Computer model of the effects of overdrive pacing during atrioventricular reentrant tachycardia

A computer model reproduced atrio-ventricular (AV) reentrant tachycardia and its termination by overdrive on-circuit pacing. The model simulated activation waves radiating along a one-dimensional circular pathway, the portions of which represent the atrial, AV nodal, His-Purkinje, ventricular, and bypass parts of the tachycardia circuit. The modeled pathway was composed of 289 elements, and the model distinguished only the depolarized and resting states of constituent elements and introduced differential refractoriness and conduction velocity for each element. Cycle length dependence of AV nodal decremental conduction is also introduced. The experiments with the model examined the capability of overdrive on-circuit pacing to terminate the tachycardia. The results of the study suggest that the usual impression of a regular recovery wave and of a regular excitable window moving uniformly along the macro-reentrant circuit is incorrect