Texas Children's Hospital / Baylor College of Medicine, United States
Abstract: Introduction Limited reports exist of acute myocardial infarction (AMI) in pediatric single ventricle patients and management strategies vary. We describe a 4-year-old male following Fontan palliation found to have a native aortic root thrombus in the early postoperative period resulting in AMI requiring thrombectomy, and severe RV failure requiring durable mechanical circulatory support (MCS).
Case Description This is a 4-year-old male with Hypoplastic Left Heart Syndrome (Mitral Stenosis, Aortic Stenosis) without overt history of hypercoagulability who most recently underwent Glenn palliation. Pre-Fontan catheterization demonstrated favorable hemodynamics but noted IVC stenosis requiring an intrahepatic IVC stent. He was admitted to the CICU following uncomplicated extracardiac, non-fenestrated Fontan with unchanged moderate tricuspid regurgitation and mildly depressed RV systolic function. Bivalirudin was started for the IVC stent as a bridge to Warfarin. During anticoagulant transition, there was a profound Warfarin effect (peak INR 5.4) that may have induced an early and acute prothrombotic state augmented by ongoing liver dysfunction.
Echocardiogram on POD#4 showed thrombus in the native-aortic root. Cardiac CT angiography (CTA) demonstrated a 2.5 x 2.0 mm thrombus in the native aorta occluding the left main coronary artery. Head CT and head and neck CTA were unremarkable. He underwent emergent cardiac catheterization where aortic root angiography showed complete occlusion of the left coronary artery. Tissue plasminogen activator (TPA) was infused directly into the aortic root without improvement. Therefore, thrombectomy was performed. Post-intervention angiography revealed a widely patent left coronary artery.
Despite angiographic improvement in coronary patency, RV systolic function remained severely depressed. On POD#6 due to worsening end organ perfusion he was taken to the OR for durable MCS with 25mL Berlin ventricular assist device (VAD) and surgical thrombectomy of a remaining aortic root thrombus. Kidney and liver function normalized with Berlin VAD, and coagulopathy improved with ongoing management on Bivalirudin. He continues to be well supported on Berlin VAD awaiting myocardial recovery with transplant as a backup option.
Discussion There is no standardized management of AMI in pediatric patients. This case focused on percutaneous thrombolysis with localized TPA, followed by thrombectomy, and systemic anticoagulation using Bivalirudin. Others have reported management with systemic anticoagulation using various agents, systemic thrombolysis, percutaneous local nitroglycerin injection following thrombectomy, and coronary artery stent placement. Our case presents Berlin VAD as a long-term MCS option for pediatric patients following AMI as a bridge to myocardial recovery vs. transplant. This case emphasizes cautious use of anticoagulation in Fontan patients with liver dysfunction due to their risk of developing thrombi.
