Computer models of the heart: from single beat to fatal arrhythmias

Supercomputers have greatly influenced the studies of biological cells and cellular networks. Electrophysiological properties of the cells are now known in great detail. Therefore, computer models are constructed to simulate the electrical activity of single heart cells and networks of coupled heart cells. These simulations are used to mimic the rhythms of the heart, including arrhythmias such as ventricular fibrillation (VF). Computer simulations require very large scale computational resources, with parallel or vector architectures offering distinct benefits in terms of the ease of coding the algorithms and in terms of computational performance. Three models, one implemented on a personal computer, the second on a Connection Machine and the third on a Cray C90, are reported. The computer simulations reveal the mechanism of generation of VF-like rhythms in the form of wavelets and spiral waves and suggest novel strategies for terminating these arrhythmias