Ventricular fibrillation

Ventricular fibrillation (V-fib or VF) is an abnormal heart rhythm in which the ventricles of the heartquiver. It is due to disorganized electrical activity. Ventricular fibrillation can cause cardiac arrest and loss of consciousness without pulse. This is followed by sudden cardiac death in the absence of treatment. Ventricular fibrillation is initially found in about 10% of people with cardiac arrest.

Ventricular fibrillation can occur due to coronary heart disease, valvular heart disease, cardiomyopathy, Brugada syndrome, long QT syndrome, electric shock, or intracranial hemorrhage. Diagnosis is by an electrocardiogram (ECG) showing irregular unformed QRS complexes without any clear P waves. An important differential diagnosis is torsades de pointes.

Treatment is with (CPR) and defibrillation. Biphasic defibrillation may be better than monophasic. The medication epinephrine or amiodarone may be given if initial treatments are not effective. Rates of survival among those who are out of hospital when the arrhythmia is detected is about 17%, while for those in hospital it is about 46%.