In ventricular fibrillation, rapid, chaotic electrical impulses cause the ventricles to quiver uselessly instead of pumping blood. Without an effective heartbeat the blood pressure plummets, instantly cutting off blood supply to vital organs including the brain. Most people lose consciousness within seconds and require immediate medical assistance including cardiopulmonary resuscitation (CPR). Without CPR, death results in minutes. Ventricular fibrillation is frequently triggered by a heart attack.
Attribution: Straight Talk Foundation