Staged mechanical circulatory support in paediatric HIT: Bivalirudin anticoagulation across ECMO, VAD, and cardiac transplantation

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IntroductionHeparin induced thrombocytopenia (HIT) with in paediatric population is rare and subsequent anticoagulation management is challenging. Bivalirudin is a viable alternative to heparin for anticoagulating paediatric patients with HIT, though clinical data are limited. We describe the successful management of anticoagulation with bivalirudin from diagnosis through Extracorporeal Membrane Oxygenation (ECMO), Ventricular Assist Device (VAD) implantation, and heart transplantation in a child with dilated cardiomyopathy and HIT.MethodsA 14-year-old girl presented with acute heart failure, intracardiac thrombi, and adenovirus positivity. Heparin was exchanged for bivalirudin once HIT criteria were met, associated with thrombocytopenia and progressive thrombus formation within the right atrium and superior vena cava (SVC). Due to end-organ dysfunction and refractory cardiac failure veno-arterial ECMO was initiated. Failure to achieve sufficient recovery prompted a VAD implantation, and subsequent orthotopic heart transplantation both managed using a modified bivalirudin protocol.ResultsManaging ECMO in the presence of HIT and intracardiac thrombi required careful multidisciplinary planning. We adjusted the bivalirudin infusion from 0.35 to 1.9 mg/kg/hr to maintain an activated Partial Thromboplastin Time (aPTT) of 60-90 s, following our institutional protocol. For VAD implantation, we used citrate for circuit priming and initiated cardiopulmonary bypass without heparin, administering six bivalirudin boluses and escalating the infusion from 1.62 to 10 mg/kg/hr to achieve an Activated Clotting Time (ACT) > 400 s, with continuous ACT monitoring. During transplantation, anticoagulation involved four boluses and increasing the infusion from 0.35 to 5 mg/kg/hr to maintain an ACT >400 s. Despite significant post-CPB coagulopathy, which required delayed chest closure to control bleeding, no thrombotic events occurred. The bivalirudin protocols allowed safe progression through all three phases.ConclusionBivalirudin strategy provided safe, effective antithrombotic management across ECMO, VAD implantation, and heart transplantation in a paediatric patient with HIT. Monitoring its effectiveness at higher anticoagulation levels remains challenging, and patients may require higher doses to achieve desired endpoints.

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