THE RELATIONSHIP BETWEEN TIMING OF REPAIR OF DISRUPTIONS AND SUBSEQUENT ANEURYSM FORMATION IN LASER-ASSISTED MICROVASCULAR ANASTOMOSES

In this study we investigated the effects of duration of bleeding after laser-assisted microvascular anastomoses and the amount of laser energy used to control bleeding on aneurysm formation. Eighty femoral arteries were exposed in 40 Sprague-Dawley rats anesthetized with chloral hydrate. The arteries were transected and then anastomosed end-to-end with three nylon stay sutures followed by irradiation of the vessels with energy from a CO2 laser. The laser power was kept at 90 mW, and each of three segments between stay sutures was exposed for 6 seconds to continuous laser energy. If anastomotic disruption (defined as bleeding after completion of the anastomosis) occurred, it was controlled with pressure over the disrupted site for 10, 25, or 40 seconds. Disruptions were repaired with exposure to additional laser energy for either 6 (group 1) or 12 seconds (group 2). The anastomoses were inspected at 21 days postoperatively to assess patency and aneurysm formation. Twenty-six of 80 vessels (32%) were anastomosed without the occurrence of disruptions: these 26 vessels had a 100 per cent patency rate and did not develop aneurysms. In group 1, the incidence of redisruption following a primary disruption was the same irrespective of duration of bleeding (4/8, 3/6, and 3/6 for 10-, 25-, and 40-seconds bleeding time, respectively P = NS). Similarly, there was no difference in the incidence of aneurysm formation in this group (0/8, 2/6, and 2/6 for 10, 25, and 40'', respectively, P = NS). The incidence of redisruption was significantly different between groups 1 and 2,10/30 (33%) vs 0/24 (0%), P < 0.05, respectively: however, there was no difference in the rate of aneurysm formation between the two groups, 8/27 (30%) in group 1 vs 3/24 (12.5%) in group 2, P > 0.05. There was a statistically significant difference in the rate of aneurysm development when vessels with no disruption were compared to vessels with one disruption in group 1 (0/26 vs 4/20 P < 0.05). The rate of aneurysm formation differed significantly between vessels with one and vessels with three disruptions (4/20 vs 4/6, P < 0.05). Of interest, there was no difference in the incidence of aneurysm formation between vessels without disruption and group 2, disrupted vessels repaired with additional laser energy for 12 seconds (0/26 vs 3/24 P > 0.05). Patency rates did not differ between groups (90 vs 100%, P > 0.05). Based on our results we conclude that early repair of primary disruptions with increased laser energy minimizes the incidence of re-disruption and may decrease the rate of aneurysm formation following laser-assisted microvascular anastomoses.