Classification of Pulmonary
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 constitutes 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 have PH 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 includes PH with multifactorial
mechanisms like hematologic disorders (eg, myeloproliferative disorders and chronic hemolytic anemia), systemic disorders
(eg, sarcoidosis), metabolic disorders (eg, glycogen storage disease), and others.