Improvement of skin paddle survival by application of vascular endothelialgrowth factor in a rat TRAM flap model

The effect of vascular endothelial growth factor (VEGF) on skin flap surviv al and its ability to induce a pharmacological delay by promoting angiogene sis in a flap was studied in a rat transverse rectus abdominis musculocutan eous flap, using a 3 x 8-cm skin paddle with the inferior epigastric vessel s as its main vascular supply. Forty-three Sprague-Dawley rats were divided into four groups. In group 1, VEGF was injected into the femoral vein afte r the flap was elevated. In group 2, VEGF was injected intraarterially into the flap through the superior epigastric artery after the flap was elevate d. In group 3, VEGF was injected into the subcutaneous fascial layer in the area where the flap would be dissected, and the flap was then raised 7 day s after injection. In group 4, the flap was dissected and replaced, using s aline injection as the control. On postoperative day 5, the survival area o f each skin paddle was measured and the flap was harvested for histological analysis, The results showed that the mean survival area +/- standard devi ation for the skin paddle was 6.82 +/- 4.89 cm(2) (28.4 +/- 20.4% of the wh ole skin paddle) in the control group, and 4.2 +/- 3.0 cm(2) (17.5 +/- 12.5 %) and 6.02 +/- 5.97 cm(2) (25.1 +/- 24.9%) in the groups with VEGF systemi c and intraarterial administration respectively, The skin survival area in the group with preoperative subcutaneous administration of VEGF was 17.85 /- 2.88 cm(2) (74.4 +/- 12%), which was significantly higher than the other three groups (p < 0.01). Histological semiquantitative analysis showed inc reased neovascularization in the flap treated with VEGF preoperatively. The data demonstrate that preoperative treatment with VEGF can induce angiogen esis and enhance skin paddle survival in a musculocutaneous flap.