Gap Phenomena: Antegrade and Retrograde

Abstract

The phenomenon of ‘Gap in A-V Conduction’ was originally described by Moe and associates (559). During experiments designed to evaluate conduction characteristics with the canine heart, it was noted that premature atrial beats evoked progressively earlier in the cardiac cycle conducted to the ventricles with prolonged P-R intervals. With decreasing prematurity a zone within the cardiac cycle was reached where in premature atrial responses no longer conducted to the ventricles. However, as the atrial responses were made even more premature, conduction resumed. Within this context, the term ‘gap in A-V conduction’ as originally used, defined a zone within the cardiac cycle where in premature atrial impulses failed to evoke ventricular responses while atrial beats of greater and lesser prematurity did.

This work was supported in part by Bureau of Medical Services Grant Py76-1 and National Heart and Lung Institute Grant No. HL-12536-05.