Simulation of late potentials and arrhythmias by use of a three-dimensional heart model: casuality of peri-infarctional slow conduction in ventricular fibrillation.

A three-dimensional heart model was constructed to simulate late potentials and ventricular fibrillation (VF). The model consisted of 50,000 discrete elements having a 1.5-mm spatial resolution. Each element represented excitable ventricular tissue, including a conduction system, and was characterized with classical features of the action potential, refractory period, and conduction velocity (theta). An infarcted area on the lateral wall was identified as dead (inexcitable) cells or scar tissue, and peri-infarctional (PI) cells with slow conduction. Body surface potentials were calculated by using the boundary element method. When theta of PI cells was reduced below 0.3 m/s, late potentials became evident after the J point of simulated electrocardiograms (ECGs), and VF was induced by applying four consecutive premature stimuli. However, when Purkinje fibers were removed, VF could not be initiated. Late potentials were induced when slow conduction was present. The presence of PI slow conduction and Purkinje fibers, which were normally contained in the model, was essential for the induction of VF.