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.