(MayoClinic.com) If you've ever watched medical shows on television, you've probably seen people on the brink of death shocked back to life by a doctor who yells "clear," then delivers one or more jolts of electricity to the chest.

You can perform this type of procedure in your own home with an automated external defibrillator (AED). But AEDs aren't for everyone. An AED won't resuscitate you if you don't have the specific type of heart rhythm problem that an AED can correct. And in some circumstances, other emergency medical procedures, such as cardiopulmonary resuscitation (CPR), may be just as likely to save your life as shocks from an AED.

Home AEDs are available over-the-counter, without a prescription. The question is whether an automated external defibrillator could be useful to you. Consider the pros and cons of owning an AED. Then you and your doctor can decide if it's worth buying the device for home use.

Cardiac arrest usually occurs when your heart's electrical activity becomes disrupted and the heartbeat gets dangerously fast (ventricular tachycardia) or chaotic (ventricular fibrillation). Because of this chaotic, irregular heart rhythm (arrhythmia), your heart stops beating effectively and can't adequately pump blood.

During cardiac arrest, your brain and other vital organs quickly become starved of blood and the life-sustaining oxygen and nutrients it carries. You could die within a few minutes, or if you survive, you may sustain permanent damage to your brain and other organs. The sooner your heart's rhythm is restored the better, since each minute is critical to determining your chance of survival and how much damage you might have.

Although cardiopulmonary resuscitation (CPR) is a vital step in the lifesaving process and can keep some blood flowing to your heart and brain for a short time, often only defibrillation can restore the heart's normal rhythm and ultimately save your life. This is especially true if you experience a type of abnormal heart rhythm known as ventricular fibrillation.

If you're experiencing ventricular fibrillation and an AED is on hand, a bystander could grab it and easily connect it to your chest to check your heart rhythm. If your heart rhythm can be treated with an electric shock, the AED automatically sends an electrical current to your heart muscle. That jolt could reset your heart back into a normal rhythm, possibly saving your life.

If you use an AED on someone, it's still critical that you call 911 or your local emergency services to get help on the way before you begin using the AED.

The Food and Drug Administration (FDA) has approved an over-the-counter AED for home use. Because it's over-the-counter, you don't need a prescription to buy it. The only automated external defibrillator approved for home use without a prescription is the Philips HeartStart Home Defibrillator. The HeartStart AED can be used on children as young as 8 who weigh at least 55 pounds.

In addition to being carried by police and ambulance crews, AEDs are now commonly available in many public places, including malls, office buildings, sports arenas, golf courses, cruise ships, schools, casinos, airports and airplanes.

The problem, though, is many cardiac arrests happen in private homes. With an automated external defibrillator in your home, you wouldn't lose precious minutes waiting for rescue workers to arrive with an AED.

Proponents of in-home AEDs say putting them where they're most needed will save thousands of lives each year. If you collapse from cardiac arrest, a family member or friend could quickly grab your home AED, send a jolt of electricity to your heart and, in theory, save your life.

But critics argue there's no reliable evidence that home defibrillators actually save more lives. Critics also fear that people won't call for emergency medical services at all or quickly enough, that they won't maintain their AED properly, or that they'll forget where it's kept.

An AED is a device that can be attached to your chest. It senses your heart's rhythm during cardiac arrest and, in some cases, delivers an electric shock to get your heart beating again.

The home AED comes with a short instructional training video that shows how to use and maintain the device. You should watch the video when you buy the device, and periodically review the video to refresh your memory on how to use the device.

In an emergency, the automated external defibrillator essentially makes the decisions. It offers step-by-step voice instructions to guide a user through the defibrillation process. It explains how to check for breathing and a pulse and how to position electrode pads on the person's chest.

Once the pads are in place, the AED automatically measures the person's heart rhythm and determines if a shock is needed. If it is, the machine tells a user to stand back and instructs the user to push a button to deliver the shock. It will also guide users through CPR. The process can be repeated as needed until emergency crews take over.

Having a home AED isn't right for everyone. A home AED will deliver a shock only if a person's heart has stopped due to a specific heart rhythm problem. It's also possible a person using an AED may not use the device correctly under the stressful circumstances of providing care to a person who's in cardiac arrest.

But for some people who have a high risk of cardiac arrest, having an AED may provide peace of mind, and may help save a life. There's no specific list of criteria to decide if an automated external defibrillator would be appropriate for your home. But here are some things to keep in mind as you consider whether to buy an automated external defibrillator:

• Your risk of sudden cardiac death. Your doctor can help you understand if you have a condition that may put you at higher risk of cardiac arrest or if you're leading a lifestyle that could cause heart problems. In most people who are at high risk of sudden cardiac death, doctors will recommend a device called an implantable cardioverter-defibrillator (ICD) rather than an AED. Remember that AEDs work only for cardiac arrest that involves specific types of heart fibrillation. It will not revive everyone in cardiac arrest. And with certain types of heart disease, you may need a defibrillator that's actually implanted in your chest instead of an external device for emergencies.
• Your living arrangements. If you live alone, an AED will be of little use if you have cardiac arrest — there won't be anyone to use the machine on you.
• Your physical abilities. You or a family member must have the flexibility and strength to sit or squat on the floor, use the device, and get back up.
• Your costs. Home AEDs can be expensive, costing about $1,300 or more. Health insurance doesn't generally pick up the tab.
• Your overall health and philosophy. If you have numerous medical problems, a terminal illness or a very weak heart that hasn't responded to treatment, you may decide that you wouldn't want to be resuscitated from sudden cardiac death.

If you decide to get an AED for your home, with or without your doctor's approval, make sure you learn how to use it and maintain it properly. If you don't, an AED will be of little use in an emergency.

Here are some tips for maintaining your home AED:

• Don't rely only on instructional material provided with the AED. Enroll yourself and your family members in a community education class, such as those offered by the American Red Cross, to learn how to use your automated external defibrillator properly. This will also allow you to come to the rescue if someone has cardiac arrest in a public place and there's an AED nearby.
• Take the AED to your doctor's office. It may be helpful to demonstrate how you and your family would use it, to make sure you're using it correctly.
• Have a family practice run using the AED as you would in an actual emergency. Remember, the AED works only on certain types of cardiac arrest. Know what steps to take if the AED indicates a shock isn't needed, but the person remains unresponsive.
• Review your AED instructions. Refreshing your memory every three to six months can help you remember how to use the AED in an emergency situation.
• Store your AED in an easily accessible place. Make sure all family members know where it is.
• Keep the AED maintained properly, including installation of new batteries as needed.
• Learn CPR. Take a course to learn the signs of cardiac arrest, how and when to summon emergency responders and how to perform CPR.
• Only the Philips HeartStart Home Defibrillator is available without a prescription. Other brands require a prescription because the FDA hasn't found that they can be used safely and effectively by a layperson without formal training. Prescription AEDs aren't intended for home use, but rather for use by emergency crews or for installation in public places. Don't be lured by unscrupulous Web sites or other sellers offering other AEDs without a prescription.

AEDs offer a way to save someone's life, perhaps your own. But they may not be suitable for everyone's home. Before buying one, talk to your doctor and do a little research. And don't forget to learn the basics, like CPR.

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