Dispersion of refractoriness in a simulated ischemic 2D tissue and implications in vulnerability to reentry

During the acute phase of myocardial ischemia, electrophysiological changes and heterogeneities predispose the heart to arrhythmogenic reentrant excitation. In this computational work we analyze the role of dispersion of refractoriness on reentry generation in a two-dimensional sheet of ischemic tissue at different stages after the onset of ischemia. A realistic model of regional ischemia was used basing our simulations on a modified version of the 2000 Luo-Rudy action potential model. Our results are consistent with experimental studies in which vulnerability to ventricular arrhythmias has an unimodal behavior in the acute phase of myocardial ischemia. We also observed that dispersion of refractoriness was necessary for reentry to ensue, but its dispersion degree did not correlate with vulnerability. Thus, other ionic factors such as axial currents must be involved in the modulation of the vulnerability to reentry.