Background: The rat abdominal island model has proved to be a reliable and reproducible model for the study of surgical delay procedures. It has been customary to simultaneously divide both the artery and the accompanying vein to obtain maximum survival of the rat TRAM flap undergoing delay procedure. This study evaluates the effect of selective arterial interruption compared to standard vascular delay on flap survival in the rat TRAM flap model.
Methods: Thirty-six Wistar rats were randomly assigned to three groups (n=12), depending on the vascular ligation selected for the initial experimental delay stage. In group A (control group) no vessels were ligated. In group B the right deep inferior epigastric vessels were preserved and the right superior and left inferior and superior deep vessels were ligated. In group C the right inferior epigastric vessels and the left inferior epigastric vein were preserved while superior epigastric vessels and the left inferior epigastric artery were ligated. For the second stage one week later, TRAM flaps were elevated based on the right deep inferior epigastric vessels, re-inset in their original position and digitally photographed. Skin island viability was determined 96 hours later using digital photography and image-analysis software SigmaScan (SPSS, Inc., Chicago, IL).
Results: The percentage of flap survival in control group A was 50+/-6%, in group B 60+/-4% and in group C 85+/-4%. The occlusion of the three vascular pairs in group B improved the survival percentage in comparison to the control group A, but this did not achieve statistical significance. In contrast, the percentage of flap survival in control group C was statistically significant compared to groups A and B (p<0.05, ANOVA). Zone IV exhibited no necrosis in any group C animals.
Conclusions: This indicates that delay with preservation of the venous outflow of zone IV results in increased blood supply.