Effect of the endogenous vascular endothelial growth factor on flap surgical delay in a rat flap model.

BACKGROUND: Experimental evidence suggests that endogenous vascular endothelial growth factor (VEGF) may play a major role in the surgical delay phenomenon. The purpose of this study was to investigate the effect of the endogenous vascular endothelial growth factor on flap surgical delay.

METHODS: A total of 82 adult male Sprague-Dawley rats with an average weight of 330g were used for these experiments. These experiments were then conducted in two parts. In part 1, thirty-two rats were used to assess the effectiveness of VEGF inhibitor through western blot assay and ELISA. In part 2, fifty rats were used to investigate the effect of VEGF on flap surgical delay via arteriography, histology analysis, and flap viability.

RESULTS: The VEGF protein inhibition ratio reached the maximum (approximately 91.6%) on the 5 to 7 days. The number of transverse arteries and the number of vessels > 0.1mm in diameter on the 3-day delay duration and the 6-day delay duration were significantly greater than those of the normal group. The number of transverse arteries and the number of vessels > 0.1mm in diameter on the 6-day inhibition duration were not significantly changed compared with the normal group. Microvascular density on the 6-day delay duration obviously increased whereas the 6-day inhibition duration was not significantly changed in comparison to the normal group.

CONCLUSIONS: Endogenous VEGF is an initiating factor of the surgical delay effect by controlling choke vessel dilation and neovascularization within the choke zones.