Viscoelastic hemostatic assay has been reported to be superior to predict perioperative bleeding in cardiac surgical patients compared with conventional blood coagulation test. However, the role of rotational thromboelastometry (ROTEM) in predicting perioperative bleeding and transfusion requirements in pediatric patients who undergoing surgery for congenital heart disease. Therefore, the investigators attempt to evaluate the predictability of intraoperative rotational thromboelastometry for perioperative bleeding and transfusion requirements in pediatric cardiac surgical patients by comparing with conventional coagulation test. The investigators also attempt to evaluate the correlation between ROTEM parameters, platelet count, and results of conventional coagulation test results.

Viscoelastic hemostatic assay has been reported to be superior to predict perioperative bleeding in cardiac surgical patients compared with conventional blood coagulation test. However, the role of rotational thromboelastometry (ROTEM) in predicting perioperative bleeding and transfusion requirements in pediatric patients who undergoing surgery for congenital heart disease. Therefore, the investigators attempt to evaluate the predictability of intraoperative rotational thromboelastometry for perioperative bleeding and transfusion requirements in pediatric cardiac surgical patients by comparing with conventional coagulation test. The investigators also attempt to evaluate the correlation between ROTEM parameters, platelet count, and results of conventional coagulation test results.

Inclusion Criteria:

• pediatric patients (< 10 years) who underwent surgery for congenital heart disease with cardiopulmonary bypass in 2013 at Samsung Medical Center

Exclusion Criteria:

• incomplete data about blood loss count or transfusion requirements during seven days after surgery

pediatric patients who underwent surgery for congential heart disease with cardiopulmonary bypass