Systemic and Flap Inflammatory Response Associates with Thrombosis in Flap Venous Crisis

Venous crisis represents the most common complication in flap surgery and often results in flap failure. The gold standard for free flap monitoring is frequent clinical examination. The current study examined the systemic inflammatory response during the immediate post-operative period following flap venous crisis. Superficial epigastric artery perforator flap transplantation was performed in a total of 30 rabbits. Fifteen animals received venous obstruction by vein ligation (venous crisis group, n = 15) and others were sham treated (control group, n = 15). Venous thrombosis was examined by immunohistochemistry staining. Plasma levels of inflammatory response markers (IL-6, IL-8, TNF-α, and C-reactive protein) and thrombosis biomarkers (von Willebrand factor and tissue factor) were measured at 0, 2, and 4 h post-operation by enzyme-linked immunosorbent assay. The mRNA levels of relevant biomarkers in the flap were analyzed with quantitative real-time PCR. Flap histopathological examination showed erythrocyte and neutrophil aggregations in venous lumen and erythrocyte diapedesis. At 8 h post-operation, serious edema and fibrinoid necrosis were observed and the venous lumen was almost blocked by thrombus. The venous crisis group had higher plasma levels of IL-8, TNF-α, and thrombosis biomarkers. Vein ligation also increased the mRNA levels of IL-8, TNF-α, C-reactive protein, von Willebrand factor, and tissue factor in the flap. No significant change in IL-6 levels was observed between the control group and the venous crisis group. Flap venous crisis was accompanied by the increase in a number of inflammatory and thrombosis markers, both in the peripheral blood and the flaps.