Vulnerability to Reentry during the Acute Phase of Myocardial Ischemia: a Simulation Study

The aim of this work was to analyze the vulnerability to reentry in a two-dimensional sheet of regionallyischemic and anisotropic myocardial tissue at different stages of acute myocardial ischemia. We used computer modelling in order to elucidate the main factors responsible for initiation and maintenance of reentry. Simulations were carried out using a modified version of the Luo-Rudy-II model. The simulated 2D tissue included a central ischemic zone, a border zone and a normal zone and was prematurely stimulated. The degree of severity of the central zone was changed depending on the stage of acute ischemia. Our results offer a theoretical explanation of the existence of a vulnerable phase for reentry between the fifth and tenth minute of acute ischemia, and lead to the conclusion that (a) strong hyperkalemia is needed to sustain reentry and (b) severe degrees of hypoxia tend to reduce myocardial vulnerability to reentry.