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Beat machine

Mechanical heart a possible
alternative to transplants
Sunday, October 1, 2006 | 12:00 a.m. CDT; updated 11:02 a.m. CDT, Monday, July 21, 2008

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After days of feeling dizzy, ill and having difficulty breathing, 23-year-old Lisa Britt was rushed to the emergency room. Her heart went into failure.

She was in her second year of veterinary school and studying for a final exam.

Britt hadn’t felt well throughout the semester, but she said she thought it was because of the semester’s stresses or some sort of virus.

Shortly after she arrived at the hospital, she was moved to a transplant center. Five months later, she had a different heart.

That was 15 years ago. Today, Britt, an MU clinical assistant and professor of radiology for the governor’s Organ Donation Advisory Committee, has two children and looks as healthy as anyone.

Because of limited availability and eligibility, not everyone with heart problems can be as fortunate as Britt. But a recent development is a step toward perhaps providing another opportunity.

The Food and Drug Administration recently approved initial implantations of the first artificial heart to be completely implanted in the body. The heart, called the AbioCor Implantable Replacement Heart, is the result of 30 years of research by ABIOMED Inc.

Patients eligible to receive the heart have to meet certain criteria: They must have advanced heart failure in both pumping chambers of the heart, they cannot be eligible for a heart transplant or other treatment options and they must be expected to live for less than a month, according to the FDA’s Web site.

The AbioCor weighs about two pounds and is connected to an internal rechargeable battery and electronics package. Both the battery and electronics package are implanted in the patient’s abdominal area and are powered by a wireless energy transfer system through the skin. The electronics package monitors and controls the pumping, or beat, of the heart.

The AbioCor also has external battery packs that, when fully charged, could power the heart for up to four hours.

Pierantonio Russo, MU associate professor of surgery and child health and chief of cardiothoracic surgery at University Hospital, participated in several of the AbioCor’s experimental implants performed on cows in 2001. The device proved to be mechanically reliable; however, Russo said that clot formation is a problem.

Russo said the first human patients who had the AbioCor implanted have died from strokes caused by clot formations. The risk of stroke can and must be reduced with blood thinners, he said.

Despite the problems, Russo said that the AbioCor represents an important step toward a complete mechanical replacement of the heart.

“The AbioCor is different from other ventricular assist devices in that it replaces the function of both ventricles,” he said. “Therefore it is a true alternative to heart transplantation because it is implanted in patients with biventricular failure (both ventricles have failed). The other implantable assist devices assist the left ventricle only.”

Russo also said that there is an overwhelming need for devices such as the AbioCor. He said that the number of heart transplants performed in the United States has not changed very much in the last five years because of the limited number of heart donors, and the number of patients transplanted every year is only a small fraction of the new patients with congestive heart failure who fail medical therapy.

The number of transplanted hearts appears to be declining in the United States. In 2003, there were 2,026 heart transplants nationwide, and in 2004, there were 1,961 heart transplants, a 3 percent decrease, according to a collaborative annual report by Scientific Registry of Transplant Recipients and the Organ Procurement and Transplantation Network.

Russo said he believes that future heart transplants will be replaced with a hybrid treatment consisting of mechanical rehabilitation and genetic therapy that would regulate the molecular rehabilitation of the heart. Mechanical rehabilitation involves allowing the heart to rest by using various assist devices. In some patients, it appeared that the rest allowed the heart to reshape, remodel and eventually take over by itself. But this sort of treatment has been found to work in only certain patients, so genetic therapy will be necessary to assist the mechanical rehabilitation in others.

Surgery will not be the only option for dealing with heart failure in the future, Russo said.

“It is not different than treating effectively other fatal diseases, including cancer, diabetes, limbs replacement and even certain congenital or birth defects,” Russo said. “The key word is ‘effective.’ Other current therapies for congestive heart failure are not as effective.”

Britt said that organ donation is the best alternative to heart failure. Despite the problems with clot formation with the AbioCor, she is happy to see such devices being developed. She said it is a “fantastic option for those in which transplantation is not possible,” and better than being hooked up to a machine that necessitates being in a hospital.

Britt added that the development of devices such as the AbioCor should not discourage people from organ donation.

“I would stress that any of these advances are not for the general population,” Britt said. “The only way to improve the quality of life is to have more organ donors. No one is immune to organ failure.”


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