Comparative study of different combinations of microvascular anastomoses in a rat model: End-to-end, end-to-side, and flow-through anastomosis

Background: This study aimed to compare several microvascular anastomotic techniques by patency rate using a free flap model in rats. Methods: A microsurgical transfer model of a pectoral skin flap to the cervical region was used. In experiment 1, 120 rats were divided into four groups (n = 30 in each group) depending on the type of microvascular anastomotic technique. For group 1, end-to-end anastomoses were performed for arteries and veins. For group 2, end-to-side anastomoses were performed for arteries and end-to-end anastomoses were performed for veins. For group 3, flow-through anastomoses were performed for arteries and end-to-end anastomoses were performed for veins. For group 4, end-to-end anastomoses were performed for arteries and end-to-side anastomoses were performed for veins. Flap survival was assessed on day 3 and the success rates of the four groups compared. In experiment 2 (n = 10), postoperative blood flows of end-to-end and flow-through arterial anastomoses were measured. Results: In experiment 1, the success rates in groups 1, 2, 3, and 4 were 76.7, 83.3, 100, and 83.3 percent, respectively. Differences between group 3 and the other groups were statistically significant. In experiment 2, the blood flow of flow-through arterial anastomosis (1.8 ml/minute) was much higher than that end-to-end anastomosis (0.18 ml/minute). Conclusions: Flow-through arterial anastomosis presented a higher blood flow through the anastomotic site, resulting in a higher success rate than conventional anastomoses. In veins, end-to-side anastomosis was equivalent to end-to-end end anastomosis even though the diameter of the donor vein was larger than the recipient vein.