Pulmonary arterial hypertension (PAH) is a very specific type of pulmonary hypertension that is not caused by chronic heart or lung disease or prior blood clots.
PAH is a life-threatening condition that occurs when the arteries in the lungs become narrowed or blocked. This restricts blood flow in the lungs and increases pressure in the pulmonary arteries. As a result, the right side of the heart must work harder in order to pump blood through the lungs. Over time, the heart's right chamber becomes weak and will eventually fail if PAH remains untreated.
Major types of PAH include:
- Idiopathic PAH, meaning the cause is unknown
- Heritable PAH, meaning it is inherited
- Associated PAH, meaning it occurs in the presence of another disease, such as connective tissue diseases, congenital heart disease or chronic liver disease.