Investigators enrolled 264 patients from February 2014 to February 2015, the principal inclusion criterion included CHF: left ventricular eject fraction (LVEF) <= 50%; moderate to severe CKD was diagnosed as an eGFR 15 to 59 mL/min per 1.73 m2, calculated via the abbreviated Modification of Diet in Renal Disease (MDRD) study equation from SCr obtained within 72 hours of enrollment, patients were scheduled to undergo diagnostic cardiac angiography or percutaneous coronary interventions. We randomly assigned eligible patients in a 1:1 ratio to either CVP guided therapy or a standard hydration administration protocol. Investigators used the same fluid type commercially available 0.9% sodium chloride in all patients. Investigators monitored the CVP by placing an 5-French catheter in the jugular vein. Investigators recorded the CVP with commercially available haemodynamic monitoring software. In the CVP guided group the fluid rate was adjusted according to the CVP as follows: 3 mL/kg/h for CVP lower than 6 mmHg, 1.5 mL/kg/h for pressure of 6-12 mmHg, and 1mL/kg/h for pressure higher than 12 mmHg. The control group was hydrated at 1 mL/kg per h. The fluid rate was set at the start of the procedure (before contrast exposure). Thus, both study groups received intravenous fluids for the same duration but at different rates. All study participants received intra-arterial Visipaque(320 mg I/ml; GE Healthcare) iso-osmolar contrast medium.