Effects of pneumonectomy on pulmonary circulation in adult and young animals.

THE POSSIBLE relationship between pulmonary vascular pathological changes and an increased pulmonary blood flow and pulmonary-arterial blood pressure has been the subject of investigation for many years. Muller et al. and Ferguson et al. have demonstrated the development of vascular changes in the lungs following the surgical production of aortopulmonary shunts. The physiological changes associated with this procedure are complicated, involving changes of pulmonary blood flow, pulmonary-arterial pressure, and pulmonary-venous pressure. In an attempt to study the effects of increased pulmonary blood flow, long-term observations have been made in a group of animals in which the total pulmonary vascular bed was restricted by means of pneumonectomy or ligation of one pulmonary artery, thereby diverting the total cardiac output through the remaining lung tissue. Since the histological features of the small pulmonary vessels are different in young animals as compared with the adult, possible differences in the effects of these procedures in puppies as compared with adult dogs were also examined.