Demonstration of preferential flow of blood from inferior vena cava and from right pulmonary veins through experimental atrial septal defects in dogs.

UTILIZING ft technic of continuously recording the dilution pattern of an indicator substance, Swan, Burchell and Wood have demonstrated some interesting patterns of flow of blood in patients with atrial septal defects. By injecting Evans blue dye (T-1824) into the venae cavae they obtained dilution patterns indicating that some of the caval blood crossed the atrial septal defect from the right atrium to the left atrium. The greater portion of this right-to-left shunted blood came from the inferior vena cava. By this same technic they also showed that the right lung contributes most of the blood shunting in the usual left-to-right direction through atrial septal defects. These authors attributed this phenomenon of preferential flow to the proximity of the vessels involved (that is, right pulmonary veins and inferior vena cava) to the defect in the atrial septum. Some confirmation of this explanation has come from postmortem study of hearts with congenital atrial septal defects. Further confirmation was obtained by exploration of the heart during surgical repair of the defects. The study herein presented was undertaken to provide information concerning preferential