Beginning 2001, however, a second type of artificial heart, the AbioCor, was implanted in a number of patients. Unlike the Jarvik-7, the AbioCor is powered by electrical energy that is transmitted from a battery across the skin to an internal coil and backup battery. Because an opening in the skin is not needed to allow passage for tubes or wires, the risk of infection is greatly reduced. In addition, the external battery pack is designed to worn on a belt or suspenders, enabling the patient to be mobile. On average, the patients who received the heart from 2001 to 2004 and survived the operation lived for five months; the longest lived not quite 17 months. In 2006 the AbioCor was approved for use in patients who do not qualify for a heart transplant if their life expectancy as a result of heart failure is less than month; the device is also approved as a temporary measure for patients awaiting a transplant.
A related device, the ventricular assist device (VAD), or "artificial ventricle," is an internally implanted pump designed to aid a person with a failing left ventricle; unlike an artificial heart, it does not require removal of the patient's heart. A version for temporary use was developed in 1964. In 1991 doctors implanted the first portable VAD; it was powered by a battery pack. Its pump used a special interior lining to promote the growth of a surface similar to that which lines the blood vessels, reducing the risk of the formation of blood clots, which can cause stroke.
Machine or mechanical pump that maintains blood circulation in the human body. The heart-lung machine, a mechanical pump, can maintain circulation for a few hours while the heart is stopped for surgery. It shunts blood away from the heart, oxygenates it, and returns it to the body. No device has yet been developed for total, long-term replacement of the heart; existing artificial hearts reduce the heart's workload by pumping between beats or acting as an auxiliary ventricle and are suitable only as temporary replacements in patients awaiting transplant. Seealso pacemaker.
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