This study is a retrospective, observational study that aims to include patients undergoing cardiac surgery. 1. Evaluate the preventive effect of ursodeoxycholic acid on post-cardiac surgery cognitive dysfunction over the past eight years. 2. Utilize the pre-existing preoperative and postoperative 24-hour plasma samples from previous studies to measure the levels of glycocalyx and its related regulatory factors. 3. Assess the clinical correlation between the measured parameters and patient outcomes.