What it is: The cell lining of small blood vessels or capillaries in the lungs start to peel off, allowing blood to leak out of the capillaries and into surrounding muscle cells, causing the muscle to constrict. The constriction chokes off blood flow between the heart and lungs, causing dizziness, exhaustion, fainting and finally heart failure.

Two types: Primary, with no known cause, and secondary, for which the cause is known, such as emphysema and bronchitis.

Whom it affects: One out of 250,000-500,000 people, all ages, females more than males.

Life expectancy: The prognosis depends on the severity of the problem when diagnosed. Recent data indicate that the length of survival is continuing to improve, with some patients able to manage the disease for 15 to 20 years or longer.

Treatment: Depending on severity of the disease, drugs or a lung transplant.

Resources:

. The Pulmonary Hypertension Program at Maine Medical Center in Portland has been involved with pulmonary hypertension patient care, education and research for many years. Current efforts are focused on clinical research for patients with primary pulmonary hypertension. The center has been a participant in early trials of several new drugs.

. The Maine Pulmonary Hypertension Support Group meets at 6 p.m. the second Wednesday of every other month, at Gentiva Health Services, 105 Main St., South Portland. The meeting is open to anyone affected by pulmonary hypertension, their friends and family.

. Founded in 1995, the PPH Cure Foundation is the world’s largest nongovernmental financial supporter of medical research into the causes and therapies for primary pulmonary hypertension. In the past year, grants totaling $1.7 million have been awarded. The foundation is supporting an “orphan” drug development effort focused specifically on PPH.

. The Pulmonary Hypertension Association can be reached on the Web at www.phassociation.org.

. Jeannette Morrill is starting support groups in Bangor and Waterville. She can be reached by e-mail at morrill@midmaine.com.