Significance of the Lateral Thoracic Artery in Pectoralis Major Musculocutaneous Flap Reconstruction: Quantitative Assessment of Blood Circulation Using Indocyanine Green Angiography

Abstract: Free tissue transfer is the preferred reconstruction option in most major head and neck reconstructions. The pectoralis major muscle musculocutaneous (PMMC) flap is commonly used in salvage of necrotic free flaps and is the first choice for patients who are not candidates for free flaps. The lateral thoracic artery (LTA), which is thought to contribute to blood perfusion of the inferior and lateral mammary area, is not preserved in a conventionally harvested PMMC flap. With regard to blood supply, it has been suggested that the LTA should be preserved, in addition to the pectoral branch of the thoracoacromial artery, when a skin island is designed in the lower chest to attain a pedicle length sufficient for head and neck reconstruction. However, an effect on hemodynamic improvement using the LTA has not been shown quantitatively. In this study, we examined 8 patients with oral cancer who underwent reconstruction procedures with a bipedicle PMMC flap that included the LTA, in addition to the thoracoacromial artery. Intraoperative indocyanine green angiography was performed to examine circulation to the PMMC flap with or without LTA clamping after harvesting. After image processing, data were analyzed using a new quantitative perfusion assessment system with parameters that we recently established for assessment of peripheral arterial disease of the lower limbs. All patients had good clinical courses with whole-flap survival, no vascular insufficiency of the skin island, and no fistula formation. Intraoperative indocyanine green angiography showed an increased inflow rate into the skin island in an LTA-declamped condition in all cases, implying that the preserved LTA increased the blood supply to skin islands in the pectoralis major muscle. We conclude that preserving the LTA in a PMMC flap can increase blood perfusion and stabilize the vascularity of the flap, making the reconstruction more effective and reliable than with use of a conventionally harvested flap. Therefore, it is worthwhile to preserve the LTA as a major contributor to a lateral and distal PMMC flap.