Bridging The Gap: Extending Free Flap Pedicle Length With Interposition Vein Grafts And Arteriovenous Loops
Tobias J. Bos, BSc1, Nicholas A. Calotta, MD1, Michelle Y. Seu, BA1, Brian H. Cho, MD1, Aladdin H. Hassanein, MD MMSc2, Gedge D. Rosson, MD1, Damon S. Cooney, MD PhD1, Justin M. Sacks, MD MBA FACS1.
1Johns Hopkins University School of Medicine, Baltimore, MD, USA, 2Indiana University School of Medicine, Indianapolis, IN, USA.
PURPOSE - The purpose of this study is to assess clinical outcomes for utilization of vein grafts and arteriovenous loops in the context of free flap reconstruction. Free tissue transfer in complex oncological and traumatic defects may require extension of the vascular pedicle to reach recipient vessels and complete microvascular anastomosis. This can be accomplished by using vein grafts as a bridging medium. When interposition vein grafts (IVG) are needed for extension of both the arterial and venous conduit, a temporary arteriovenous fistula (AV loop) can be constructed as an intermediary step. These techniques have traditionally been regarded with increased risk of thrombosis and flap failure, but the body of clinically relevant published data lags behind.
METHODS - Following approval by our Institutional Review Board, we retrospectively analyzed patients requiring free flap reconstruction between March 2007 and June 2017. All patients utilizing any vein graft in this context were identified. Data collection included demographic, medical, surgical, and outcome variables.
RESULTS - A total of 90 IVG were used in 56 patients, receiving a total of 54 free flaps. Reconstructive sites included: head/neck (29; 51.8%), breast (13; 23.2%), upper extremity/trunk (9; 16.1%), and lower extremity (5; 8.9%). Twenty out of 26 AV loops created received flaps (11 immediate; 9 staged). Five AV loops thrombosed in staging and were discarded; one patient died in staging due to medical comorbidity. The duration of staging ranged from 1 to 59 days (median=4). Forty-two procedures utilized IVG (n=22; 3 arterial conduit only, 13 venous conduit only and 6 both) or AV loops (n=19) in the index flap surgery, of which 10 (24.4%) were taken back for emergent flap salvage (2 AV loops, 8 IVG group). Seven of these cases (eight flaps) were successfully salvaged. In 13 cases (14 flaps) IVG was utilized for free flap salvage (3 arterial conduit IVG, 10 venous conduit IVG), with a 78.6% successful flap salvage rate (n=11). Out of 54 flaps overall, 11 flap failures occurred (20.4%; 95% CI 10.6-33.5%). All flap failures occurred in the patients that used any IVG (with or without AV loop) for immediate reconstruction (two in AV loop group, 1 in IVG for both conduits, 5 in IVG for single conduit) or failed salvage utilizing IVG (3 in IVG for single conduit). Of the nine staged AV loops that received flaps, flap survival was 100%.
CONCLUSIONS - Interposition vein grafts and AV loops offer practical solutions for pedicle lengthening in order to successfully perform microvascular anastomosis, but increase risk of take-back and flap failure when utilized in the index flap surgery. Our data demonstrate that staged AV loops may be superior to immediate AV loops, owing to a de facto pre-identification of patients who may otherwise develop a flap complication after immediate reconstruction. Additionally, IVG appears to be an especially effective tool in cases of free flap salvage.
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