The Shield Protection Technique for Microvascular Anastomoses

Abstract

Sir: The keys to patent microvascular anastomoses are the technical competence of the operating surgeon and his or her assistant.1 In anastomosis of very small vessels, such as in perforator flaps, additional techniques to increase the procedure's reliability are desirable.2 Many techniques to improve the overall success rates of microvascular procedures in free flap surgery are available but are based mainly on the application of tubes or stents that require an additional incision for removal of the tube, causing extravascular damage and the additional risk of thrombosis. We evaluated a microsurgical technique based on a 0.1-mm piece of sterilized tinfoil with a convex and circular form (in the shape of a shield) with an 8-0 or 9-0 microsuture placed in the middle for ease of handling while performing anastomoses. The shield was inserted carefully into the vessel lumen after completion of the first two interrupted sutures (Figs. 1 and 2, above, left). The vessel was turned and the posterior wall sutured completely (Fig. 2, above, right). The vessel was again turned and the gap in the anterior wall was closed (Fig. 2, center, left). Finally, the shield was removed through the open sutures, which were then tied (Fig. 2, center, right and below).Fig. 1.: Insertion of the shield into the lumen of the vessel. (Above) Insertion into the inferior cava vein of the rat. (Below) Insertion into the aorta.Fig. 2.: Anastomosis using the shield protection technique in the inferior cava vein of the rat. (Above, left) First, two stitches were performed at an angle of 150 to 180 degrees in the vessel. The shield was inserted between the first two stitches. (Above, right) The inserted shield was then used to avoid suturing the back wall and to dilate the vein. The concavity of the shield allows an overview of the back walls of the vessel. (Center, left) Starting the front wall of the vein, placing sutures, and leaving. (Center, right) The open guide sutures were used to allow removal of the inserted shield. The shield was easily removed from the lumen of the vessel. (Below, left) Completion of the venous anastomosis after the last interrupted sutures were completed. (Below, right) Both vessels, the aorta and the inferior vena cava, were completed using the shield protection technique.The described technique was evaluated in a total of 249 anastomoses in rats, 133 arterial and 116 venous. In 73 arterial anastomoses (54.89 percent) and in 58 venous anastomoses (50 percent), the shield protection technique was used. A total of 25 complications (6.3 percent) were noted in arteries, whereas 54 complications occurred in veins (15.5 percent). There was a significant difference in the rate of complications between arteries and veins (p < 0.0001). The rate of stenoses caused by suturing the back wall was significantly lower by using the shield protection technique in both arteries (p = 0.02) and veins (p < 0.0001). No difference was noted between the time of anastomosis between the control group and the shield protection technique in arteries (p = 0.08) or in veins (p = 0.71). The shield protection technique has been shown to be effective for both arterial and venous anastomoses. There seems to be little reason why this cannot be transferred to clinical cases where small-vessel anastomosis may be particularly difficult. It is well recognized that venous anastomoses are more challenging to perform than arterial anastomoses and are associated with up to threefold higher rates of complications, something we found in the evaluation comparing the rate of complications between arterial and venous anastomoses.3 Although successful free-flap transfer and replantation surgery requires more than simply the microvascular anastomoses, it is considered to be the chief culprit behind vascular compromise and is worthy of special attention.4,5 We feel that the inserted shield reduced the overall rate of complications in both groups because of improved visual control of the gap between the vessel edges and dilatation of the vessel, and because this procedure makes it more difficult to accidentally pick up the posterior wall with the anterior wall. The most important factor associated with the shield technique might be that less experienced microsurgeons can more easily visualize suturing of the vessels, especially in venous anastomosis. DISCLOSURE The authors have no financial interest to declare in relation to the content of this article. No outside funding was required. Thomas Mücke, M.D. Lucas Ritschl Department of Oral and Maxillofacial Surgery Technische Universität München Klinikum Rechts der Isar München, Germany David A. Mitchell, F.D.S., F.R.C.S. Anastasios Kanatas, M.F.D.S., M.R.C.S., Ph.D. Department of Oral and Maxillofacial Surgery Oral and Facial Specialties Department Mid Yorkshire Hospitals NHS Trust West Yorks, United Kingdom Klaus-Dietrich Wolff, Ph.D., M.D., D.D.S. Department of Oral and Maxillofacial Surgery Technische Universität München Klinikum Rechts der Isar München, Germany