Cardiac computed tomography angiographic identification of an uncommon right atrial outpouching in a complex congenital heart disease patient.

A 1-month-old infant had recurrent respiratory discomfort from birth. Transthoracic echocardiography revealed a significant ostium secundum atrial septal defect and a large ventricular septal defect (VSD). Subsequent-gated cardiac computerized tomographic angiography (CTA) showed a common atrio-VSD with single-ventricle physiology characterized by right ventricular morphology and preductal hypoplasia (coarctation) of the descending aorta. Furthermore, CTA revealed a smooth-walled, broad-based sac emanating from the anteroinferior right atrial wall, which collapses during systole without exerting pressure on neighboring cardiac structures, indicative of a congenital right atrial diverticulum. Right atrial diverticula are uncommon congenital malformations often identified incidentally and commonly linked with other structural cardiac conditions, such as septal defects.