Cardioversion using feedback stimuli in human atria

Beatbox, a novel cardiac simulation environment, was used to study low amplitude human atrial cardioversion. Chronic atrial fibrillation (CAF) was simulated using the Courtemanche et al. cell model with reduced I_CaL and increased I_K1 current conductances. In 2D and 3D models, re-entry was induced using the phase distribution method. The feedback stimulation method was applied to eliminate such re-entry under CAF conditions. CAF dramatically reduced action potential duration by 47%. Under CAF conditions, a single threshold amplitude shock of 4.5 pA/pF eliminated the stable reentry. In 2D simulations, multiple feedback induced stimuli of 1 pA/pF caused re-entrant waves to migrate out of the 2D tissue. In 3D CAF simulation, feedback induced stimuli also caused the re-entrant wave migration eventually eliminating the re-entry. The effectiveness of the cardioversion method is affected by the 3D anatomy and warrants further studies.