 Measurements: The investigators will analyze serum platelet markers by enzyme-linked immunosorbent assay ELISA and the characteristic changes in membrane protein expression by multicolor Fluorescence-activated cell sorting FACS. Corresponding platelet counts will be determined at each time point. Aspirin medication is given until the day of surgery and again starting on postoperative day 2 as standard of care. Because aspirin resistance may influence our outcomes, the investigators will measure 11-dehydrothromboxane B2 urine levels. Ensuing subgroup analysis will establish the relevance of aspirin resistance to our observations. Systemic inflammation will be examined by determining the plasma cytokine levels by ELISA. As an additional arm of investigation the investigators will collect patient DNA and platelet RNA to further examine the genomic characteristics and platelet gene expression profiles associated with an enhanced platelet activation during surgery. This data will inform further studies in personalized identification of risk factors for patients undergoing cardiac surgery. 