P2.100: Guidance from a Gallop: Pulmonary Artery Thrombus in an Infant with Septic Shock

Introduction: Pulmonary thromboembolism (PTE) is a rare but life-threatening condition in infants, with a mortality rate up to 26% under one year of age. Risk factors include inherited thrombophilias, systemic insults such as infection and liver disease, maternal exposures, and indwelling intravascular catheter use. We present an unusual case of PTE in a full-term infant highlighting the rapid, multidisciplinary approach needed to diagnose and manage this condition.

Case Description: A 7-week-old girl with history of in-utero HIV exposure presented to the emergency room with symptoms of a diarrheal illness, feeding intolerance, and weight less than her birth weight. She was admitted to the PICU for a sepsis workup in the setting of hypothermia and hypoxia. On day 2 she was noted to have an S3/S4 gallop, prompting an echocardiogram which revealed an echogenic mass in the right main pulmonary artery causing partial flow obstruction, right atrial dilation, and an ASD with right-to-left shunting. Due to Acinetobacter nosocomialis bacteremia, she was managed as infective endocarditis with possible septic embolization. She achieved therapeutic anticoagulation with bivalirudin and underwent mechanical thrombectomy, main pulmonary artery and SVC patch plasty, PFO closure, and PDA ligation via median sternotomy. Following the procedure, she was transitioned to enoxaparin for long-term anticoagulation and discharged with plans to complete a six-week antibiotic course. An inherited hypercoagulability workup was unremarkable. Causes of the thrombotic event were multifactorial with contributions from sepsis, dehydration, and endothelial injury.

Discussion: Infants may be at increased risk for PTE due to an immature anticoagulation system which reaches maturation around six months of age. Depending on cardiorespiratory compromise and the extent of thrombosis, management may include fibrinolytics, anticoagulation, or surgical intervention. Our patient was treated as a symptomatic DVT per the 2018 American Society of Hematology guidelines. Bivalirudin was used due to heparin failure, and she successfully underwent mechanical thrombectomy with measures to correct her PFO and open PDA to reduce further risk of thrombosis.

Conclusion: Early recognition and timely surgical intervention of PTE are essential for optimizing patient outcomes and preventing life-threatening complications. Further research is needed to better understand the underlying risk factors, improve early diagnostic strategies, and enhance treatment approaches for this rare but serious condition.