Inclusion Criteria:  Congenital cardiac patients (< 30kg) that have been consented to a planned cardiac surgery procedure requiring cardiopulmonary bypass at the IWK Health Centre. Patient or family consent to participate in the study.  Exclusion Criteria:  Patient or family refusal to participate. Known genetic syndrome with multi-organ abnormalities and immune dysfunction such as DiGeorge Syndrome, Trisomy 18 or 13, Noonan syndrome. Known immunodeficiency syndrome or bone marrow pathology. Severe liver disease with abnormal synthetic liver function tests.