Rectus Abdominis Flap

Abstract

In 1974, an upper transverse abdominal flap for breast reconstruction was described by Tai and coworkers, who gave the first description of this myocutaneous flap based on the deep superior epigastric vessels and their perforating vessels through the rectus muscle [515]. Another early report of flap raising procedures at the anterior abdominal wall including parts of the rectus muscle was given by Brown et al., who described the myocutaneous rectus abdominis flap used as a pedicled flap for covering an extensive ipsilateral defect of the arm after a shotgun injury [61]. Two years later, Drever described a superiorly based rectus abdominis flap with a vertical skin island which he used as a pedicled flap to treat a scar contracture at the chest. In this publication, he also proposed using this flap for many reconstructive purposes, especially in the head and neck region, as a free flap. Like Brown and Tai, he recognized the dependence of skin perfusion from perforators through the rectus muscle, and they pointed out that long transverse skin island of the abdominal skin could be based on these perforators. In the years to follow, the superiorly based rectus abdominis flap, nourished via the internal mammary vessels, was primarily taken with a horizontal skin paddle and used for breast reconstruction [360, 372]. These reports were followed by the first microvascular transfer with anastomoses to the deep inferior epigastric vessels performed by Pennington and Pelly [406]. In their report, they present two free flaps based on the deep inferior epigastric artery and highlight the long, wide lumen pedicle and the ease of flap raising. Nevertheless, the authors also mentioned the need to reconstruct the anterior rectus sheath and the possible bulk of the flap as disadvantages. Before that, free flaps from the lower abdominal wall have already been raised, but using the superficial epigastric vascular system. Antia and Buch [15] are credited to be the first having successfully performed a microsurgical free-flap transfer by transferring a dermis-fat flap from the lower abdomen for facial contour augmentation, thereby using the superficial inferior epigastric vessels and including a cuff of the femoral artery for safe anastomosis [15]. A few years later, Taylor and Daniel [529] gave an anatomic description on this superficial epigastric vascular system, which, compared to the deep epigastric vessel, was highly variable and consisted of small caliber vessels. Both, the deep and the superficial system, have partially overlapping vascular territories and are connected by choke arteries. Of these, the paraumbilical perforators originating from the deep system are the strongest and therefore contribute most to skin perfusion of the anterior abdominal wall [50, 59, 160]. Very soon after the first reports, a number of different flap designs and orientations of the skin paddle were described, all confirming the unique usefulness of myocutaneous flaps from the deep inferior vascular system. Intraoperatively, Harris and coworkers studied the blood flow of the deep and superficial epigastric vessels and showed that most vascular connections between both systems are concentrated centrally. Nevertheless, they emphasized elevating the entire muscle to preserve all vascular connections to the skin [201]. The main use of this conventional myocutaneous flap which includes significant parts of the rectus abdominis muscle is in breast reconstruction, but it is also used for other regions of the body like the skull base, face, head and neck, trunk, and extremities [63, 125, 129, 203, 364, 528, 549, 551, 607]. Due to the dense anastomotic network between the deep inferior and superior epigastric vessels, which was extensively investigated using cadaver dissections and angiograms [360, 372], the perfusion of the flap is also reliable via the internal mammary vessels, making the pedicled transfer to defects of the breast or thorax possible. Undoubtedly, the most common design when using the rectus abdominis flap is the TRAM flap with a horizontal orientation, using the deep inferior epigastric vessels as the pedicle and incorporating the skin from the entire lower abdomen, but many other variations of the skin paddle have been described, such as the standard longitudinal skin paddle positioned over the entire length of the rectus muscle, the oblique design, or the raising of the muscle without any skin. It has been estimated that the deep inferior epigastric artery may provide the largest territory of vascularized skin available in the human body [59]. The skin territory can be extended even more using the “supercharging” technique, if the most distal flap zone is additionally anastomosed to an artery or vein from the superficial system, thereby enhancing the blood supply to the flap provided by the deep inferior epigastric vessels [517].