Left aortic arch, right descending aorta, and right patent ductus arteriosus: precise depiction of a rare vascular ring with cardiac computed tomography.

A 14-month-old girl was evaluated for noisy breathing and swallowing. An upper gastrointestinal barium swallow study showed a filling defect of the esophagus at the level of the aortic arch suggestive of a vascular ring (Figures 1 and 2). A chest computed tomography angiogram with 3-dimensional reconstruction (1-mm sections; Movies I and II in the onlineonly Data Supplement) showed a vascular ring consisting of a left aortic arch, retropharyngeal transverse aorta, aberrant right subclavian artery, right descending aorta, and a small right-sided patent ductus arteriosus to the right pulmonary artery (Figure 3). This is an extremely rare form of vascular ring because of the presence of the right-sided patent ductus arteriosus. A left aortic arch and aberrant right subclavian artery are often considered a normal variant and not a true vascular ring because of the typical absence of a right-sided ductus arteriosus or ligamentum arteriosum. In this case, the ductus arteriosus was patent, allowing clear visualization on cross-sectional images. Often, however, this is not the case, and other indirect findings must be used for diagnosis of the presence of a ligamentum that would complete a vascular ring. As shown here, rightward tethering of the vascular structures (aberrant right subclavian and right ductus/ligamentum) may result in a “circumflex” course of the isthmus and proximal descending aorta. In addition, a Kommerell diverticulum (not seen in this case) denotes the presence of a ligamentum arteriosum. Delineation of vascular anatomy with high-resolution imaging was helpful for diagnosis and surgical planning. This patient underwent a successful surgical division of the vascular ring and reimplantation of the right aberrant subclavian artery via a right thoracotomy.