Patterns of electrical activation in an inhomogeneous ischemic sheet of myocardial tissue: a simulation study

Acute regional myocardial ischemia can lead to re-entrant activity under certain circumstances. Electrophysiological inhomogeneities within the tissue concomitant with premature stimuli may cause a specific type of re-entry called "figure-of-eight" re-entry. We reproduced and analysed the patterns of electrical activation in a 2D sheet of regionally-ischemic myocardial tissue using computer modeling. Simulations were carried out using a modified version of the Luo-Rudy-II model (C.H. Luo & Y. Rudy, 1994), which included a formulation of I _K(ATP) by J.M. Ferrero et al. (1996). The simulated 2D tissue included a central ischemic zone, a border zone and a normal zone. Our results showed differences in action potential and conduction velocity within the tissue, leading to curved patterns of activation and figure-of-eight re-entries. The vulnerable window, i.e. the time interval of the re-entrant premature stimulus, was wider under anisotropic conditions than in an isotropic tissue