Contrast Nephropathy and Nitrates

The Contrast Nephropathy and Nitrates trial (CoNaN) is a single center, randomized, 1 x 1 factorial clinical trial designed to test the effects of intravenous nitroglycerin infusion in renal function given prior to PCI. Specific aims for this trial include: * To determine whether the intravenous nitrates have any effect on the glomerular filtration rate (GFR) after the exposure to contrast media. * To determine if intravenous nitroglycerin will decrease the incidence of contrast induced Nephropathy. 400 patients with a Mehran score of \> 6 and a pre-procedural creatinine measurement will be enrolled. Following baseline assessments, patients will be randomly assigned to receive intravenous infusion nitroglycerine plus intravenous normal saline or normal saline only. Subjects will participate in this study from the time they sign consent (prior to angiographic procedure), until 48-72 hours post procedure.