The 2003 Venice clinical classification of pulmonary hypertension1
| PAH |
| IPAH |
| FPAH |
| APAH |
| Collagen vascular disease |
| Congenital systemic-to-pulmonary shunts |
| Portal hypertension |
| HIV infection |
| Drugs and toxins |
| Other (thyroid disorders, glycogen storage disease, Gaucher's disease, hereditary haemorrhagic telangiectasia, haemoglobinopathies, myeloproliferative disorders, splenectomy) |
| Associated with significant venous or capillary involvement |
| PVOD |
| PCH |
| Persistent PH of the newborn |
| PH with left heart disease |
| Left-sided atrial or ventricular heart disease |
| Left-sided valvular heart disease |
| PH associated with lung diseases and/or hypoxaemia |
| COPD |
| ILD |
| Sleep-disordered breathing |
| Alveolar hypoventilation disorders |
| Chronic exposure to high altitude |
| Developmental abnormalities |
| PH due to chronic thrombotic and/or embolic disease |
| Thromboembolic obstruction of proximal pulmonary arteries |
| Thromboembolic obstruction of distal pulmonary arteries |
| Nonthrombotic pulmonary embolism (tumour, parasites, foreign material) |
| Miscellaneous |
| Sarcoidosis |
| Histiocytosis X |
| Lymphangiomatosis |
| Compression of pulmonary vessels (adenopathy, tumour, fibrosing mediastinstis) |
PAH: pulmonary arterial hypertension; IPAH: idiopathic PAH; FPAH: familial PAH; APAH: PAH related to risk factors or associated conditions; PVOD: pulmonary veno-occlusive disease; PCH: pulmonary capillary haemangiomatosis; PH: pulmonary hypertension; COPD: chronic obstructive pulmonary disease; ILD: interstitial lung disease.