Choke Anastomosis: A Key Element Acting as a Shunt Converter Between Adjacent Angiosomes.

BACKGROUND

Choke anastomosis is commonly recognized as a resistance factor that detrimentally affects the hemodynamics of the skin flap; however, its additional potential physiological roles in normal skin function are currently not fully understood.

METHODS

Ten cadaveric forehead flap specimens pedicled with unilateral STAs were perfused with lead oxide-gelatin mixture, and then dissected into 3 layers, including the super temporal fascia-frontalis-galea aponeurotica layer, the subcutaneous adipose tissue layer, and the "super-thin flap" layer. The forehead flap and stratified specimens underwent molybdenum target x-ray and subsequent transparent processing to effectively visualize the microscopic spatial architecture of arterial vessels across all levels.

RESULTS

Based on the different anastomoses near the midline area of the flap, 2 types of arterial perfusion were identified: choke anastomosis type (8/10) and true anastomosis type (2/10). The former formed multiple choke anastomoses near the midline. In the "super-thin flap" layer, arterial perfusion density on the ipsilateral side was significantly higher compared to that on the contralateral side. The arterioles on the ipsilateral side exhibited a dense and uninterrupted distribution, whereas those on the contralateral side appeared sparse and dispersed. The latter exhibited an alternative perfusion pattern; the bilateral arterial vessels were connected with 3 to 5 true anastomoses near the midline. Furthermore, the microscopic architecture confirmed a uniform distribution of arterioles that remained continuous from ipsilateral to contralateral sides in the "super-thin flap" layer.

CONCLUSION

This study demonstrated that choke anastomosis not only impairs blood perfusion in the adjacent angiosomes but also acts as a shunt converter to impact the blood supply of distal skin flaps at different levels through the "trans-territory diversion phenomenon." This results in necrosis of the superficial dermis while preserving survival of the deep subcutaneous adipose tissue.