Preliminary arteriovenous fistula for free-flap reconstruction in the diabetic foot.

We present our experience at the American University of Beirut Medical Center with two diabetic patients suffering from large necrotic and infected foot ulcers. Both patients were ambulatory at the time of presentation despite their extensive wounds and were believed to have a useful limb with adequate protective sensation worth saving. Below-knee amputation was prevented in both cases by successful soft-tissue coverage of the ulcers using microvascular composite-tissue transfer a few days after performing a preliminary arteriovenous fistula with a long vein graft loop. The flap vessels were anastomosed end-to-end to the arterial and venous limbs of the divided arteriovenous loop. This reconstructive technique of difficult diabetic wounds of the lower extremity, though in two stages, may be safer than one long procedure in a high-risk patient. It is technically easier than long interpositional vein grafts at the same time as free-flap transfer or microvascular anastomoses with small and diseased vessels. It definitely provides more chance of success as larger vessels are used to supply the flap. It permits distension of the vein graft at normotensive physiologic pressures and allows testing the arterial anastomosis as well as the venous flow before final flap transfer. Above all, it allows extreme freedom in performing tension-free anastomoses away from the infected wound.