The Effect of Postconditioning on the Muscle Flap Survival After Ischemia-Reperfusion Injury in Rats

BACKGROUND: Timely recognition of vascular compromise of free flaps is crucial to salvaging failing flaps due to the vulnerability of muscle tissues to ischemia. The concept of postconditioning (post-con) that has been introduced as an “after injury" strategy may be beneficial to salvage the failing muscle flaps. We aim to investigate the effect of post-con on the muscle flap survival after ischemia-reperfusion (I/R) injury in rats. MATERIALS AND METHODS: The gracilis muscle flap model was used and a complete 4 hr of ischemia was generated by occlusion of the pedicle of dissected flap. The post-con procedure was started at the end of ischemia with six cycles of 15 s of reperfusion, followed by 15 s of complete reocclusion prior to the unlimited reperfusion. Muscle edema, malondialdehyde (MDA) level, muscle viability, and different time intervals (0, 3, 6, 18 hr) of gene expression of VEGF post-perfusion were assessed. RESULTS: Significant difference in muscle viability was noted between the post-con group and the control group (4 hr of ischemia followed by full reperfusion without intervention) in spite of being noncomparable with the sham group (no ischemic exposure) 3 days postoperatively. Statistically decreased muscle edema and MDA level were observed in the post-con group compared with the control group. Histological study also showed that attenuated inflammatory reaction was observed in the post-con group compared with the control group. A relatively higher level of VEGF since 3-hr post-reperfusion in the post-con group compared with the control and sham groups was recorded. CONCLUSIONS: Our results indicate that post-con procedure effectively reduces I/R injury and improves the survival of muscle flaps after ischemia. The consistent expression of VEGF in a high level may play an important role in the physiological effects of post-con.