PULMONARY-HYPERTENSION IN CHRONIC RESPIRA TORY DISORDERS

Pulmonary hypertension is the major cardiovascular complication of chr onic respiratory disorders and its development is a sign of poor progn osis. Pulmonary circulation is characterized by its low vascular tone and the response to hypoxia by vasoconstriction. Pulmonary endothelium plays an important role in modulating these characteristics. Structur al abnormalities of pulmonary arteries in pulmonary hypertension affec t preferentially the intimal layer and may damage the endothelial cell s. Endothelial dysfunction of pulmonary arteries has been recognized i n the different forms of pulmonary hypertension. Vasodilators are reco mmended for the treatment of primary pulmonary hypertension. However, in pulmonary hypertension associated with chronic respiratory disorder s, both systemic and selective pulmonary vasodilators are not indicate d since they may worsen gas exchange due to the inhibition of hypoxic vasoconstriction. The most effective treatment of pulmonary hypertensi on associated with chronic hypoxic lung diseases is long-term oxygen t herapy.