[Electrophysiology of the atrioventricular node during atrial fibrillation. II. The influence of atrial impulses].

An atrial impulse that is not conducted to the ventricle may slow down the conduction of the next atrial impulse. A ventricular extrasystole may also affect the conduction through the AV node. This phenomenon is called 'concealed conduction'. At least three mechanisms are possible to explain concealed conduction, but neither weakening of the impulse as the conduction proceeds nor electrotonic modulation of the pacemaker function of the AV node is in accordance with the observed constant irregularity of atrial fibrillation. The most probable mechanism to explain the ventricular rhythm during atrial fibrillation is the electrotonic change (inhibition) by atrial impulses of the conduction properties of the AV node.