Simulation of spiral waves in isotropic myocardium

Action potentials were simulated in a 75/spl times/75 network of cells provided with electrotonic interaction. Each action potential were described by four ion currents having time- and voltage dependent activation and inactivation kinetics. All the cells had the same electrophysiologic characteristics with a short refractory period compared to the propagation velocity, i.e. a short wavelength. A spiral wave was induced by having a second excitation wave perpendicular to the wake ofa preceding wave. The tip of the spiral wave circled around an area with non-excited cells due to decremental propagation, double spiral waves could be created by a similar excitation procedure. The spiral waves drifted along edges of nonexcitable cells. The interaction between three of more spiral waves produced chaotic excitation patterns with drifting spiral waves. The intervals between action potentials were irregular. It is concluded that a chaotic pattern with spiral waves can be created in isotropic myocardial tissue.