New experimental flap model in the rat: free flow-through epigastric flap

This study describes a free flow-through flap model in the rat for use in the evaluation of the physiologic and hemodynamic characteristics of this type of flap in clinical practice. The rat is a preferred animal model because it is inexpensive, readily available, and reliable. There is no free flow-through flap model available for laboratory animals, although this model gained popularity in clinical use recently. Twenty Wistar rats weighing 200-250 g were used in our experiment. In 5 rats, the vascular anatomy of the groin and proximal thigh region was determined by anatomic dissection. The experimental design consisted of two groups. In the experimental group (N = 5), a flow-through epigastric skin flap was harvested based on the femoral artery, preparing both its proximal and distal stumps. The flap was transferred to the contralateral groin, and end-to-end vascular anastomosis was performed between a proximal and distal stump of the femoral arteries of the flap and recipient site. The proximal stump of the femoral vein of the flap was anastomosed to the femoral vein of the recipient site. The control group was divided into two subgroups. In all control group rats (N = 10), the flap was harvested in the same manner, and transferred to the contralateral groin, but standard free-flap procedure with one artery and one vein anastomosis was performed in 5 rats (conventional free-flap subgroup), and anastomosis was not performed between the flap and the recipient site in the remaining 5 rats (graft subgroup). Survival of the flap was evaluated on postoperative day 7 by direct observation, and microangiography was performed to delineate the vascularity of the flow-through flap. The results showed that all flaps survived in the experimental group and the conventional free-flap subgroup of the control group, whereas in the graft subgroup, all flaps underwent total necrosis. The authors conclude that the flow-through epigastric flap for the rat is a simple and reliable model for future physiologic and pharmacologic studies.