• Age greater than 28 days and less than 85 years
• Planned complex cardiac surgery with planned use of cardiopulmonary bypass
• Expected order for washed or volume reduced platelets
• Patient with known anti-platelet antibodies
• Platelet transfusion refractoriness due to anti-HLA antibodies
• Known or suspected pregnancy
• Previously randomized in this study
• Conscious objection or unwillingness to receive blood products
• Known IgA deficiency
• Known congenital platelet disorder
• Known congenital bleeding disorder
• Planned post-operative extracorporeal membrane oxygenation (ECMO), ventricular assist device (VAD), and/or continuous renal replacement therapy (CRRT)/ hemodialysis
• Patients intended to receive whole blood either intra-operative or post-operative for bleeding
• Platelet transfusion (of any type) within 24 hours prior to the date of surgery
• Pre-operative thrombocytopenia, defined as platelet count <75x10(9)/L, based on the most recent labs completed within 72 hours prior to the date of surgery.

• Patients, parents, or legal guardian willing and able to sign informed consent
• Male and female subjects aged ≤18 years of age (females of child-bearing potential willing to practice an acceptable form of birth control)
• Patients undergoing cardiopulmonary bypass for repair of a large unrestrictive ventricular septal defect, an ostium primum/secundum atrial septal defect, or a partial or complete atrioventricular septal defect
• Pre-operative echocardiogram confirming cardiovascular anatomy and defect to be repaired
• Evidence of pulmonary artery or vein abnormalities that will not be addressed surgically. Specific abnormalities excluded include:
• significant pulmonary artery narrowing not amenable to surgical correction
• previous pulmonary artery stent placement
• significant left sided AV valve regurgitation not amenable to surgical correction
• pulmonary venous return abnormalities not amenable to surgical correction
• pulmonary vein stenosis not amenable to surgical correction
• Preoperative requirement for mechanical ventilation or IV inotrope support
• Presence of fixed or idiopathic pulmonary hypertension (i.e. Eisenmenger's Syndrome) prior to surgical repair
• Pre-operative use of medications to treat pulmonary hypertension
• Pregnancy; Sexually active females of child-bearing potential must be willing to practice an acceptable method of birth control for the duration of study participation (e.g. oral contraceptive, hormonal implant, intra-uterine device)
• Participation in another clinical trial within 30 days of Screening or while participating in the current study, including the 28 days of follow-up post study drug administration.
• Any condition which, in the opinion of the investigator, might interfere with the study objectives