Delay Phenomenon by Botulinum Toxin A in Transverse Rectus Abdominis Myocutaneous (TRAM) Flap of Rat

Lee, Joo Chul; Park, Eun Soo; Kim, Yong Bae

Abstract

Currently, delay procedures remain a reliable method of maximizing flap survival but the necessity of additional procedures is a persistent disadvantage. Botulinum toxin A (BTXA) is considered to exert the most powerful neuromuscular blockade. In this study, BTXA is used to demonstrate the usefulness of a chemical delay technique. Thirty rats were subdivided into three groups of 10. In the group 1(control), no procedure was performed before the transverse rectus abdominis musculocutaneous (TRAM) flap elevation. In the group 2 (surgical delay), TRAM flaps were delayed surgically one week before formal elevation. And, in the group 3 (BTXA delay) rats, 4U BTXA was injected into the under surface of TRAM flaps two weeks before surgical elevation. The TRAM flaps were designed in rectangular shape, on the rat abdomen. On the seventh day after operation, the results were evaluated and compared in terms of flap survival area, vessel counts and vascular endothelial growth factor (VEGF) expression. The mean percentages of the flap survival area in group 2 (71.76+/-.86%) and group 3 (73.92+/-.70%) were significantly higher than those in group 1 (34.60+/-.14%) (p<0.05). The vessel counts of group 2 (13.90+/-.18) and group 3 (15.40+/-.88%) were significantly higher than those of group 1 (5.10+/-.20) (p<0.05). The VEGF expression is increased in two experimental groups than in the control group. In conclusion, the injection of BTXA could increase flap survival area in rat TRAM flap model, as likely as surgical delay. These results are thought to be made due to the effect of chemodenervation and secondary inflammation.