Comparison of effective use of implanted vascular pedicles for skin flap prefabrication: an experimental study.

Thin, large, well-vascularized, and axial-pattern flaps are often desired in the clinical practice of defect reconstruction to maximize esthetic and functional results. Flap prefabrication based on the neovascularization development following vascular pedicle implantation allows surgeons to create such flaps as required. Using different types of implanted vascular pedicles, the aim of the study was to identify the most effective and suitable types of pedicles for clinical use. Five models of implanted vascular pedicles in Chinchilla Bastard rabbits were investigated as follows: model 1, arteriovenous (AV) pedicle with end ligation (minimal blood flow in the implanted vascular pedicle); model 2, AV pedicle with end anastomosis (new shunt formation between vein and artery stump for creating maximal blood flow in the implanted vascular pedicle); model 3, purely isolated arterialized venous loop; model 4, purely isolated arterial loop; model 5, AV pedicle with end anastomosis (similar to model 2) combined with flap expansion. These different types of vascular pedicles were implanted into a random-pattern abdominal skin flap as large as 8 x 15 cm. Neovascularization in the various prefabricated flaps was evaluated macroscopically, scintigraphically, microangiographically, and histologically. A total of 150 prefabricated flaps were investigated and randomly assigned to 5 models with 30 flaps each. Each model contained 5 groups of 6 flaps corresponding to the various retention times of 4, 8, 12, 16, and 20 days after vascular pedicle implantation. Six flaps were also designated to the control group. Neovascularization was best in model 5, followed by comparable results for models 2, 3, and 4, with the worst results found in model 1, especially for the time intervals of 8, 12, and 16 days. Twenty days remains the minimal length of time required for matured neovascularization in all models (P < 0.05). Models 2 and 3 both appear to be particularly promising for clinical application.

Influence of silicone sheets on microvascular anastomosis.

The use of silicone products combined with free flap transfer is well established in reconstructive surgery. We determined the risk of thrombosis as a result of direct contact between the silicone sheet and the point of microanastomosis. We performed microvascular surgery in 24 female Chinchilla Bastard rabbits weighing 3500 to 4000 g using two groups: Group 1 (n = 12), microanastomosis directly in contact with silicone sheets; and Group 2 (n = 12), microanastomosis protected by a 2 x 3 x 1-cm muscle cuff before being placed in contact with the silicone. We assessed flow-through of the microanastomosis by selective microangiography and histology at 1 and 3 weeks. All microanastomoses in Group 1 were occluded by postoperative thromboses, whereas all microanastomoses in Group 2 had adequate flow-through. Histologic analysis revealed thromboses in Group 1 formed from collagenous bundles of fiber securely attached to the intraluminal wall of the vessel. Three weeks after the procedure, these thromboses were canalized by varying small vessels. In Group 2, a slight luminal stenosis with evidence of infiltration of inflammatory cells at the microanastomosis line was observed histologically in all cases. Prefabricated flaps using silicone sheets and muscular cuffs placed around the anastomoses appear to reduce the risk of thrombosis and enhance neovascularization.

Study of the neovascularisation of prefabrication of flaps using a silicone sheet and an isolated arterial pedicle: experimental study in rabbits.

Use of an isolated artery as an implanted pedicle in prefabricated flaps has rarely been reported either clinically or experimentally. In Chinchilla Bastard rabbits (n = 36), we dissected an isolated arterial pedicle from the femoral and saphenous artery, anastomosed it end-to-end to the femoral vein at the inguinal ligament and created an isolated arterial loop pedicle. This was implanted and fixed with polyglactin 9/0 under a random-pattern vascularised abdominal fasciocutaneous flap. The neovascularisation in the prefabricated flaps was evaluated macroscopically, by blood analysis, selective microangiography, and histology. The results showed a progressive degree of neovascularisation that corresponded to the increasing length of time that the pedicle was implanted in the flaps. Twenty days after prefabrication, the abdominal fasciocutaneous flap was readily perfused by the blood supply from the arterial pedicle. The capacity of the vessels in this group as seen on angiograms had increased to 258 vessels (108%) compared with the control group (239 vessels, 100%).

Neovascularization in prefabricated flaps using a tissue expander and an implanted arteriovenous pedicle.

Creating prefabricated flaps using tissue expanders in combination with the implantation of maximal blood flow vascular pedicles into suitable tissue areas represents a new tendency in the reconstruction of large skin defects. In 42 Chinchilla Bastard female rabbits weighing 3,700-4,600 g, skeletonized arteriovenous pedicles with maximal blood flow, dissected from the femoral and saphena magna bundles, were implanted underneath abdominal fasciocutaneous flaps. Oval tissue expanders of 250 ml were placed and fixed on the abdominal wall to expand these prefabricated flaps. The evaluation parameters were macroscopic observation, blood analysis, selective microangiography, histology, and scintigraphy. The study results showed that neovascularization in expanded prefabricated flaps was established from newly formed vessels generated from the implanted pedicles and their vascular connections with the originally available vasculature in the flap. After 20 days of prefabrication, the entirety of the expanded prefabricated flaps was perfused by blood flow supplied from newly implanted arteriovenous pedicles. The study indicated that an expanded prefabricated flap can be successfully created by the simultaneous implantation of a maximal blood flow pedicle in combination with flap expansion.