external or surgically implanted mechanical device designed to replace a patient's diseased heart. The first one used on a human being, the Jarvik-7, was implanted (1982) in Barney Clark, who lived for 112 days; another patient, William Schroeder, lived 620 days. Two major drawbacks of the Jarvik-7 were the danger of stroke from clots formed in the artificial heart and the need for the patient to be hooked to the external air compressor that powered the pump. By 1989 such devices had largely become a bridge to human heart transplants (see transplantation, medical).

In 2001, however, a second type of artificial heart, the AbioCor, was implanted in several 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. Thomas Christerson has lived for more than a year since receiving (Sept., 2001) the AbioCor heart; another patient lived for nearly 10 months.

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. 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.

The Columbia Encyclopedia, Sixth Edition Copyright© 2004, Columbia University Press. Licensed from Lernout & Hauspie Speech Products N.V. All rights reserved.

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