Utilizing Indocyanine Green Dye Angiography to Detect Simulated Flap Venous Congestion in a Novel Experimental Rat Model.
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.
Department of Surgery, Stony Brook University Medical Center, Stony Brook, New York.
Ahmed
A
Nasser
Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.
Mitchell S
MS
Fourman
Department of Surgery, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania.
Robert P
RP
Gersch
Division of Plastic Surgery, Department of Surgery, Duke University Medical Center, Durham, North Carolina.
Brett T
BT
Phillips
School of Medicine, Stony Brook University Medical Center, Stony Brook, New York.
Hsingli Kai
HK
Hsi
Division of Plastic Surgery, Department of Surgery, Stony Brook University Medical Center, Stony Brook, New York.
Sami U
SU
Khan
Division of Plastic Surgery, Department of Surgery, Stony Brook University Medical Center, Stony Brook, New York.
Mark A
MA
Gelfand
Division of Plastic Surgery, Department of Surgery, Stony Brook University Medical Center, Stony Brook, New York.
Alexander B
AB
Dagum
Division of Plastic Surgery, Department of Surgery, Stony Brook University Medical Center, Stony Brook, New York.
Duc T
DT
Bui
D000792:Angiography / Q000379:methods*; D000818:Animals; D004195:Disease Models, Animal; D005268:Femoral Vein / Q000000981:diagnostic imaging; D006084:Graft Rejection / Q000000981:diagnostic imaging; D006614:Hindlimb / Q000098:blood supply*; D006940:Hyperemia / Q000000981:diagnostic imaging / Q000503:physiopathology; D007208:Indocyanine Green; D007511:Ischemia / Q000000981:diagnostic imaging*; D008297:Male; D011897:Random Allocation; D051381:Rats; D012039:Regional Blood Flow; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D013524:Surgical Flaps / Q000009:adverse effects* / Q000098:blood supply
D007208:Indocyanine Green