Cardiac Surgery With Cardiopulmonary Bypass

The purpose of this research is to learn more about how renin (a blood test) is affected by cardiopulmonary bypass, the heart-lung machine used during open heart surgery. Renin is a protein that may be elevated in response to low blood pressure or situations where organs do not receive sufficient oxygen. Renin may potentially be used as an indicator for specific treatments aimed to increase the blood pressure. This study will evaluate blood samples for renin concentration throughout the course of open heart surgery.

The goal of this clinical trial is to learn if giving inhaled nitric oxide during heart surgery can prevent acute kidney injury (AKI) in patients who are at high risk of developing this complication. AKI is a serious problem after heart surgery and can lead to longer hospital stays, higher costs, and increased risk of death or long-term kidney disease. Currently, there is no effective medicine to prevent AKI after heart surgery. The main questions it aims to answer are: * Does inhaled nitric oxide reduce the chance of developing AKI within 7 days after heart surgery compared to placebo? * Does inhaled nitric oxide help preserve kidney function up to 90 days after surgery? Researchers will compare inhaled nitric oxide (the device is turned on) to a placebo (the same device is connected to the breathing circuit but not turned on, so no nitric oxide is given). The device panel is covered so that both participants and the research team do not know who receives active treatment or placebo (double-blind). Participants in this study will: * Have the nitric oxide device connected to their breathing circuit during heart surgery; they will receive either active nitric oxide or no nitric oxide (device off) * Provide blood and urine samples to test kidney function during and after surgery * Be followed for 90 days after surgery to monitor kidney health and any side effects

This prospective, randomized controlled study is aimed to figure out suitable transfusion threshold in patients undergoing cardiac valve surgery under cardiopulmonary bypass(CPB). Patients are randomly assigned to restrictive and liberal transfusion group and receive blood transfusion during and after surgery. Compare primary and secondary outcomes of two groups.