Single-lung transplant saves failing hearts.

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A critical shortage of donor organs means that many people with pulmonary hypertension, which debilitates both the heart and lungs, must wait years for a heart-lung transplant - if they live that long. To shorten the delay, researchers have developed a bold new approach in which surgeons transplant a single lung along with an attached artery

The still-experimental procedure may prove lifesaving for people with this rare disorder, which clogs the pulmonary artery with scar tissue and biological debris, including clotted blood. Scientists don't know what triggers these deposits, but they do know that the narrowing of the pulmonary artery - which carries blood from the heart's right ventricle to the lungs - puts pressure on the right ventricle. After a few years, the heart's ability to force blood through the artery begins to falter, causing breathing difficulties and threatening sudden death from heart failure.

Since the early 1980s, the only hope for a person with pulmonary hypertension has been wholesale transplantation of the heart, the pulmonary artery and both lungs. But it's difficult to find a donor in whom all of these components are disease-free, and the heavy demand for donor hearts lengthens the waiting list. Many candidates for the combined transplant die before they reach surgery

Thoracic surgeon Joel D. Cooper of Washington University in St. Louis reasoned that transplanting a single lung, with pulmonary artery attached, would take the pressure off the right ventricle, making a heart transplant unnecessary and shortening the waiting period. This week, at the American Heart Association's annual science writers forum in Savannah, Ga., Cooper reported on the first seven people to undergo the single-lung transplants.

Six women and one man with advanced pulmonary hypertension, their ages ranging from 29 to 41, received the transplants between November 1989 and July 1990. Before surgery, they had experienced severe fatigue and breathing difficulties. Even mild exertion, such as climbing stairs, posed a risk of lethal heart failure, Cooper says.

Despite their dire preoperative conditions, all seven volunteers survived the surgery, showed recovery of the heart and now lead active lives, he reports. Before surgery their hearts pumped an average of about 25 percent of the blood through the pulmonary artery; about three weeks after surgery the average rose to approximately 52 percent-within the normal range, Cooper says. All seven returned to work or school and resumed normal activities, including jogging and other exercise, he adds.

The experimental operation remains risky; Cooper notes that several people nearly died of heart failure during the postoperative recovery period. Moreover, while the volunteers seem healthy today, Cooper says he doesn't know whether the transplanted arteries will accumulate their own deposits. And, like all transplant procedures, the operation requires that patients take harsh immunosuppressive drugs to help prevent organ rejection.