Non-pharmacologial, Non-invassive Intervention Before Cardiac Surgery: a Randomized Controlled Trial

Perioperative neurological complications in cardiovascular surgical procedures are associated with a significant risk of mortality and disability. The goal of this clinical trial is to learn if ischemic preconditioning and transcranial electrical stimulation to reduce perioperative neurological complications. It will also learn about the safety of remote ischemic preconditioning and transcranial electrical stimulation before cardiac surgery. The main questions it aims to answer are "Do remote ischemic preconditioning and transcranial electrical stimulation make good effect on perioperative neurological complications?" "Are remote ischemic preconditioning and transcranial electrical stimulation safe?" Researchers will compare remote ischemic preconditioning and transcranial electrical stimulation to traditional treatment to see if remote ischemic preconditioning and transcranial electrical stimulation work to reduce perioperative neurological complications. Participants will:Undergo remote ischemic preconditioning and transcranial electrical stimulation or sham treatment twice every day for 3 days before surgery. Undertake psychological assessment and clinical symptom follow-up after cardiac surgery.