A simple finite-element model of ventricular conduction processes that explicitly incorporates spatial dispersion of refractoriness was developed. This model revealed that spatial dispersion of refractoriness is a sufficient condition to produce self-sustained reentry even in the absence of unidirectional block, inhomogeneity in local conduction velocities, or the presence of ectopic pacemakers. The model displayed a wide variety of rhythm disturbances qualitatively similar to clinically familiar cardiac dysrhythmias. Electrical stability of the model was determined as a function of the model parameters including ventricular stimulation rate, conduction velocity, and mean refractory period as well as standard deviation of refractory periods. We conclude that spatial dispersion of refractoriness is a sufficient condition to initiate reentrant dysrhythmias but that other physiologic variables such as ventricular rate and conduction velocity strongly influence the dysrhythmogenic effect of spatial dispersion of refractoriness.