Pulmonary hypertension pathophysiology

Overview

There are different types and causes of pulmonary hypertension, however most of them share the same pathophysiology: An initiating factor leads to increased resistance in the pulmonary vasculature. As a consequence, the right ventricle adapts by increasing right ventricular systolic pressures to preserve the cardiac output from the right heart. With time, increasing right ventricular systolic pressures will subsequently result in chronic changes in the pulmonary circulation and progressive remodeling of the vessel walls further exacerbating the pulmonary hypertension. 

The ability of the right ventricle to adapt to increased pulmonary vascular resistance is influenced by several factors, including the age of the patient at onset, rapidity of onset of pulmonary hypertension and coexisting hypoxemia.

Both primary and secondary pulmonary hypertension are associated with narrowing and obliteration of the pulmonary arterioles due to thickening of the intima by fibromuscular dysplasia.This constant finding has created increased our interest in the role of endothelial injury and the release of vasoactive mediators in the pathogenesis of pulmonary hypertension.These mediators include both vasoconstrictors and vasodilators.The main vasoconstrictor is Endothelin, whereas Nitric Oxide (NO), PGI2 and endothelium derived hyperpolarizing factor (EDHF) are vasodilators of which NO is the most potent in reversing the effects of Endothelin.