WEDNESDAY, May 26, 2004 (HealthDayNews) -- An unexpectedly large number of patients who survive a blood clot in the lungs develop potentially dangerous high blood pressure in the pulmonary artery, Dutch researchers report.
"We found that pulmonary hypertension occurs far more frequently than we had expected," said study author Dr. Anthonie W.A. Lensing, a professor of medicine at the Academic Medical Center in Amsterdam.
Pulmonary embolism, a blockage of an artery in the lungs, strikes an estimated 600,000 Americans every year and causes 60,000 deaths. It is, in fact, one of the leading causes of sudden death in this country.
Pulmonary hypertension, on the other hand, is a condition that can strain the heart, which must work harder to push blood through the lungs, but one that is often ignored because it causes few or no symptoms in many patients, Lensing said.
It has been thought that only a few of those who survive an embolism go on to develop pulmonary hypertension -- one in 1,000 at most. But the incidence among the 223 patients studied by Lensing and his colleagues was much higher, says a report in the May 27 issue of the New England Journal of Medicine.
Hypertension generally develops slowly after a pulmonary embolism, Lessing said. There is "a honeymoon period" of a few months, and then the incidence begins to increase, he noted.
"At six months, 1 percent of patients had pulmonary hypertension," Lensing said of his findings. "That increased to 3.1 percent after one year and 3.8 percent after two years."
The new report adds to the list of conditions that can cause pulmonary hypertension, said Dr. Valentin Fuster, director of the Cardiovascular Institute at Mount Sinai Medical Center in New York City.
The condition can be caused by lung disease, by failure of the left side of the heart or by a congenital heart disorder such as a faulty valve. In a small number of cases, usually involving young women, there is no apparent cause.
"These often are difficult to diagnose and have treatments that are quite different," Fuster said. For example, if the cause is a bad heart valve, surgery is done to replace the valve. If the cause is lung disease, treatment is aimed at correcting the lung condition.
When the cause is a pulmonary embolism, an effective treatment is endarterectomy, surgery to remove the clots that are blocking the artery. The technique was developed at the University of California, San Diego, and is now widely used.
Often, the only warning sign of pulmonary hypertension is shortness of breath, Fuster said. "You have to think about it when a patient is always short of breath," he added.
The pulmonary hypertension story is told by the American Heart Association.