To observe the effect of RIPC on the function of vital organs after cardiac surgery, and to explore its possible mechanism.

Inclusion Criteria:

• patients with aortic valve, mitral valve, tricuspid valve, ascending aortic disease and coronary atherosclerosis who were admitted to hospital for elective valve repair, replacement, artificial vascular replacement or coronary artery bypass grafting.
• age 18-80 years old.
• No restriction on gender.
• ASA grade II~III.
• NYHAII~III level.
• the patient or his family member has signed the informed consent form for the clinical trial

Exclusion Criteria:

• those who are disabled in the selected test.
• less than 5 years of education.
• The preoperative left ventricular ejection fraction ((LVEF)) was less than 40%.
• Myocardial infarction occurred in nearly one month.
• malignant tumor, hematological disease, severe liver and kidney dysfunction, recent severe infection, etc.
• History of nervous system, immune system and mental illness.
• recent operation history of heart, brain, lung, liver, kidney and other important organs