TY - GEN ID - cogprints5239 UR - http://cogprints.org/5239/ A1 - Alasti, Mohammad A1 - Alizadeh, Abolfath A1 - Fazelifar, Amirfarjam A1 - Ali Sadr-Ameli, Mohammad Y1 - 2006/07// N2 - 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? PB - Indian Pacing and Electrophysiology Group KW - His-purkinje system; infra-his block TI - Infra-His Block in a Normal Heart SP - 184 AV - public EP - 185 ER -