"Plasmatic imbibition" in the rat musculocutaneous pedicled venous flap: enzymatic proof using horseradish peroxidase.

To determine the reason for survival of a pedicled venous flap in which only a draining vein is preserved, it is important to clarify what kind of blood flow is present in the preserved draining vein. Pedicled venous flaps were prepared on the dorsum of the rat and histologically evaluated using horseradish peroxidase (HRP). HRP was applied between the flap and recipient bed in one group. In the other group, HRP was injected into the femoral vein after the flap was turned over (to prevent contact with the recipient bed). The flaps in these HRP-treated groups were compared with untreated control groups. HRP applied between the flap and recipient bed was imbibed into the flap and subsequently transferred into the preserved draining vein. HRP that was injected into the femoral vein was also found in the draining vein of the flap. These results suggest that (1) plasmatic imbibition occurs in pedicled venous flaps; and (2) antegrade and retrograde blood flow are present in the draining vein.