 This will be a retrospective review of data collected between 1998 and present nearly 900 patients on adult patients having had ascending aorta and or aortic arch surgery at the NewYork Presbyterian Hospital. Data on demographics, preoperative, intraoperative, and postoperative clinical events will be extracted from the patients electronic record and recorded on a database Variables to be collected are presented in Appendix 1. A renal event will be comprised of renal dysfunction; defined by a serum creatinine level of at least 2.0 mgdL 177 μmolL, accompanied by an increase of at least 0.70 mgdL 62 μmolL from baseline or renal failure; defined need for renal replacement therapy. Creatinine values and creatinine clearance will be recordedcalculated preoperatively and postoperatively until hospital discharge. 