Inclusion Criteria:  ASA Ⅱ - Ⅲ; No cognitive impairment was assessed one day before surgery; Patients undergoing elective heart valve replacement under CPB and signed informed consent.  Exclusion Criteria:  Non-CPB surgery, macrovascular surgery, heart transplantation, correction of congenital heart disease; Stroke, schizophrenia, depression, Parkinson's disease, epilepsy or dementia; Inability to communicate with language impairment or major hearing or visual impairment; Liver function child-pugh Grade C, severe liver dysfunction; Severe renal insufficiency requires preoperative renal replacement therapy; A past history of intraoperative knowledge.