Arrhythmogenic role of the border between two areas of cardiac cell alignment.

The goal of this study is to develop experimental and computational models of the excitation transition between areas of cardiac tissue with different anatomical anisotropy. Alignment of seeded neonatal rat cardiomyocytes was achieved with the aid of guiding polymer (PMGI) nanofibers, and two areas with orthogonal alignment were placed into a contact. It was found that the excitation wave crossing border between the areas with different alignment direction experiences substantial perturbation, up to the complete conduction block. In addition to the experimental study, this effect was analyzed computationally using generic FitzHugh-Nagumo reaction-diffusion model. It was shown that the non-monotonous changes of the excitation wave velocity on this boundary may be explained by the source/sink mismatch. Thus, the border may play pro-arrhythmogenic role.