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A surgical cure for long-lasting clots.

A California team reports success with an experimental operation that removes life-threatening blood clots lodged in the lung's arteries. This condition afflicts an estimated 500 to 1,000 people in the United States each year, researchers say

The clots in question form in veins in the leg. If part of such a clot breaks loose and gets into the bloodstream, it can reach the heart's right ventricle. which pumps venous blood into the pulmonary arteries. The body dissolves most clots trapped in these arteries; however, some clots take up permanent residence in the lungs. There they attract blood cells and debris, forming a rubbery clog impervious to drugs that dissolve fresh clots.

At first, the symptoms of the blockage are mild. A patient may notice episodic shortness of breath, especially upon exertion. Later, the breathing difficulties get worse. Eventually, patients with this disorder require continuous oxygen. At the same time, the right ventricle must work harder and harder to pump blood past the obstruction. If there is no treatment, the ventricle stops pumping effectively

Kenneth M. Moser and his colleagues at the University of California, San Diego, School of Medicine have been working on a surgical correction for this condition. Now, Moser reports, they have performed the procedure on more than 400 people. In the risky days and weeks following the operation, 9 percent of those patients died, Moser says. In the most recent 150 cases, however, the death rate has dropped to 5 percent. Moser reported his team's data this week in Monterey, Calif., at a science writers seminar sponsored by the American Heart Association.

Although 5 percent is still too high, the surgery's record is much better than its alternative: Most of the patients would almost certainly have died without treatment, Moser says.

Despite the promising results, the surgery remains tricky First, the anesthetized patient is put on a heart-lung machine that oxygenates his or her blood and then pumps it back into the body, Next, the surgeon isolates the lung's pulmonary artery and finds the clot.

At this point, the patient's body is cooled to 23[degrees]C, a temperature that puts it into a hibernation of sorts and protects brain cells and other vulnerable organs from damage caused by a lack of oxygen. The heart-lung machine is then stopped because the blood rushing through the arteries obscures the surgeon's vision. Finally, with tiny instruments, the surgeon carefully removes the clot from the artery wall.

People who make it through the postoperative period fare relatively well, Moser says. Ninety percent of patients enter the operating room with severe or total disability because of poor lung and heart function. Yet one year after surgery, most of them can resume work and other normal activities, he says. Not one has suffered a recurrence of the condition, he adds.
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Title Annotation:blood clots in lung
Author:Fackelmann, K.A.
Publication:Science News
Date:Jan 23, 1993
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