ABSTRACT
Background Patients with hypoplastic left heart syndrome (HLHS) undergo a Fontan procedure as part of single ventricle surgical palliation. Post-Fontan, sluggish blood flow and an imbalance in coagulant factor proteins may predispose to thrombus formation. Other risk factors may include chylothorax as well as acute and chronic inflammation. Currently, there is no standardized surveillance strategy to detect thrombus in Fontan patients. Case A 34-month old male with HLHS underwent an extracardiac non-fenestrated Fontan complicated by chylothorax treated with 5 days of IV steroids and diuretics. He was on therapeutic aspirin. After progressive worsening of right pleural effusion, a chest tube was placed three weeks post-Fontan with continued chylous output. Stool alpha 1 antitrypsin was negative. Decision-making Given persistent chylothorax, a repeat echocardiogram was performed revealing a large mass in the Fontan circuit less than one month post-op. Cardiac CT showed occlusive thrombus filling the entirety of the Fontan conduit extending into hepatic veins and bilateral pulmonary arteries. He underwent extensive surgical thrombectomy and Fontan conduit revision. Hypercoagulable work-up revealed elevated factor 8 and von Willebrand factor activity which persisted more than one month post-op. Patient's history was also significant for COVID-19 infection 6 months prior. He was initially anticoagulated with bivalirudin with tirofiban initiated for antiplatelet therapy. He was ultimately transitioned to rivaroxaban, pentoxifylline and aspirin with chylothorax resolution over one month without thrombus recurrence. Conclusion Development of risk stratification tools to identify patients at higher risk for thrombi formation post-Fontan may facilitate patient selection for more aggressive anticoagulation. Consideration of elevated factor 8 as well as persistent or recurrent chylothorax may be beneficial, as increased thrombosis risk has been reported for both conditions in Fontan patients.Copyright © 2023 American College of Cardiology Foundation
ABSTRACT
Background: Ascending aortic thrombus is rare in children without history of trauma, hypercoagulable condition or vascular disease and carries a high mortality risk necessitating rapid identification and management. Aim(s): We aim to present the clinical course for a rare pediatric case. Method(s): We reviewed the medical record for a child with recurrent life-threatening thrombi. Result(s): A 12-year old previously healthy male presented with chest pain. ECG revealed ST segment elevation. Echocardiography revealed an ejection fraction of 25% and a mobile mass (10 x 20 mm) in the ascending aorta. COVID testing was negative. Troponin-I was elevated. He was emergently placed on cardiopulmonary bypass where a large organized thrombus was removed. The left anterior descending coronary artery was occluded. He underwent intracoronary tPA, aspiration thrombectomy and balloon angioplasty. Hypercoagulable and autoimmune work-up revealed elevated factor 8 activity, von willebrand factor (vWF) activity and thrombocytosis with increased function by viscoelastic testing (ROTEM). Myocarditis, cardiogenetics and genetic testing for thrombophilia were negative. He was discharged on heart failure therapy, triple anti-platelet therapy (aspirin, clopidogrel, dipyridamole) and apixiban. He underwent a heart transplant 5 months later. Three weeks post-transplantion, he was incidentally found to have a large left atrial thrombus. At this time, he was only on aspirin. Factor 8 activity at time of transplant and second thrombus discovery was >400%. vWF activity and platelet count were also elevated. ROTEM revealed elevated platelet and fibrinogen activity. He underwent left atrial thrombectomy and was restarted on triple antiplatelet therapy and apixiban. He has not had recurrence on this regimen for 8 months. Conclusion(s): Thrombocytosis and elevated pro-inflammatory coagulation factors may predispose to development of potentially fatal thrombi. Besides inflammation, etiology may be unknown, particularly in apparently healthy children, prompting additional research into potentially genetic conditions in these complex pathways to further elucidate patients at risk.