Abstract
Background Venous congestion is a leading cause for free flap failure and still relies on clinical
observation as the diagnostic gold standard. We sought to characterize blood flow
in a variable venous congestion murine hind limb model using indocyanine green (ICG,
SPY Pack, LifeCell, Branchburg, NJ) angiography.
Methods Male Sprague–Dawley rats (Charles River, Hudson, NY) underwent bilateral partial
amputation at the inguinal ligament, leaving only the femoral vessels and femur intact.
Complete unilateral venous occlusion was achieved via suture ligation, while partial
occlusion was achieved by surrounding the femoral vein with a synthetic microtube
to achieve 25, 75, 85, or 92% occlusion. Relative blood flow of occluded and control
limbs was tracked with ICG angiography throughout a 90-minute time course.
Results ICG angiography detected statistically significant (p < 0.05) reductions in limb blood flow 1 and 2 minutes following ICG injection in
the 100, 92, and 85% occluded limbs when compared with contralateral control limbs.
Dynamic tracking using the slope of ICG inflow for 45 seconds postinjection reflected
this same significant difference. No statistically significant change in limb blood
flow or dye influx rate was observed in the 25 and 75% occlusion groups.
Conclusions ICG angiography can detect venous congestion in a rat lower extremity model reliably
at occlusion rates ≥ 85%. This method may offer surgeons an intraoperative diagnostic
tool to identify venous congestion at extremely early time points, allowing for immediate
intervention. Further investigation and characterization is warranted in a larger
animal model before clinical adaptation.
Keywords
venous occlusion - rat model - indocyanine green
