Kinking of pedicle vessels and its effect on blood flow and patency in free flaps: An experimental study in rats

Aim: Head rotation may significantly alter the initial position of the vascular pedicle of free flaps in reconstructive surgery of the oral cavity. This may lead to kinking of venous and/or arterial vessels. In spite of some precautions as rotating the head contralaterally for the first few days postoperatively or shortening the pedicle, the problem is still not well understood and remains unsolved. In order to understand the matter better, an experimental study was devised to create intentional kinking of the pedicle of a free-flap. Material and Methods: Twenty CD-outbred rats were subdivided into two groups. All rats were operated on by harvesting a muscular free flap from the right-hind limb. Microvascular anastomoses were performed on the femoral artery and vein. In group A (kinking group), the free flap was twisted and placed within the abdomen just under the spleen; by this way the pedicle was rotated by 180° creating a kink. In group B (no kinking, the control-group), the same microvascular flap was performed leaving the limb in the normal anatomical position. Rats were sacrificed 48 h postoperatively and patency of the vessels was established both clinically (Acland test) and microscopically. Results: Only one vein of a rat of group B had preanastomotic thrombosis, so no statistically significant difference was found among the two groups. Conclusions: From this experimental protocol a 180° narrow kinking with a curvature rather than acute angulation of the pedicle does not influence the survival rate of the free flap negatively. This, however, does not refute the possibility that a more acute angular kinking may reduce survival rates of microvascular flaps.