An automated external defibrillator (AED) is a medical device designed to analyze the heart rhythm and deliver an electric shock to victims of ventricular fibrillation to restore the heart rhythm to normal.

Ventricular fibrillation is the uncoordinated heart rhythm most often responsible for sudden cardiac arrest. Sudden cardiac arrest occurs when ventricular fibrillation takes place or when the heart stops beating altogether.

Without medical attention, the victim collapses, lose consciousness, becomes unresponsive, and dies. Many victims have no prior history of heart disease and are stricken without warning.

Chances of survival from sudden cardiac death diminish by 7 – 10 percent for each minute without immediate CPR or defibrillation. After 10 minutes, resuscitation rarely succeeds.