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Indian
RACING.and ELECTROPHYSIOLOGY www.ipej.org ™
Journal
Interesting ECG
Infra-His Block in a Normal Heart
Mohammad Alasti, MD, Abolfath Alizadeh, MD, Amirfarjam Fazelifar, MD, Mohammad Ali
Sadr-Ameli, MD
Department of Pacemaker and Electrophysiology, Rajaie Cardiovascular Medical Center, Vali-
asr Avenue, Tehran, IRAN.
Address for correspondence: Mohammad Alasti, M.D., Department of Pacemaker and
Electrophysiology, Rajaie Cardiovascular Medial Center, Vali-asr Avenue, Tehran, IRAN.
E Mail: [email protected]
Key Words: His-purkinje system; infra-his block
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?
Figure 1
Indian Pacing and Electrophysiology Journal (ISSN 0972-6292), 6(3): 184-185 (2006)