Spatiotemporal Chaos in a Simulated Ring of Cardiac Cells

We recently presented evidence that cardiac fibrillation is a form of spatiotemporal chaos arising via a quasiperiodic transition. To investigate the origin of this quasiperiodicity, we studied reentrant excitation in a ring of cardiac cells. We modified the Beeler-Reuter model, changing the action potential duration (APD) restitution so that it agreed qualitatively with experimental studies. We found that chaos could occur by reentrant excitation, in a transition from quasiperiodicity to spatiotemporal chaos. This occurred only when the APD restitution curve was nonmonotonic.