Table 1.

Clinical Classification of Pulmonary Hypertension. (ALK1, activin receptor-like kinase type 1; BMPR, bone morphogenetic protein receptor type 2; HIV, human immunodeficiency virus) (Dana Point, 2008). ¹

Group 1 Pulmonary arterial hypertension (PAH)
1.1	Idiopathic PAH
1.2	Heritable
	1.2.1 BMPR2
	1.2.2 ALK1, endoglin (with or without hereditary hemorrhagic telangiectasia)
	1.2.3 Unknown
1.3	Drug- and toxin-induced
1.4	Associated with
	1.4.1 Connective tissue diseases
	1.4.2 HIV infection
	1.4.3 Portal hypertension
	1.4.4 Congenital heart diseases
	1.4.5 Schistosomiasis
	1.4.6 Chronic hemolytic anemia
1.5	Persistent pulmonary hypertension of the newborn
Group 1′ Pulmonary veno-occlusive disease (PVOD) and/or pulmonary capillary hemangiomatosis (PCH)
Group 2 Pulmonary hypertension owing to left heart disease
2.1	Systolic dysfunction
2.2	Diastolic dysfunction
2.3	Valvular disease
Group 3 Pulmonary hypertension owing to lung diseases 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 abnormalities
Group 4 Chronic thromboembolic pulmonary hypertension (CTEPH)
Group 5 Pulmonary hypertension with unclear multifactorial mechanisms
5.1	Hematologic disorders: myeloproliferative disorders, splenectomy
5.2	Systemic disorders: sarcoidosis, pulmonary Langerhans cell histiocytosis: lymphangioleiomyomatosis, neurofibromatosis, vasculitis
5.3	Metabolic disorders: glycogen storage disease, Gaucher disease, thyroid disorders
5.4	Others: tumoral obstruction, fibrosing mediastinitis, chronic renal failure on dialysis