Pulmonary hypertension is a multifaceted disease. It either results from primary pulmonary arterial vasculopathy or is secondary to metabolic, thrombotic, or hemodynamic disease. The condition is characterized by a mean pulmonary arterial pressure > 25 mm Hg at rest measured by right heart catheterization. It can be divided into the following 5 groups:

Pulmonary arterial hypertension (PAH)

• Group 1 – Elevation of pressure in the pulmonary arteries (idiopathic, hereditary, or toxin induced). A progressive disorder of primary pulmonary arterial vasculopathy characterized by a mean pulmonary arterial pressure > 25 mm Hg at rest or > 30 mm Hg during exercise. Examples include idiopathic PAH, hereditary PAH, and PAH due to connective tissue disease, HIV infection, portal hypertension, congenital heart disease, congenital abnormality (eg, cardiac, hepatic, extrahepatic), schistosomiasis, or drug use. Several genetic mutations may be implicated in the pathogenesis of PAH.

Pulmonary hypertension

• Group 2 – Elevation of pressure in the pulmonary venous system due to left heart disease.
• Group 3 – Elevation of pressure in the pulmonary venous system due to lung disease or hypoxia.
• Group 4 – Chronic thromboembolic pulmonary hypertension.
• Group 5 – Pulmonary hypertension with unclear or multifactorial mechanisms.

Diagnosis can be challenging because other disease manifestations may mask pulmonary hypertension symptoms. The most common symptoms include dyspnea, orthopnea, paroxysmal nocturnal dyspnea, chest pain, fatigue, peripheral edema, palpitations, and syncope. On physical examination, there may be signs of right-sided heart failure.

PAH is sometimes associated with pulmonary artery aneurysm and, rarely, in long-standing cases, pulmonary artery dissection.

Multiple pulmonary metastases can be a cause of rapid-onset pulmonary hypertension.

Related topic: portopulmonary hypertension