RESUMEN
Background: Fontan surgery aims to palliate univentricular congenital heart diseases in which biventricular repair is not feasible. A large spectrum of early and late complications has been described in literature. However, pulmonary thromboembolism represents a rare complication in these patients, leading to a scarcity of evidence regarding diagnosis and treatment strategies. Case summary: We present a case of a 27-year-old woman born with a complex cyanotic congenital heart disease, namely pulmonary and tricuspid stenosis with subaortic interventricular communication and atrial septal defect, who underwent palliation surgery with Blalock-Taussig shunt, bidirectional Glenn, and extracardiac Fontan. She developed acute respiratory failure and was admitted to the hospital, being diagnosed with bilateral thromboembolism. Since she was haemodynamically stable, initially, a conservative approach was chosen. However, due to no clinical improvement, she subsequently underwent bilateral thromboaspiration with restoration of pulmonary circulation. Discussion: Due to the unique Fontan pathophysiology, the possible physiological and clinical implications of pulmonary thromboembolism in this condition are profound. Thus, care and imaging tests in specialized centres are important as the management of these patients is different from those with biventricular physiology.