Pulmonary embolus a danger to those prone to blood clots

On Call

February 25, 1997|By Dr. Simeon Margolis | Dr. Simeon Margolis,SPECIAL TO THE SUN

7/8 TC A few days after an operation, my wife's condition suddenly worsened, and we were told she had a pulmonary embolus. She recovered completely, but we would like to know what causes a pulmonary embolus and how it can be prevented.

A pulmonary embolus results when all or part of a blood clot (thrombus) breaks away from the place where it formed within a vein and travels through the heart and into the arteries supplying blood to the lungs (pulmonary arteries). The vast majority of pulmonary emboli originate as blood clots in the large veins of the legs (called deep venous thromboses or DVTs).

Pulmonary emboli are quite common and potentially dangerous. Population studies suggest that pulmonary emboli affect nearly a half-million people a year in the United States, and cause more than 50,000 deaths.

Factors that predispose to DVTs include surgery under general anesthesia, especially surgery involving the legs; fractures or other injuries to the legs; prolonged bed rest; certain types of cancer; heart failure; obesity; and abnormalities of blood clotting. Women are also more prone to DVTs shortly after delivering a baby. The best strategy against pulmonary emboli is prevention of DVTs, followed by aggressive treatment as soon as they develop.

People who are at especially high risk for developing DVT, for example those with heart failure and a prior episode of DVT, may be treated with an anti-coagulant pill, such as warfarin (coumadin), to lessen the likelihood of clot formation.

When the danger of bleeding with anti-coagulant treatment is too great in patients confined to bed, an alternative approach is a device that repeatedly compresses the calves and thighs in order to keep blood moving through the leg veins, since "pooling" blood is a factory for clots.

The bad news is that little can be done in most cases when a massive pulmonary embolus almost completely shuts off the blood supply to the lungs. Such large emboli usually cause death within one to two hours. Fortunately, in about 90 percent of people, the pulmonary emboli are smaller and resolve completely over a period of weeks. Sudden onset of shortness of breath is the most common symptom of such pulmonary emboli.

Both pulmonary emboli and DVTs are initially treated with intravenous infusions of another anti-coagulant, heparin, and then for a variable period of time with warfarin by mouth.

Bed rest and elastic support hose are also employed during DVT treatment.

Dr. Margolis is professor of medicine and biological chemistry at the Johns Hopkins School of Medicine.

Pub Date: 2/25/97

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