Comparison of flow rates in the antegrade and retrograde internal mammary vein for free flap breast reconstruction

Background:The internal mammary vein (IMV) is commonly used as a recipient vessel in the direction of antegrade flow for free flap breast reconstruction. Recent reports show that the distal IMV is valveless and can accommodate retrograde flow. We sought to quantify blood velocity and flow through the distal IMV following free tissue transfer. Methods:Ten free flap breast reconstructions were performed. The larger vena comitans of the DIEA was anastomosed to the antegrade internal mammary vein (AIMV). The smaller vena comitans was anastomosed to the retrograde internal mammary vein (RIMV) in five free flaps, and the superficial inferior epigastric vein (SIEV) was anastomosed to the RIMV in five other free flaps.Results:The mean diameter of the larger vena comitans (3.4 ± 0.5 mm) was significantly greater than that of the smaller vena comitans (2.4 ± 0.4 mm; P = 0.003). Mean velocity in the AIMV after anastomosis was 10.13 ± 5.21 mm/s compared with 7.01 ± 2.93 mm/s in the RIMV (P = 0.12). Mean blood flow in the AIMV and the RIMV was 81.33 ± 52.81 mm ³/s and 57.84 ± 45.11 mm ³/s, respectively (P = 0.30). Mean blood flow in the RIMV was not significantly affected by whether the donor vein was the smaller vena comitans (70.78 ± 61.43 mm ³/s) or the SIEV (44.90 ± 19.70 mm ³/s; P = 0.40).Conclusions:Blood flow in the RIMV was less but not significantly different from flow in the AIMV. The difference is likely due to the smaller-sized donor vein anastomosed to the RIMV. The RIMV is a reliable, useful option when the antegrade vein is not available, or when a second recipient vein is needed.