Development of a TRAM flap model in the rat and study of vascular dominance

To investigate the suitability of the rat TRAM flap model for human TRAM flap research, we designed four different TRAM flaps with 10 x 3 cm rectangular skin paddles in rats: type 1 (n = 6), superior TRAM flap with unilateral superior rectus muscle pedicle; type 2 (n = 6), superior TRAM flap with unilateral inferior rectus muscle pedicle; type 3 (n = 6), inferior TRAM flap with unilateral superior rectus muscle pedicle; and type 4 (n = 6), inferior TRAM flap with unilateral inferior rectus muscle pedicle. We elevated and sutured back the TRAM flaps and measured the survival skin paddle areas. Our study demonstrated that in the rat TRAM flap model, the superior deep epigastric vessels are a more important source of vascularity for the skin paddle than the inferior deep epigastric vessels. A 5-cm lateral extension from the midvertical line was enough to cause some distal necrosis in every flap. A cephalically placed, inferiorly pedicled rat TRAM flap (type 2) has the smallest area of skin paddle survival; we concluded, therefore, that this flap placement is the most suitable for TRAM flap research.