Idiopathic pulmonary arterial hypertension

Idiopathic pulmonary arterial hypertension (IPAH) refers to an unexplained increase in pulmonary vascular resistance causing persistent elevation of pulmonary arterial pressure, resulting in a mean pulmonary arterial pressure ≥25 mmHg at rest, after excluding all secondary causes of pulmonary arterial hypertension. Primary pulmonary hypertension originally referred to pulmonary arterial hypertension of unknown cause; however, causes of primary pulmonary hypertension such as bone morphogenetic protein receptor type II gene mutations have now been identified. Among former patients with primary pulmonary hypertension, those with a family history of pulmonary arterial hypertension are classified as having familial pulmonary arterial hypertension, while the remainder are classified as having idiopathic pulmonary arterial hypertension. This disease is more common in young and middle-aged adults, with a male-to-female ratio of 1:2–3.