Platelets in Pulmonary Hypertension: a Causative Role or a Simple Association?

PATHOPHYSIOLOGY OF PULMONARY ARTERIAL HYPERTENSION IS BASED ON THREE BASIC MECHANISMS: thrombotic pulmonary vascular lesions, vasoconstriction and vascular remodeling. Platelets are related to all of these mechanisms by their aggregation, production, storage and release of several mediators. The role of platelets is more prominent in some types of pulmonary arterial hypertension, including those which are secondary to inflammatory and infectious diseases, hemoglobinopathies, essential thrombocythemia, drugs, thromboembolism, and cardiac surgery. Most pulmonary antihypertensive drugs have a negative effect on platelets. In this review, the mechanisms of platelets association with pulmonary arterial hypertension, those types of pulmonary arterial hypertension with greatest platelet contribution to their pathophysiology, and the effects of pulmonary antihypertensive drugs on platelets are summarized.