Critical limb-threatening ischemia is a severe medical condition that occurs when there is an inadequate supply of blood and oxygen to the limbs. The narrowing of blood vessels typically causes this due to the accumulation of plaque, which prevents oxygenated blood from flowing to the limbs properly. As a result, there is a risk of tissue damage and possible amputation. This condition can be clinically defined in three ways: ischaemic rest pain for greater than two weeks duration requiring opiat