Classification of Pulmonary Hypertension (PH)

The World Health Organization (WHO) classifies patients with PH into five groups based upon etiology - and may carry different management plan due to underlying cause of the PH.

Group 1  — Patients with group 1 pulmonary arterial hypertension (PAH). It was called idiopathic pulmonary arterial hypertension (IPAH) or primary pulmonary hypertension. It may be hereditary or due to diseases that localize to small pulmonary arterioles, such as connective tissue diseases, HIV, portal hypertension, congenital heart disease, schistosomiasis, and possible drug use.

Group 2  — Patients with group 2 have PH secondary to left heart disease including valvular heart disease. This requires underlying cardiac disease management.

Group 3  — Patients with group 3  have PH secondary to diseases causing hypoxemia, such as COPD, ILD, sleep-disorders and others. Supplemental oxygen may be a mainstay of treatment.

Group 4  — Patients with group 4 PH have  due to thromboembolic occlusion of the proximal or distal pulmonary vasculature. In this group anticoagulation is primary medical therapy, at least in earlier stage.

Group 5 — Group 5 PH includes with multi-factorial mechanisms like hematologic disorders (eg, myeloproliferative disorders and chronic hemolytic anemia), systemic disorders (eg, sarcoidosis), metabolic disorders (eg, glycogen storage disease), and others.