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Anastomotic failure with a ring anastomotic coupler due to disengagement of its rings

Dear Editor, Microvascular anastomosis is a crucial aspect of free flap reconstruction, as risk for flap failure relies heavily on its success. Intravascular thrombosis at the site of anastomosis is the most commonly encountered complication at this site, and although infrequent, may have disastrous outcomes when it occurs. In terms of the technique for performing a microvascular anastomosis, suturing is the more traditionally performed technique, however, other techniques include fibrin glue, vascular staples, and ring couplers. The use of microvascular anastomotic couplers instead of traditional sutures has been shown to reduce operative time, has comparable or reduced risk for thrombosis and patency and can be performed in areas with limited access. Few clinical studies have addressed potential complications that can occur with this procedure (Institutional Ethical Approval was obtained prospectively, and conforms to the provisions of the Declaration of Helsinki in 1995). Although we have had considerable experience with this device with positive results, we would like to report a complication with the use of these devices that may offer some cautionary steps for future use. During the course of a bilateral breast reconstruction using deep inferior epigastric artery perforator free flaps, anastomosis of each deep inferior epigastric vein to an internal mammary vein was planned with the Unilink ring anastomotic coupler (Microvascular Anastomotic Coupling System, Synovis Micro Companies Alliance, St. Paul, MN), and traditional interrupted suturing was used for arterial anastomosis. All the anastomoses were completed successfully with established flow. During insetting of the flap, it was noted that there was a sudden and rapid increase in bleeding around one flap, and re-exploration of the pedicles was undertaken. It was found that a coupled venous anastomosis had completely disengaged, with separation of each of the eight pins that were engaged around the ring. It was decided that reanastomosis with the same rings would be appropriate, and the same coupler was easily readjoined. Despite this, blood flow across the anastomosis was not achieved. The coupled anastomosis was excised (see Fig. 1), and a new anastomotic coupler was used successfully and without complication. The excised coupler was actually completely patent, and the cause for lack of pedicle flow after reanastomosis with the first coupler was unclear. One possibility was that the multiple attempts at coupled anastomosis might have affected the coupler itself or the vessel. The decision to excise the coupler and the vessel ends being anastomosed aimed to address both of these possibilities. This is a rare complication, and in our experience with more than 1,000 uses of the anastomotic coupler, we have not had a complication from their use. The literature similarly supports a low complication rate with these devices. An avulsion complication has been described by Nishimoto et al., where a tear in the vessel wall occurred after completion of the microvascular anastomosis. However, this avulsion did not occur at the original anastomotic site and coupler rings remained intact. Jandali et al. described the risk of pin disengagement and avulsion of anastomosis postoperatively if coupler rings were not engaged using forcep reinforcement. Other reported complications include vessel wall tearing and *Correspondence to: Warren M Rozen, M.B.B.S., Department of Plastic and Reconstructive Surgery, Dandenong Hospital, Southern Health, Dandenong, Victoria, Australia. E-mail: warrenrozen@hotmail.com