Table 1 Pulmonary hypertension classification [3]. Forms of pulmonary hypertension directly due to congenital cardiac and/or pulmonary arterial defects in bold

1. Pulmonary Arterial Hypertension

 1.1 Idiopathic

 1.2 Heritable

  1.2.1 BMPR2 mutation

  1.2.2 Other mutations

 1.3 Drugs and toxins induced

 1.4 Associated with:

  1.4.1 Connective tissue disease

  1.4.3 Portal hypertension

  1.4.4 Congenital heart disease

  1.4.5 Schistosomiasis

1′. Pulmonary veno-occlusive disease/capillary haemangiomatosis

 1′.1 Idiopathic

 1′.2 Heritable

  1′.2.1 EIF2AK4 mutation

  1′.2.2 Other mutations

 1′.3 Drugs, toxins and radiation induced

 1′.4 Associated with:

  1′.4.1 Connective tissue disease

  1′.4.2 HIV infection

1″. Persistent pulmonary hypertension of the newborn

2. Pulmonary hypertension due to left heart disease

 2.1 Left ventricular systolic dysfunction

 2.2 Left ventricular diastolic dysfunction

 2.3 Valvular disease

 2.4 Congenital/acquired left heart inflow/outflow tract obstruction and congenital cardiomyopathies

 2.5 Congenital/acquired pulmonary veins stenosis

3. Pulmonary hypertension due to lung disease and/or hypoxia

 3.1 Chronic obstructive pulmonary disease

 3.2 Interstitial lung disease

 3.3 Other pulmonary diseases with mixed restrictive and obstructive pattern

 3.4 Sleep-disordered breathing

 3.5 Alveolar hypoventilation disorders

 3.6 Chronic exposure to high altitude

 3.7 Developmental lung diseases

4. Chronic thromboembolic disease and other pulmonary arterial obstructions

 4.1 Chronic thromboembolic pulmonary hypertension

 4.2 Other pulmonary artery obstructions:

  4.2.1 Angiosarcoma

  4.2.2 Other intravascular tumours

  4.2.3 Arteritis

  4.2.4 Congenital pulmonary arterial stenoses

  4.2.5 Parasites (hydatidosis)

5. Pulmonary hypertension with unclear and/or multifactorial mechanisms

 5.1 Haematological disorders: chronic haemolytic anaemia, myeloproliferative disorders, splenectomy

 5.2 Systemic disorders: sarcoidosis, pulmonary histiocytosis, lymphangioleiomyomatosis neurofibromatosis

 5.3 Metabolic disorders: glycogen storage disease, Gaucher disease, thyroid disorders

 5.4 Others: pulmonary tumoural thrombotic microangiopathy, fibrosing mediastinitis, chronic renal failure (with/without dialysis), segmental pulmonary hypertension