Lysine analogs, like tranexamic acid (TXA) or epsilon aminocaproic acid (EACA), are antifibrinolytic agents routinely administered in children undergoing different surgeries associated with a high bleeding risk (e.g. cardiac, craniofacial, and orthopedic surgeries). Although there is a growing literature regarding the pharmacokinetic characteristics of these drugs in children, the plasmatic concentration required to completely inhibit fibrinolysis remains to be determined. In this in vitro study, the investigators will use an experimental model of fibrinolysis designed for rotational thromboelastometry (ROTEM®) to determine the minimal concentration inhibiting fibrinolysis for both TXA and EACA. In addition, this study will be used to create and validate a new experimental assay to measure fibrinolysis and the effect of antifibrinolytic agents.

Inclusion Criteria:

• infants between 2 months of age and equal to or less than 12 months of age
• weigh over 5.0 kg
• either have CHD and are scheduled to undergo an elective cardiac catheterization lab procedure or do not have CHD and are scheduled to undergo a non-cardiac surgery (such as craniofacial surgery, neurosurgery, or orthopedic surgery) in the operating room

Exclusion Criteria:

• undergoing an emergent procedure,
• child in a moribund condition (American Society of Anesthesiology (ASA 5)
• children with a hematological and/or oncological disease
• Jehovah witnesses
• children with preoperative coagulopathy, defined as a platelet count < 100,000/μL, fibrinogen level < 100 mg/dL, prothrombin time (PT) and activated partial thromboplastin time (PTT) > 1.5 normal range

This is a prospective in vitro study being performed on whole blood obtained from two groups of infants. The first group will include infants with congenital heart disease (CHD) who are scheduled to undergo an elective cardiac catheterization lab procedure at Boston Children's Hospital. The second group will include infants who do not have congenital heart disease (No-CHD) and are scheduled to undergo a non-cardiac surgery (such as craniofacial surgery, neurosurgery, or orthopedic surgery) in the operating room at Boston Children's Hospital.