PURPOSE: Internal mammary artery and internal mammary vein (IMV) are one of the most widely used recipient vessels for performing the free autologous tissue-based breast reconstruction. In some cases, however, additional vessels may be required to handle multiple flaps for volume addition, to boost a blood flow for supercharging purposes, or to use the other vessels when an anterograde flow of IMV is obstructed. In these situations, the opposite direction of the internal mammary vessel can be used as a retrograde flow.1,2 However, there are doubts and concerns about the safety of using this flow.
METHODS AND MATERIALS: Forty sides of the chest from 20 fresh cadavers with intact thoracic cage and IMV were used for the study. The numbers and location of the IMV valves were checked, and the location of starting vein bifurcation was also confirmed. Infusion of indocyanine green in the retrograde direction was followed by fluorescent angiography to confirm the direction of flow. Additional flow using saline infusion was checked to verify the flow in the opposite vein over the sternum.
RESULTS: Twenty-eight valves were identified in 40 sides of the chest, and an average of 0.7 valves per each side of the chest was identified. Twenty-three (82.1%) valves out of 28 were located above the second intercostal space (ICS). The bifurcation the IMV most commonly occurred at third ICS (18/41, 43.9%), followed by second (9/41, 22%), fourth (8/41, 19.5%), and first (4/41, 9.8%) ICS. The average number of communicating veins between the 2 veins after branching was 1.76 numbers. Indocyanine green fluorescent angiography proved that the retrograde flow was shown to the caudal direction through the bypass. A large amount of the retrograde flow was drained to each level of the intercostal veins and the opposite IMV cross over the caudal border of the sternum around the xiphoid.
CONCLUSION: IMV valves are located concentrically above second costal cartilage level even though 0.7 IMV valves of each side of the chests were confirmed. Based on these results, it is highly unlikely the retrograde flow to be disturbed by the valve because the level of the retrograde anastomosis would be used below the second ICS. Furthermore, vein starts to make the bifurcation below the second or third ICS which having the 1.76 average number of communicating veins. It will allow keeping the flow if the valve interferes. The bypass flows into the intercostal vein, and the sternal vein through crossing the xiphoid is also possible. In conclusion, IMV retrograde flow is considered safe.
1. Sugawara J, Satake T, Muto M, et al. Dynamic blood flow to the retrograde limb of the internal mammary vein in breast reconstruction with free flap. Microsurgery. 2015;35:622–626.
2. Tomioka YK, Uda H, Yoshimura K, et al. Studying the blood pressures of antegrade and retrograde internal mammary vessels: do they really work as recipient vessels? J Plast Reconstr Aesthet Surg. 2017;70:1391–1396.