Basic versus Complex Arteriovenous Loop Positions in Reconstructive Free Flap Surgery: An Outcome Analysis Focusing on the Antithrombotic Treatment Regimen

Arteriovenous (AV) loop followed by free flap reconstruction remains a challenging and high-risk intervention and is therefore reserved for a selective patient population. It is unclear to what extent factors such as defect localization, choice of free flap, positioning of the AV loop, and especially the antithrombotic regimen have an influence on complications such as thromboembolic events or flap failure.Medical records from 123 patients between 2003 and 2023 were reviewed. Postoperative outcomes were compared between the complexity of AV loop positioning, one- and two-stage reconstruction, defect locations, free flap type, and antithrombotic regimen.After AV loop creation and before free flap transfer (first-stage), loop thrombosis (<i>p</i> = 0.025) and loop failure (<i>p</i> = 0.003) rates differed significantly between defect sites. The flap failure rate after free flap transfer (second-stage), which was performed on average 8 days after AV loop creation, differed significantly between defect sites with basic (3%) and complex (17%) AV loop positioning and routing (<i>p</i> = 0.028). Low-dose heparin was applied significantly more frequently in cases with basic loop positioning, while high-dose heparin was applied significantly more frequently in complex loop cases (<i>p</i> = 0.002). The combined use of low-dose heparin with acetylsalicylic acid in complex loops is associated with a significantly higher thrombosis rate than in basic loops (<i>p</i> = 0.046)Defect localization and the complexity of the AV loop position have an influence on the occurrence of vascular thrombosis and flap failure. For this reason, consideration of defect localization and AV loop position is crucial for the choice of the appropriate antithrombotic regimen.