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Home Defibrillators And Your Heart

With heart disease being a major killer in this nation, home defibrillators are promising to improve survival from sudden cardiac arrests. On Monday, Medical Correspondent Dr. Emily Senay kicks off The Early Show's "Crossroads" series by explaining how home defibrillators work.

Ninety-five percent of people who suffer sudden cardiac arrest die before they reach the hospital. But use of a defibrillator, where a jolt of electricity is used to snap a person out of cardiac arrest and allow the heart to start beating again, could mean the difference between life and death.

If you think you're having a heart attack, call 911 first. If you think you might be a candidate for a defibrillator in your home, talk to your doctor. Automatic defibrillators are very easy to use but training is essential for them to be effective, and you need to know CPR, too.

In its Operation Heartbeat, the American Heart Association is committed to promoting Automated External Defibrillator (AED) programs in more than 200 communities.

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The following are some questions and answers to explain how AED works. They are provided by the American Heart Association:

Q: What's an AED?

A: An AED is a computerized medical device that can be used to treat a victim of cardiac arrest. The AED evaluates a cardiac arrest victim's heart rhythm, determines if shock is needed and delivers an electric shock through the chest wall to the heart. Audible and/or visual prompts guide the user through the process.

Q: How does an AED work?

A: Adhesive electrode pads are placed on the victim's chest and they are joined by cables to the AED. The adhesive pads capture the victim's heart rhythm and transmit the rhythm to the AED. A computer inside the defibrillator analyzes the victim's heart rhythm and advises the operator whether a shock is needed. AEDs advise a shock only for a "shockable" rhythm, most often ventricular fibrillation (VF).

Ventricular fibrillation is a life-threatening abnormal heart rhythm in which the heart's electrical impulses become chaotic, causing the heart to quiver and stop pumping blood. The shock is delivered through the adhesive electrode pads that are attached to the victim's chest. If the shock is effective, it will stop the abnormal heart rhythm, allowing the heart's normal rhythm to resume.

Q: Why are AEDs important?

A: AEDs strengthen the chain of survival because they can reduce the time to defibrillation for victims of sudden cardiac arrest. When a person suffers a sudden cardiac arrest caused by ventricular fibrillation (VF), the treatment is defibrillation within minutes. Defibrillation is the delivery of a shock that stops VF and allows the heart's normal rhythm to resume.

When a victim collapses in sudden VF cardiac arrest, for each minute that passes without CPR and defibrillation, the victim's chances of survival decrease by 7 percent to 10 percent. AEDs can be placed throughout the community as part of Public Access Defibrillation (PAD) programs with rescuers trained in CPR and use of an AED. PAD programs can help sudden cardiac arrest victims receive immediate bystander CPR and defibrillation within minutes. CPR and defibrillation can significantly increase survival from sudden cardiac arrest.

Q: Who can use an AED?

A: AEDs can be used by non-medical personnel such as police, fire service personnel, flight attendants, security guards and other lay rescuers who've been properly trained.

Q: Can an AED make mistakes?

A: It is unlikely that an AED will make a mistake. Studies have shown that AEDs interpret the victim's heart rhythm more accurately and more quickly than trained emergency professionals. If the operator has attached the AED to an adult victim who's not responsive, not breathing normally, with no signs of circulation (in cardiac arrest), the AED is very accurate in determining if the victim has a "shockable" or a "non-shockable" rhythm.

Q: If AEDs are so easy to use, why is formal training needed?

A: Commercially available AEDs are very user-friendly and contain voice and light prompts to guide the rescuer. In fact, school children can operate an AED effectively. However, safe use of an AED requires more than the simple operation of the device.

An AED operator must know how to recognize the signs of sudden cardiac arrest, when to activate the EMS system and how to perform CPR. It's also important to receive formal training on the AED that will be used. That way the user becomes comfortable with the device and can successfully operate it in an emergency.

Training also teaches the user how to respond to special situations such as placement of AED electrode pads when the victim has an implanted pacemaker, a very hairy chest or a medication patch. Finally, training helps the rescuer be skilled in performing CPR and efficient in delivering the shock in the shortest time possible — these factors can improve survival from VF cardiac arrest.

Designated potential rescuers should complete training in CPR and the use of AEDs. The American Heart Association developed a 3 1/2 - 4 hour course called Heartsaver AED, available through American Heart Association training centers across the country. Course participants receive course completion cards after passing a basic written and skills performance evaluation. To find the closest training center, call 1-877-AHA-4CPR (1-877-242-4277), or visit

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