A large atrial septal aneurysm presenting with severe arrhythmias: A case report

An atrial septal aneurysm is defined by an excursion of the septal tissue ≥10 mm beyond the plane of the atrial septum, or a total septal excursion ≥15 mm. These malformations may protrude into the right or left atrium, or oscillate between both chambers, and carry potential risks of arrhythmia and thromboembolism.

A 23-year-old woman presented with a two-month history of worsening palpitations. Baseline electrocardiography was unremarkable. Given persistent symptoms, transesophageal echocardiography was performed, demonstrating a 3.1 cm atrial septal aneurysm in both length and diameter, without evidence of thrombus, patent foramen ovale, or interatrial shunt. The patient underwent surgical resection of the aneurysmal tissue and primary closure of the septum using 4-0 polypropylene sutures. At follow-up, she remained asymptomatic with no new complications.

The widespread use of two-dimensional and transesophageal echocardiography has increased recognition of atrial septal aneurysms, which were once considered rare. Although these aneurysms frequently coexist with patent foramen ovale, in this case no interatrial communication was detected. In the absence of thrombus or shunting and given the lack of consensus guidelines on anticoagulation for isolated aneurysms, no antithrombotic therapy was initiated.

Early transesophageal echocardiography is essential for accurate diagnosis of large isolated atrial septal aneurysms. In symptomatic patients, proactive surgical resection can alleviate symptoms, reduce arrhythmia recurrence, and mitigate potential thromboembolic complications.