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High Blood Pressure in Lungs Boosts Death Risk in Sickle Cell Patients

Nearly a third have the condition, study finds

WEDNESDAY, Feb. 25, 2004 (HealthDayNews) -- Almost a third of American adults with sickle cell disease develop high blood pressure in their lungs.

And that health threat boosts the risk of death, compared to sickle cell patients without that complication, a new study finds.

To catch the condition early, adults with sickle cell should consider having an echocardiogram, a test that uses sound waves to evaluate the heart and assess pulmonary artery pressures, says study author Dr. Mark Gladwin. He is a lung specialist at the National Institutes of Health, and his report appears in the Feb. 26 issue of the New England Journal of Medicine.

Gladwin's team followed 195 patients, average age 37, for an average of 18 months. They screened each with Doppler echocardiography to assess the pressures within their pulmonary arteries, which carry blood to the lungs. It detected high blood pressure in the lungs in 32 percent of the patients.

Over the next two years, 20 percent of those with pulmonary hypertension died, while all but two of those without it survived.

Sickle cell anemia afflicts about 72,000 Americans, according to the American Sickle Cell Anemia Association, primarily those of African descent. The chronic, often fatal anemia is marked by severe attacks of pain in the joints, leg ulcers and failure of many organs. Blood vessels are blocked when red blood cells become rigid as they are robbed of oxygen, forming a sickle shape.

While it has long been known that pulmonary hypertension develops in sickle cell patients and others with chronic anemias, the new study suggests the hypertension may be a major cause of sudden death in sickle cell patients. In pulmonary hypertension, the vessels that supply the lungs narrow and can't carry as much blood.

What happens in sickle cell and other anemias, Gladwin says, is that "in the plasma the hemoglobin destroys nitric oxide, and nitric oxide is a critical dilator of blood vessels. I call it the WD40 of blood vessels."

Pulmonary hypertension "is a single, independent predictor of mortality" in sickle cell patients, Gladwin says. But it's not known if it is the cause of death or a marker for something else that causes death. It could explain the high number of sudden deaths among sickle cell patients, he says.

Other experts call the new study exciting and hope it will lead to better screening and testing of sickle cell patients.

"A lot of these patients have pulmonary hypertension and are asymptomatic," says Dr. Claudia R. Morris, a pediatric emergency department physician and clinical researcher at Children's Hospital and Research Center in Oakland, Calif.

"To get an echo [echocardiogram] is very easy," she says.

Dr. Elliott Vichinsky wrote a commentary on the new study in the same issue of the journal, and is director of the Northern California NIH Sickle Cell Center in Oakland. He says, "I think this study could change the landscape of survival for 30 percent of sickle cell patients."

If the pulmonary hypertension is detected early, Vichinsky says, patients "can be started early on therapy such as transfusion." Eventually, the death rate might decline, he adds.

"I think every adult with sickle cell needs an echo every year," Vichinsky says. But he and Gladwin agree that persuading insurance plans to pay for the test, which Gladwin estimates costs $500 to $800, is not always easy or possible.

Currently, Vichinsky suspects most sickle cells patients are not being screened at all for lung hypertension.

More information

For more information on sickle cell, visit the American Sickle Cell Anemia Association or the National Library of Medicine.

SOURCES: Mark Gladwin, M.D., pulmonary specialist, National Institutes of Health Clinical Center, Bethesda, Md.; Claudia R. Morris, M.D., pediatric emergency physician, clinical researcher, Children's Hospital and Research Center, Oakland, Calif.; Elliott Vichinsky, M.D., director, hematology-oncology, Children's Hospital and Research Center, and director, Northern California National Institutes of Health Sickle Cell Center, Oakland, and professor, pediatrics, University of California, San Francisco; Feb. 26, 2004, New England Journal of Medicine
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