Heart pump extends patients' survival

Science News, Nov 17, 2001 by N. Seppa

Of the heart's four chambers, the left ventricle does the heavy lifting, thrusting blood to distant parts of the body. In people with the disease called heart failure, this flow becomes feeble and extreme weakness and fatigue result.

Scientists have developed implantable mechanical, pumps that can take over the left ventricle's duty. Physicians have used these devices as a last resort to keep a patient alive until a donor heart becomes available for transplant. Researchers now report that these so-called left ventricular assist devices can also significantly extend the lives of terminally ill heart-failure patients who are ineligible for transplants.

Scientists implant the compact electric pump below a patient's heart. One tube carries oxygenated blood from the left ventricle to the device, and another routes this blood to the aorta and beyond. The device is powered by a videotape-size battery worn in a holster. The pump and its battery are connected by a tube that runs through the skin.

To assess the value of the heart pump as a treatment in itself, researchers enlisted 129 terminally ill heart-failure patients who didn't qualify for a transplant because they were over age 65 or had other serious medical problems, such as diabetes or cancer. The scientists randomly assigned some of these patients to continue on heart medication and others to get an assist pump made by Thoratec Corp. of Pleasanton, Calif.

After 1 year, 22 of the 68 with the implanted pump remained alive, compared with 11 of the 61 patients getting heart medication. During the full 3 years of the study, those with assist pumps lived, on average, 408 days after getting the implant, while patients receiving only medication survived an average of 150 days after entering the study. Patients with the device also experienced less depression and faced fewer limitations performing physical tasks, such as climbing stairs. That difference suggests a higher quality of life for people getting an assist pump, says Eric A. Rose of Columbia University College of Physicians and Surgeons in New York.

Other scientists are perfecting full artificial hearts, which have helped some people who have more extensive heart damage than the participants in this study had. As many as 100,000 terminal heart failure patients could benefit from the left ventricular assist device, Rose estimates. He presented the findings at an American Heart Association meeting in Anaheim, Calif., this week. The study also appears in the Nov. 15 NEW ENGLAND JOURNAL OF MEDICINE.

"There's a clear survival benefit for patients who were treated with the implantable [device]," says Timothy Gardner of the University of Pennsylvania in Philadelphia. But it remains to be seen which patients will be willing "to take on the risks associated with it," he says. The main danger is infection introduced by the tube passing through the skin. During this study, 17 of the 68 people who had the heart pump died from infections traceable to it. Rose considers the infection problem surmountable.