A computer simulation of the time-dependent conduction properties of the atrioventricular (AV) node

The conduction behavior of the AV node was studied in autonomically blocked dogs during rapid atrial stimulation. It is shown that conduction time through the node depends on the recovery time since the last ventricular activation (recovery), and also on the time-dependent changes of the node due to lengthy prior stimulation, which leads to an increased conduction time (fatigue). A theoretical model is presented that incorporates both recovery and fatigue which can be used to predict AV modal behavior, on a beat-to-beat basis given any simulation history. The validity of this model was tested by attempting to simulate the time-dependent changes observed in AV nodal conduction during Wenckebach pattern generation (second degree AV nodal block). The predictions showed good agreement with the experimental observations