Computerized mapping of ventricular fibrillation.
Ventricular fibrillation (VF) is a complicated rhythm disorder. To study the mechanisms of VF, we used computerized mapping techniques with up to 512 channels of simultaneous multisite recordings for data acquisition. The data were then processed for dynamic display of the activation patterns and for mathematical analyses of the activation intervals. The results show that VF can be initiated by a single strong premature stimulus given during the vulnerable period of the cardiac cycle. The initial activations form figure-eight patterns. Afterwards, VF perpetuates itself without any outside help. The ability to perpetuate itself is, in part, due to the ability to generate new reentry by wavebreak. When two wavelets intersected perpendicular to each other, the second wavelet was broken by the residual refractoriness left over from the first wavelet. In diseased hearts, such as in hearts with dilated cardiomyopathy, the generation of reentry is facilitated by tissue inhomogeneity and anisotropy. We conclude that VF is a form of reentrant cardiac arrhythmia. Strong electrical stimulus initiated single or dual reentrant wavefronts that broke up into multiple wavelets. Sometimes short-lived organized reentry is also generated during the course of VF. These organized reentry and broken wavelets serve as the source of activations that sustain VF.