Neovascularization Perfusion of Melolabial Flaps Using Intraoperative Indocyanine Green Angiography

Abstract

IMPORTANCE Assessment of melolabial flap perfusion using indocyanine green (ICG) angiography for nasal reconstruction has not been previously described.OBJECTIVE To assess melolabial flap relative perfusion using ICG angiography in nasal reconstruction and highlight its clinical relevance. DESIGN, SETTING, AND PARTICIPANTSIn this retrospective case series at a tertiary referral center, 10 patients undergoing melolabial flap reconstruction of nasal defects between January 2015 to April 2018 with flap perfusion were assessed by ICG angiography. EXPOSURES Indocyanine green angiography was performed to assess melolabial flap perfusion at second stage surgery after temporary clamping of the pedicle and after pedicle division and flap inset. MAIN OUTCOMES AND MEASURESFlap perfusion in relation to a reference point on the cheek was calculated after both pedicle clamping and division by 2 methods: (1) ingress (arterial inflow) and egress (venous outflow) flap-to-cheek ratio; (2) flap-to-cheek perfusion (fluorescence) ratio at 3 time points (midpoint of ICG flap inflow, maximum [peak] fluorescence, and midpoint of ICG outflow), and their calculated mean. Correlations of perfusion with time between stages, and patient factors were performed; perfusion parameters after temporary pedicle clamping and after division and flap inset were compared.RESULTS Ten patients (mean [SD] age, 66 [7.5] years) were enrolled with a mean (SD) interval of 23 (4) days between first and second surgery. No correlation existed between perfusion parameters and time interval between first and second stage, or any other patient factors. Of the different perfusion parameters, a statistically significant difference was observed when comparing temporary clamping and postdivision mean (SD) flap-to-cheek perfusion ratio (0.89 [0.22] and 0.80 [0.19]; 95% CI, 4.1-12.6; P = .001), as well as mean (SD) peak perfusion ratio (0.81 [0.2] and 0.77 [0.2]; 95% CI, 0.005-0.080; P = .02) only. No partial or complete flap necrosis was reported after pedicle division.CONCLUSIONS AND RELEVANCE Indocyanine green angiography is an effective method to determine neovascularization perfusion of melolabial flaps, with a mean perfusion of 89% after pedicle clamping. Future applications of this technology include use in patients at high risk for flap necrosis, or those who may benefit from early flap division to ensure adequate perfusion and minimize the time interval between staged procedures.LEVEL OF EVIDENCE NA.

The Use of Indocyanine Green Angiography for Cosmetic and Reconstructive Assessment in the Head and Neck

“…An average perfusion (SD) of the distal flap was 89% (22), with an average of 23 days interval between both stages. 25 This study has shown a significant difference between perfusion parameters after pedicle clamping (being higher in the beginning of the second stage) and after pedicle division. This suggests that flap modifications such as thinning, or refinement of the flap may jeopardize retrograde neovascularization from the bed and, therefore, should be performed with caution.…”

“…59 Although the venous drainage rate is known to be much slower than the arterial flow rate, 60 the ICG provides quantification of both flow rates using time-independent software modalities. This was observed in both free flaps 24 and pedicled flaps 1,25 and was noted to be an independent predictor of flap survival and revision surgery. 57,61 Moreover, it has also been observed that the rate of venous neovascularization in pedicled flaps occurs at a slower rate than arteries.…”

“…These tools may be helpful in qualitative or quantitative assessments. 1,25 Qualitative tools evaluate the generated fluorescence to evaluate the success of the inset of pedicled flaps or the anastomosis patency in free flaps. This provides a dynamic map of the dermal circulation that serves as a topographic analysis of the effective perfusion to the flap tissue, as shown in ►Fig.…”

“…2. 1,25,26 Others used time-dependent methods including the fluorescence intensity measured 10 seconds after the onset of fluorescence. 23 On the other hand, time-independent measures include the use of the time from fluorescence onset to maximum intensity (Tmax), the time elapsed to reach half the maximum intensity (t1/2 of fluorescence), and the arterial and venous flow rate (sometimes described as the blood flow intensity for the artery and the vein), as shown in ►Fig.…”

“…This range includes 0.1 mg/kg, 23 0.2 mg/kg, 27 0.3 mg/ kg, 3 0.5 mg/kg, 24 and up to 1 mg/kg in the evaluation of large vessels (e.g., jugular vein thrombosis). 28 Fixed doses in head and neck reconstruction have also been reported according to the region assessed, which include 5 mg in forehead flaps and supraclavicular flaps, 1,22,25 6.25 mg in deep plane facelift, 29 7.5 mg in radial forearm and fibula free flaps, 30 10 mg in salvage laryngectomy, 14 12.5 mg in anterolateral thigh flaps, 31 and up to 25 mg in nasoseptal flaps. 32,33 After the bolus is injected in a central or peripheral line, usually a 10-mL 0.9% normal saline flush is administered.…”