Effect of Heterogeneity on Spiral Wave Dynamics in Simulated Cardiac Tissue

There is considerable spatial heterogeneity in the electrical properties of the heart muscle and there are indications that anisotropic conduction may play an important role in the pathogenesis of clinical cardiac arrhythmias. Spiral waves of electrical activity are related to reentrant cardiac arrhythmias as ventricular tachycardia and ventricular fibrillation, and the generation of a wave breakup is hypothesized to underlie the transition from ventricular tachycardia to ventricular fibrillation — the leading cause of sudden cardiac death. Here we investigate the effect of heterogeneity on spiral wave reentry in a two-dimensional modified FitzHugh–Nagumo membrane model. Spiral wave breakup induced by the heterogeneity is found. The spiral wave dynamics is invariant under translational and rotational transformations in homogeneous tissue, but for heterogeneous tissue, this symmetry is broken due to the heterogeneity. The reentry dynamics depends on the degree of heterogeneity and the point where the reentry is initiated within the simulated tissue. This study may open potentially exciting new diagnostic and therapeutic possibilities in a clinical context.