Endovascular revascularization consists of percutaneous dilation of the renal artery (often termed percutaneous transluminal angioplasty, or PTA). The femoral or radial artery is catheterized using the classic or modified Seldinger technique. Under fluoroscopic guidance, with occasional injections of contrast material to opacify the vasculature, a flexible guidewire is advanced across the stenotic segment of the renal artery. A balloon catheter is then selected that is approximately equal to the diameter of the nonstenotic portion of the renal artery. The balloon is placed over the wire to the level of the lesion and then inflated to a high pressure. In patients with atherosclerosis, the inflated balloon fractures the plaque, whereas in patients with FMD, the balloon stretches the vessel wall. In either case, perfusion to the kidney is markedly improved. A postdilation angiogram is performed to assess the results and determine the presence of any complications, such as injury to the vessel wall. An adjunct to PTA is the deployment of an endovascular stent, which is an expandable, metallic mesh sheath that helps maintain vessel patency. Stents are especially useful in the treatment of atherosclerotic stenoses, which tend to be rigid and may recoil after balloon dilation.