- 1. Age: 18 to 75 years old; Gender: not limited; 2. Diagnosis for coronary heart disease or valvular heart disease, and patients scheduled for elective surgery; 3. Body mass index (BMI): 18<BMI≤31 kg.m-2; 4. American Society of Anaesthesiologists (ASA) physical status classification: Ⅰ-Ⅲ; 5. Signing informed consent; 6. CABG or valve operation performed for the first time.