Surgeons Save Infant From Massive Saddle Pulmonary Embolism in Rare Case

A thirteen-month-old girl who arrived at a Florida emergency department with what seemed like a routine viral illness and some alarming but vague episodes ended up at the center of one of the rarest medical emergencies in pediatric medicine. Clinicians at AdventHealth Orlando and Nemours Children’s Hospital in Florida report that the otherwise healthy infant had developed a massive saddle pulmonary embolism — a clot straddling the main artery that carries blood from the heart to both lungs — together with clots in her inferior vena cava and hepatic veins, and right-sided heart failure known as cor pulmonale. The case, published as an open-access case report in BMC Pediatrics, describes how rapid imaging, anticoagulation, and an emergent surgical embolectomy saved her life, and it carries a message that the authors hope will change how physicians think about shock in babies.

The story began with symptoms that could easily have been dismissed. The infant had recently experienced upper respiratory symptoms and seizure-like activity, which her care team considered might represent gastroesophageal reflux, breath-holding spells, a brief resolved unexplained event, or another non-epileptic event. None of these possibilities pointed toward a vascular catastrophe. What changed the trajectory was the acute onset of vomiting and hypotension — a sudden drop in blood pressure that signaled something far more dangerous than a minor infection. In an infant, hypotension is a red flag that demands an immediate search for a cause, and the team escalated their diagnostic workup accordingly.

The first decisive clue came from an abdominal ultrasound, a noninvasive imaging study that uses sound waves to visualize organs and blood vessels. Instead of the expected findings, the sonographers identified thrombus — a blood clot — within the inferior vena cava, the large vein that returns deoxygenated blood from the lower half of the body to the heart. This discovery transformed the clinical picture. A clot in the inferior vena cava is not merely a local problem; it sits directly upstream of the heart and lungs, and any fragment that breaks loose can travel with the venous blood flow into the pulmonary arteries, where it can abruptly block circulation.

To define the full extent of the disease, the team turned to computed tomography angiography, a technique in which intravenous contrast dye is imaged with a CT scanner to map blood vessels in exquisite detail. The scan revealed a massive saddle pulmonary embolism, so named because the clot straddles the bifurcation where the pulmonary artery splits into the left and right branches, obstructing blood flow to both lungs simultaneously. In adults, saddle emboli are recognized as among the most dangerous forms of venous thromboembolism; in infants, they are exceedingly rare, particularly in children with no known predisposition to hypercoagulability, meaning no identifiable condition that makes the blood abnormally prone to clotting.

Echocardiography — ultrasound of the heart — confirmed the downstream consequence: cor pulmonale, or failure of the right ventricle. The physiology is straightforward but unforgiving. The right ventricle is a relatively thin-walled pump designed to push blood through the low-resistance pulmonary circulation. When a large clot suddenly blocks the pulmonary arteries, the pressure the ventricle must generate skyrockets, and the infant heart, unlike the adult heart, has limited reserve to compensate. Blood backs up, cardiac output falls, and the patient spirals toward cardiovascular collapse. Recognizing this, the clinicians anticoagulated the infant with heparin, a fast-acting blood thinner that prevents clot propagation, and transferred her to a higher level of care with cardiac surgical services available.

Despite anticoagulation, the infant’s hemodynamics deteriorated. Heparin can stop new clot from forming, but it cannot quickly dissolve an established, life-obstructing thrombus, and in a patient whose right heart is already failing, waiting for the body’s own clot-dissolving systems to work is a gamble with very poor odds. The surgical team therefore performed an emergent pulmonary embolectomy — the physical removal of clot from the pulmonary arteries — along with embolectomy of the inferior vena cava and hepatic veins, clearing the thrombus from the entire involved venous circuit. The operation required cardiopulmonary bypass and the precision of a pediatric cardiac surgery team, but it achieved what medications alone could not: immediate relief of the obstruction.

The outcome was a complete recovery, a result the authors emphasize is achievable when diagnosis and surgical intervention happen quickly. Venous thromboembolism with a saddle pulmonary embolus carries high mortality in infants, and survival with an excellent neurological and cardiac outcome is far from guaranteed. The report stands as proof of concept that an efficient, coordinated pathway — from bedside recognition, through targeted imaging, to definitive surgery — can rescue even the smallest and most fragile patients from an otherwise lethal event.

Perhaps the most unsettling aspect of the case is that no predisposing thrombotic condition was ever identified. The team investigated for hypercoagulable states and came up empty-handed. The leading hypothesis is that dehydration associated with a recent presumed viral illness acted as a contributing factor, thickening the blood and slowing venous flow enough to permit clot formation, although the authors are careful to note that a definitive etiology was never established. This uncertainty matters scientifically. Infant thrombosis is usually seen in the context of central venous catheters, congenital heart disease, infections, or inherited clotting disorders; a multisite thrombosis arising spontaneously in a previously healthy toddler challenges that framework and suggests that common childhood illnesses may occasionally trigger catastrophic thrombotic events through mechanisms that remain poorly understood.

The clinical lesson the authors draw is equally important. Pulmonary embolism is classically a disease of immobilized adults, and in infants it rarely makes the differential diagnosis of shock. Yet the presenting signs in this case — vomiting, hypotension, and nonspecific episodes that mimicked seizures or reflux — are exactly the kinds of complaints pediatricians encounter every day. The report argues that pulmonary embolus should be considered in the differential diagnosis for infants presenting in shock, because the window for intervention is narrow and the diagnostic tools, including bedside ultrasound, CT angiography, and echocardiography, are widely available in modern hospitals. A low threshold for vascular imaging in a deteriorating infant, the case suggests, could mean the difference between survival and death.

The case also highlights the evolving role of surgical embolectomy in pediatric thromboembolic disease. Alternatives such as systemic or catheter-directed thrombolysis with tissue-type plasminogen activator carry significant bleeding risks in infants, and anticoagulation alone is often too slow for patients in extremis. Direct surgical removal of clot, once considered a last resort, is increasingly recognized as a definitive option when hemodynamic instability leaves no time for other strategies. For the family of this thirteen-month-old, the decision made in the operating room produced an outcome that few would have predicted at the moment of diagnosis: a child who arrived in near-collapse walked out of the hospital with her heart recovered and her future intact. The report, published with written informed consent from the patient’s parent, adds a rare and valuable data point to the pediatric literature, and its authors hope it will prompt clinicians everywhere to keep pulmonary embolism in mind when an infant in shock does not fit the usual patterns.

Subject of Research: A rare case of multisite venous thrombosis and cor pulmonale in an infant treated with surgical pulmonary embolectomy

Article Title: Multisite thrombosis and cor pulmonale in an infant treated with surgical embolectomy: a case report

Article References: Sanchez, S. D., Bullington, T. M., Braley, K. T., Lindsay, D. D., Baker, K. N., & Nelson, J. S. (2026). Multisite thrombosis and cor pulmonale in an infant treated with surgical embolectomy: a case report. BMC Pediatrics. https://doi.org/10.1186/s12887-026-07832-0

Image Credits: AI Generated

DOI: 10.1186/s12887-026-07832-0

Keywords: pulmonary embolism, saddle embolism, infant, cor pulmonale, surgical embolectomy, venous thromboembolism, inferior vena cava thrombosis, pediatric surgery, heparin anticoagulation, echocardiography, CT angiography, case report