Three-dimensional aspects of re-entry in experimental and numerical modelsof ventricular fibrillation

Ventricular fibrillation is believed to be produced by the breakdown of re- entrant propagation waves of excitation into multiple re-entrant sources. T hese re-entrant waves may be idealized as spiral waves in two-dimensional, and scroll waves in three-dimensional excitable media. Optically monitored, simultaneously recorded endocardial and epicardial patterns of activation on the ventricular wall do not always show spiral waves. We show that numer ical simulations, even with a simple homogeneous excitable medium, can repr oduce the key features of the simultaneous endo- and epicardial visualizati ons of propagating activity, and so these recordings may be interpreted in terms of scroll waves within the ventricular wall.