What is primary pulmonary hypertension (or unexplained pulmonary hypertension)?
Primary or unexplained pulmonary hypertension (PPH) is a rare lung disorder in which the blood pressure in the pulmonary artery rises far above normal levels for no apparent reason. The pulmonary artery is a blood vessel carrying oxygen-poor blood from the right ventricle (one of the heart’s pumping chambers) to the lungs. In the lungs, the blood picks up oxygen, then flows to the heart’s left side, where the left ventricle pumps it to the rest of the body through the aorta. Hypertension is a medical term for abnormally high blood pressure. Normal average (also called “mean”) pulmonary artery pressure is about 14 mm Hg at rest. In patients with PPH, the average blood pressure in the pulmonary artery is greater than 25 mm Hg at rest and greater than 30 mm Hg during exercise. This abnormally high pressure (pulmonary hypertension) is linked with changes in the small blood vessels in the lungs. These changes increase resistance to blood flowing through the vessels. This increased resistanc
