Simulation of figure-of-eight reentry during acute inhomogeneous myocardial ischemia: role of ATP-sensitive potassium current

Figure-of-eight reentry is an abnormal pattern of excitation which is commonly found in hearts subject to acute myocardial regional ischemia. This type of reentry can lead to ventricular tachycardia and fibrillation, which are potentially mortal arrhythmias. In this work, the authors use a detailed mathematical model of the electrical activity of an acutely ischemic tissue to simulate and study this type of reentry. Regional ischemia is modeled by considering the effects of hyperkalemia, hypoxia (K_ATP channel activation) and acidosis in a 2D tissue comprising normal, ischemic and border zone cells. The vulnerable window for reentry was measured for different degrees of K_ATP channel activation. The model successfully simulates figure-of-eight reentry, and the results show that the duration of the vulnerable window depends on the severity of hypoxia in a biphasic manner.