Background: Multiple studies have shown superior outcomes with two- versus one-vein anastomoses in head and neck reconstruction. However, the physiology of these flaps remains unexplored. There is speculation that one vein becomes dominant in two-vein flaps, and that there are higher rates of venous thrombosis in two-vein flaps due to decreased blood flow. In addition, it is unknown if certain donor and recipient veins are more prone to venous thrombosis in two-vein flaps.
Methods: The venous flow coupler was used in 94 consecutive head and neck free flap cases performed by a single surgeon with double venous anastomoses (“two-vein flaps”). Two anastomoses were performed whenever appropriate donor and recipient vessels were available. We have previously shown high sensitivity and specificity of the flow coupler for loss of venous flow requiring operating room (OR) takeback in one-vein flaps therefore signal loss was considered indicative of venous flow loss. Two-vein flaps were analyzed for patterns of venous flow loss by signal at the end of the case, recipient vein, and donor vein.
Results: Overall rates of permanent signal loss were equivalent in one- versus two-vein flaps (26% versus 23%, p=0.765). The remainder of the analysis was performed in only two-vein flaps. 52 (59%) had good venous signal in both veins, 27 (31%) had permanent signal loss in one vein, and 9 (10%) had permanent signal loss in both veins (figure 1). OR takeback was required in 3 (5%) of flaps with good signal in both veins at the end of the case, and 1 (5%) of flaps with good signal in only one vein at the end of the case. 3 flaps had poor signal in both veins at the end of the case; of these, 1 (33%) was taken back to the OR.
The most common recipient veins used in two-vein flaps were external jugular vein (EJV) and common facial vein (CFV), making up 71 (40%) and 46 (26%) of veins. 23 (32%) of EJV anastomoses, versus 5 (11%) of CFV anastomoses lost venous flow. In flaps in which signal was lost in one vein, 16/23 (57%) lost signal in the EJV versus 1/9 (11%) in the CFV. In radial forearm flaps, signal loss occurred in 10 (24%) of cephalic veins and 10 (22%) of venae comitantes (VC). In the 12 radial forearm flaps with both VC and cephalic anastomoses in which signal was lost in one vein, 7 (58%) lost signal in the VC and 5 (42%) in the cephalic vein.
Conclusions: Flaps with one- and two-vein anastomoses have similar rates of venous flow loss. Both veins retain flow in most two-vein flaps, however a single vein loses flow in a significant number of flaps. Higher rates of loss of flow were seen in EJV versus CFV anastomoses. In radial forearm flaps, similar rates of venous flow loss were seen in cephalic and VC anastomoses.