of electromagnetic interference (EMI) and patients with Implantable rhythm devices (IRD) like pacemakers, implantable cardioverter defibrillators or implantable loop recorders often ask about the use of microwave ovens, walking through airport metal detectors and the use of cellular phones.
Electromagnetic interference occurs when electromagnetic waves emitted by one device impede the normal function of another electronic device. The potential for interaction between implanted pacing systems and cardioverter-defibrillators (electromagnetic interference, EMI) has been recognized for years.1,2,3,4. It has been shown that EMI can produce clinically significant effects on patients with implanted pacemakers and ICDs. For these reasons the following text discusses the influence of several EMI generating devices on IRD .Marcos de SousaGunnar KleinThomas KorteMichael Niehaus2005-05-02Z2011-03-11T08:56:01Zhttp://cogprints.org/id/eprint/4307This item is in the repository with the URL: http://cogprints.org/id/eprint/43072005-05-02ZElectromagnetic Interference on PacemakersExternal sources, either within or outside the hospital environment, may interfere with the appropriate function of pacemakers which are being implanted all around the world in current medical practice. The patient and the physician who is responsible for follow-up of the pacing systems may be confronted with some specific problems regarding the various types of electromagnetic interference (EMI). To avoid these unwanted EMI effects one must be aware of this potential problem and need to take some precautions. The effects of EMI on pacemaker function and precautions to overcome some specific problems were discussed in this review article. There are many sources of EMI interacting with pacemakers. Magnetic resonance imaging creates real problem and should be avoided in pacemaker patients. Cellular phones might be responsible for EMI when they were held on the same side with the pacemaker. Otherwise they don't cause any specific type of interaction with pacemakers. Sale security systems are not a problem if one walks through it without lingering in or near it. Patients having unipolar pacemaker systems are prone to develop EMI because of pectoral muscle artifacts during vigorous active physical exercise. Okan Erdogan2005-05-02Z2011-03-11T08:56:01Zhttp://cogprints.org/id/eprint/4306This item is in the repository with the URL: http://cogprints.org/id/eprint/43062005-05-02ZTemperature Controlled Radiofrequency Ablation
Monitoring catheter tip temperature and closed loop control of power output are useful to avoid excessive heating at the tissue surface, that may result in coagulum formation, and to accomplish effective heating at the target area. However, the catheter tip temperature is affected by cooling effects and electrode-tissue contact and thus poorly correlated to lesion size. New means should be developed to assess tissue temperatures during radiofrequency delivery to achieve predictable and reproducible lesions.
Olaf J. Eick2005-05-02Z2011-03-11T08:56:02Zhttp://cogprints.org/id/eprint/4317This item is in the repository with the URL: http://cogprints.org/id/eprint/43172005-05-02ZArrhythmia Care In India - Poised For The Big LeapTill the late 1980s, there was precious little one could do to permanently cure arrhythmias. Cardiac surgery did not live up to its promise for ventricular tachycardia. For WPW syndrome, surgery was too invasive a procedure, with a significant chance of major complications. Electrophysiologists spent hours trying to unravel tachycardia mechanisms, and were often referred to as "electrophilosophers". Since the advent of RF ablation, this scenario underwent a sea change. Suddenly one was able to get rid of many arrhythmias with a much less invasive procedure. Electrophysiology centers mushroomed and got upgraded in the developed world.Yash Lokhandwala2005-05-02Z2011-03-11T08:56:02Zhttp://cogprints.org/id/eprint/4311This item is in the repository with the URL: http://cogprints.org/id/eprint/43112005-05-02ZBiventricular Pacing in Congestive Heart Failure
Congestive heart failure (CHF) is a common, debilitating and usually lethal condition responsible for enormous burden on health care. The recent trials have shown improvement in morbidity and mortality with ACE inhibitors and beta blockers1,2,3. However, despite this the overall prognosis remains dismal. The other alternative of cardiac transplantation has several limitations including the donor organ scarcity. In view of this gloomy prognosis, several alternative strategies are being explored, one of which has been pacing for heart failure. In this form of therapy pacing is used in absence of the conventional bradyarrhthymic indications with an attempt to lead to optimization of AV delay and co-ordination of ventricular contraction.
Balbir Singh2005-05-02Z2011-03-11T08:56:02Zhttp://cogprints.org/id/eprint/4312This item is in the repository with the URL: http://cogprints.org/id/eprint/43122005-05-02ZCurrent Status of Internal Cardioversion in Atrial Fibrillation
The method of internal cardioversion for restoration of sinus rhythm using transvenous electrodes has been reported in several animal6,7 and human studies 8,9,10,11,12,13,14,15. Cooper et al6 tested multiple electrode configurations in a sheep model of atrial fibrillation. They demonstrated that the optimal single current pathway for internal atrial defibrillation employed two electrodes that surrounded both atria (e.g., right atrial appendage and distal coronary sinus). Similar results have been reported in several human studies12,13,14. Internal cardioversion has been shown to be superior to conventional external cardioversion in terms of primary success rate, energy requirements and the need for sedation; this superiority holds especially true for patients with a high body mass index of > 25 kg/m2 and increased transthoracic diameter1Andreas PlewanEckhard Alt2005-05-02Z2011-03-11T08:56:02Zhttp://cogprints.org/id/eprint/4315This item is in the repository with the URL: http://cogprints.org/id/eprint/43152005-05-02ZDevelopment of Pacing, Electrophysiology and Defibrillation in IndiaHistory of cardiac pacing in India dates back to late 1960s. Kar1 reported that cardiac pacing was introduced in India in 1966. Basu2 while discussing on cardiac pacemaking in Calcutta, mentions that the first pacing was performed in April 1967 at the Institute of Post Graduate Medical Education and Research (IPGME&R). Bhatia et al3 started pacemaker implantation at AIIMS, New Delhi in 1968. Their first patient was a doctor from Assam and the pulse generator was supplied by Medtronic Inc. The pulse generator was powered by a mercury-iodide battery which lasted for about 2 ½ years, after which the patient underwent pulse generator replacement. Unfortunately he succumbed to miliary tuberculosis about a year after that. Currently around 8000 pacemakers are being implanted annually in India, in various centers around the country.Mohan NairJohnson FrancisVenugopal K2005-05-02Z2011-03-11T08:56:02Zhttp://cogprints.org/id/eprint/4314This item is in the repository with the URL: http://cogprints.org/id/eprint/43142005-05-02ZHigh Resolution ElectrocardiographyOver the past decade, significant advances were made in the research, diagnosis, and treatment of cardiovascular diseases. Such progress was in every sphere of cardiology that includes non-invasive, minimally invasive, and invasive technologies. Interpretive electrocardiography, cardiac pacemakers, cardiac stents, and angioplasty are some areas where the progress has been significant. Non-invasive methods of diagnosis of cardiac disorders involve digital recording of cardiac signals at the body surface (chest) and subsequent computerized analysis. Such methods and instruments provide a vital first step to the diagnosis of the heart without involving surgical procedures. One such non-invasive field is High Resolution Electrocardiography (HRECG). A high-resolution electrocardiogram detects very low amplitude signals in the ventricles called 'Late Potentials' in patients with abnormal heart conditions. A standard electrocardiogram cannot detect these signals. The presence of late potentials is widely accepted to have prognostic significance in patients after Acute Myocardial Infarction (AMI)1,2,3.
High Resolution Electrocardiography enhances the diagnostic capabilities of ECGs. This article describes the principles involved in HRECG and the techniques that are employed to derive such superior diagnostic capabilities. The use of these techniques may lead to more discoveries in the causes of cardiac disorders and improved drug discoveries to combat such conditions.Suresh Narayanaswamy2005-05-02Z2011-03-11T08:56:02Zhttp://cogprints.org/id/eprint/4313This item is in the repository with the URL: http://cogprints.org/id/eprint/43132005-05-02ZRadiofrequency Catheter Ablation of Supraventricular Tachycardia Supraventricular tachycardias are quite common in clinical practice. Medical treatment of supraventricular tachycardia often involves regular intake of drugs for several years. Problems of drug therapy include poor efficacy and bothersome side effects including proarrhythmia. This has lead to the development of non-pharmacological therapies. Arrhythmia surgery initially demonstrated that many types of supraventricular arrhythmias could be cured. However during the past decade arrhythmia surgery has been largely replaced by catheter ablation. Catheter ablation can be defined as the use of an electrode catheter to destroy small areas of myocardial tissue or conduction system, or both, that are critical to the initiation or maintenance of cardiac arrhythmias. Arrhythmias most likely to be amenable to cure with catheter ablation are those which have a focal origin or involve a narrow, anatomically defined isthmus.1 This review aims to provide an update on the technique and results associated that can be achieved with catheter ablation of supraventricular tachycardias.
Hugh CalkinsV.K Ajit KumarJohnson Francis2005-05-02Z2011-03-11T08:56:02Zhttp://cogprints.org/id/eprint/4316This item is in the repository with the URL: http://cogprints.org/id/eprint/43162005-05-02ZReminiscences Of The First His Bundle Electrography In India We spent two hectic years in AIIMS in 1972 and ''73 while undergoing our training for DM Cardiology. Dr Rajan Manjuran and myself were the two candidates and we worked day and night, but thoroughly enjoyed it as it was so exciting and educative. The cutting edge remarks by the inimitable Professor Sujoy B Roy, the meticulous precision of Prof M.L.Bhatia and the tender auscultatory sessions on infants with Prof Raj Tandon all are still fresh in mind. Another fascinating aspect of those days was the frequent visits by the leading innovators in cardiology and cardiac surgery.
C.A Nambiar2005-05-02Z2011-03-11T08:56:02Zhttp://cogprints.org/id/eprint/4325This item is in the repository with the URL: http://cogprints.org/id/eprint/43252005-05-02ZArrhythmia Diagnosis Following an ICD Shock: Comment This case study by Dr. John1 demonstrates the care that one must take in programming an implantable cardioverter defibrillator, the complexity of these patients and the utility of the internal diagnostics in the system to facilitate the physician's understanding of device behavior. Even the single chamber ICDs have SVT discrimination algorithms that can be enabled in an effort to differentiate SVT from VT allowing the device to withhold ATP and shock therapy in the setting of an SVT. Many physicians, myself included, will initially utilize these discriminators in a monitoring mode preferring to deliver unnecessary therapy rather than inappropriately withholding needed therapy. This also provides an opportunity to better understand all the rhythms that may be occurring in a patient, many of which may not have been appreciated prior to the implant. After one or more SVT episodes have occurred and the clinician has a chance to review the stored electrograms (first introduced by Ventritex) along with the response of the device to any discriminators, a decision can be made as to how the ICD prescription might be adjusted.Paul A. Levine2005-05-02Z2011-03-11T08:56:02Zhttp://cogprints.org/id/eprint/4326This item is in the repository with the URL: http://cogprints.org/id/eprint/43262005-05-02ZArrhythmia Diagnosis Following an ICD Shock: Reply Dr. Levine's comments1 are greatly appreciated. Most modern ICDs have arrhythmia discrimination algorithms that have variable success in withholding inappropriate therapy. It must be borne in mind that enhancing specificity for ventricular arrhythmia detection can entail a loss of
sensitivity. Accordingly, all algorithms necessarily err on the side of safety and will withhold therapy for only brief period of time. A persistent high rate will eventually be treated as a ventricular arrhythmia and can result in unnecessary and repetetive shocks. Hence the importance of aggressive management of supraventricular arrhythmias in these patients cannot be overemphasized.Roy M. John2005-05-02Z2011-03-11T08:56:02Zhttp://cogprints.org/id/eprint/4324This item is in the repository with the URL: http://cogprints.org/id/eprint/43242005-05-02ZCardiac Mapping: Utility or Futility?
Cardiac mapping is a broad term that covers several modes of mapping such as body surface,1 endocardial,2 and epicardial3 mapping. The recording and analysis of extracellular electrograms, reported as early as 1915, forms the basis for cardiac mapping.4 More commonly, cardiac mapping is performed with catheters that are introduced percutaneously into the heart chambers and sequentially record the endocardial electrograms with the purpose of correlating local electrogram to cardiac anatomy. These electrophysiological catheters are navigated and localized with the use of fluoroscopy. Nevertheless, the use of fluoroscopy for these purposes may be problematic for a number of reasons, including: 1) the inability to accurately associate intracardiac electrograms with their precise location within the heart; 2) the endocardial surface is invisible using fluoroscopy and the target sites can only be approximated by their relationship with nearby structures such as ribs, blood vessels, and the position of other catheters; 3) due to the limitations of two-dimensional fluoroscopy, navigation is not exact, time consuming, and requires multiple views to estimate the three-dimensional location of the catheter; 4) inability to accurately return the catheter precisely to a previously mapped site; and 5) exposure of the patient and medical team to radiation.
Anoop Kumar GuptaAlok MaheshwariRanjan ThakurYash Y. Lokhandwala2005-05-02Z2011-03-11T08:56:02Zhttp://cogprints.org/id/eprint/4321This item is in the repository with the URL: http://cogprints.org/id/eprint/43212005-05-02ZEarly History of Cardiac Pacing and Defibrillation
The Electricity and the Heart website1 is intended to facilitate the collection, cataloging and presentation of historical information about technical and scientific advances in cardiac devices. Over the course of the past century as the fields of cardiac pacing and electrophysiology have evolved, the technological devices used by physicians and researchers has been a fascinating and rapidly changing portion of the history of the fields. NASPE's Oral History Project houses hundreds of devices collected over the years that illustrate the evolution from crude and simple machines to the sophisticated and advanced technological wonders that are used in the field today. The photos and descriptions of many of these devices show just how far we have come in the advancement of treatment and patient care.
Seymour Furman2005-05-02Z2011-03-11T08:56:02Zhttp://cogprints.org/id/eprint/4323This item is in the repository with the URL: http://cogprints.org/id/eprint/43232005-05-02ZThe implantable loop recorder: A tool that is "here to stay"
Syncope is a common clinical disorder accounting for 3 % for emergency room presentations and 1 % of hospital admissions 1. Moreover it has not always a benign course, with mortality rates up to 33 % at 1 year in patients with a structural cardiac disorders 2, 5. In addition costs for investigation for syncope is substantial and about 25 % of all patients remain undiagnosed 6.
Investigation of patients with recurrent unexplained syncope may include electrocardiography and treadmill exercise testing, neurologic testing, tilt table testing, ambulatory Holter monitoring and electrophysiological testing.
This review will briefly discuss these current available strategies and focus on the usefulness of a recently introduced tool using an implantable loop recorder (ILR) in the treatment of patients with a recurrent unexplained syncope.Carel C. Cock2005-05-02Z2011-03-11T08:56:02Zhttp://cogprints.org/id/eprint/4327This item is in the repository with the URL: http://cogprints.org/id/eprint/43272005-05-02ZManaging Ventricular Tachyarrhythmias In The Developing World: Insights From Recent ICD TrialsSince the introduction of the implantable cardioverter defibrillator (ICD) by Michel Mirowski in the 1980's, these devices have become an important tenet in management of ventricular arrhythmias1. Numerous observational and randomized trials have demonstrated the superiority of this device over antiarrhythmic drugs in treating ventricular arrhythmias. The clinical implications of these trials are tremendous as sudden cardiac death (SCD) maybe the presenting symptom in these arrhythmias. It is estimated that in the United States alone around 350,000 deaths occur each year due to SCD alone2 . As resuscitation is seldom successful in the community, methods to identify and appropriately treat such patients alone can prevent these events. However, the public health impact of this approach is tremendous, as the ICD is extremely expensive and is out of reach for many individuals. Moreover, not all patients with structural heart disease and ventricular arrhythmias have a malignant outcome. Thus efforts to appropriately stratify patients according to their risk profile and accordingly advocate ICD implant has important fiscal implications for the state with meager health resources, especially in those patients in whom survival benefit with the ICD is modest. K.K TalwarN Naik2005-05-02Z2011-03-11T08:56:02Zhttp://cogprints.org/id/eprint/4319This item is in the repository with the URL: http://cogprints.org/id/eprint/43192005-05-02ZNon-pharmacological Treatment of Atrial FibrillationIn selected patients with atrial fibrillation and severe symptoms, non-pharmacological treatment may be an alternative or supplement to drug therapy. Atrioventricular nodal radiofrequency ablation (requires pacemaker implantation), or atrial pacing for sick sinus syndrome, are established treatment modalities. All other non-pharmacological therapies for atrial fibrillation are still experimental. After the Maze operation, atrial depolarization has to follow one specific path determined by surgical scars in the myocardium. This prevents new episodes of atrial fibrillation, but at a cost of perioperative morbidity and mortality. Catheter-based “Maze-like” radiofrequency ablation is technically difficult, and thrombo-embolic complications may occur. Paroxysmal atrial fibrillation sometimes is initiated by spontaneous depolarizations in a pulmonary vein inlet. Radio frequency ablation against such focal activity has been reported with high therapeutic success, but the results await confirmation from several centres. For ventricular rate control, most electrophysiologists presently prefer ablation to induce a complete atrioventricular conduction block (with pacemaker) rather than trying to modify conduction by incomplete block. Atrial or dual chamber pacing may prevent atrial fibrillation induced by bradycardia. It remains to confirm that biatrial or multisite right atrial pacing prevents atrial fibrillation more efficiently than ordinary right atrial pacing. An atrial defibrillator is able to diagnose and convert atrial fibrillation. The equipment is expensive, and therapy without sedation may be unpleasant beyond tolerability.Ole-Gunnar Anfinsen2005-05-02Z2011-03-11T08:56:02Zhttp://cogprints.org/id/eprint/4328This item is in the repository with the URL: http://cogprints.org/id/eprint/43282005-05-02ZBrugada Syndrome: The Syndrome of Right Bundle Branch Block, ST segment Elevation in V1 to V3 and Sudden DeathIn 1992 a new syndrome consisting of syncopal episodes and/or sudden death in patients with a structurally normal heart and a characteristic electrocardiogram (ECG) with a pattern of right bundle branch block with an ST segment elevation in leads V1 to V3 was described 1 In 1998 the poor prognosis of patients with the syndrome not receiving an implantable defibrillator was reported 2,3 In 1998 the genetic nature of the disease and its assotiation to a mutation in the cardiac sodium channel gene was described 4 . Because the diagnosis is easily made by means of the ECG, an increasing number of patients with the ECG pattern are being identified worldwide. In this article we will review our present knowledge concerning patients with the classical ECG pattern of the disease. Josep BrugadaPedro BrugadaRamon Brugada2005-05-02Z2011-03-11T08:56:02Zhttp://cogprints.org/id/eprint/4330This item is in the repository with the URL: http://cogprints.org/id/eprint/43302005-05-02ZManagement of the Patient with an Acute Massive Rise in the Capture ThresholdSince the introduction of steroid eluting electrodes, the incidence of an early massive rise in the capture threshold that either exceeds or threatens to exceed the programmed output of the pacemaker has declined but has not totally disappeared1 If a persistent or massive threshold rise is encountered in the days to months post-implant, one consideration is microinstability of the lead. In this setting, there may be a change in the morphology of the pacemaker evoked depolarization on the ECG or a change in the physical location of the lead as assessed with a chest x-ray. Another marker is fluctuations in the capture threshold on repeated assessments at the same office or clinic visit. The options for this problem include an operative procedure to reposition or replace the lead or to closely observe the patient hoping that the lead settles into a secure location. Another potential totally reversible cause is the introduction of an new medication or herb. If the possible explanations for threshold increase cited above have been excluded and the high capture threshold is believed to be due to lead maturation, increasing the output or possible lead replacement or repositioning have been the usual options.
Paul A. Levine2005-05-02Z2011-03-11T08:56:02Zhttp://cogprints.org/id/eprint/4331This item is in the repository with the URL: http://cogprints.org/id/eprint/43312005-05-02ZA Re-analysis of Our Current Understanding of Isthmus-Dependent Atrial Flutter: Some Gaps, Some HypothesesThe macro-reentrant circuit of isthmus-dependent atrial flutter (AFL) is located in the right atrium around the tricuspid annulus. High acute success and low recurrence rate makes isthmus ablation a definitive therapy for patients with only AFL. However, a review of the literature suggests that, different aspects of this macro-reentrant circuit are still not entirely understood, while new information continues to emerge. The aim of this article is to discuss some gaps in our “complete” understanding of isthmus-dependent AFL. Few hypotheses have been stated which are open to investigation. Ashish Nabar