Table 1

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