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Findings: Chest X - ray - The lateral view demonstrates the distal tracheal air column displaced anteriorly. Displacement to right or left can't be determined.

Esophogram - A posterior impression is obvious in the mid-esophagus on the lateral projection. On the AP projection there are abnormal impressions bilaterally at the level of the aortic arch on both the left and right side.

Diagnosis:

Vascular ring formed by right aortic arch with aberrant left subclavian artery.

Discussion: In infants which present with feeding disorders, spitting or dyspnea, congenital vascular anomalies should be high on the differential diagnosis list. Vascular rings seen in the neonate may be present in the symptomatic patient or represent an incidental finding. All congenital vascular rings are ultimately determined by which portions of the paired ascending branchial arches has persisted or degenerated during the developmental period.

The development of the right aortic arch with an aberrant left subclavian artery is due to interruption of the left arch between the left common carotid and the left subclavian arteries. This anomaly is a mirror image of the aberrant right subclavian artery. The incidence of intracardiac defects is 5-12% which is higher than the normal population (<1%) but considerably less than patients with mirror image branching right aortic arch (98%). If congenital heart disease is present in a patient with right sided aortic arch and aberrant left subclavian artery the lesions include Tetralogy of Fallot (71% ). ASD or VSD (21%) and coarctation of the aorta (7%). Only 5% of these patients develop compression symptoms due to a tight vascular ring.

The appearance of a posterior esophageal impression is more commonly seen as a result of an aberrant right subclavian artery with a left-sided aortic arch, and less commonly by an aberrant left subclavian artery with a right-sided aortic arch. Concomitant posterior esophageal and anterior tracheal impressions is a result of a true vascular ring. The most common entity being a double aortic arch or a right aortic arch combined with an aberrant left subclavian artery (as in this case).

The ring in this case is completed by the ductus remnant. If the ring causes tracheal compression surgical treatment may be necessary.

Other vascular impressions include an anterior tracheal impression caused by the innominate artery arising to the left of the trachea and ascending anteriorly. This is normal finding unless accompanied by symptoms. An impression between the esophagus and trachea (excluding lymph nodes the rare bronchogenic cyst) is pathognomonic of an aberrant left pulmonary artery (pulmonary sling).

References:
Blickman JC, Pediatric Radiology; The Requisites Mosby, 1994:72-74.

Caffey, J. Pediatric X-Ray Diagnosis, Year Book 1978:555-558

Kirks, D.D., Practical Pediatric Imaging, Diagnostic Radiology of Infants
and Children. Little/Brown 1991:488-492

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