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Pulmonary Arterial Hypertension

What is pulmonary arterial hypertension (PAH)?

Pulmonary arterial hypertension (PAH) is a rare cause of high blood pressure in the lungs. Blood, after giving up its oxygen to the body tissues, is returned through the veins to the right lower heart chamber (right ventricle). The right ventricle then pumps the blood through the lungs to pick up a new supply of oxygen. Blood pressure in the lungs and the right ventricle is normally about one-fifth as much as elsewhere in the body.

When there is increased blood pressure in the lungs, the right ventricle must work harder to pump blood to the lungs. The heart muscle tries to compensate by becoming thicker and stronger. As the disease gets worse, the right ventricle can't compensate any more and symptoms appear.

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How does it occur?

The cause of PAH is unknown. The small blood vessels in the lungs get thicker and stiffer. High pressure is needed to force blood through the thicker and stiffer blood vessels.

PAH is more likely to affect women in young adulthood and middle age. PAH also seems to run in families. Some drugs and viruses have been linked to PAH, but this only accounts for a small number of cases.

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What are the symptoms?

Shortness of breath with exertion is the main symptom. This happens because the right ventricle can't force enough blood through the lungs to furnish enough oxygen. Chest pain often occurs. You may faint, especially during exercise. Symptoms may become worse over time.

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How is it diagnosed?

Your healthcare provider will ask you to describe your symptoms and other things about your health, especially what medicines and drugs you have been taking. He or she will examine you.

If your provider suspects PAH, you may have an electrocardiogram. A chest X-ray may show decreased blood flow in the lungs and enlargement of the main blood vessels to the lungs. An echocardiogram, a test that uses ultrasound waves to create a picture of the heart, shows thickening of the right ventricle. The ultrasound waves can also help measure the blood pressure in the arteries in the lungs. Sometimes a heart catheterization is needed to measure the pressure in the blood vessels in the lungs directly. Your healthcare provider will also need to test for other causes of high blood pressure in the lungs, such as blood clots in the lungs, diseases of the lung tissue and liver diseases.

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How is it treated?

PAH used to be untreatable and always fatal, but current treatments seem to prolong survival. Blood thinners (anticoagulants) are often used to prevent small blood clots that might further block blood flow through the lungs.

The response to treatment varies from person to person. Some people benefit from the use of drugs called calcium antagonists. These drugs improve symptoms but aren't a cure. They expand (dilate) blood vessels in the lungs and improve blood flow. Prostacyclin, a normally occurring body hormone, may be given through a vein with the help of a special pump. Prostacyclin and a combination mixture of air and nitric oxide both may improve symptoms temporarily. In unusual cases, people may be offered a heart-lung transplant.

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