Magnitude and Time of Development of the Collateral Circulation to the Lung after Occlusion of the Left Pulmonary Artery

Direct measurements were made of the collateral flow to the left lower lobe of the lung after occlusion of the left pulmonary artery in anesthetized, open-chest dogs. Immediately after ligation of the pulmonary artery flow ranged from 4.4 to 9 cc. per minute and varied with the height of the systemic blood pressure. The flow at a given blood pressure did not increase during 2 to 4 hours of observation. After chronic ligation of the left pulmonary artery, the flow increased, ranging from 68 to 376 cc. per minute at the end of approximately one year.