An automated external defibrillator (AED) is a portable device that can be used to treat a person whose heart has suddenly stopped working. This condition is called sudden cardiac arrest.

AEDs are available in many public places, such as government buildings, schools, airports and other community spaces. Small, lightweight AEDs are available without a prescription for use at home.

People with severe heart disease who are at risk of sudden cardiac arrest might consider having an AED at home. Talk to your healthcare professional about whether you should buy an AED for your home.

An AED is used to revive someone from sudden cardiac arrest. This usually happens when a problem in the heart's electrical activity causes a dangerously irregular heartbeat. The irregular heartbeat prevents the heart from pumping as it should and causes the heart to stop.

When this happens, the brain and other organs don't get the blood and oxygen they need. Treatment is needed within minutes to prevent death. The sooner the heartbeat is restored, the greater the chance there won't be permanent damage to the brain and other organs.

All AEDs include instructions on when and how to use them. Training on proper use of an AED is recommended. But someone with no training also can use the device to reset the heartbeat of a person who has had a sudden cardiac arrest. 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 heartbeat. Together these treatments can improve the chances of survival.

Police and ambulance crews carry AEDs. Also, they're commonly found in many public places, such as malls, office buildings, schools, sports arenas, gyms and airplanes. But many cardiac arrests occur at home. Having a home AED may save precious minutes in treating a person who has a sudden cardiac arrest.

Supporters of home AEDs say putting them where they're needed most will save many lives. But critics argue there's not enough evidence to show that home AEDs save more lives.

For some people at high risk of cardiac arrest, an AED can provide peace of mind and might help save their lives. Here are some things to keep in mind when considering whether to buy an AED:

• Risk of sudden cardiac arrest. For someone at high risk of sudden cardiac arrest due to a specific heartbeat problem, a healthcare professional will likely recommend an implantable cardioverter-defibrillator (ICD) rather than an AED. An ICD is implanted in the chest. It's connected to the heart through a wire that can deliver a shock when needed.
• Living arrangements. You need someone with you to use the AED if you have cardiac arrest. And the person needs to be able to get on the floor to use the device and get back up. If you live alone or if the person you live with can't get up and down, a home AED might not make sense.
• Costs. Home AEDs can be expensive and aren't usually covered by insurance.
• Overall health and quality of life. Someone who has serious, long-term medical conditions or hasn't responded to treatment for heart conditions might decide not to be resuscitated from sudden cardiac arrest.

If you are thinking about an AED for your home, here are some tips for buying and maintaining a home AED:

• Buy an AED approved by the Food and Drug Administration (FDA). The FDA's website lists approved devices.
• Register the AED with the manufacturer. If there are safety alerts and recall notices, you will be notified. Also, check the manufacturer's website from time to time to keep current on information about your device.
• Learn what you need to know. Consider enrolling yourself and others who might need to use your home AED in a class. The American Red Cross, for example, teaches how to use an automated external defibrillator properly and how to perform CPR.
• Have a practice run using the AED. It's helpful for the people who might need to use an AED to be comfortable checking for a pulse and breathing, following the instructions, and placing pads. It's also important for them to know what to do if a shock isn't required.
• Store your AED in a place that's easy to get to. Make sure family, friends and visitors know where it is.
• Keep the AED working properly. Install new batteries as needed, typically every four years. Replace electrode pads as needed. Have spare pads on hand. Follow the manufacturer's instructions.
• Heed alarms. Home AEDs are designed to test themselves to make sure they're working properly. Be sure you can hear the alarm. If your machine starts beeping or you see a light flashing, call the device manufacturer. Keep the number handy.
• Buy the right AED for you. Some AEDs aren't intended for home use, but rather for use by emergency crews or in public places. Don't be lured by websites or other sellers offering AEDs not intended for home use.

AEDs offer a way to save a life. Before buying one, talk to a healthcare professional and do research. And don't forget to learn the basics, such as CPR.