VENTRICULAR-FIBRILLATION - ONE SPIRAL OR MANY

Ventricular fibrillation is the major cause of sudden cardiac death, t he leading cause of death in the industrialized world; however, the me chanisms for its onset are not well understood. To further understand the dynamics of fibrillation at and near its onset, we compared spatia l and temporal variability of mean interactivation intervals in a stab le canine model fbr ventricular fibrillation. Temporal variability was very small, suggesting that the relevant physiological parameters rem ained constant during our experiments. Spatial variability was usually significantly larger and appeared incompatible with. the dynamics of a single, meandering spiral wave. This confirmed recent results that a single spiral wave cannot generate ventricular fibrillation. Thus the onset of fibrillation is a multistage process, with spiral-wave break down providing a crucial step in the quasi-periodic route to fibrillat ion.