Neonates, children with single ventricle congenital heart disease, and those undergoing multiple complex cardiac surgeries are at high risk of increased perioperative blood loss, and blood product transfusions. In addition, some of these patients will present an increased risk of postoperative thromboembolic complications. For a long time, bleeding management has been based on the empiric administration of different blood products (e.g. platelet concentrates, cryoprecipitates, and/or activated factor VII), topical hemostatic agents, and surgical manipulation. Recently, the use of viscoelastic tests (e.g. thromboelastography (TEG) or thromboelastometry (ROTEM)) increased, and allowed a better assessment of perioperative coagulopathy, and a more 'rational' treatment of bleeding. While TEG and ROTEM record the viscoelastic properties of whole blood by measuring mechanical impedance and related changes during clot formation, T2MR, a miniaturized, magnetic resonance-based diagnostic platform, measures how water molecules react in the presence of magnetic fields to evaluate a broad range of hemostasis measurements. In this study, we will prospectively collect demographic data, surgical characteristics, the amount of perioperative bleeding and blood product transfusion, results of laboratory assays, and postoperative outcomes (30-day follow-up or until discharge), with the aim to assess our current practice, and develop an algorithm-based approach for the administration of targeted blood product and pro-coagulant therapies. Our goals are: the reduction of blood product utilization, the reduction of the incidence of massive bleeding and postoperative thrombosis.

Inclusion Criteria:

• Neonates and infant patients (0 -12 months of age) undergoing complex cardiac surgical procedures
• cardiac surgery patient > 12 months of age who has previously undergone 2 or more sternotomies

Exclusion Criteria:

• child in a moribund condition (American Society of Anesthesiology (ASA 5)
• children with a hematological and/or oncological disease
• Jehovah witnesses
• If the child is only undergoing a patent ductus arteriosus (PDA) ligation or other procedures not considered at risk for thrombosis and/or bleeding or they do not provide consent for enrollment (e.g. Ventricular Septal Defect repair)

Neonates and infants undergoing cardiac surgery with cardiopulmonary bypass