A defibrillator is a device used to stop an abnormal heart rhythm. It works by sending a harmless electrical shock to the heart. The heart often responds by returning to a normal beat.

An automated external defibrillator (AED) is small and self-contained. It has simple controls and can be used without much training.

Who is a candidate for the procedure?

This can be a life-saving procedure for people whose hearts stop beating, a condition called cardiac arrest, or who have a heart attack. In these cases, an electrical shock is often the only way to get the heart back to a normal heartbeat. The quicker the shock is given, the more likely the person is to recover.

How is the procedure performed?

The operator applies two electrodes to the person's chest. These electrodes are attached to the AED. The AED has a microprocessor that is able to identify the heart rhythm. It prompts the operator to give a shock if needed. A shock is given by pressing a button on the unit.

AEDs are becoming more common in malls, airports, airplanes, and other places where large crowds gather. Everyone who takes an advanced cardiac life support course is taught how to use an AED.