In announcing its approval, the Food and Drug Administration called the device "a significant advance in defibrillator technology" and an alternative for patients who may not be candidates for an implantable defibrillator.
A defibrillator is for people at high risk of dying of sudden cardiac arrest because of irregular rhythms in their heartbeats. It monitors the heart for those abnormalities, and once it senses danger, it delivers an electric shock to restore rhythmic order.The new device, called the Wearable Cardioverter Defibrillator (WCD), can be worn underneath a person's clothing.
"These are patients who aren't going to need an implantable defibrillator because they are not expected to have a long-term need for the device," says Donna-Bea Tillman, deputy director of the FDA's cardiovascular and respiratory devices division in Rockville, Md. "And there are two major categories of patients where this kind of device is appropriate: Patients waiting for a heart transplant and patients who recently had a heart attack. There's a vulnerable period of time for heart attack patients where they are prone to lethal arrhythmias, usually about a six-month period."
The WCD has been in development for 14 years, and is the brainchild of Dr. Steven Heilman, the chief executive office of Lifecor, Inc., of Pittsburgh, according to Kathleen Higgs, Lifecor's vice president of sales and marketing. Heilman was the co-developer of the first implantable defibrillator more than 20 years ago, Higgs says.
The device, which weighs about two pounds, fits in a "a fabric gun holster," as Higgs describes it. "The belt is a harness that fits over the shoulders and around the chest. It has three therapy electrodes and four electrocardiogram-sensing electrodes, which attach to the chest, through which the shock is delivered."
It is designed to detect certain kinds of arrhythmias, Tillman says -- ventricular tachycardia (a fast heartbeat) and ventricular fibrillation (an irregular or chaotic heartbeat).
"If it detects one of those arrhythmias, it sounds a tone and flashes a light because of the possibility that the device might think it detects an arrhythmia. But if the patient is indeed having arrhythmias, the patient will be unconscious, and the device will then deliver a shock to the heart, restoring normal heart rhythm," Tillman adds.
While most people have felt a skipped or racing heartbeat at one time or another, people who have had a heart attack often suffer damage to the ventricles, the heart's pumping chambers. The result can be ventricular tachycardia. Scar tissue in the ventricles can disrupt the heart's electrical impulses, causing irregular or inefficient heartbeats. The result can be low blood pressure or a heart that doesn't pump any blood at all, leading to unconsciousness or death.
Heart disease affects about 68 million Americans and costs an estimated $117 billion annually, according to the National Institutes of Health. About 250,000 Americans die each year of sudden cardiac arrest, according to the American Heart Association.
The WCD performed well in clinical trials in the United States and Europe, the FDA says. The device was tested on 289 patients who were either awaiting heart transplants or recovering from a recent heart attack. The patients wore the defibrillator for about 20 hours a day for approximately three months.
The defibrillator successfully detected and treated five sudden cardiac arrests. It also failed to treat two other episodes, but researchers say those patients had incorrectly installed the vest's electrodes. (Since the clinical trial, Lifecor changed the design of the vest to make it easier to use.) Two percent of the patients experienced unnecessary shocks, and about 6 percent of the patients suffered a temporary skin rash from wearing the device.
The company is working on an even smaller device, Higgs says.
Higgs says the defibrillator will cost between $20,000 and $22,000. "We expect that most people will rent or lease the device if the indication is temporary risk for sudden cardiac death. They may use it for only a week or up to several month, and it's more economical to rent the device in that scenario," she notes.