Tachyarrhythmia threshold of ischemic heart in 3-dimensional computer model

A three-dimensional (3-D) computer model of electrical propagation through an ischemic heart is presented. Thirty-eight slices through a real dog heart are discretized into 9532 1.5-mm-sided cubic elements to form the anatomical basis of the model. Each element can be in one of five states: absolutely refractory, three relative refractory states, and an excitable state. Propagation from an excited element to its neighbors occurs in 3-D with varying velocities, depending upon the current state of those neighbors. Ischemia in a specific region of the heart in this model is represented by a reduction in conduction velocities in that region. By varying both the number of extra-stimuli applied to the heart and the severity of the ischemia, this model simulates transitions into sustained, as well as spontaneously terminating, ventricular tachycardias and fibrillations. In addition, this model demonstrates that the threshold for sustained tachyarrhythmia decreases as the ischemia becomes more severe