[Studies on anastomoses of rat abdominal aorta using the carbon dioxide laser--histological changes and elastic properties of the anastomotic sites].

End-to-end anastomoses of rat abdominal aorta (about 1.8 mm in external diameter) were performed using the carbon dioxide laser, and histological change and dynamic compliance of the anastomotic site were compared with the control group with continuous suture technique. To anastomose vessels with laser energy, four to five stay sutures were placed, and laser energy of 30 to 35 mW with a 100 microns focal spot size was applied to the anastomotic site in the continuous mode. The rats were sacrificed for histological evaluation and measurement of dynamic compliance (Cd) at 2 hours and at 2, 6, and 8 weeks after anastomosis. Cd was calculated from the variables which were measured using the ultrasonic displacement meter at the mean pressure of 55 mmHg with the vessels connecting to the experimental circuit. All laser-assisted and suture anastomoses were patent (laser 21/21, suture 16/16). The rate of aneurysm formation was 4.8% (1/21) for the laser group and 12.5% (2/16) for the suture group. Histological examination showed that the anastomotic site of the laser-assisted anastomosis demonstrated less foreign-body reaction than that of the suture anastomosis and regeneration of the elastic fibers at 6 weeks postoperatively in the optimally coaptated cases. Cd of both laser-assisted and suture anastomoses decreased significantly (p less than 0.01) as compared with that of the untreated aorta. But Cd of the laser-assisted anastomoses had recovered 6 weeks after surgery, and was significantly (p less than 0.05) greater than that of suture anastomoses. From the present study of histological change and dynamic compliance, the results of the laser-assisted arterial anastomoses were more favorable than that of the suture anastomoses.