PAH is a type of PH that is specifically due to narrowing of the pulmonary arteries (blood vessels) that carry blood to the lungs.
The exact cause of PAH is not well understood. Narrowing of pulmonary arteries in PAH is due to multiplication and growth of cells in the walls of the pulmonary arteries, as well as scar tissue formation in the pulmonary arteries. Tremendous ongoing research has identified many biologic abnormalities in PAH, including genes, proteins, and small chemicals in the body.
PAH is a broad category which includes many patients with different types of PAH. These include:
- Heritable (genetic)
- Associated with connective tissue disease
- Associated with other conditions