THE EFFECT OF THE DELAY PHENOMENON ON THE VASCULARITY OF RABBIT RECTUS-ABDOMINIS MUSCLES

The transverse rectus abdominis muscle (TRAM) flap has become the ''go ld standard'' for autogenous breast tissue reconstruction. Complicatio ns are reported in 10 to 40 percent of patients undergoing this proced ure, and many are related to soft-tissue necrosis secondary to ischemi a. Various methods have been proposed to improve TRAM flap survival, i ncluding surgical delay of the flap. The beneficial effects of the del ay phenomenon have been well established in laboratory studies and cli nical evaluations. Many investigators agree that the delay phenomenon will enhance arterial inflow and venous outflow from the TRAM flap. No study has quantified the changes seen in the rectus abdominis muscle following a delay procedure. In this prospective, controlled, and blin ded experiment, we evaluate the effect of a unilateral superficial inf erior epigastric and deep inferior epigastric artery and vein ligation on the vascularity of the rectus abdominis muscles in rabbits. Thirty -eight rabbits underwent a left superficial inferior epigastric and de ep inferior epigastric pedicle ligation as a delay procedure. The rect us abdominis muscle vasculature was then evaluated by lead oxide micro angiography at 0, 5, 10, 15, 21, and 27 days following the delay proce dure. Magnification (x2) was used to count the number of vessels at th e periphery of the deep inferior epigastric artery angiosomes in the m icroangiograms. An increase in the number of vessels from day 0 to day 27 was seen on both the ligated and nonligated sides in all the follo wing: the number of large (>0.5 mm) ''choke'' vessels and total number of vessels (all sizes) crossing the abdominal wall midline and the to tal number of vessels (all sizes) at the medial, superior, and lateral aspects of the right and left deep inferior epigastric artery angioso mes, A statistically significant increase in these vessels was not see n until day 21. The effect of the delay phenomenon was significantly g reater on the ligated side compared with the nonligated side. The area s of the rectus abdominis muscles that were relatively more ischemic f ollowing left deep inferior epigastric pedicle ligation (medial aspect of the left deep inferior epigastric artery angiosome) showed greater increases invascularity with the delay procedure than did areas of le sser ischemia (lateral aspect of the right deep inferior epigastric ar tery angiosome).