A review of pulmonary arterial hypertension: Part 1. Novel insights and classification.

Pulmonary arterial hypertension (PAH) is a disease characterised by an increased pulmonary artery pressure. The precapillary pulmonary arteries show distinct pathobiological changes, i.e. medial hypertrophy, intimal fibrosis, microthrombi and plexiform lesions. Although the pathogenesis is not completely understood, pulmonary vascular proliferation and remodelling, due to a variety of mediators, is believed to play the pathogenetic key role. Genetic research reveals molecular deformities and gene mutations associated with phenotypic PAH. This article covers novel insights into pathobiology, pathogenesis and genes of PAH, which led to a novel classification system and a diagnostic work-up, emanated from the World Health Organisation Symposium on Pulmonary Hypertension in Venice in June 2003.