The influence of vein ligation on the survival of reverse-flow island flaps: an experimental study in rabbits

Abstract

Objective To evaluate the effect of ligating venae commutantes in the pedicle on the survival of reverse-flow island flaps. Methods Ten New Zealand rabbits were used. Reverse flow island flap based on the saphenous artery and vein was created on both hind limbs,with a total of 20 flaps. The size of the flap was 3 cm×3 cm with a 4 cm long vascular pedicle containing 1 cm strip of connective tissue. These flaps were randomly divided into 2 groups of 10 flaps each. In group Ⅰ,the vascular pedicle (1 saphenous artery and 2 venae commutantes) was raised and its sheath was not disturbed,maintaining communicating and collateral branches intact. In group Ⅱ,the 2 venae commutantes were ligated with 8-0 suture at both ends of the pedicle under 10X microscope and the connective tissue was maintained intact. The color and congestion of flaps were observed daily. Flap survival rate was measured after one week. The vascular pedicle was harvested and observed histologically. Results The flaps began to appear obviously swelling after blood oozing stopped. The extent of swelling was more severe in group Ⅱ than in group Ⅰ. Flap survival rate of group Ⅰ (92.7±12.1)% was significantly higher than that of group Ⅱ (46.8±38.3)% (t=3.61,P<0.01). Histological examination revealed lots of dilated venules in the vascular pedicle. The amount of dilated venules in group Ⅱ was more than that in group Ⅰ. Lots of thrombi could be seen in the dilated venules in the pedicle of completely or partially necrotic flaps. Conclusion Venous crisis takes place more easily in flaps without venae commutantes,resulting in flap necrosis. The venous thrombosis may be the other important influencing factor for necrosis of reverse-flow flaps. Key words: Island flaps; Veins; Animal experimentation