An automated external defibrillator can help those whose hearts stop working effectively.

But may owners and emergency workers don't know about the high recall rate for AEDs, according to a report in the Journal of the American Medical Association.

The devices are found in medical areas such as hospitals and ambulances, but they're also available elsewhere.

"There are AEDs throughout airports, casinos, a church may decide to buy an AED, a school, and apartment building. There are also AEDs that are available for home use without a prescription," said Dr. William Miasel, of Beth Israel Deaconess Medical Center.

Maisel reviewed device recalls from 1996 to 2005.

"The chances that your AED would be recalled in any given year was one in twenty. The chances that your AED would be recalled during the entire 10-year study period was one in five," he said.

He said that's a high rate. And he also found that there were 370 fatal malfunctions from the 775,000 AEDs in circulation.

"The number of malfunctions pales in comparison to the number of lives that have been saved by these important devices over the past decade," he said.

But he added that a better notification system is needed.

"People who purchase a device should return the card that comes with the device so that they can register their name and address with the manufacturer, so they can be directly contacted if their device has a problem," he said.

Maisel stressed that not all recalled devices are actually defective, and the high number of recalls is likely a "better safe than sorry" approach.