Table 2.

Clinical classification of pulmonary hypertension

Type of pulmonary hypertensionCauses
Grade 1
Pulmonary arterial hypertensionIdiopathic
Heritable: (eg BMPR, ALK1, mutations)
Drugs and toxins
Connective tissue diseases
HIV infection
Portal hypertension
Congenital heart disease
Persistent pulmonary hypertension of the newborn
Pulmonary veno-occlusive disease and/or pulmonary capillary haemangiomatosis
Grade 2
Pulmonary hypertension resulting from left heart diseaseLV systolic dysfunction
LV diastolic dysfunction
Valvular heart disease
Grade 3
Pulmonary hypertension resulting from lung diseases and/or hypoxiaChronic obstructive pulmonary disease
Interstitial lung disease
Other pulmonary diseases with mixed restrictive and obstructive patterns
Sleep-disordered breathing
Alveolar hypoventilation disorders
Chronic exposure to high altitude
Developmental abnormalities
Grade 4
Chronic thromboembolic pulmonary hypertension
Grade 5
Pulmonary hypertension with unclear and/or multifactorial mechanismsHaematological disorders (eg myeloproliferative disorders, splenectomy)
Systemic disorders (eg sarcoidosis, pulmonary Langerhans cell histiocytosis, lymphangioleiomyomatosis, neurofibromatosis, vasculitis)
Metabolic disorders (eg glycogen storage disease, Gaucher's disease, thyroid disorders)
Others: tumoural obstruction, fibrosing mediastinitis, chronic renal failure
  • ALK = anaplastic lymphoma kinase; BMPR = bone morphogenetic protein receptor; LV = left ventricular