Pre-arterialisation of the arterialised venous flap: an experimental study in the rat.

Arteriovenous fistulae cause haemodynamic and morphological changes to the local venous channels. We have used the concept of preformed arteriovenous fistulae to study the viability improvement of arterialised venous flaps. Five groups of flaps were created using the abdominal skin of the Wistar rat (n= 10 in each group) with a silastic sheet implanted underneath. Group 1 (control) contained a flap without a vascular supply, group 2 (venous perfusion flap) contained a single pedicled skeletonised vein and a draining vein, and group 3 (arterialised venous flap) contained an arteriovenous shunt proximal to the single pedicled skeletonised vein and a draining vein; in group 4 (7 day pre-arterialised flap) the arteriovenous shunt was performed 7 days before the flap was raised in the same procedure as group 3, and in group 5 (14 day pre-arterialised flap) the arteriovenous shunt was performed 14 days before the flap was raised. The surviving surface areas of the flaps in each group, assessed 7 days after raising, were 0%, 22.21%, 54.32%, 62.21% and 97.47%, respectively. There was a statistically significant difference in survival between venous perfusion flaps and arterialised venous flaps (P= 0.05). Only the 14 day pre-arterialised flaps had a statistically significantly larger area of survival than arterialised venous flaps (P= 0.05). Microangioarchitecture of the pre-arterialised group, studied by the microvascular corrosion-cast technique combined with scanning electron microscopy and transmission electron microscopy, revealed dilatation of veins, numerous small neo-vessels and a decrease in or total absence of functioning valves. We conclude that 14-day pre-arterialisation in the rat model improved the survival of arterialised venous flaps by increasing collateral pathways for arterialised blood flow through the flap.