| 1 Pulmonary arterial hypertension (PAH) |
| 1.1 Idiopathic |
| 1.2 Heritable |
| 1.3 Drugs and toxin induced |
| 1.4 Associated with (APAH) |
| 1.41 Connective tissue disease |
| 1.42 HIV infection |
| 1.43 Portal hypertension |
| 1.44 Congenital heart disease |
| 1.45 Schistosomiasis |
| 1.46 Chronic haemolytic anaemia |
| 1′ Pulmonary veno-occlusive disease and/or pulmonary capillary haemagiomatosis |
| 2 Pulmonary hypertension due to left heart disease |
| 2.1 Systolic dysfunction |
| 2.2 Diastolic dysfunction |
| 2.3 Valvular disease |
| 3 Pulmonary hypertension secondary to lung disease and/or hypoxia |
| 3.1 Chronic obstructive pulmonary disease |
| 3.2 Interstitial lung disease |
| 3.3 Lung diseases with mixed restrictive and obstructive patterns |
| 3.4 Sleep-disordered breathing |
| 3.5 Alveolar hypoventilation disorders |
| 3.6 Chronic high-altitude exposure |
| 3.7 Developmental abnormalities |
| 4. Chronic thrombo-embolic pulmonary hypertension |
| 5. Pulmonary hypertension with unclear and/or multifactorial mechanisms |
| 5.1 Haematological disorders: myeloproliferative disorders, splenectomy |
| 5.2 Systemic disorders: sarcoidosis, neurofibromatosis, vasculitis |
| 5.3 Metabolic disorders: glycogen storage disease, Gauchers, thyroid disorders |
| 5.4 Others: tumour obstruction, fibrosing mediastinitis, chronic renal failure on dialysis |
