Electrophysiological and mathematical characteristics of the escape rhythm during complete AV block

Abstract

During complete AV block produced by selective administration of physostigmine into the AV node artery of the dog, there is a stable escape rhythm which has properties of automaticity (rather than re-entry) and which has narrow QRS complexes similar to those during sinus rhythm. No other stable escape rhythm occurred. This rhythm (AVJ-2) had a rate which bore a constant mathematical relation to that of control sinus rhythm (AVJ-2 :SR = 2:9) and also to the rate of the escape AV junctional rhythm (AVJ-1) which emerges during selective suppression of the sinus node without AV block (AVJ-2:AVJ-1 = 1:3).