Success and failure of the defibrillation shock: does it depend on the fiber field?

This modeling study demonstrates that shocks of the same strength and duration are more successful in extinguishing spiral wave activity in cases when the preparation incorporates fiber curvature. The tissue is represented as a two-dimensional bidomain of unequal anisotropy ratios. Stable reentry is induced via cross-field stimulation of the myocardial sheet. The defibrillation shock is delivered by extracellular line electrodes located at opposite tissue borders. The simulation results demonstrate that the defibrillation shock induces virtual electrodes in the curved fiber preparation. These virtual electrodes are responsible for depolarizing the tissue away from the physical cathode and for giving rise to new activation fronts after the defibrillation shock. Thus, shocks of the same strength and duration are successful in preparations with fiber curvature, while in straight-fiber preparations they only minimally disturb the spiral wave