It is a life-threatening heart rhythm that results in a rapid, inadequate heartbeat.  It is because the heart doesn't pump appropriate amount of blood during ventricular fibrillation, sustained VF can cause low blood pressure, loss of consciousness and lead to death also. Emergency treatment constitutes an immediate defibrillation along with an automated external defibrillator (AED) and cardiopulmonary resuscitation (CPR). Long-term therapy includes implantable defibrillators and medications, hence to avoid it from occurring again. It could be diagnosed by ECG, Blood tests. Chest X-ray., Echocardiogram. Coronary catheterization (angiogram), computerized tomography (CT), Magnetic resonance imaging (MRI).  It is considered the most serious cardiac rhythm disturbance. Disordered electrical activity causes the heart's lower chambers. This rapid and irregular electrical activity renders the ventricles unable to contract in a synchronized manner, resulting in immediate loss of cardiac output. Cardiopulmonary resuscitation (CPR) must be started within a few minutes, and it must be followed by defibrillation (an electrical shock delivered to the chest) to restore normal heart rhythm. People develop irreversible brain damage after about 5 minutes because oxygen no longer reaches the brain. Death soon follows.