Purpose
The DIEP flap is a common method for breast reconstruction. Traditionally, zones III and IV are often discarded due to perfusion concerns. In Asian patients with low BMI and smaller abdominal size, the entire flap is used to ensure sufficient volume and both perforators are anastomosed for better tissue perfusion. Previously, retrograde and antegrade internal mammary artery (IMA) were common for recipient vessels. Due to lateral approaches and short incisions, robotic-assisted mastectomy's development necessitates a shift to using lateral thoracodorsal and thoracic arteries. This study compares the reliability of using thoracodorsal and lateral thoracic arteries versus the traditional IMA combination for breast reconstruction.

Materials and Methods
Between July 2019 and November 2022, patients who underwent bi-pedicled DIEP flap reconstruction by the senior surgeon (J.J.H.) after mastectomy. Patient related parameters were recorded. We compared the utilization rates, surgery duration, vascular complications, and postoperative fat necrosis rates of thoracodorsal artery and lateral thoracic artery-based DIEP flap reconstructions with traditional mastectomy excision and IMA-based reconstructions.

Results
A total of 36 patients participated in the study, with 17 patients in the IMA group and 19 patients in the TDA-LDA group. Most patients in the TDA-LDA group underwent robotic mastectomy, while the IMA group underwent a traditional open approach. The mastectomy specimen weight was similar in both groups (365 g for the IMA group and 349 g for the TDA-LDA group, p=0.39). The final flap use rate and ischemic time were also similar in both groups.
There were no vascular issues in the IMA group, but two cases in the TDA-LDA group experienced venous thrombosis and required emergent exploration surgery. In the IMA group, five patients required one revision surgery each, including fat injection, liposuction, removal of flap monitor skin, and flap repositioning. Two patients required secondary revisions. In the TDA-LDA group, a total of five patients required one revision surgery each, which were similar to those in the IMA group. The revision rate and asymmetry rate were similar in two groups.

Conclusion
This study found that the combination of thoracodorsal artery and lateral thoracic artery as the recipient vessel for bipedicled DIEP flap is comparable to the traditional IMA-based breast reconstruction. Surgeons can use TDA-LTA based reconstruction as an alternative method in patients who undergo lateral approach and short incision difficult for IMA-based anastomosis.