What Is Pulmonary Arterial Hypertension?
Pulmonary (PULL-mun-ary) arterial hypertension (PAH)
is continuous high blood pressure in the pulmonary artery. The average blood
pressure in a normal pulmonary artery is about 14 mmHg when the person is
resting. In PAH, the average is usually greater than 25 mmHg.
PAH is a serious condition for which there are
treatments but no cure. Treatment benefits many patients.
The pulmonary arteries are the blood vessels that
carry oxygen-poor blood from the right ventricle (VEN-trih-kul) in the heart to
the small arteries in the lungs. In PAH, three types of changes may occur in
the pulmonary arteries:
- The muscles within the walls of the arteries may
tighten up. This makes the inside of the arteries narrower.
- The walls of the pulmonary arteries may thicken
as the amount of muscle increases in some arteries. Scar tissue may form in the
walls of arteries. As the walls thicken and scar, the arteries become
increasingly narrow.
- Tiny blood clots may form within the smaller
arteries, causing blockages.
There is less room for the blood to flow through
these narrower arteries. The arteries may also stiffen. Over time, some of the
arteries may become completely blocked.
The narrowing of the pulmonary arteries causes the
right side of heart to work harder to pump blood through the lungs. Over time,
the heart muscle weakens and loses its ability to pump enough blood for the
body's needs. This is called right
heart
failure. Heart failure is the most common cause of death in people with
PAH.
There are two types of PAH:
- Primary pulmonary arterial
hypertension (PPAH) is inherited or occurs for no known reason.
- Secondary pulmonary arterial
hypertension (SPAH) either is caused by or occurs because of another condition.
The conditions include chronic heart or lung disease, blood clots in the lungs,
or a disease like
scleroderma (skler-o-DER-ma).
About 300 new cases of PPAH are diagnosed in the
United States each year. SPAH is much more common.
Doctors have learned a lot about PAH in recent
years. More treatments are now available. Researchers are also studying several
promising new treatments that may prolong lives as well as improve the quality
of life for people living with PAH.
August 2006
|