This paper is a review of the continued experiences, over the past four years in this laboratory, of segmental replacement of both the superior and the inferior venae cavae in the dog. When uniform success in venous substitution is achieved experimentally, there will be adequate opportunity for clinical application in the bridging of major venous defects caused by thrombosis, radical operations for cancer, or as a sequel to injuries of the venous system.
East and Muller,1 in a review of the literature of the superior vena caval obstruction syndrome, pointed out that its treatment has been discouraging and that although the ideal replacement of the superior vena cava would be a large autogenous vein graft, these grafts are difficult to obtain. In their experimental work they found knitted Teflon grafts to be less liable to occlusion than nylon grafts. More recent reports indicate increasing success both in the experimental