Effectiveness of the proximal medial branch in DIEP flaps for breast reconstruction using Hartrampf zone IV.

[BACKGROUND] When performing breast reconstruction using a deep inferior epigastric artery (DIEA) perforator (DIEP) flap, including Hartrampf zone IV, the bipedicled DIEP flap has been argued to be necessary to ensure stable perfusion. However, a proximal medial branch (PMB), which is the most proximal perforator of DIEA, may make it possible to obtain adequate perfusion in a unilateral DIEP flap. This study aimed to clarify the detailed anatomical characteristics of PMB and its potential clinical applications in breast reconstruction.

[METHODS] This retrospective study was conducted on breast reconstruction using the DIEP flap between May 2020 and July 2023. Data on PMB anatomy were collected from preoperative contrast-enhanced computed tomography angiography, and contralateral perfusion of the flap was estimated using intraoperative indocyanine green angiography.

[RESULTS] PMB was present in approximately 85% of the cases, arising near the lateral border of the rectus abdominis, branching caudomedially in more than half of the cases, and perforating 2.3 cm laterally and 8.8 cm caudally, on average, from the umbilicus. The average perfusion area of zones II and IV significantly expanded to 96.5% and 74.2%, respectively, when PMB was included in the DIEP flap, and 9 of 22 cases showed contrast extending to the entire zone IV.

[CONCLUSIONS] The use of the DIEP flap with PMB is a good option for substantial-volume breast reconstruction. When utilizing PMB, it is important to consider its specific anatomy, location of the main perforator, and pedicle length.