European Respiratory Society Monograph, Vol. 57. 2012
Pulmonary arterial hypertension (PAH) is characterised by vasoconstriction, thrombosis and remodelling of the small pulmonary arteries, leading to chronic pre-capillary pulmonary hypertension (PH) and fatal right heart failure. PAH is a rare and devastating condition with a prevalence of less than 50 cases per million adults in the European Union and a median survival of less than 5 years after diagnosis. As emphasised in the updated PH classification, there are many other causes of PH and its global burden is currently unknown and certainly underestimated. Indeed, common diseases such as chronic obstructive pulmonary disease (COPD), pulmonary embolism and hepatosplenic schistosomiasis are frequent causes of PH worldwide.