Blood and urine samples of over 200 pediatric subjects (over 28 days to 3 years) undergoing complex cardiac surgery with cardiopulmonary bypass (CPB) will be collected at several time points to measure corresponding biomarkers such as serum creatinine, serum urea concentration, or NephroCheck test ([TIMP-2]*[IGFBP7) to evaluate the diagnostic performance of AKI by NephroCheck test .](streamdown:incomplete-link)

At least 200 subjects having undergone pediatric cardiac surgery with cardiopulmonary bypass (CPB). Enrollment will continue with a maximum of 350 subjects until 30 cases of AKI (stage 2 and 3) are reached.

Blood and urines samples will be collected at several time points to measure biomarkers and set up a biobank.

The samples used within the scope of this protocol will be fresh urine samples (1 to 2 ml) and blood samples.

Urine samples for [TIMP-2]*[IGFBP7] measurements will be taken from each subject included in the study during the first 48 hours following cardiopulmonary bypass initiation according to the following schedule:

• baseline before initiation of cardiopulmonary bypass (CPB, 0h).
• - 2h, 4h, 6h, 8h, 12h, 24h, 48h after initiation of CPB

Blood samples for serum creatinine and urea concentration measurement will be taken from each subject included in the study during the first 48 hours following cardiopulmonary bypass initiation according to the following schedule:

• baseline before initiation of cardiopulmonary bypass (CPB, 0h).
• 12h, 24h, 48h, 60h after initiation of CPB

Primary objective:

To evaluate the proportion of subjects predicted to be at risk of AKI (stage 2 and 3) using at least one measurement of NephroCheck in subjects having undergone pediatric cardiac surgery.

Secondary objectives:

• To evaluate the incidence of AKI (stage 2 and 3) according to the KDIGO guideline
• To study the kinetic profile of cell cycle arrest biomarkers (TIMP-2*IGFBP-7) during the first 48 hours in subjects having undergone pediatric cardiac surgery
• To determine the baseline values of [TIMP-2]*[IGFBP7] in the targeted population before surgery
• To determine profile differences of [TIMP-2]*[IGFBP7] between AKI (stage 2 and 3) and non-AKI groups
• To evaluate the diagnostic performances of [TIMP-2]*[IGFBP7] to predict AKI after pediatric cardiac surgery using a cut-off value of 0.3

Inclusion Criteria:

• Must sign the consent form
• Clinical diagnosis of complex congenital heart surgery (Risk Adjusted classification for Congenital Heart Surgery [RACHS] score >=2)
• Must undergo elective cardiac surgery with CPB

Exclusion Criteria:

• Clinical diagnosis of severe pre-existing renal insufficiency (SCr >2 times age-adjusted normal range)
• Significant abnormalities of the kidneys or genitourinary tract

At least 200 subjects having undergone pediatric cardiac surgery with cardiopulmonary bypass (CPB). Enrollment will continue with a maximum of 350 subjects until 30 cases of AKI (stage 2 and 3) are reached.