Effect of Flow and Pressure on Pulmonary Vessels

Abstract

Of a total of over 1,000 lung biopsies, carried out over a 3½-year period on patients, the great majority of whom were operated on for various acquired or congenital cardiac diseases, 86 were on patients operated upon for atrial septal defect, 99 on patients with a ventricular septal defect, and 82 on patients with patent ductus arteriosus. The morphological data, particularly with regard to the lung vessels, were correlated with hemodynamic findings in these patients. In atrial septal defect the pulmonary vessels did not differ significantly from those in normal controls of the same ages. Notably there were no differences between patients with relatively low pulmonary arterial flow and those with high flow. In patent ductus arteriosus the only difference was an increase in intimal fibrosis of the pulmonary arteries as compared to normals. In ventricular septal defect, on the other hand, there was an increase in thickness of both media and intima and also in incidence of hemosiderosis. These changes did show a correlation with increased pulmonary arterial pressure but not with pulmonary arterial flow. It is concluded that pulmonary hypertension may provoke these vascular lesions and conversely may be maintained or increased by these lesions, while an increased flow in itself has little or no effect with regard to the morphological alterations, if it is not accompanied by pulmonary hypertension.