Relationship between restitution and the breakdown of reentry into fibrillation in a 3-D model of cardiac tissue

Ventricular fibrillation begins with a reentrant tachycardia which deteriorates into multiple meandering wavefronts. Using a 3-D model of cardiac tissue with ionic currents, a single wavefront reentry (monomorphic tachycardia) was initiated in the block which quickly broke down into disorganized, multiple wavefronts (fibrillation). By altering the parameters of the model it was possible to keep the activity from degenerating. Restitution curves were computed both from single cell and from the reentrant activity. Results indicate that multiple wavefronts are associated with a restitution curve having a significant region with a slope greater than one. Also, fibrillation can be prevented by decreasing the slow inward calcium current or increasing the potassium current