- Group Dexmedetomidine (Group DEX): During bypass, patients in this group will receive propofol infusion 50 - 70 mcg/kg/min plus dexmedetomidine infusion 0.5 mcg/kg/hr Patients and investigators performing the study and assessing its outcomes will all be blinded to the study group allocation. The study drugs will be prepared by a separate investigator not involved in either study performance or analysis.