Modification in flap design of the epigastric artery flap in rats--a new experimental flap model.

The standard rat epigastric artery flap has been a very reliable model for flap research. The purpose of this study was to describe a modified design of this flap that included only the medial branch of the epigastric artery. Axial-pattern epigastric island skin flaps, measuring 8 x 8 cm, were raised in two groups of Sprague-Dawley male rats. In group A (N = 20) the vascular pedicle consisted of the main trunk of the epigastric vessel and both medial and lateral branches. In group B (N = 20) the flap was based solely on the medial branch of the epigastric artery, excluding the large lateral branch. The flaps were elevated and then sutured back to their beds. Flap survival was studied and the amount of viable skin in both groups was compared 1 week later. The rats were photographed using a digital camera and the images were analyzed using imaging software. The mean percentage surviving flap area in group A was 86.24% and in group B it was 69.72%, which is statistically significant (p < 0.001). We believe that this flap model, with its new modified design that includes a larger flap and inclusion of only the medial branch, will broaden its application to microsurgery. The main advantage of this flap over the conventional epigastric flap is that in this model it is possible to achieve predictable and consistent necrosis in the random extension of the flap.