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June 20, 1996

Pitt researchers' artificial heart could someday replace transplants

Many of Pitt's medical researchers are internationally known for contributions to their fields and have been at the forefront of some lifesaving discoveries. Some of those researchers are so good, in fact, that they could end up putting some colleagues out of business. Like UPMC surgeons William Wagner, Harvey Borovetz and Bartley Griffith. They are part of a research team that has helped create the Pitt/Nimbus Rotary Blood Pump, a device that eventually could replace the traditional heart transplant. "Instead of taking your heart out, you add this pump," Wagner said, simplifying the matter a little bit. Placed in the heart's left ventricle, the Pitt/Nimbus Rotary Blood Pump uses a turbine. Researchers say it will be less invasive than a heart transplant while holding down the medical costs. The pump wouldn't replace a heart; instead, it would become the chief method of pumping blood from the heart's main chamber into the body's main artery. The Pitt-Nimbus pump is smaller than the device currently being used — Griffith says it's not much bigger than a D cell battery — and thus should be usable in individuals with smaller body cavities, such as women and children. "It would address a number of shortfalls of the current device," said Borovetz, the program manager and chief bioengineer for the artificial heart program at UPMC. In addition to expanding the number of patients who could utilize a heart pump, the Pitt-Nimbus pump should have a longer operating life than its predecessors, Borovetz says.

Griffith, the UPMC chief of cardiothoracic surgery and a co-principal investigator in the project, adds: "One of the unique features of the pump is that it will produce blood flow without a pulse." The Pitt researchers are working with Nimbus Inc., a medical research and development firm near Sacramento, Calif., and are being funded by a five-year, nearly $5 million grant from the National Institutes of Health. Pitt is one of six schools sharing $27 million awarded last year for development of this type of heart pump.

"Right now we put a [different] pump into patients waiting for a heart transplant, and after [they get the new heart the pump] goes out," Wagner said. "But there's a limited number of hearts available and we're trying to implement a device that we can leave in there, eliminating the need to transplant a heart." The Pitt/Nimbus pump is designed to take over the work done by half of the heart, the left ventricle. Griffith says a second one could be implanted to bypass the right ventricle. The Pitt/Nimbus pump will be able to push all the required blood through the body of even the largest person, according to Griffith. Researchers are aiming for a pump that will work in humans for at least five years. The Pitt research team recently finished testing the pump on animals and Griffith said "it's possible there might be an opportunity to utilize this device in humans" within a month. Additional experiments on the pump are being done at the McGowan Center for Artificial Organ Development at Pitt's Biotech Center on Second Avenue.

"A basic feasibility has been demonstrated," Borovetz said. "It appears to be well tolerated on animals." Griffith, who has worked on various artificial heart programs at Pitt since 1985, said the research team is pleased with the progress on the Pitt/Nimbus pump. "It has sustained numerous calves for long periods of time and we have noted that these calves can grow and exercise and that the function of the pump proves to be quite adequate." Nimbus president Ken Butler also is optimistic about the project. "The prospects are good that this will work and ultimately produce an affordable method to rehabilitate seriously ill patients and permit them to have a near normal quality of life," Butler said in a written statement.

The researchers agree that an alternative to human heart transplants is necessary because there aren't enough hearts to meet the demand. About 2,000 hearts are available for transplant each year, a fraction of the 40,000-50,000 people who need them. –Mark Gordon n

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