Rings and Slings:
A vascular ring is an aortic arch abnormality in which the trachea and esophagus are surrounded by vascular structures [3]. Vascular rings are uncommon anomalies (less than 1% of all congenital cardiac defects) [3]. Complete (symptomatic) rings:
1- Double aortic arch and variants- a double aortic accounts for 50-60% of vascular rings [3].
2- Right aortic arch with aberrant left subclavian and a left liagmentum arteriosum- this is the second most common vascular ring (accounting for 12-25% of cases [3].
3- Circumflex aorta with persistant ductus (left aortic arch with a right-sided descending aorta): The aorta normally descends on the same side as the arch. In a circumflex aorta, the aorta descends on the side opposite the arch. Thus, the aorta must cross posterior to the trachea and esophagus to reach the opposite side- this will create a posterior esophageal impression on barium swallow. These patients are generally asymptomatic, but if there is a persistent ductus, this lesion may also produce a complete ring and be symptomatic.
4- Right aortic arch with mirror image branching and a retroesophageal left ligamentum arteriosum [3].
5- Pulmonary sling (Aberrant left pulmonary artery)
In one study, at least one abnormality could be detected on the chest radiographs in all children with a symptomatic vascular ring. Therefore, a normal PA and lateral chest radiograph is evidence against the presence of a vascular ring in symptomatic children.
REFERENCES:
(1) Radiology 1997; 203: 423-426
(2) AJR 2005; Schlesinger AE, et al. Incomplete double aortic arch with atresia of the distal left arch: distinctive imaging appearance. 184: 1634-1639
(3) Radiographics 2010; Kimura-Hayama ET, et al. Uncommon congenital and acquired aortic diseases: role of multidetector CT angiography. 30: 79-98
