Prefabrication of large fasciocutaneous flaps using an isolated arterialised vein as implanted vascular pedicle

Flap prefabrication represents a new trend in microsurgical tissue transfer. Based on the concept of neovascularisation, in Chinchilla Bastard rabbits (n=40), an isolated venous pedicle dissected from the femoral and saphena magna vein was arterialised by end-to-end anastomosis to the femoral artery at the inguinal ligament. This arterialised venous loop was implanted beneath a random-pattern vascularised abdominal fasciocutaneous flap as large as 8 x 15 cm(2) to investigate the development of neovascularisation at various evaluating times of 4, 8, 12, 16 and 20 days. To prevent neoangiogenesis from occurring between the underlying vascular bed and abdominal flap, a silicone sheet with the corresponding dimension of 8 cm x 15 cm x 0.25 mm was placed and fixed on the abdominal wall. The flap viability and the neovascularisation process in the prefabricated abdominal skin flaps were evaluated by macroscopic observation, blood analysis, selective microangiography and histology. The experimental results showed that newly formed vessels originating from the implanted isolated venous pedicle were evident on the angiograms 4 days after pedicle implantation. In the 8- and 12-day groups, newly formed vessels became larger and some were connected to the originally available vasculature in the abdominal fasciocutaneous flaps. In the 20-day group, entire flaps were perfused by the blood flow supplied from the newly implanted venous pedicles through newly formed vessels and their vascular connections. This study indicated that large flap prefabrication can be created by implantation of an isolated arterialised venous pedicle into a random-pattern vascularised fasciocutaneous flap. Twenty days appears to be the minimal length of time required after arterialised venous pedicle implantation for the maturation of neovascularisation in the prefabricated flap.