Safety of Retrograde Flow of Internal Mammary Vein: Cadaveric Study and Anatomical Evidence.

Background  Additional second vessels may be required to handle multiple flaps used to add breast volume, boost blood flow for supercharging, or use salvage recipient vessels. In these situations, retrograde internal mammary vessel flow can be used although this causes doubts and concerns. Patients and Methods  Forty sides of the chests of 20 fresh cadavers with intact thoracic cages and internal mammary veins (IMV) were used in the study. IMV valve numbers and locations were checked, and the bifurcation was confirmed. A retrograde fluorescent angiography and a saline infusion test were followed to confirm flow direction. Results  Twenty-eight vessels were identified in 40 sides of the chest; of them, 45% had no valves. A mean 0.7 valves per chest side were identified; 23 (82.1%) of 28 valves were located above the second intercostal space (ICS). A mean 1.76 communicating veins were found between the IMV bifurcation. In all cadavers, a crossing vein connecting the left and right medial IMV was confirmed just below the xiphoid process. Fluorescent angiography and a saline infusion test proved that the retrograde flow was caudal through the bifurcated IMV to the communicating, intercostal, and crossing veins. Conclusion  The IMV valve was present in 55% of our subjects and located concentrically above the second ICS level. It is highly unlikely that the retrograde flow was disturbed because the retrograde anastomosis level was below the second ICS. Furthermore, the bifurcation, intercostal, and crossing veins across the xiphoid process enabled valve-less detour flow. Thus, retrograde IMV flow is considered safe. [ABSTRACT FROM AUTHOR]