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June 14, 1992
Hershey Researchers Unveil Wireless Artificial Heart

Hershey, Pa. -- The era of the wireless artificial heart has arrived, beating inside a five-month-old calf named Winston.

"It's really a major step--no one else in the world has even come close to implanting an animal with a total artificial heart with a completely sealed system," says Gerson Rosenberg, Ph.D., principal investigator of the electric total artificial heart project at Penn State's Milton S. Hershey Medical Center.

"What's significant about Winston is that the heart's electronics are miniaturized and totally implanted," says Rosenberg, research professor of surgery and professor of bioengineering.

On March 24, Winston became the long-term recipient of a wireless electric artificial heart.

As Winston scampers in the fields adjacent to the Medical Center, he carries within him the latest metal and plastic version of what Penn State researchers hope will someday. Perhaps by the end of the decade, become a permanent replacement for a failing human heart.

"It's an important step in the development of a clinically useful artificial heart," says co-investigator William Pierce, M. D., professor of surgery and chief of the division of cardiothoracic surgery. "It reaffirms our group's leadership role."

The heart is powered by an external battery kept near the recipient. Energy is transmitted from the battery across the skin by a pair of electric coils. A four- inch-long coil lays on the skin and transmits energy to a three-inch-long coil implanted under the skin. This energy is then used by an implanted electronic control system to power the small electric motor that provides the moving force for the blood pump. A tiny battery, housed in the same container as the electronics, provides about 30 minutes of operation when the external coil is removed.

Before human clinical trials become a reality, the group will have to run the electric heart through its paces, beginning with additional testing on a mock circulation system that was used to verify the operation of the device before it was implanted in animals.

"We'll have to do device readiness testing," Rosenberg says, which entails testing the heart as if it was pumping within a person's chest. "We will have to run 10 to 20 of these devices, funning each one continuously for one to two years, looking for failures and trying to predict the reliability of the system. This will probably take four years."

Rosenberg says the team's initial goal is to develop a wireless, electric total artificial heart that will last for two years, and with further development as long as five--which is the current average survival time for heart transplant patients.

The only artificial heart currently approved by the federal Food and Drug Administration for humans is the air-driven Penn state artificial heart, which is sanctioned for use only as a temporary bridge to a transplant.

The National Institutes of Health currently funds four groups to develop a permanent artificial heart: the Penn State team; the University of Utah; a private company, Numbus, working with the Cleveland Clinic; and Abiomed, a company collaborating with the Texas Heart Institute. Researchers at the Baylor College of medicine also are pursuing implantable permanent artificial hearts.

In December, another Medical Center calf, Holly, set a new record after spending 388 days on a Penn State electric total artificial heart that used wires running through her skin to an external electronic controller. Holly was the longest surviving animal on any kind of artificial heart. Still, Rosenberg sees the next step for a human artificial heart lies in the current model sitting in Winston.

"I don't feel there's much advantage in having an electric heart with the wires attached through the skin," he says. "Even though they're small, and considerably less bulky than the air-driven device. I think it's feasible to run the system entirely implanted. If you do that, theoretically, you eliminate much of the potential for infection."

Rosenberg says that persons implanted with such a device would carry a battery pack over the shoulder with two five-pound batteries, each one lasting for 4 to 5 hours.

Rosenberg cautions that while a wireless artificial heart poses a lesser threat of infection than previous models, it will remains a potential complication because of the body's limited ability to fight infection on any foreign surface.

Blood clots may present problems as well, though careful design and the use of Biolon, a medical polyurethane manufactured by DuPont, can reduce the risk, the researchers say.

According to Pierce, the nation's demand for heart transplants exceeds its supply by about 10 to 1. Roughly 20 percent of heart transplant patients die before they can get on a waiting list, he notes, and while some 2,000 persons received transplants last year, another 2,000 remain on a waiting list.

The Institute of medicine estimates that between 35,000 and 70,000 patients a year could be helped by permanent artificial hearts and left ventricular assist device, which aid ailing left ventricles in pumping blood.


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