The purpose of this study is to investigate the affects of ketamine use for anesthesia at the beginning of heart surgery on kidneys compared to the use of propofol.

Inclusion Criteria:

• Presenting for cardiac surgery at the Mayo Clinic in Rochester, Minnesota.
• Scheduled to undergo complex cardiac surgery with the use of cardiopulmonary bypass. Complex cardiac surgery will be defined as surgery involving more than one heart valve, redo-sternotomy procedures, or combined valvular and coronary artery bypass graft procedures (aortic repair not excluded if meets other criteria).

Exclusion Criteria:

• Left or right ventricular assist device implantation or explantation.
• Procedures not requiring cardiopulmonary bypass.
• Active infection or sepsis requiring antimicrobial therapy and/or vasopressor therapy (treated endocarditis is not excluded).
• Severe hepatic disease resulting in ascites.
• Pre-operative significant renal dysfunction including a baseline creatinine equal to or greater than 2 mg/dL or requiring dialysis.
• Immunosuppressive medication use (including current IV or oral steroids use, use of anti-rejection medications for transplant within 1 month, or chemotherapy within 6 months).
• Immunodeficiency syndrome including HIV/AIDS, leukemia, and multiple myeloma