Patients at moderate and high risk for contrast induced nephropathy (CIN) should receive sufficient hydration before application of contrast to prevent CIN, but hydration could obviously increase the preload for congestive heart failure (CHF) patients. Isosorbide Dinitrate could reduce cardiac preload and afterload by expanding vein and artery.so adequate hydration therapy combined with intravenous infusion of isosorbide dinitrate could better prevent contrast-induced nephropathy theoretically.This prospective, randomized, double-blind, comparative clinical trial randomly selected 264 patients with estimated glomerular filtration rate, (eGFR) <60 ml/min per 1.73 m2 and CHF undergoing coronary angiography to receive either the convention hydration (n=200) or the hydration therapy combined with intravenous infusion of isosorbide dinitrate(n=200).