Covered Stents to Treat Hemodialysis Access Stenoses in the Cephalic Arch and Central Veins

Inclusion Criteria: * Hemodialysis patient with a mature forearm or upper arm access that was created \> 2 months before enrollment in study. * The patient is ≥ 18 years of age. * The patient has a reasonable expectation of remaining on hemodialysis for 12 months. * The patient or his/her legal guardian understands the study and is willing and able to comply with follow-up requirements. * The patient or his/her legal guardian is willing to provide informed consent. * The patient has lesions that meet the angiographic inclusion / exclusion criteria and induce clinical, hemodynamic or functional abnormality. Exclusion Criteria: * The patient has a known or suspected systemic infection. * The patient has a known or suspected infection of the hemodialysis access and / or bacteremia. * The patient is currently taking maintenance immunosuppressant medication such as rapamycin, mycophenolate or mycophenolic acid, prednisone (\>10 mg per day), cyclosporine, tacrolimus, or cyclophosphamide. * The patient has known bleeding disorder (e.g., hemophilia or von Willebrand's disease). * The patient has known sensitivity to heparin. * The patient is scheduled for a live donor kidney transplant. * The patient is enrolled in another investigational study or another access maintenance trial * The patient has comorbid conditions that may limit their ability to comply with the follow-up requirements. * Life expectancy is ≤ 24 months. * The patient has an untreatable allergy to radiographic contrast material. * The patient is pregnant. * In the opinion of the operating physician, the patient's hemodialysis access circuit is unsuitable for endovascular treatment. * The patient's access is planned to be abandoned within 1 year. * The patient has indwelling catheters (dialysis, pacemakers, ports). * The patient has a central vein stent that would lead to jailing of the internal jugular vein. * The patient experiences angioplasty-induced venous rupture. * The patient has a flow limiting dissection after angioplasty. * The patient's hemodialysis access is thrombosed.