Primary endpoint: To evaluate predictive value of plasmatic levels of Neutrophil Gelatinase Associated Lipocalin (NGAL) to reveal acute kidney failure after cardiac surgery in patients with preoperative chronic kidney failure Secondary endpoint is to obtain threshold values of NGAL.

(N/A)

Inclusion Criteria:

• Renal clearance less than 60 mL/min
• Able to give written consent
• Elective valve surgery
• Elective CABG surgery

Exclusion Criteria:

• Less than 18 years old
• Iodine injection within 3 days before surgery
• Iodine injection within 24 first postoperative hours
• preoperative infection
• evolutive cancer disease
• Refusal
• Pregnancy
• Unable to give written consent

Patients with a chronic kidney failure, undergoing cardiac surgery.