Continued...

See Fig. 3.

The diagram on the left illustrates the rightward deviation of the distal trachea which occurs when the normal left sided aorta crosses over the left mainstem bronchus. The diagram on the right illustrates the left sided deviation of the distal trachea which occurs when the right sided aorta crosses over the right mainstem bronchus. In a double aortic arch, leftward deviation of the carina may not be visible on the chest radiograph because both left and right aortic arches are present. However, since a double aortic arch often forms a large caliber ring, tracheal compression is often visible on the lateral view of the chest radiograph. In cases where no carina deviation is present and the side of the aorta cannot be determined, a double aortic arch should be suspected. The lateral view of the chest radiograph may reveal a narrowed or constricted tracheal air column (as was seen in the patient in this case). Once an airway anomaly or right sided aortic arch is suspected on plain chest radiographs, a more advanced imaging study should be performed to delineate the anatomy definitively.

Occasionally, bronchial compression is severe and unilateral hyperinflation can be seen on the AP or PA view of the chest radiograph. This usually suggests a pulmonary artery sling, a bronchial anomaly or compression of the bronchus by some other structure. An esophagram (barium swallow) is helpful in making the diagnosis and historically, the esophagram was heavily relied upon to delineate the malformation until angiography was performed. Currently, advanced imaging methods such as echocardiography, CT scanning, magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) may eliminate the need for esophagrams, since they are non-invasive and they define the anatomy of the malformation well. Treatment focuses on the surgical correction of the malformation with the goal of relieving the patient's symptoms.

References

1. Morrow WR, Huhta JC. Aortic Arch and Pulmonary Artery Anomalies (Chapter 59). In: Garson J, Bricker JT, Fisher DJ, Neish SR (eds). The Science and Practice of Pediatric Cardiology. Baltimore, Williams & Wilkins, 1998, pp. 1347-1381.
2. Backer CL, Mavroudis C. Vascular Rings and Pulmonary Artery Sling (Chapter 12). In: Mavroudis C, Backer CL (eds). Pediatric Cardiac Surgery. St. Louis, Mosby, 1994, pp. 147-165.

Copyrighted: Radiology Cases in Pediatric Emergency Medicine Volume 6, Case 19 Loren Yamamoto, MD, MPH s, Professor of Pediatrics, University of Hawaii John A. Burns School of Medicine.Loreny@hawaii.edu

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Last created on 01-07-2006