Vascular filling and protein extravasation in three varieties of vascularized venous nerve grafts

The purpose of this study was to compare the microcirculation perfusion and plasma-protein extravasation in varieties of venous nerve grafts. Venous nerve grafts were created from the left median nerve and brachial vein of the rabbit. The vein was interposed between (a) brachial artery to brachial artery (AVA); or (b) brachial artery to proximal cephalic vein (AVV); or (c) brachial vein to brachial vein (VVV). A standard, vascularized, nerve graft was created in the opposite limb, to serve as a control, and the untouched sciatic nerve served as a second control. Microcirculation perfusion and permeability of endoneurial vessels were evaluated using intravenously-injected albumin labelled with Evans blue dye (EBA) as a fluorescent tracer within 1 hr after surgery. Six hours after surgery, the nerves were removed and evaluated for tracer content and distribution. Extravasation of EBA was extensive in both AVA and AVV forms of the venous nerve graft, suggesting good perfusion but showing significant protein leakage and edema. VVV, on the other hand, had only slight extravasation, comparable to untouched sciatic nerves. Although the number of vessels filled with blood in the VVV was 69 percent of the vascularized nerve graft, the lack of marked extravasation may make it the venous nerve graft of choice.