Lung function in chronic persistent pulmonary embolism

: Chronic thromboembolic pulmonary hypertension is characterized by widespread obstruction of the pulmonary arteries with organized thrombus. Typically, the afflicted patients present with complaints of progressive dyspnea and exercise intolerance. The typical functional picture of the 22 patients in this series revealed normal lung volumes. Only about 10% of the subjects had mild restrictive defects. The universal findings were mild to moderate hypoxemia, chronic respiratory alkalosis, high pulmonary vascular resistance and low cardiac output. Pathophysiological mechanisms responsible for dyspnea in chronic thromboembolic pulmonary hypertension are discussed.