Effects of preserving different veins on flow-through flap survival: An experimental study.

Flow-through skin flap grafting is becoming widely used for the reconstruction of skin and soft tissue defects, particularly for patients with poor blood supply around the defect. However, the treatment of the veins remains controversial. In the present study, 5×2-cm skin flaps were created on the left inner thighs of rabbits in order to investigate the effects of various treatments of the veins on the survival of a flow-through skin flap. A femoral artery perforator running through the flap was preserved. Five groups were established in which no veins, one superficial vein (SV), one accompanying vein (AV), one SV plus one AV, or all trunk veins (control) were retained. The percentage of flap area survival was determined on day 10. On days 3, 5, 7 and 9, tissues were harvested from the skin flaps and immunohistochemical analysis was performed in order to count the number of microvessels. Western blot analysis was subsequently completed in order to determine the expression levels of vascular endothelial growth factor (VEGF). The flap areas in which no veins were retained demonstrated significantly reduced survival rates on day 10, as compared with those in the other four groups (P<0.01). Furthermore, flaps with the retention of a SV also demonstrated reduced survival rates, as compared with the AV, AV plus SV and all veins groups (P<0.01); however, there no significant differences were detected between the latter three groups (P>0.05). Immunohistochemical analysis on day 3 detected a greater number of microvessels in the flaps of the control group, as compared with the flaps of the other groups. Furthermore, the AV and AV plus SV groups demonstrated a greater number of microvessels, as compared with the SV and no vein groups, and he no vein group demonstrated the fewest microvessels. No significant differences were found between the AV, AV plus SV and control groups on day 5, 7 and 9. Western blot analysis on day 5 demonstrated that the expression levles of VEGF were significantly increased in the flaps of the AV, AV plus SV and control groups, as compared with those in the SV and no vein groups. No significant differences were detected between the former three groups, and increased VEGF expression levels were detected in the flaps of the SV group, as compared with the no vein group. The flow-through flap grafts with no retained veins barely survived. Anastomosing one AV was adequate for flap survival; however, further studies are required in order to investigate the survival of flow-through flaps in more detail.