374 Flap-Retraction Suture Technique for End to Side Microvascular Anastomosis – A Novel Technical Innovation in Experimental Rat Femoral Model and Successful Use for STA-MCA Bypass in Moya-Moya Disease

INTRODUCTION: End-to-side (ES) microvascular anastomosis is the most commonly performed anastomosis by neuro-vascular surgeons. The inherent tendency of cerebral arteries to collapse after the placement of clamps can lead to visual obscuration of the lumen, repeated intimal handling of the artery walls, and prolonged procedure time. METHODS: ES anastomosis was performed on the femoral vessels of 25 male Sprague Dawley rats. A modified excisional teardrop vesselotomy was done on the recipient vessel. A small flap attached to the venotomy margins on one side was loosely sutured to the surrounding soft tissue for luminal retraction. An ES-interrupted two-throw anastomosis was then carried out. Towards the end of the anastomosis, this flap was excised and the remaining wall was sutured. RESULTS: In the rat model, 12.18±1.37 sutures were used, the average suture duration was 45.25±11.72 minutes and the immediate patency was 100%. Delayed patency was 24/25 (96%) confirmed by the cut-open method after an average observation of 16.18±3.41 days. In the clinical series, 32 STA-MCA anastomoses were performed with this method. The immediate patency was 100% and no peri-procedural complications were noted. CONCLUSIONS: The retraction sutures allow continuous visualization of the vessel lumen, avoid incorporating the back wall in sutures, and reduce the handling of intimal edges; these factors directly influence the final anastomosis patency. The feasibility and utility of flap retraction sutures were successfully demonstrated in an experimental setting and with excellent surgical outcomes in cases of MMD.