Mechanical Heart

In 1982, a 61-year-old dentist, Barney Clark, became the first human to receive a permanently implanted artificial heart. It was known as the Jarvik-7 after its inventor, Dr. Robert Jarvik. Barney Clark lived 112 days after the operation. William Schroeder lived 620 days after he received a Jarvik-7 mechanical heart in November 1984.

Several thousand people have received the SynCardia artificial heart. The SynCardia heart is a total heart, in that all four chambers are replaced. SynCardia is located in Tucson, Arizona. It has been approved in Europe and is undergoing FDA clinical trials in the U.S. as a bridge to transplant for both pediatric and adult patients.

SynCardia is totally implanted, and the internal battery is charged via two coils, one internal and one external to the body.  Power is transmitted, via magnetic force, across the skin without piercing the surface. The rechargeable battery is implanted inside the patient’s abdomen.

The advantage of this method of power delivery is that there are no wires or tubes coming out of the body. This technique lowers the chance of infection and allows greater patient movement. The “recharging through the body” permits the person an hour to get up out of the bed, take a shower, walk the dog, and go back and get a recharge.

Heart failure causes 40,000 deaths per year. Yet only about 3,000 hearts are transplanted each year. The need for human hearts greatly outpaces the supply. This makes a totally self-contained implanted mechanical heart a high priority item. People diagnosed with heart failure live 5 years on average. They will need a transplant or artificial heart to extend their life.

There are a number of problems to overcome to get a true “put it in and forget about it” mechanical heart. The power to operate a mechanical heart is substantial.  Much more than a pacemaker, which requires very little power. The power supplies for the Jarvik-7 resembled the farm milking machines. Two large plastic tubes went through the patient’s chest wall and were connected to a small refrigerator-size unit that did the pumping.

The heart is a pump, but not the kind of pump we use in our homes and cars. These pumps have impeller blades and can’t be used in an artificial heart. Impeller blades would crush the red blood cells. Artificial hearts use hemispherical diaphragms that inflate and deflate to move the blood.

The seams and valves are places where blood will clot. These clots can later break loose, and cause life-ending strokes. Rejection is a problem. The body tends to reject anything that is not “home grown.” Some parts of newer machines are made from chemically treated animal tissues or biomaterials.

Skumin syndrome is a mental disorder developed by a quarter of all patients who get an artificial heart, or even a valve replacement. There is something very disconcerting about feeling and hearing that pump working inside them. They have persistent doubts about the reliability of the devices, fear of breakdown, and suffer anxiety and depression.

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