A Prospective, Multi-center, Single Arm Study Evaluating the Express™ Renal Premounted Stent System in the Treatment of Atherosclerotic Lesions in the Aortorenal Ostium.

Inclusion Criteria: * Eligible for PTRA and stenting. * One or more of the following: (1-3) * Hypertension * Recurrent "flash" pulmonary edema out of proportion to any impairment of left ventricular function * Renal Dysfunction * Single, de novo, or restenotic (from prior PTRA) atherosclerotic lesion in the ostium of the renal artery * Lesion involving the aortorenal ostium or the leading edge of the stenosis is located within 5 mm of the opacified aortic lumen * Renal Artery Stenosis: bilateral renal artery stenosis (one stent for one lesion in each renal artery) or unilateral renal artery stenosis, including a solitary functioning kidney Exclusion Criteria: * Any previous or planned, surgery or percutaneous intervention ≤30 days prior to or after index procedure * Advanced renal disease: serum creatinine \> 3.0 mg/dl * End stage renal disease requiring dialysis; or previously diagnosed ephrosclerosis * Recent vascular event ≤30 days pre-procedure (i.e. acute coronary syndrome, decompensated heart failure, transient ischemic attack or stroke.) * Documented allergy or reaction to iodinated contrast media, including laryngeal edema, convulsions, profound hypotension,unresponsiveness, cardiopulmonary arrest, and clinically manifest arrhythmias (a mild allergy to contrast media that can be pretreated with medication is acceptable) * Documented allergy to heparin, acetylsalicylic acid (ASA) or clopidogrel * NYHA Class IV * Bleeding diathesis * Thrombocytopenia (platelets \< 100,000/mm3) * Renal atrophy (renal length ≤ 8 cm determined by renal ultrasound) * Patients requiring immunosuppressive therapy * Renal allograft * Stenosis location in a vascular graft or in a transplant artery Angiographic Exclusion * Total occlusions * Thrombus containing lesion * Prior treatment of target lesion with stent (in-stent restenosis) * More than one (1) lesion in target vessel * Non-atherosclerotic stenosis (fibromuscular dysplasia) * Excessive vessel tortuosity * Lesion involving a side-branch * Lesion in accessory renal artery * Abdominal aortic aneurysm \> 3.5 cm * Perforated vessels evidenced by extravasation of contrast media