Low-voltage defibrillation in bidomain virtual ventricular tissue: effect of the bath

Mechanisms for termination of re-entry and defibrillation still remain a challenge. Using the Luo-Rudy family of virtual ventricular tissues we simulate termination of re-entrant spiral waves with a periodic low-voltage shock studying a new mechanism for defibrillation. Essential for the simulations is extension of the bidomain tissue representation in order to account for the existence of an external bath ("tridomain"), where the shock is applied The bidomain model with the bath reproduces periodic patterns of depolarization in the virtual tissue - standing waves, previously observed in experiments. In contrast to the classical exponential decay of voltage near the electrodes, standing waves entrain the whole tissue, thus canceling the spiral waves. The mechanism of this far-field effect is based on redistribution of the externally applied current by the conductive bath.