Contrast-Induced Nephropathy (CIN) can occur when patients with pre-existing kidney problems undergo procedures that use iodinated contrast media, such as cardiac catheterizations. RenalGuard Therapy was developed to enable the patient to clear the contrast out of their kidney before it can do significant damage. This study aims to enroll patients with increased risk of developing CIN who are scheduled for a cardiovascular catheterization. Patients will be randomized to either RenalGuard therapy or standard therapy.