Ventricular fibrillation


![Log-log graph of the effect of alternating current I of duration T passing from left hand to feet as defined in IEC publication 60479-1.[6]
AC-1: imperceptible
AC-2: perceptible but no muscle reaction
AC-3: muscle contraction with reversible effects
AC-4: possible irreversible effects
AC-4.1: up to 5% probability of ventricular fibrillation
AC-4.2: 5-50% probability of fibrillation
AC-4.3: over 50% probability of fibrillation](/uploads/202501/19/IEC_TS_60479-1_electric_shock_graph.svg4316.png)

Ventricular fibrillation (V-fib or VF) is a condition in which there is uncoordinated contraction of the cardiac muscle of the ventricles in the heart, making them quiver rather than contract properly. Because there is no co-ordinated contraction of the ventricles, there is no significant cardiac output, thus fulfilling the conditions of a cardiac arrest. It is the most commonly identified arrhythmia in cardiac arrest patients, and requires prompt treatment if identified on electrocardiography. Left untreated, ventricular fibrillation will quickly degenerate into asystole and is associated with a high mortality. Patients who are not revived soon enough (within about five minutes at room temperature) can sustain irreversible brain damage and can become brain-dead, because of cerebral hypoxia.