Three-dimensional numerical Simulation of the excitation and repolarisation process in the entire human heart with special emphasis onreentrant tachycardias

A computer model of the entire human heart has been developed for three- dimensional simulation of the excitation and repolarization process. Spatial distribution of refractory periods and conduction velocities in the different cardiac tissues, the anisotropy of conduction in the ventricles and the cycle length dependence of refractory periods and conduction velocities are taken into account. The algorithm calculating the activation process is based on a modified version of Huygen's principle for constructing wavefronts. Sinus rhythm as well as extrasystoles for initiation of excitation wavefronts can be simulated. The time-course of the electrocardiogram (ECG) and the magnetocardiogram (MCG) is calculated by numerical evaluation of a simplified version of the equations of the bidomain model. Results of simulations show good agreement of isochrones of excitation and ECG with measurements in normal case as well as in the case of bundle branch block and Wolff-Parkinson- White syndrome. Simulations have been successfully performed concerning various other conduction phenomena in the human heart: the gap phenomenon of the conduction system, supraventricular tachycardia in the presence of an accessory pathway connecting atria and ventricles. The model may be useful for investigating numerous problems in cardiologic and electrocardiographic research.