Isolated focus of ventricular fibrillation

Mechanisms underlying the initiation of ventricular tachycardia have been described as either rapidly firing focus initiated by triggered activity or automaticity, or a reentrant wavefront initiated by a premature ventricular depolarization. Ventricular fibrillation can occur after ventricular tachycardia; however, uncertainty exists concerning its mechanism, whether it is caused by multiple wavelets, mother rotor, or a combination of both. This report describes the finding of a spontaneously isolated focus of ultrarapid ventricular activity recorded and ablated in a patient with nonischemic cardiomyopathy and ventricular tachycardia.