Plastic Surgery Research Council

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One Stage Versus Two-Stage Microsurgical Arteriovenous Loop Reconstructions - A 10-Year Experience On 103 Cases from a Single Center
Dominic Henn, M.D.1, Matthias S. T. Waehmann, M.D.1, Miriam Horsch, B.S.1, Svetlana Hetjens, PhD2, Christoph Hirche, M.D.1, Volker J. Schmidt, M.D.1, Ulrich Kneser, M.D.1.
1Dept. of Hand, Plastic and Reconstructive Surgery, Heidelberg University, BG Trauma Center Ludwigshafen, Ludwigshafen, Germany, 2Dept. of Medical Statistics, University Medicine Mannheim, University of Heidelberg, Mannheim, Germany.

PURPOSE
A paucity of healthy recipient vessels in microsurgical reconstructions may be managed by the placement of arteriovenous (AV) loops, which enable microvascular anastomoses of free flaps. The optimal time for flap anastomosis to an AV loop still remains a topic of controversy in the literature. A recently published meta-analysis yielded a higher rate of major complications and flap failures in two-stage compared to one-stage AV loop reconstructions (Knackstedt et al. 2017). These data, however, were derived from heterogeneous case series with low sample sizes, the largest of which included 52 patients (Cavadas et al. 2008). Evidence is also lacking on whether perforator flaps are suitable for AV loop based reconstructions and lead to outcomes comparable with large-pedicle muscle or fasciocutaneous flaps. Here, we present the largest cohort of AV loop reconstructions in the literature performed at a single microsurgical center.
METHODS
Medical records from 103 patients undergoing AV loop reconstructions (76 one-stage, 27 two-stage) at our institution between 2007 and 2017 were reviewed. One-stage and two-stage reconstructions as well as different types of free flap reconstructions were compared with respect to postoperative complications and outcomes.
RESULTS
Rates of flap thrombosis did not show significant differences between one- and two-stage reconstructions (14.47% vs. 11.11%, p=1.00). Also, no significant differences between one- and two-stage reconstructions were found for major wound complications (30.26% vs. 25.93%, p=0.67) and flap failure (10.53% vs. 7.41%), p=1.00). For two-stage reconstructions, the length of the time interval between AV loop placement and flap anastomosis was identified as a predictor for thrombotic events by logistic regression analysis (Odds Ratio: 1.31; p<0.05), yielding high thrombosis rates for intervals of > 10 days. Anterolateral thigh perforator (ALT) flaps in conjunction with AV loops (n=12) showed higher rates of flap failure compared to latissimus dorsi (LD, n=35) (33.33% vs. 8.57%, p=0.059) and combined LD and parascapular flaps (LD/PSC, n=15) (33.33% vs. 0%, p<0.05). Thrombosis rates were higher in ALT flaps compared to LD (33.33% vs. 17.14%, p=0.25), LD/PSC (33.33% vs. 0%, p<0.05), and tensor fasciae latae flaps (TFL, n=12)(33.33% vs. 0%, p=0.09).
CONCLUSIONS
Our data indicate that two-stage AV loop reconstructions do not lead to increased postoperative complications compared to one-stage reconstructions and may be favorable in selected complicated cases due to an increased safety of the staged procedure and shorter operative times. To avoid increased thrombosis rates, flap anastomosis should not be delayed beyond 10 days in two-stage reconstructions. ALT flaps are not suitable for AV loop reconstructions since they have a significantly higher resistance and therefore cause a reduced flow rate in the vein graft. This may explain higher flap thrombosis and failure rates.


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