Introduction: The ability to perform microvascular anastomosis for free tissue transfers and digital replants is tedious, time consuming, and requires a skilled microsurgeon. While a myriad of devices have simplified these challenging operations, all the current devices introduce foreign materials which stimulate a foreign body reaction predisposing such anastomoses to stenosis or thrombosis.  We have developed a novel sutureless technique for performing these complex procedures using thermoreversible poloxamers.

Materials and Methods: Rheological studies were used to engineer a formulation of P407/P188 to obtain a phase transition temperature at 40°C.  Poloxamer formulations were tested on HUVECs in vitro to assess for toxicity and effects on proliferation. Anastomoses were performed on Fisher rat aortas (avg. diameter 1.18±0.02mm) using our sutureless technique (n=30) and with conventional 10-0 nylon sutures (n=30).  CT angiograms, ultrasound Doppler, burst strength assays, and histology were performed at designated timepoints.  Poloxamer mediated heparin delivery was assessed in vitro using HUVECs and tissue factor pathway inhibitor (TFPI) ELISA. 

Results: A formulation of 17% P407 and 6% P188 achieved a phase transition temperature of 40°C and was used for all subsequent experiments.  Sutureless anastomoses were completed more efficiently than the hand sewn technique (8.1 ± 2.4 min vs. 47.3 ± 5.0 min, p<0.05) with equivalent burst strengths (>1200mm Hg, p>0.05).  CT angiograms demonstrated equivalent patency in end-to-end anastomoses; however, end-to-side anastomoses could not be performed using traditional techniques (p<0.001). Doppler analysis demonstrated equivalent patency, vessel diameter, and volumetric flow (116.1mL/sec vs. 107.2 mL/sec, p>0.05) between sutureless and hand-sewn anastomoses. Histology demonstrated dramatically decreased inflammation and fibrosis in the sutureless group compared with the traditional technique. Application of poloxamer did not demonstrate any evidence of toxicity in vitro or in vivo. Heparinized poloxamer-induced a significant percentage increase in secretion of TFPI compared with heparin administered directly to HUVECs (231.8%, p<0.05) with effects lasting up to 24 hours (125.4%, p<0.05). 

Conclusions: Sutureless anastomosis can be performed reliably, more efficiently, and with less intimal damage than hand-sewn anastmosis. In addition, poloxamers can also be employed as a delivery agent for anti-thrombotics simultaneously to further preserve graft patency. This technology offers a promising alternative to sutured anastomosis and may have a profound impact on the field of reconstructive microsurgery.