(808) Single-Ventricle Coagulopathy and Microvesicles Generated From Cardiopulmonary Bypass Surgery

Introduction: Over ten percent of children develop thrombosis after cardiac surgery for congenital heart disease. Children with a single ventricle have the highest risk of thrombosis associated with increased length of the post-operative stay, neurological complications, and mortality. The purpose of this study is to understand the generation of prothrombotic microvesicles (MV) and thrombin generation in samples from children collected before, during, and after cardiopulmonary bypass surgery.

Methods: A prospective study assessed platelet microvesicles, platelet aggregation, coagulation, and thrombin generation in 21 children requiring cardiopulmonary bypass (CPB) surgery. Inclusion criteria included age between birth to five years of age and weight on day of surgery greater than three kilograms. Blood samples were centrifuged to platelet-free plasma samples collected at the start, end of cardiopulmonary bypass, upon arrival in the intensive care unit (ICU), and twenty to twenty-four hours after arrival in ICU. High-resolution flow cytometry measured platelet MV (PMV) using an antibody to glycoprotein IIIa (CD61) and phosphatidylserine. Calibrated automated thrombogram (CAT) and thromboelastogram measured thrombin generation and clot formation.

Results: Children with single ventricle physiology had increased levels of PMV, platelet aggregation, and d-dimer upon arrival to the ICU compared to children with a dual ventricle. Single ventricle had greater increase in peak thrombin (p=0.019) and d-dimer (p=0.029) than dual ventricle upon arrival to the ICU. Single ventricle samples had decreased time to peak thrombin generation than dual ventricle upon arrival to the ICU (p=0.007). Only single ventricle children had a weak but significant positive correlation between generation of PMVs (platelet MV) with peak thrombin (p=0.010) and ASPI platelet aggregation (p=0.034), R2 of 0.29 and 0.23, respectively.

Conclusions: Cardiopulmonary bypass surgery for single ventricle increases prothrombotic microvesicles greater than dual ventricle. Multicenter prospective studies are needed to prove if prothrombotic microvesicles can predict children at risk for thrombotic events.