Post-operative Anticoagulation Strategy Following Comprehensive Stage 2 Procedure for Single Ventricle Physiology.

Thrombosis, especially thrombosis of the pulmonary artery, is a large contributor to morbidity and mortality following comprehensive stage 2 procedure for single ventricle cardiac physiology. A peri-operative management protocol was implemented at our institution in March 2010. It includes 6 weeks of therapeutic anticoagulation post-operatively to mitigate the thrombotic risks in this patient population. This is a retrospective study of hospitalized children who received post-operative anticoagulation following a comprehensive stage 2 procedure for single ventricle cardiac physiology at a free-standing children's hospital. The primary objectives are to describe our institution's anticoagulation strategy and report on the number of thromboses and major bleeding episodes in the 6 weeks post-operatively. Secondary objectives include the dose of enoxaparin required to obtain a therapeutic low-molecular weight anti-factor-Xa (AFXaLMWH) level, and the number of patients outside of the therapeutic range. A total of 71 infants were included in the final analysis. Four patients experienced a thrombosis episode and three patients experienced clinically significant bleeding. The mean dose of enoxaparin required to obtain a therapeutic AFXaLMWH level between 0.5-1 unit/mL was 1.23 mg/kg SQ every 12 h and 37% of patients achieved goal AFXaLMWH levels with the initial starting dose of enoxaparin 1 mg/kg SQ every 12 h. We describe a 9-year experience of anticoagulation after single ventricle palliation. Anticoagulation with therapeutic AFXaLMWH goals of 0.5-1 unit/mL may reduce the rates of clinically significant thrombosis post-operatively in this population and appears safe without increase in significant bleeding episodes when compared to a historical cohort. Further studies comparing this population to those who do not receive post-operative anticoagulation are warranted.

Enoxaparin Dose Requirements to Achieve Therapeutic Low-molecular-weight Heparin Anti-factor Xa Levels in Infants and Young Children.

INTRODUCTION: Enoxaparin is commonly used to treat pediatric thrombosis. Several small retrospective studies have suggested that infants and young children require higher enoxaparin doses to achieve therapeutic anti-factor Xa levels compared with adults. MATERIALS AND METHODS: This is a retrospective study of hospitalized children who received enoxaparin for the treatment of thrombosis at a free-standing children's hospital. The primary objective was to ascertain the enoxaparin dose required to achieve an anti-factor Xa level of 0.5 to 1.0 U/mL among 4 age groups in a large cohort of infants and young children between 60 days and 5 years of age. RESULTS: A total of 176 infants and children were evaluated. The majority of patients were less than 1 year of age (n=104). An inverse relationship between enoxaparin dose needed to achieve therapeutic anti-factor Xa levels and patient age was noted, particularly in the first year of life. Patients who were 60 days to less than 7 months at the time of enoxaparin initiation (n=73) required the highest mean dose among the age groups at 1.73 mg/kg subcutaneously every 12 hours (P<0.0001). CONCLUSION: Infants and young children require higher doses of enoxaparin to achieve therapeutic anti-factor Xa levels compared with adults.