Ventricular fibrillation
Ventricular fibrillation (VF or V-fib) is, like pulseless VT, a ventricular arrhythmia and an emergency which must be handled with cardiopulmonary resuscitation and defibrillation, as the patient has no cardiac output. Like VT, it most commonly occurs in diseased hearts. Sustained VT can quickly develop into ventricular fibrillation, as well. It invariably causes loss of consciousness and death if untreated.