Extending Free Flap Pedicle Length with Interposition Vein Grafts and Arteriovenous Loops: An Outcome Study
Tobias J. Bos, BSc, Nicholas A. Calotta, BA, Michelle Y. Seu, BA, Brian H. Cho, MD, Aladdin H. Hassanein, MD MMSc, Gedge D. Rosson, MD, Damon S. Cooney, MD, Justin M. Sacks, MD MBA FACS.
Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Background: 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. The purpose of this study is to assess clinical outcomes of free flaps with vein grafts used for both interposition grafts and AV loops (in an intermediate or staged fashion). These findings will inform and guide clinical practice for these challenging reconstructive scenarios.
Methods: Following approval by our Institutional Review Board, we retrospectively analyzed patients requiring free flap reconstruction between March 2007 and December 2016. All patients utilizing any vein graft in this context were identified. Data collection included demographic, medical, surgical, and outcome variables.
Results: A total of 85 IVG were used in 53 patients, receiving a total of 50 free flaps. Reconstructive sites included: head/neck (29; 54.7%), breast (13; 24.5%), upper extremity/trunk (8; 15.1%), and lower extremity (3; 5.7%). Eighteen out of 23 AV loops created received flaps (10 immediate; 8 staged). Four 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 procedures utilized IVG (n=22; 3 arterial conduit only, 13 venous conduit only and 6 both) or AV loops (n=18) in the index flap surgery, of which 10 (25%) were taken back for emergent flap salvage (2 AV loops, 8 IVG group). Six of these cases were successfully salvaged. In 13 cases IVG was utilized for free flap salvage (2 arterial conduit IVG, 11 venous conduit IVG), with an 84.6% successful salvage rate (n=11). Out of 50 flaps overall, 9 flap failures occurred (18%: 95% CI: 8.6-31.4%). 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, 6 in IVG for single conduit). Of the eight staged AV loops that received flaps, flap survival was 100%.
Conclusion: Interposition vein grafts and AV loops offer practical solutions for pedicle lengthening in order to successfully perform microvascular anastomosis. 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. When there is need to extend both the arterial and venous pedicle, we therefore recommend staging the reconstruction with an AV loop. Additionally, IVG appears to be an especially effective tool in cases of free flap salvage.
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