The effect of preoperative distal venous arterialization on flap survival in a cranial pedicled transverse rectus abdominis muscle-skin flap in the rat

The ischemic complications of the pedicled transverse rectus abdominis myocutaneous (TRAM) flap are the most significant factors that limit the utilization of this flap. This ischemia has both arterial and venous components; however, the insufficiency in venous outflow that is caused by the vascular anatomy of the flap is more prominent. Several techniques were defined in order to decrease the ischemic complications and to increase the flap survival. In fact, delay procedures, arterial and venous supercharge technqiues, turbocharge technique, double pedicled TRAM flap and prophylactic venous cannulation were among these techniques. The aim of this study was the evaluation of the preoperative distal arteriovenous arterialization technique for the pedicled TRAM flap in order to increase the survival of the flap. To our knowledge, this experimental technique was not performed before. Three experimental groups were formed in this study. Cranially pedicled TRAM flap was performed in Group 1. The contrlateral superficial inferior epigastric vein (SIEV) was left intact as a venous supercharge model and the cranially pedicled TRAM flap was elevated in Group 2. In Group 3, the femoral artery and vein were anastomosed as a loop at the contrlateral side of the pedicle of the TRAM flap. In fact, the anastomosis was ligated and the cranially pedicled TRAM flap was elevated in the same fashion at the postoperative third day. The preoperative distal venous arterialization model was formed with this technique. Infrared aided indocyanine green (ICG) angiography was performed in two rats from each group at the first postoperative day of the flap surgery. All rats were sacrificed at the seventh postoperative day and the flap survival rates were calculated. Tissue samples were obtained for histologic evaluation. According to the results of the ICG angiographies, the venous supercharge and the preoperative distal venous arterialization increased the venous outflow of the flap. However, this result may be caused by different drainage pathways and the preoperative distal venous arterialization may increase both the arterial flow and the perfusion of the flap. Both venous supercharge procedure and the preoperative distal venous arterialization procedure increased the flap survival rates and the related analyses were statistically significant. However, these procedures were not superior to each other. The vascular density and the mean vascular diameter were evaluated histologically. Both venous supercharge procedure and the preoperative distal venous arterialization procedure increased the vascular density significantly; however, no statistically significant difference was found between the two techniques. Mean vascular diameters were not significantly different between the groups. The preoperative distal venous arterialization procedure that was performed three days before the cranially pedicled TRAM flap in rats increased the flap survival as much as the venous supercharge procedure. This effect may be caused by the increase in the reverse venous outflow. In fact, it may be caused by the dilatation of the "choke" anastomoses, the increase in angiogenesis and the changes in the venous vascular supply. However, the prominent cause was not found. Theoretically, the preoperative distal venous arterialization procedure may be utilized for increasing the survival in pedicled TRAM flaps of humans. However, the anatomy of the pedicled TRAM flaps in rats and humans are not identical and more experimental and clinical studies are required in order to support our hypothesis.