Continued...

See normal aorta.

Note that the normal aortic arch crosses over the left mainstem bronchus. This is the normal left-sided aortic arch. In the vascular ring malformations diagrammed in Fig. 1 and 2, note that the aortic arch passes over the right mainstem bronchus instead. This is an abnormal right sided aortic arch. In Fig. 1 (the double aortic arch), the aortic arch bifurcates such that one half of the aorta crosses over the left mainstem bronchus, while the other half of the aorta crosses over the right mainstem bronchus. In Fig. 2 (the right sided aorta with anomalous left subclavian), the aortic arch crosses only over the right mainstem bronchus.

Review Fig. 1 and 2 again.

Recognition of the right-sided aortic arch is often a valuable clinical clue in suspecting a vascular ring. A vascular sling (as opposed to a vascular ring) is said to be present when the vessels form an incomplete circle around the trachea and esophagus.

Children with vascular rings are often diagnosed during infancy, but presentations later in life my occur in more mild cases and many cases are totally asymptomatic. Presenting symptoms are usually due to tracheal or esophageal compression such as stridor, noisy breathing, frequent respiratory infections, wheezing, dysphagia, choking, apnea, wheezing, croupy cough, hoarse cry, etc. A typical presenting history is that of noisy breathing since birth. It is common for these infants to have more severe symptoms during a respiratory infection. A young infant with a history of "asthma" is another typical way that these patients present. Sometimes these children are diagnosed with cardiac disease, but the vascular ring may be occult until an appropriate imaging study is performed.

The key in making the diagnosis is to suspect an airway problem based on symptoms described by the parents. Clinical findings may or may not be present during an examination. Two view chest radiographs are useful in identifying many pulmonary and cardiac anomalies, but the findings are often subtle. Since a right-sided aortic arch is almost always present in a vascular ring, identifying this on a chest radiograph is critical. A right-sided aortic arch is defined as an aortic arch that crosses over the right mainstem bronchus instead of the usual left mainstem bronchus. Thus, the arch itself may not necessarily occupy the right hemithorax. The normal left-sided aortic arch normally pushes the carina to the right as it courses over the left mainstem bronchus. This slight deviation in the normal tracheal air shadow can often be appreciated on the AP or PA view of the chest radiograph. In a right-sided aortic arch, the carina deviates to the left instead as the aorta courses over the right mainstem bronchus.