|Budget Amount *help
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1996: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1995: ¥1,700,000 (Direct Cost: ¥1,700,000)
1.We had been using rats for the experimental model for microvascular anastomosis. However, rats were not suitable either for the research of long term patency or for the irradiation test. A rabbit was suitable animal for this experiment. So we confirmed weather the auricular vessels of rabbit were compatible with inguinal vessels of rat as a model of microvascular anastomosis. The inguinal artery of rat was 1.5 to 1.8 mm in diameter. We once severed this artery and reanastomosed under operation microscope and examined the patency rate 2 days later. the rate was 100% (20 vessels patent in 20 vessels anastomosed). On the other hand, the auricular central artery of rabbit was 1.0-1.5 mm in diameter. The same experiment on this vessel revealed 97.5% (39/40). The inguinal artery of rat and the auricular artery of rabbit were equally suitable for model of vascular anastomosis. The high patency rate of almost 100% was obtained in both animals, provided of which vessels were more than 1.0 mm
2.The clinical patency rate of the same operator was examined. The free radial forearm flap were applied for 230 clinical cases of head and neck reconstruction. The arterial pedicle of this flap was 1.5-2.0 mm in diameter. The flap failure occurred in 2 cases, and patency rate was 99.1%. The arterial pedicle of free jejunum flap was 1.0-1.5 mm in diameter. And clinical patency rate was 96.3% (79 successes in 82 grafts). Thus we considered that the auricular central artery of rabbit was suitable for the model of microvascular free tissue transfer n clinical cases.
3.We made an experiment of irradiation, supposing the preoperative irradiation in head and neck surgery. Five rabbits, 10 auricle made one group. Six groups underwent irradiation of various dose. Three weeks after the irradiation of each dose 20,30,40,50 Gy, and control (0 Gy), we made microvascular anastomosis on the auricular central artery, and examined the patency rate 2 days later. The patency rates of each group were 90% in 20 Gy group, 60% in 30 Gy group, 0% in 40 Gy group, 0% in 50 Gy group and 100% in control. Over 40 Gy of preoperative irradiation remarkably imperiled the patency of anastomosed vessels. Thus we emphasise that we should take a recipient vessels in non-irradiated field, when the patient had undergone the preoperative radiation therapy more than 40 Gy in dose.
4.We are now planning to examine the specimen of anastomosed vessels histologically, and to clarify the mechanism of obstruction of blood flow resulting from the preoperative irradiation. Less