Shunt thrombosis in pediatric patients undergoing staged cardiac reconstruction for cyanotic congenital heart disease

Three stage cardiac reconstruction is a common surgical procedure performed in children with complex cyanotic congenital heart diseases (CCHD) such as hypoplastic left heart syndrome (HLHS) and related single ventricle physiology. The perioperative period in these patients poses a unique challenge of concomitantly increased risk of bleeding and thrombosis. Thrombosis of systemic and cavo-pulmonary shunt/conduit (modified BT shunt, bidirectional Glenn and Fontan circulation) remains a leading cause of shunt failure and mortality. Acute shunt thrombosis usually needs emergent catheter-based intervention, such as balloon angioplasty, stent placement, surgical thrombectomy or local administration of thrombolytics. Judicious anticoagulation with unfractionated heparin (UFH) in the early postoperative period has been shown to decrease the risk of thrombosis, and also increases the likelihood of subsequent completion of staged Fontan reconstruction. Furthermore, these children remain at higher risk of thrombosis after systemic and cavo-pulmonary shunt placement for at least 3-12 months after the procedure. Prophylactic anticoagulation is generally recommended during that period. However, there is a paucity of evidence on anticoagulation beyond 12 months after the surgery. Here, we describe the unique risk factors for thrombosis in neonates, infants and children with CCHD who undergo staged cardiac reconstruction, and summarize the clinical presentation, diagnosis and management of shunt thrombosis.