Spiral breakup in a new model of discrete excitable media

The transition from the dangerous cardiac arrhythmia, ventricular tachycardia, to the fatal cardiac arrhythmia, ventricular fibrillation, is believed to be associated with the breakup of spiral waves of excitation into multiple reentrant waves. A new computational method for wave propagation in discrete excitable media employing coupled maps with continuous time is used to derive analytical criteria for parameter ranges in which spiral waves show a stationary rotation, wandering, and breakup into multiple spirals.