SPIRAL BREAKUP IN EXCITABLE TISSUE DUE TO LATERAL INSTABILITY

In a simple two-component model of excitable tissue a spiral wave is f ound to break up into a large number of small spirals. More specifical ly, we used a modified FitzHugh-Nagumo model. Spiral breakup is found to occur when the recovery variable diffuses at a high rate. The break up is caused by lateral instability of the wave front. We analyzed thi s instability using quasi-one-dimensional computations and found that it could be connected to a negative eikonal-curvature relation for the parameter values at which spiral breakup occurs.