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Glossary

6-minute walk test (6MWT)—A test to measure how far (usually measured in meters) a person can walk on a flat surface in 6 minutes. This test is used to evaluate the severity of PAH both before and during treatment, and can help doctors prescribe and monitor treatments.

Amphetamine—A class of drugs that stimulates the central nervous system (nerves and brain). Street drugs such as "meth" and "speed" are amphetamines that have been associated with PAH.

Associated PAH (APAH)—PAH that is associated with another disease or condition, such as connective tissue disease, congenital heart disease, HIV infection, exposure to drugs or toxins, and others.

Chest CT (computerized tomography)—A computerized x-ray examination that takes detailed, three-dimensional pictures of the body's internal organs.

Chest x-ray—An x-ray that shows the heart, lungs, bones, and other structures of the chest.

Congenital heart disease—A defect or deformity in one or more parts of the heart or large blood vessels that is present at birth. Most heart defects either block blood flow in the heart or vessels near it or cause blood to flow through the heart abnormally.

Connective tissue disease (also known as CTD or collagen vascular disease)—A varied group of immune system disorders affecting the skin, joints, and other organs in the body. Examples include scleroderma, systemic lupus erythematosus (SLE), and rheumatoid arthritis. PAH can occur in association with several connective tissue diseases.

Diuretic—A medication that helps individuals to lose water by increasing the amount of urine they make. Sometimes called a "water pill."

Echocardiography—A procedure that uses ultrasound to create video images of the heart, so that the structure, size, and motion of the heart and blood flow through the heart can be viewed. This test is used to help diagnose PAH.

Electrocardiogram (ECG)—A diagnostic test that measures electrical activity of the heart. This diagnostic test can record abnormalities of heart rhythm and may offer information about whether the heart is enlarged or working under strain.

Familial PAH (FPAH)—PAH that runs in families and is caused by changes in certain genes. Also known as heritable PAH (HPAH).

High blood pressure—A condition where the blood circulates through the arteries with more force than normal, all or most of the time.

Human immunodeficiency virus (HIV)—The virus associated with acquired immunodeficiency syndrome (AIDS). PAH occurs in a small number of HIV-infected patients.

Idiopathic—A medical term that means without an identifiable cause.

Idiopathic PAH (IPAH)—A type of PAH for which the cause cannot be identified. IPAH used to be called primary pulmonary hypertension (PPH).

Intravenous infusion—A drug delivery method in which a medication is given directly into a vein over a long period of time.

Oximetry/sleep study—A test that measures the amount of oxygen in the blood and records the patterns of a person's breathing while he or she is asleep.

Pulmonary arterial hypertension (PAH)—A rare disease in which the arteries of the lungs become narrower than they should be, leading to high blood pressure in the arteries of the lungs (pulmonary arteries), and putting strain on the right ventricle of the heart.

Pulmonary arteries—The blood vessels that carry blood from the right ventricle of the heart to the lungs, where the blood picks up oxygen.

Pulmonary function test—A group of tests that measure how well the lungs work. Pulmonary function tests help doctors learn whether a disease of the lung tissues or airways is present.

Right heart catheterization—A diagnostic test in which a thin, flexible tube, called a catheter, is inserted into a vein and guided into the heart and pulmonary arteries in order to measure blood pressure, pumping capacity, oxygenation, and other factors related to heart and lung function. This test is required for confirming a diagnosis of PAH.

Right ventricle—The chamber of the heart that pumps low-oxygen blood through the pulmonary arteries to the lungs. In patients with PAH, this chamber may become enlarged and lose its pumping capacity. The left ventricle, by contrast, pumps oxygen-rich blood returning from the lungs to the rest of the body.

Sedation—The administration of medication to induce calmness and sleepiness; useful for minor surgical procedures.

Subcutaneous infusion—A drug delivery method in which a medication is injected under the skin over a long period of time.

Systemic sclerosis (scleroderma)—A progressive disease in which some of the body's tissues slowly become scarred and hardened as a result of being mistakenly attacked by the immune system. In some people, only the skin is affected; in others, the internal organs (including the lungs) are affected, as well. People with scleroderma are at risk for developing PAH.

Ventilation/perfusion (V/Q) scan—A diagnostic test used to evaluate for pulmonary embolism. If there are any blockages in the blood vessels of the lungs, this test can help locate them.

WHO functional class—Defined by the World Heath Organization (WHO), this measure of PAH severity (on a scale of I to IV) is based on a person's symptoms and physical limitations.