MEDICINE

Help in a small package

MARY McIVER May 16 1988
MEDICINE

Help in a small package

MARY McIVER May 16 1988

Help in a small package

MEDICINE

On April 26 in a landmark 20-minute operation at the Texas Heart Institute in Houston, heart surgeon Dr. Howard Frazier inserted a tiny electric pump into the heart of a gravely ill 62-year-old Colorado man—and gave him a new lease on life. The experimental device, called the Nimbus Hemopump, is simple in construction, composed of a six-inchlong, pencil-thin rubbery casing enclosing a miniature stainless steel propeller. But the tiny mechanism, designed to temporarily take over the heart’s blood-flow function, shows strong potential in saving the lives of hundreds of thousands of people who suffer from heart disease. Declared Frazier: “I must say it is the most remarkable thing I have seen or experienced. That a device this small could take over the function of the human heart is really incredible.”

In recent years heart specialists have successfully used pumps—known as ventricle assist devices (vads)—to assist the function of diseased hearts as bridging mechanisms. Their purpose is

to keep patients with critical heart failure alive—by helping the pulmonary muscle beat—while they await heart transplants. But even state-of-the-art VADS are limited in their application, requiring a certain degree of natural heart function. The major advantage of the Hemopump, says Frazier, is that it

Said the impressed surgeon: ‘That a device this small could take over the function of the human heart is really incredible•

can provide 100-per-cent circulatory support—whether cardiac function is present or not—giving damaged heart muscles a chance to rest and recover. “That allows doctors,” said Frazier, “to tap the healing powers of the heart.” And its compact size means that doctors do not have to undertake the risky business of opening up a patient’s chest

in order to implant it. Instead, they merely thread the device through an artery. Declared Frazier: “It is small, safe and effective.”

Frazier’s patient underwent a transplant six days before but had shown definite signs of rejecting his new heart—and Frazier said that he faced certain death. He added: “He was out of the game a week ago, totally out, and the only reason he’s in it is because of the device. I say that with absolute certainty.” Following the administration of a general anesthetic, Frazier made a 3-inch incision in the man’s groin. Then he threaded the tiny pump—attached to and driven by a spaghetti-sized drive-cable powered by an electric motor outside the body—through an artery in the patient’s thigh. Monitoring its progress by watching fluoroscopic imagery—a continuous series of internal X-rays projected onto a screen—he implanted the Hemopump into the left ventricle, the heart’s main pumping chamber. The pump immediately took over the heart’s function, providing all the blood flow through the body. Fortysix hours later, when immunosuppressive drugs had overcome the body’s rejection of the transplant and the patient’s new heart had gained enough strength to take over, Frazier removed the pump.

The pump’s inventor, Dr. Richard

Wampler, director of medical affairs of Nimbus Medical Inc., the Rancho Cordova, Calif.-based manufacturer of the Hemopump, said that he began working on the device about five years ago. Equipped with a turbine-type blade that rotates 25,000 times a minute, the Hemopump draws oxygenated blood from the heart to the aorta—the main artery supplying oxygenated blood to the body.

It pumps more than five pints of blood a minute through the heart—in comparison with a natural rate of about 11 pints per minute—more than enough, said Wampler, to sustain the body’s vital needs.

In March the U.S. Food and Drug Administration (FDA) gave company officials permission to allow clinical trials on patients at three medical institutions: the Texas Heart Institute, Mercy Hospital in Des Moines and Humana Hospital in Louisville, Ky. So far, tests have shown that the Hemopump can be implanted for up to seven days with no signs of rejection. The second of Frazier’s two Hemopump recipients has died, but the doctor said

that complications unrelated to the pump caused the death.

Nimbus spokesman Michael McCue said that he expects the tests will be completed by mid-1988 and that if there are no negative side effects and the FDA authorizes its use, the disposable pumps may be on the market as early as mid-1989. But he added that the company had not yet determined

how expensive the pumps would be. For his part, Dr. Leonard Schwartz, director of interventional cardiology at Toronto General Hospital, said that the pump’s effectiveness will have to be more thoroughly documented before the procedure gains general acceptance among members of the medical community. But he added: “It sounds like an interesting concept and, if it works, it’s a major breakthrough. There are lots of possible uses—and lots of patients who need them.” Although Frazier said that he expressed skepticism when he first heard about the pump two years ago, the widely respected surgeon is now among its most enthusiastic supporters. In one of his more cautious comments, he said that “unless complications ensue, it will have an important impact in the treatment of all patients with reversible heart failure.” Clearly, even though it is still in the experimental stages, the tiny device can stir the heart in more ways than one.

MARY McIVER