As one of the obstructive diseases in the peripheral arteries, it mainly involves the medium and small arteries and veins of the four limbs, blood vessels of the lower limbs in particular, characterized clinically by cold sensation, chills, soreness, numbness and intermittent claudication primarily, and pain at night and intolerable pain progressively. In the late stage, necrosis and exfoliation of digital segments can occur. It is similar to the category of "Gangrene" in Chinese medicine. It is mostly caused by constitutional weakness in spleen qi, insufficiency of kidney yang, plus invasion of pathogenic cold.