A new mechanism for cardiac spiral wave meandering

The mechanism responsible for cardiac spiral wave meandering in the Fitzhugh-Nagumo equations is studied in detail using linear perturbation theory. We find that the key process for meandering is the diffusion of perturbations in the membrane potential from the refractory region radially inward into the tail of the action potential a short distance away from the spiral wave tip. This mechanism is distinct from both electrical restitution dynamics and the dynamics of pulse instabilities, and thus suggests that other criteria may be important in determining the stability of spiral waves and functional reentry in the heart