Figure 1.

Pathobiology of PAH. (a) Cross-sectional representation of a healthy pulmonary artery. (b) Early stages of PAH include vasoconstriction due to pulmonary endothelial dysfunction and medial hypertrophy. (c) Progressive vascular remodelling of distal pulmonary arteries is characterised by proliferation and migration of smooth muscle cells, endothelial cells, and fibroblasts. (d) Plexiform lesions, due to endothelial dysfunction, proliferation and apoptotic resistance are a hallmark feature of late-stage PAH.