A stent is a frame for the vessel and acts as a vascular support. The diameter ranges from 3 to 12mm and can expand by themselves or with the help with the inflation of a balloon, which can stabilise a venous occlusion. The self expanding stents can, due to a memory effect of the metal or of the mesh, return to their original state and are used, as a rule, for constrictions of the arteries of the thigh. The balloon-mounted stent, can only expand with the help of an inflatable balloon and as a rule are used for the constricted vessels of the pelvis and abdomen (e.g. the renal arteries).