Pathobiology of pulmonary hypertension - The role of platelets and thrombosis

Thrombotic lesions are among the most frequent histopathological lesions seen in pulmonary arterial hypertension. However, with the rare exceptions of pulmonary arterial hypertension associated with antiphospholipid antibodies, or genetic platelet dysfunction, or inherited deficiencies of antithrombotic pathways, these thrombotic lesions are secondary in most cases of primary or secondary pulmonary arterial hypertension. Pulmonary arterial hypertension is associated not only with thrombotic lesions but also with persistent vasoconstriction and structural remodeling of pulmonary arteries. By interacting with the pulmonary arterial wall, activated platelets may contribute to the functional and structural alterations of pulmonary vessels through the release of various vasoactive mediators and growth factors.