What is an AED?
An AED, or automated external defibrillator, is a device that automatically analyzes heart rhythms and advises the operator to deliver a shock if the heart is in a fatal heart rhythm. AEDs are safe and will not shock anyone who is not in a fatal heart rhythm. Non-medical personnel can use AEDs safely and effectively with minimal training.

How does an AED work?
A computer inside the defibrillator analyzes the victim's heart rhythm. The device decides whether a shock is needed. Some devices shock the victim automatically if a shock is needed. Other devices require that the operator press a button to deliver the shock. The shock is delivered through pads stuck to the victim's bare chest. The shock stuns the heart, stopping abnormal heart activity, and allowing a normal heart rhythm to resume.

What if the victim has a medication patch, such as nitroglycerin?
Never place electrodes directly on top of medication patches. If the patch is in the way of the AED pads, remove it and wipe off the area with the victim's shirt. Then apply the pads to the clean, bare skin.

What if the victim has an implantable pacemaker or defibrillator?
If the victim has a pacemaker or internal defibrillator with a battery pack (visible as a lump under the skin about two inches long), avoid placing pad directely on top of the implanted medical device.