Pathobiology of pulmonary hypertension - The role of platelets and thrombosis

Thrombotic lesions are among the most frequent histopathological lesions se en in pulmonary arterial hypertension. However, with the rare exceptions of pulmonary arterial hypertension associated with antiphospholipid antibodie s, or genetic platelet dysfunction, or inherited deficiencies of antithromb otic pathways, these thrombotic lesions are secondary in most cases of prim ary or secondary pulmonary arterial hypertension. Pulmonary arterial hypert ension is associated not only with thrombotic lesions but also with persist ent vasoconstriction and structural remodeling of pulmonary arteries. By in teracting with the pulmonary arterial wall, activated platelets may contrib ute to the functional and structural alterations of pulmonary vessels throu gh the release of various vasoactive mediators and growth factors.