Bilateral Atrial Appendage Aneurysms With Atrial Septal Defect in an Infant

A 2-month-old male infant presented a heart murmur during auscultation. Examination suggested sinus tachycardia, frequent atrial premature beats, and decreased cardiac function. Chest X-ray showed enlargement of the bilateral cardiac boundaries (Figure A), and transthoracic echocardiography (TTE) demonstrated cystic dilatation of both the right and left atrial appendages with incomplete septation (Figure B,C) and a secundum atrial septal defect (ASD; Figure D). Computed tomography angiography (CTA) confirmed the ASD (Figure E) and bilateral multicystic atrial appendage aneurysms (RAAA: 49×38 mm; LAAA: 34×32 mm) without internal thrombi (Figure E–H, Supplementary Movie). After 32 days of treatment to correct the arrhythmias, improve cardiac function and for anticoagulation, the infant underwent thoracotomy for ASD repair and bilateral AAAs resection. Histopathology revealed marked thinning of the myocardium in the wall of both AAAs with interstitial fibrosis (Figure I). Clinical symptoms disappeared postoperatively, and no adverse cardiac events occurred during the 3-month follow-up.

Figure.

Imaging of the 2-month-old infant’s heart: chest X-ray (A), transthoracic echocardiography (B–D) and computed tomography angiography (E–H). Histopathology of the AAAs (I, ×100, H&E). AAA, atrial appendage aneurysm; AO, aorta; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RA, right atrium; RV, right ventricle; SVC, superior vena cava.

Atrial appendage aneurysm, which may be due to pectinate muscles dysplasia or increased atrial pressure, is a localized or diffuse dilatation of the atrial appendage.¹ Patients are usually asymptomatic, while those with symptoms may manifest exertional dyspnea, atrial tachycardia, and/or thromboembolism.¹ Surgery is the recommended treatment to avoid these severe complications.²

Supplementary Files

Supplementary Movie. Computed tomography angiography of the AAAs.

Please find supplementary file(s);

https://doi.org/10.1253/circj.CJ-23-0684

References

• 1.   Norozi K, Subasri M, Diaz LA, Honjo O. Left atrial appendage aneurysm in pediatrics: Case study and literature review. Front Cardiovasc Med 2023; 10: 1211619.
• 2.   Nakamura M, Takemoto K, Terada K, Fujita S, Tanimoto T, Tanaka A. Left atrial appendage aneurysm diagnosed by transthoracic echocardiography. Circ J 2022; 86: 1147.