When is an AED needed?
AEDs are used to revive someone from sudden cardiac arrest. This usually occurs when a disruption in the heart's electrical activity causes a dangerously fast heartbeat (ventricular tachycardia) or a fast and irregular heartbeat (ventricular fibrillation). Either of these irregular heart rhythms keeps the heart from pumping effectively and can cause it to stop.

When this happens, the brain and other vital organs don't get the blood and oxygen they need. This requires treatment within minutes to prevent death. The sooner the heart's rhythm is restored, the greater the chance there won't be permanent damage to the brain and other organs.

If an AED is near someone having ventricular fibrillation or ventricular tachycardia, a bystander in a public place or a family member can use it to jolt the heart back to a regular rhythm. Using the AED could possibly save a life.

Cardiopulmonary resuscitation (CPR) after cardiac arrest can keep blood flowing to the heart and brain for a time. But often only defibrillation can restore the heart's rhythm. Together these treatments can improve the chances of survival.