Endothelial glycocalyx, the luminal structure of healthy vasculature, plays critical roles in regulation of inflammatory responses, vascular permeability, blood coagulation. It can be easily damaged by ischemia/reperfusion, hypoxemia, oxidative stress, endotoxin. Accordingly, the relationship between the shedding of endothelial glycocalyx and the prognosis of diseases such as diabetes mellitus, atherosclerosis, malignancy has been researched.

In cases of cardiac surgery, patients cannot help but be exposed to ischemia/reperfusion, oxidative stress which can damage endothelial glycocalyx. In this research, the investigators would like to discover the impact of perioperative shedding of the endothelial glycocalyx on the incidence of postoperative acute kidney injury in patients undergoing valvular heart surgery.

Syndecan-1, Heparan sulfate serve as biomarkers of glycocalyx degradation. Both biomarkers will be measured 2 times, before the anesthetic induction, and immediately after weaning from cardiopulmonary bypass, during the valvular heart surgery.

Postoperative acute kidney injury up to postoperative 48 hours, Composite morbidity and mortality up to postoperative 30 days will be checked.

Inclusion Criteria:

- Patients undergoing valvular heart surgery (>20 years old)

Exclusion Criteria:

• Emergency operation
• Aorta surgery (Graft replacement of Total arch or Descending thoracic aorta)
• Minimal invasive surgery
• Chronic kidney disease (eGFR<30mL/min/1.73m2) / Dialysis history
• Infective endocarditis
• Malignancy
• Patients who cannot give Informed consent (e.g. Illiterate, Foreigners)
• Patients who are already enrolled to another study than can affect the results

Patients undergoing valvular heart surgery (>20 years old)