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Artificial Hearts: Building a Better Heart

In some cases, heart disease may be so severe that the patient may not survive the wait for a donor heart. Medical scientists have developed electronic devices such as defibrillators, pacemakers, and artificial heart models that can keep the patient alive until a heart becomes available.

Some pacemakers can be visible from outside the body, as shown here.

CLICK to enlarge: Pacemakers can be visible from outside the body, as shown here.

One of the best known devices is the "Jarvik-7" artificial heart, named for its designer Robert K. Jarvik, an American physician. Designed to function like the natural heart, the Jarvik-7 has two pumps (like the ventricles), each with a disk-shaped mechanism that pushes the blood from the inlet valve to the outlet valve.

The action of the artificial heart is entirely similar to the action of the natural heart. There is, however, one huge difference: the natural heart is living muscle, while the artificial heart is plastic, aluminum, and Dacron polyester. As a result, the artificial heart needs some external source of "life." An external power system energizes and regulates the pump through a system of compressed air hoses that enter the heart through the chest. Since the system is cumbersome and open to infection, the use of an artificial heart is meant to be temporary.

The Jarvik-7 was first used during the early-1980s. However, earlier artificial hearts date back to the mid-1950s. In 1957, a team of scientists, led by Willem Kolff, a Dutch-born physician, tested their model in animals to identify problems. In 1969, a team led by Denton Cooley of the Texas Heart Institute successfully kept a human patient alive for more than sixty hours with their model. During the years that followed, the notion of a permanent, rather than temporary, implantation began to take hold.

In 1982, a team led by William DeVries of the University of Utah implanted the Jarvik-7 into a patient named Barney Clark. For various medical reasons, a transplant operation was not an option for Clark. Therefore, he was a prime candidate for a permanent artificial heart. He survived with the Jarvik-7 for 112 days.

Since then, development of an improved artificial heart has continued. One possibility is an electrical heart powered by a small wearable battery that does not require any break in the skin. Perhaps, someday, the artificial heart will become a realistic, permanent option for survival.

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You are viewing a page in The Franklin Institute's online exploration of the human heart. It is one of many Resources for Science Learning which inspire scientific curiosity.

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