Volumetric changes in transplanted vascularized fat flaps after ischemic or congestive stresses and their relationship to capillary density in a zucker fatty rat model.

Abstract

The aim of this study was to examine volumetric changes in fat flaps after stresses as well as their relationship with capillary density (CD) in a Zucker fatty rat model. A total of 12 male Zucker-fa/fa rats were randomly divided into two stress groups. Superficial epigastric fat flaps were evaluated on the right side as control and on the left side as the stress (ischemic or congestive) condition in the same rat in order to avoid biases. Stress conditions were made by obstructing the pedicle vessels with a vascular clip for 3 hours. The volumes of these flaps were measured weekly. After 12 weeks of measurements, the CD of harvested flaps was examined in histologically immunostained sections. Percent changes in the body-weight-corrected flap volume [cFV(%)], the stress/control ratio [FV-ratio(%)], and the stress/control ratio of CD (CD-ratio) were defined. cFV(%) 12 weeks after surgery was 34.7 ± 26.7 in the control flaps and 13.2 ± 10.5 in the stress flaps. The FV-ratio(%) after 12 weeks was 7.4-202.5 (70.2 ± 77.9) in the ischemic group and 14.6-66.3 (37.7 ± 22.2) in the congestive group. The difference in variance between two groups was significant (P = 0.030). cFV(%) correlated with total CD (P = 0.011). The FV-ratio(%) correlated with the CD-ratio (P = 0.002). Weekly measurements of flap volumes in the Zucker fatty rat model were new and useful methods. The FV-ratio(%) in the congestive group decreased at a constant rate, while that in the ischemic group decreased or increased slightly. The rate of decreases in the flap volume correlated with CD.