Introduction to Pulmonary Arterial Hypertension

Arterial Hypertension Pulmonary hypertension (PH) is a haemodynamic and pathophysiological condition defined as an increase in mean pulmonary arterial pressure (PAP) ≥25mmHg at rest, as assessed by right heart catheterisation. PH covers a heterogeneous group of clinical conditions and is classified (according to the most recent classification system defined during the fourth World Symposium on PH held in 2008 in Dana Point, CA, US) into five clinical groups with specific characteristics (see Table 1). Pulmonary arterial hypertension (PAH; group 1 in the Dana Point classification) is a rare and devastating clinical condition characterised by the presence of pre-capillary PH and is caused by functional and structural changes in the pulmonary vasculature, leading to a progressive increase in pulmonary vascular resistance (PVr), right ventricular failure and, eventually, death. PAH can be idiopathic (IPAH), heritable (HPAH) or associated with a number of risk factors or conditions, such as connective tissue disease or congenital heart disease (associated PAH [APAH]).