Inverted left atrial appendage mimicking potential left atrial thrombus in an infant following cardiac surgery: a case report.

Background: Inverted left atrial appendage (iLAA) is an infrequent complication following cardiac surgery, seen both in children and adults. Following a recent encounter, this review article is aimed to remind the reader about its occurrence, clinical manifestations, differential diagnoses, and management options.

Case Summary: A 3-month-old baby underwent successful surgical repair of a large ventricular septal defect. Intraoperative epicardial echocardiogram at the end of the case demonstrated an unexpected left atrial mass, raising suspicion of a thrombus adjacent to the mitral valve. Urgent re-establishment of cardiopulmonary bypass and exploration of the left atrium did not reveal a thrombus, but this was subsequently identified as an iLAA. This completely resolved after manual external reduction of the appendage.

Discussion: Published literature is confined to case reports only, with most cases observed post-operatively, but some occurring spontaneously. Awareness of this unusual manifestation is particularly important in the intraoperative period as it can usually be addressed without the need for further cardiopulmonary bypass.