WHO classification of pulmonary hypertension
| 1.Pulmonary arterial hypertension |
| 1.1 Primary pulmonary hypertension |
| (a) Sporadic |
| (b) Familial |
| 1.2 Related to |
| (a) Collagen vascular disease |
| (b) Congenital systemic to pulmonary shunts |
| (c) Portal hypertension |
| (d) Human immunodeficiency virus infection |
| (e) Drugs/toxins |
| (1) Anorexigens |
| (2) Other |
| (f) Persistent pulmonary hypertension of the newborn |
| (g) Other |
| 2. Pulmonary venous hypertension |
| 2.1 Left sided atrial or ventricular heart disease |
| 2.2 Left sided valvular heart disease |
| 2.3 Extrinsic compression of central pulmonary veins |
| (a) Fibrosing mediastinitis |
| (b) Adenopathy/tumours |
| 2.4 Pulmonary veno-occlusive disease |
| 2.5 Other |
| 3.Pulmonary hypertension associated with disorders of the respiratory system and/or hypoxaemia |
| 3.1 Chronic obstructive pulmonary disease |
| 3.2 Interstitial lung disease |
| 3.3 Sleep disordered breathing |
| 3.4 Alveolar hypoventilation disorders |
| 3.5 Chronic exposure to high altitude |
| 3.6 Neonatal lung disease |
| 3.7 Alveolar capillary dysplasia |
| 3.8 Other |
| 4. Pulmonary hypertension as a result of chronic thrombotic and/or embolic disease |
| 4.1 Thromboembolic obstruction of proximal pulmonary arteries |
| 4.2 Obstruction of distal pulmonary arteries |
| (a) Pulmonary embolism (thrombus, tumour, ova and/or parasites, foreign material) |
| (b) In situ thrombosis |
| (c) Sickle cell disease |
| 5. Pulmonary hypertension as a result of disorders directly affecting the pulmonary vasculature |
| 5.1 Inflammatory |
| (a) Schistosomiasis |
| (b) Sarcoidosis |
| (c) Other |
| 5.2 Pulmonary capillary haemangiomatosis |