Patterns of wave break during ventricular fibrillation in isolated swine right ventricle

Several different patterns of wave break have been described by mapping of the tissue surface during fibrillation. However, it is not clear whether th ese surface patterns are caused by multiple distinct mechanisms or by a sin gle mechanism. To determine the mechanism by which wave breaks are generate d during ventricular fibrillation, we conducted optical mapping studies and single cell transmembrane potential recording in six isolated swine right ventricles (RV). Among 763 episodes of wave break (0.75 times.s(-1).cm(-2)) , optical maps showed three patterns: 80% due to a wave front encountering the refractory wave back of another wave, 11.5% due to wave fronts passing perpendicular to each other, and 8.5% due to a new (target) wave arising ju st beyond the refractory tail of a previous wave. Computer simulations of s croll waves in three-dimensional tissue showed that these surface patterns could be attributed to two fundamental mechanisms: head-tail interactions a nd filament break. We conclude that during sustained ventricular fibrillati on in swine RV, surface patterns of wave break are produced by two fundamen tal mechanisms: head-tail interaction between waves and filament break.