DYNAMICS OF ROTATING VORTICES IN THE BEELER-REUTER MODEL OF CARDIAC TISSUE

Cardiac muscle is a highly nonlinear active medium which may undergo r otating vortices of electrical activity. We have studied vortex dynami cs using a detailed mathematical model of cardiac muscle based an the Beeler-Reuter equations. Specifically, we have investigated the depend ence of vortex dynamics on parameters of the excitable cardiac cell me mbrane in a homogeneous isotropic medium. The results demonstrate that there is a transition from the vortex with circular core that is typi cal of most excitable media, including the Belousov-Zhabotinsky reacti on, to a vortex with linear core that has been observed in heart muscl e during so-called reentrant arrhythmias. The transition is net direct but goes through the well-known sequence of nonstationary quasiperiod ic rotating vortices. In the parameter space there are domains of diff erent types of vortex dynamics. Such domains include regions where: (1 ) vortices can not be generated, (2) vortices occur readily, and (3) v ortices arise but have a short lifetime. The results provide testable predictions about dynamics associated with initiation, maintenance and termination of cardiac arrhythmias.