CO2-welded venous anastomosis: enhancement of weld strength with heterologous fibrin glue. The milliwatt CO2 laser was used to perform end-to-end anastomoses in canine jugular veins. There was a high disruption rate (50%) in laser-welded veins (n = 10). Fibrin glue (n = 17), formed from human fresh-frozen plasma, enhanced the weld strength decreasing the disruption rate (18%), resulting in an 82% patency which nearly equaled the contralateral sutured vein patency (93%). The bursting strength was improved with fibrin glue. Transmural necrosis was present initially in all groups but extended for a longer distance in the vessel wall in laser-welded anastomoses. Sutured anastomoses exhibited a greater inflammatory response. In laser-welded anastomoses endothelial cells were not as confluent as in sutured anastomoses by six weeks. Carbon dioxide laser-welded end-to-end vein anastomoses appear to be impractical because they disrupt too easily. However, the addition of heterologous fibrin glue to the weld results in a reasonably strong anastomosis with histologic properties that may be beneficial in vein bypass grafts. 