A Novel Intraluminal Microtube Anastomosis System (IMAS) for Rapid Rat Microvascular Reconstruction: Development and Experimental Evaluation

Background/Objectives: Conventional interrupted microvascular anastomosis is technically demanding and time-consuming. We developed an intraluminal microtube anastomosis system (IMAS) in which circumferential anchoring ridges on the outer surface mechanically retain each arterial end while two external circumferential ligatures secure the reconstruction. This study compared IMAS with conventional interrupted microsurgical anastomosis in a rat infrarenal abdominal aortic model. Methods: Forty male Sprague Dawley rats (250–300 g) were allocated to IMAS (n = 20) or conventional interrupted microsurgical anastomosis (n = 20). Random-sequence generation and allocation concealment were handled by an animal-experiment assistant. All formal procedures were performed by the same surgeon, who was proficient in conventional microsuturing and had completed 10 pilot IMAS procedures before the study. Anastomosis time was measured from complete aortic transection to restoration of flow after clamp removal. Patency was assessed at 1 week and 1 month by color Doppler ultrasonography, with terminal gross examination at 1 month. The study was exploratory and was not powered as a patency non-inferiority or equivalence study. Results: Mean anastomosis time was 5 min 30 s ± 60 s with IMAS and 20 min 32 s ± 75 s with conventional suturing (p < 0.001). The between-group mean difference (conventional minus IMAS) was 902 s (95% CI, 859–945 s), corresponding to an approximately 73% reduction. Patency was 19/20 (95%) in both groups at 1 week (p = 1.000) and 18/20 (90%) in both groups at 1 month (p = 1.000). No gross device migration, aneurysmal dilatation, or anastomotic leakage was observed in patent IMAS-treated vessels at necropsy. Conclusions: In this exploratory rat model, IMAS substantially shortened reconstruction time. The observed short-term patency proportions were the same in the two groups, but the study was not sufficiently powered to establish equivalence or non-inferiority in patency. Histological response, lumen stenosis, quantitative flow, mechanical strength, material biocompatibility, and longer-term outcomes require further evaluation.