Prevention of Contrast Renal Injury With Different Hydration Strategies

The study population will be recruited from subjects undergoing cardiac catheterization. Subjects will be randomized to one of two hydration protocols: 1. normal saline at 3 mL/kg for one hour prior to contrast exposure and 1.5 mL/kg/hr during and for four hours post procedure. 2. normal saline at 3 mL/kg for one hour prior to contrast exposure and then the fluid rate would be adjusted according to the left ventricular end diastolic pressure (LVEDP). The fluid rate based upon the LVEDP measurement is maintained during the procedure and for four hours post procedure. The LVEDP hydration strategy follows: (2A) \< 13 mmHg, 5 mL/kg/hr during and for four hours post procedure. (2B) 13-18 mmHg, 3 mL/kg during and for four hours post procedure. (2C) \> 18 mmHg, 1.5 mL/kg during and four hours post procedure. Renal function assessment will be made using standard laboratory measures post procedure.