Deadly Lung Disorder in Sickle Cell Disease
High blood pressure in the lungs is a major risk factor
for death in sickle cell disease. Almost one-third of adults with sickle cell
have pulmonary hypertension and those with pulmonary hypertension have a much higher mortality
rate than those without pulmonary hypertension.
Comments: Pulmonary
hypertension develops in most genetic diseases with chronic hemolysis (breakup of red blood cells) and anemia, including sickle
cell disease, thalassemia, and hereditary spherocytosis. Everyone with these
diseases should be screened for pulmonary hypertension. The screening can be
done by a noninvasive method called Doppler echocardiography.
Barbara K. Hecht,
Ph.D.
Frederick Hecht, M.D.
Medical Editors, MedicineNet.com
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High Blood Pressure in the Lungs a Major Risk for Death in Adults with
Sickle Cell Disease
A new study reveals that nearly one third of adults with
sickle cell disease develop high blood pressure in their lungs and that the
condition, known as pulmonary hypertension, causes a much higher death rate in
patients with the complication than those without it. The findings, according to
researchers from the Warren Grant Magnuson Clinical Center at the National
Institutes of Health (NIH), demonstrate an urgent need to diagnose this complication in adults with
sickle cell disease as it is a major risk factor for death. The study was
conducted as a multi-center collaboration between NIH and the Howard University
Center for Sickle Cell Disease. A complete report will publish in the February
26 edition of the New England Journal of Medicine.
Sickle cell disease is a chronic, often fatal anemia
that is classically characterized by severe attacks of pain from blood vessels
being blocked by red blood cells that become rigid and form a sickle shape when
deoxygenated. In the United States this genetic disease occurs predominantly in
people of African descent, and is accompanied by episodic severe pain in the
joints, leg ulcers, jaundice and multi-organ failure. A serious complication of sickle cell disease
is pulmonary hypertension.
Pulmonary hypertension is high blood pressure (not
related to the pressure measured by cuff on the arm) in the arteries that supply
the lungs. The blood vessels that supply the lungs narrow and their walls
thicken, so they can't carry as much blood. Like a kinked garden hose, pressure
builds up and backs up. The heart works harder, trying to force the blood
through. If the pressure is high enough, eventually the heart can't keep up, and
is unable to pump enough blood through the lungs to pick up adequate amounts of
oxygen. Patients become tired, dizzy and short of breath. When an underlying
cause can't be found, the condition is called primary pulmonary hypertension. When a pre-existing disease
such as sickle cell triggers high blood pressure in the lungs, doctors call it
secondary pulmonary hypertension because it is secondary to another problem.
This is the type of pulmonary hypertension evaluated in the NIH project.
"Secondary pulmonary hypertension develops in most types
of hereditary and chronic anemias that are caused by hemolysis, the destruction
of red blood cells. This suggests that there is a distinct syndrome of
hemolysis-associated pulmonary hypertension, a complication that has been
reported with increasing frequency in sickle cell patients," said Dr. Mark
Gladwin, pulmonary specialist, NIH Clinical Center and lead investigator of this
current research. He pointed out that retrospective studies show a prevalence of pulmonary
hypertension ranging from 20-to-40 percent in patients with sickle cell disease.
The research project followed 195 patients, 82 men and 113 women, with an
average age of 37, over two years. Doppler echocardiography, a test that uses
sound waves to 'see' the heart, was performed on each person to assess their
pulmonary-artery pressures. Doppler-defined pulmonary hypertension occurred in
32 percent of the patients. "The 'echo' is a test that is reasonably
priced, non-invasive and should be recommended screening for adults with sickle
cell disease just as the colonoscopy, cholesterol panel, mammogram, and
other tests are. This would save lives and help to minimize a public health
problem." said co-investigator Dr. Griffin Rodgers, chief, Clinical Hematology,
National Institute of Diabetes and Digestive and Kidney Diseases.
"This is similar to what occurred in the mid-nineties. We saw that use of a
transcranial Doppler exam changed the screening and management of pediatric
patients with sickle cell disease in that it defined important clinical decision
points that successfully led to preventing - or at least improving - the
odds of reducing strokes in children and adolescents," added Dr. Rodgers.
Of the 195 individuals evaluated in the current study,
20 percent with pulmonary hypertension died and all but two of the patients without the
condition survived. Even patients with mild arterial pressure in the lungs had a
high rate of fatality.
Sickle cell treatment continues to improve and people with the disease are
living longer. "This," said co-investigator Dr. Oswaldo Castro, Acting
Director, Howard University Center for Sickle Cell Disease, "may be why we are
seeing such a high prevalence of pulmonary hypertension in sickle cell patients."
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