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The Latest in Heart-Wear

High-tech vest can shock the heart back to normal

FRIDAY, May 4 (HealthScout) -- The latest in fashion for heart patients is a vest that's really a wearable defibrillator, designed to shock your heart back into normal rhythms if it's beating too fast.

Many patients risk a heart attack because their heart muscle is weakened, or they've had a recent heart attack or they're waiting for a heart transplant. A temporary external defibrillator may be worth considering for them, says Dr. Stephen L. Winters, director of the cardiac electrophysiology program at Morristown Memorial Hospital in Morristown, N.J., one of the U.S. sites where the vest was tested. The vest contains electrical sensors that can continuously monitor heart rate and electrodes that automatically deliver shocks if needed.

"Anyone who has serious heart disease may be at risk for experiencing very rapid heartbeats, which can lead to cardiac arrest and sudden death," Winters says.

More than 350,000 Americans die each year from heart attacks, the country's leading cause of death, says the American Heart Association. About half are caused by an irregular heartbeat, usually because blood vessels have become so narrowed they can't deliver oxygen and other nutrients to the heart. The heart's electrical system stops working properly, sending the regular rhythm into chaos, eventually depriving the brain and other vital organs of blood.

Other devices have been invented to cope with irregular heartbeats, says Dr. Douglas Zipes, director of cardiology at the University of Indiana School of Medicine. But he says, "Indeed, this may represent a step forward." For example, in the past patients were sometimes given portable defibrillators to bring home, but these could only be activated by another person. If the patient was home alone, the defibrillator could not work.

Trials of the new device are underway, and Winters and others report preliminary findings at this week's annual meeting of the North American Society of Pacing and Electrophysiology in Boston. For example, 58 patients in Germany wore the vests for four months. Three had rapid heartbeats, and shocks from the vest corrected the problem.

"They probably would have died," Winters says.

Many patients with irregular heart rates after heart attacks have implantable cardioverter defibrillators (ICDs) surgically lodged in the chest to continually monitor heart rates and give shocks when needed.

But some patients are not candidates for the ICDs, Winters says. Perhaps their heart muscle is weakened but can be strengthened with medicine, and they simply need short-term protection. He says maybe they're waiting for a heart transplant. One of his patients was a young man who had suffered a serious heart attack but had no symptoms. A genetic predisposition was the likely culprit, but, in the meantime, he was at an increased risk for three to six months following the heart attack, as all patients are.

The vest can provide a measure of safety and security temporarily, Winters says.

The vest is worn over bare skin, like a T-shirt; a cable connects it to a monitor worn on a harness or belt strap. Altogether, the device weighs about 3 pounds.

One way in which the vest is an improvement over other devices is a button that deactivates the shock. When a racing heartbeat is detected, the vest begins to vibrate and emit beeps, warning the wearer that a shock is imminent. If the patient is conscious, he should deactivate the vest and call 911, Winters says. While a normal resting heart rate is about 65 beats per minute, a racing heartbeat would be 200 or higher.

On the other hand, if the patient is unconscious and can't deactivate the vest, it's presumably because the racing heartbeat has already meant less blood is being pumped to the brain, and a shock is needed to reverse the problem.

Although the device possibly could pick up another electrical signal from the body and mistakenly shock the patient, potentially causing a heart attack, Winters says that risk is low. Other electrical signals, like those used to detect shoplifters in department stores, don't activate the device, he says.

What To Do

Zipes, who is at the Indiana School of Medicine, says doctors should remind patients to call 911 if the warning vibrations and beep occur. Sometimes patients aren't even aware their hearts are racing dangerously fast, though he says this is rare.

For more on defibrillation, try the American Heart Association. The Mayo Clinic also has more related information.

Read other articles on defibrillation at HealthScout, including one that describes how you can help someone who's having a heart attack.

SOURCES: Interviews with Stephen L. Winters, M.D., director, cardiac electrophysiology program, Morristown Memorial Hospital, Morristown, N.J.; Douglas Zipes, cardiology director, University of Indiana School of Medicine, Indianapolis, Ind.
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