AUGMENTATION OF TRANSMIDLINE SKIN PERFUSION AND VIABILITY IN TRANSVERSE RECTUS-ABDOMINIS MYOCUTANEOUS (TRAM) FLAPS IN THE PIG

The aim of this experiment was to design a clinically relevant TRAM flap in the pig and to use this flap model to study the effectiveness of preoperative ligation of the dominant vascular pedicle in augmentation of muscle and skin capillary blood flow and skin viability in the TRAM flap. This TRAM flap model was based on the deep inferior epigastric vascular pedicle, with the center of the transverse skin paddle attached to the underlying rectus abdominis muscle at the superior end of the muscle and extending bilaterally from its attached muscle. The transverse skin paddle (8 x 30 cm) included a contralateral and ipsilateral random portion of skin. This flap model was based on the deep inferior epigastric rather than the superior epigastric vascular pedicle because the deep inferior epigastric vascular pedicle is the smaller of the two in the pig and augmentation of its blood supply by ligation of the dominant superior epigastric vascular pedicle resembles more closely the clinical situation. It was observed that ligation of the dominant superior epigastric vascular pedicle 14 days prior to raising the TRAM flap significantly (p < 0.05; n = 5) increased the total muscle and skin capillary blood flow and skin viability in the transverse skin paddle compared with the sham-operated control (n = 5). More important, the skin perfusion (0.86 +/- 0.02 ml/min) and viability (22 +/- 3 cm2) across the midline in the contralateral random portion of the treatment skin paddle were significantly (p < 0.05) higher than the skin perfusion (0.15 +/- 0.08 ml/min) and viability (5 +/- 2 cm2) in the contralateral random portion of the control skin paddle. It is concluded that ligation of the dominant vascular pedicle prior to raising the TRAM flap is effective in augmenting skin perfusion and viability in the TRAM flap, and the mechanism is discussed.