Imaging Case of the Week 164 Answer

The frontal chest x-ray shows an abnormal superior mediastinum. The aortic knob is to the right of trachea and the trachea is mildly displaced to the left, suggestive of a right sided aortic arch.

The lateral chest x-ray shows posterior indentation of the trachea.

There is no cardiomegaly and rest of the lung fields are clear.

Echocardiogram confirmed a right sided aortic arch. The retrotracheal bulge seen is likely due to aberrant left subclavian artery.

Right sided aortic arch

Aberrant left subclavian artery

Incidence of right sided aortic arch is about 0.1%. It can be associated with cardiac abnormality such as VSD. Echocardiogram will help to confirm the diagnosis as well as rule out cardiac abnormality.

Patients with a right sided aortic arch can present to the ED with proximal airway obstruction or dysphagia due to proximal oesophageal constriction.

In the above patient, it was an incidental finding.