The Type 4 DIEA: A Newly Identified Branching Pattern of the Deep Inferior Epigastric Artery

Abstract

Sir: The deep inferior epigastric artery (DIEA) is a reliable vessel used routinely as the basis for DIEA perforator flaps, with anatomical variations infrequent and operative success widespread.1 Although the perforating branches of the DIEA may show significant individual variability in size, location, and course, the DIEA itself has been shown to be ever present as a vascular pedicle and highly dependable.1–3 Despite this consistency, the DIEA exhibits a variable branching pattern as it ascends cranially within the rectus sheath, with this pattern classified by Moon and Taylor in 1988 (Fig. 1) into three patterns: a single trunk (type 1), a bifurcating trunk (type 2), or trifurcating trunk (type 3).4Fig. 1.: Schematic diagrams of the original classification system of the branching patterns of the DIEA by Moon and Taylor. The DIEA is shown as a single, bifurcating, or trifurcating trunk below the umbilicus. The arcuate line is dotted. These schematics present the findings of the original study by Moon and Taylor. (Reproduced from Moon HK, Taylor GI. The vascular anatomy of rectus abdominis musculocutaneous flaps based on the deep superior epigastric system. Plast Reconstr Surg. 1988;82:815–829.)Previous studies assessing this anatomy have been limited by both postmortem analysis and the number of available cadaveric specimens; however, with the widespread use of preoperative imaging before abdominal wall free flaps, particularly with computed tomographic angiography, this anatomy has become routinely visualized in large numbers.5 We describe a unique case in which four major DIEA trunks were identified, suggesting a new addition to the current nomenclature. A 42-year-old woman presented for delayed autologous breast reconstruction following previous mastectomy for breast cancer. She underwent routine preoperative imaging with computed tomographic angiography, using a standardized protocol as reported previously.5 She had a body mass index in the normal range and had not undergone any previous abdominal surgery. Three-dimensional volume-rendered technique reconstructions of the computed tomographic angiograms were performed to demonstrate the DIEA, its branching pattern, and its communications. Multiple images were assessed to confirm major branches. The scan demonstrated bilateral DIEAs originating from the external iliac artery as a single trunk on each side. Although the left side ascended cranially as a single trunk (a type 1 branching pattern), the right side branched into four major branches above the arcuate line (Fig. 2). This finding does not fit the previous classification system by Moon and Taylor, but by extension would be classified as a “type 4” pattern.Fig. 2.: Computed tomographic angiogram, volume-rendered technique reconstruction of the anterior abdominal wall vasculature. The DIEA on the right side is shown to divide into four major trunks (type 4). The left-sided DIEA ascends as a single trunk (type 1).The DIEA is a consistent vessel supplying the lower anterior abdominal wall integument. Originating from the external iliac artery, the artery pierces the transversalis fascia to enter the rectus sheath. After supplying two large branches, a pubic branch that may represent an accessory obturator artery and an early muscular branch to the rectus abdominis, the artery ascends within the rectus sheath to display a variable branching pattern before anastomosing with branches of the deep superior epigastric artery. The Moon and Taylor nomenclature was the first such classification system described. Although this system describes three branching patterns of the DIEA, either a single, bifurcating, or trifurcating trunk,4 the current case highlights a fourth branching pattern. These variations in the branching pattern of the DIEA can have a significant impact on the surgical approach to DIEA perforator flap harvest, with perforators arising from a single branch preferred. Such an approach can spare rectus abdominis muscle damage, preserve vascular supply, and potentially spare motor nerve damage where a medial branch is harvested. DISCLOSURE The authors have no conflicts of interest to disclose. Warren M. Rozen, M.B.B.S., B.Med.Sc., P.G.Dip.Surg.Anat., Ph.D. Mark W. Ashton, M.B.B.S., M.D. Damien Grinsell, M.B.B.S. Jack Brockhoff Reconstructive Plastic Surgery Research Unit Department of Anatomy and Cell Biology University of Melbourne Parkville, Victoria, Australia