Interpreting Lower Trapezius Musculocutaneous Flap Skin Paddle Perfusion with Indocyanine Green Angiography

Background: The lower trapezius myocutaneous flap (LTF) is a pedicled flap with clinically significant variability of distal skin flap perfusion. Objective: To compare the incidence of partial flap necrosis before and after the institution of routine intraoperative laser-assisted indocyanine green (ICG) angiography. Methods: This is a retrospective review of all LTF performed between November 2021 and July 2022. The outcomes measured in this study are the distance distal to the inferior border of the trapezius muscle with adequate perfusion, and incidence and degree of partial flap necrosis. Results: Sixteen patients met inclusion criteria with a median age of 64.5 years, and a median defect size of 147 cm². Most patients (11/16) had undergone previous treatment for malignancy. Before utilizing ICG angiography, 40% (2/5) had partial flap necrosis, whereas after utilizing ICG angiography, 9% (1/11) of patients had partial flap necrosis. Seventy-three percent (8/11) of cases who underwent ICG angiography demonstrated a portion of the skin paddle with inadequate perfusion. The range of skin perfusion distal to the inferior border of the trapezius muscle was 0-7 cm (median, 4). Conclusions: The incidence of partial flap necrosis decreased after institution of routine ICG angiography.