Simulation of propagation in a realistic-geometry computer heart model with parallel processing

The simulation of the propagation of electrical activity in a realistic-geometry computer model of the ventricles of the human heart using the governing reaction-diffusion equation is described. Each model point is represented by the phase 1 Luo-Rudy membrane model, appropriately modified to represent human action potentials. A separate longer-duration action potential waveform was used for the M cells found in the ventricular mid-wall. Cardiac fiber rotation across the ventricular wall was implemented via an analytic equation, resulting in a spatially-varying anisotropic conductivity tensor and consequently anisotropic propagation. Since the model comprises approximately 12 million points, parallel processing was used to cut down on simulation time. The model generated acceptably-normal electrocardiograms, vectorcardiograms and body surface potential maps on the surface of a numerical human torso model. Interestingly, it was found that the intrinsic difference in action potential duration between M cells and other myocardial cells was greatly diminished due to electrotonic coupling.