Ventricular Response in Atrial Fibrillation Role of Concealed Conduction in the AV Junction

CONCEALED CONDUCTION in the atrioventricular (AV) junction in association with coordinated atrial activity is a well-recognized phenomenon,1-3 recently confirmed with new technics in animal experiments.4-6 Its operation in atrial fibrillation has received less attention, although it appears to offer the best explanation for the characteristic irregularity of the ventricular responses.7 11 It is the purpose of this report based on clinical electrocardiograms to demonstrate evidence of concealed conduction in its various manifestations during atrial fibrillation; and to point out how concealed conduction in any type of rapid atrial activity may become a major factor which determines rate and sequence of ventricular responses.