New microvenous anastomosis model for microsurgical training: external jugular vein.

In microsurgical training, the femoral vein is used frequently for a microvenous anastomosis model. But the femoral vein in the rat does not completely simulate the human vein because of its thin wall, fragility, and tendency to collapse. These anatomic characteristics cause some difficulty in carrying out anastomoses in microsurgery training particularly for beginners. The authors propose the external jugular vein of the rat for microsurgical training in microvenous anastomoses. In 10 Wistar rats, the anatomy of the external jugular vein was studied by dissection and histology. Anatomic dissections demonstrate that the external jugular vein has an average diameter of 1.9 mm (range: 1.6 to 2.1 mm) without tendency to collapse. The vein is easily dissected without any accompanying anatomic structure for an average segment of 45 mm, allowing effortless approximator clamp placement. Comparison of its cross section with that of the femoral vein and other previously described models by light microscopy and scanning electron microscopy reveals a larger diameter and much thicker vessel wall with a prominent tunica media and adventitia. Based on the anatomic findings in 20 rats, the external jugular vein was anastomosed with end-to-end standard microsurgical technique using 8-0 (n = 10) and 10-0 (n = 10) nylon sutures. Results indicate a 100 percent patency rate immediately after the anastomosis for the two subgroups and 100 percent and 90 percent patency rates 1 week after the procedure for the 10-0 and 8-0 nylon suture groups, respectively. This model presents some advantages: the vein is easily dissected with the naked eye without using the operating microscope because it is the largest vein among the superficially located veins in the rat, and has a thick vessel wall without tendency to collapse. The operative area allows for training inbilateral microsurgical anastomoses using a single skin incision and is safe from autocannibalization. The model simulates clinical microvenous anastomosis better because of its similarities to human large diameter flap veins.