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Engineers and Doctors Develop Heart Pump for Babies


A $4.5 million grant from the U.S. government-sponsored National Heart, Lung and Blood Institute is helping to make medical history. The funds are supporting a collaborative effort by scientists, doctors and engineers from five research institutions across the United States to develop a new medical device that will help save babies' lives.

Baby Isabella was born five days ago. She has a condition called pulmonary hypertension or high pressure in the lungs, which causes the heart to fail.

Rushed by helicopter to Children's Hospital in Pittsburgh, Pennsylvania, she was hooked up to a heart/lung machine, the same machine routinely used by adults during heart bypass surgery. Pediatric surgeon Peter Wearden says it is a short-term fix for Isabella. "It is a very large machine. It requires the children to be completely relaxed with medicines, to be on a ventilator. Their families can't hold them. And really, it will only work for about two weeks before they can develop serious complications that ultimately can be fatal."

For Isabella, two weeks is enough time for her heart to rest. But many babies waiting for heart transplants need more time. One quarter of the 4,000 babies waiting die before a new heart becomes available.

James Antaki wants to change that. He is associate professor of biomedical engineering at Carnegie Mellon University in Pittsburgh where he heads a team working on an infant heart pump.

"It assists part of the heart while the heart is recovering or is too weak to provide the pressure and flow to keep the baby alive and in some cases it is used as a bridge to a transplant. You can think of it as a crutch," Antaki says.

But in this case the crutch can last, not two weeks, but six months. Antaki says the artificial device must mimic the baby heart.

"The heart itself is a pump. It provides pressure and flow of blood to all the vital organs of the body and when the heart takes a break there is really no substitute."

The device is a booster pump inserted into the circulation. Antaki says, "It provides a extra flow or pressure to keep the baby alive and unload the weak heart to get it a chance to take a break."

Holding a prototype of the pump in his hand, Antaki explains that the walnut-sized device uses so-called turbo-dynamic technology to delicately circulate the baby's blood with a tiny turbine: "Our [prototype] is supported by a magnetic bearing or magnetic levitation. A rotor will spin indefinitely because there is no friction and nothing to wear out and in the case of a blood pump, it would never damage the blood cells."

Antaki says the challenge is to get the blood to flow at exactly the proper rate. Pumping too fast could harm blood cells. Pumping too slow could make the blood clot. Testing so far has been computer-based with models and simulations, such as the kind engineering graduate student Dorian Arnold is using on virtual patients. "What this work allows us to do is test how the pump is going to perform under a whole set of conditions that are not available to us in the clinic or in animals. In doing so we can develop controllers that guide how the pump operates when it is implanted in a patient."

James Antaki says these cyber tools allow engineers to design components and predict outcomes before actually building anything. But he adds the prototype is the result of collaboration among engineers and teams of doctors and research scientists. "We are really looking forward to the first baby's life that we save and (to) just feel(ing) good that we made a difference."

Antaki says the infant heart pump will be tested in a baby lamb in late October. He expects the device to be available for a human baby within three years.

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