Mohammad Alasti, Abolfath Alizadeh, Amirfarjam Fazelifar, 185
Mohammad Ali Sadr-Ameli, “Infra-His Block in a Normal Heart”
During 2:1 AV conduction, AH interval was 252 msec and conducting system below His
was in absolute refractory period so the impulse could not propagate and infra-his block
occurred. After increasing of AH interval to 282, the conducting system below His had enough
time to enter the relative refractory period. So AH conduction delay permitted transition from
2:1 AV conduction to 1:1 AV conduction. Infra-his block can be produced at paced cycle
lengths of less than 400 msec in normal His-purkinje system and is not considered abnormal in
this case.
Indian Pacing and Electrophysiology Journal (ISSN 0972-6292), 6(3): 184-185 (2006)