Radiology Cases in Pediatric Emergency Medicine Volume 6, Case 20
Daniel D. Guzman, MD Collin S. Goto, MD

This is a 15-month old male who presents to the Emergency Department with his parents stating that while he was standing, he became red in the face while gagging and his head began to rock forward and backward with his eyes closed. This episode lasted less that 5 minutes, then he became quiet and resumed playing. This occurred one more time and his parents then brought him in to the Emergency Department.

His past history is remarkable for multiple upper respiratory infections in the past several months.He has also been seen in the past for two separate episodes of esophageal coins requiring endoscopic removal 5 months ago and 1 week ago. He was born at 36 weeks gestation, but without complications.He has no previous history of seizures and no family history of seizures. He is on no medications.There is no witnessed foreign body ingestion or aspiration for his current episode.

VS T 37.7, P 104, R 33, BP 111/83, oxygen saturation 98% on room air. He is alert, active, and in no distress. He has mild inspiratory stridor at rest. His lung fields demonstrate good aeration. No cyanosis is noted. He has a grade 1/6 systolic murmur at the left sternal border, with no radiation. No diastolic murmurs, ejection clicks or gallops are appreciated and his peripheral pulses are brisk. His abdomen is soft, non-tender and without organomegaly. His neurologic exam reveals no deficits. His previous radiographs are examined. Five months prior, he presented with an esophageal coin diagnosed on chest radiographs.

The esophageal coin is visible on the PA and lateral views. The coin was endoscopically removed.

This chest radiograph is obtained from the fluoroscope. The esophageal coin is visible on the PA and lateral views. The coin was again endoscopically removed.

A careful review of these two previous chest radiographs reveals a narrowed tracheal air column best visible on both lateral views. On the set of radiographs 1 week ago (#2), the tracheal air column on the lateral appears to be bent suggesting a mass pushing on it.

An esophageal mass or edema surrounding the foreign body could result in extrinsic compression of the trachea. Once the esophageal coin is removed, it would not be routine to repeat the chest radiographs to examine the caliber of the tracheal air column again. Clinical examination following the coin removal is generally sufficient. In this case, the stridor appears to be persistent. The presentation of a child with persistent stridor and the two previous occurrences of a foreign body lodged in the esophagus, suggests intrathoracic compression of both the trachea and the esophagus. The differential diagnosis includes vascular rings or slings, a mediastinal mass, or an intrinsic esophageal tumor or duplication. Another chest radiograph is obtained.

These chest radiographs show a normal cardiac silhouette without mediastinal widening, but there is some suggestion of a right-sided aortic arch with slight narrowing of the trachea on the frontal view. There are also perihilar opacities in the lungs likely secondary to a poor inspiration. The tracheal air column on this set of radiographs is not as narrow as it was on the previous chest radiographs, but the bend in the trachea seen on the lateral view is still present.

At this time, a vascular ring is suspected and a barium swallow is performed.

The barium swallow study confirms the presence of a right sided aortic arch. The views shown here demonstrate an extrinsic mass compressing the esophagus at the level of the aortic arch. Real time fluoroscopy also revealed intermittent narrowing of the trachea at the same level. This is consistent with a vascular ring due to a double aortic arch encircling and compressing both the trachea and the esophagus. Refer to the anatomic drawing (Fig 1) in the previous case (Case 19 of Volume 6).

An MRI was performed to further delineate the intrathoracic anatomy. The MRI showed a double aortic arch with the right arch being larger than the left arch. The two arches meet to form one descending aorta on the left. The right common carotid artery and the right subclavian originate from the right arch and the left common carotid and the left subclavian originate from the left arch. The cardiac size is normal. The trachea is narrowed at the site of the double aortic arch and is more severely narrowed inferiorly with the narrowing extending to the carinal region and to the right main stem bronchus. The narrowing is due to tracheomalacia, which is associated with the vascular ring.

An echocardiogram revealed normal intracardiac anatomy and function. The cardiology and cardiothoracic surgery teams were involved and the patient underwent operative repair with an uneventful postoperative course.

Vascular rings are congenital anomalies of the aortic arch and its tributaries, causing varying degrees of compression of the trachea and esophagus. Five different variations of vascular rings exist:

1) double aortic arch (most common),

2) right aortic arch with left ligamentum arteriosum,

3) anomalous right subclavian artery,

4) anomalous innominate artery, and

5) anomalous left common carotid artery.

Double aortic arch is an anomaly in which both right and left arches are present and may be one of several variations: 1) both arches widely patent, 2) hypoplasia of one arch (usually the left), 3) atresia of one arch (usually the left). Double aortic arch represents a persistence of both right and left embryonic fourth branchial arches joining the aortic portion of the truncoaortic sac to their respective dorsal aorta. The ascending aorta bifurcates anterior to the trachea and each arch courses either to the left or to the right of the trachea or esophagus. The larger of the two arches usually crosses posterior to the esophagus and joins with the other arch in the posterior mediastinum to form the unified descending aorta. Thus a complete vascular ring is formed. Double aortic arch is rarely associated with congenital heart disease, but when present, Tetralogy of Fallot and transposition of the great vessels are most common.

Clinical manifestations are related to the nature of malformation and tightness of the ring. If both arches are widely patent, the rings are tight and patients present with stridor in the first weeks of life. When one arch is hypoplastic or atretic, the rings are usually looser, with presentation at 3-6 months of age. Rarely, does double aortic arch present in adulthood.

Children with double aortic arch are often small, poorly developed and hold their head in hyperextension. Repeated severe respiratory infections may occur. Physical exam may be within normal limits, but one may see coughing, dyspnea, drooling or dysphagia. Infants will feed poorly due respiratory distress and may have life-threatening episodes of apnea and cyanosis. Cardiac exam will most often be normal. Lung exam may or may not show evidence of pneumonia.

Radiographs may show no significant abnormalities. Tracheal deformities can sometimes be detected or at least suspected from the shadow of the air column in the trachea without contrast. Both arches may be seen on either side of the trachea in the anteroposterior projection. There may also be evidence of hyperinflation of either or both lungs due to obstruction of the lower trachea and main stem bronchi. An esophagram may not only establish the diagnosis, but also identify the structures making up the constricting ring. Computerized imaging (CT and/or MRI) provides information noninvasively and identifies important spatial relationships between the vessels, trachea and esophagus to better permit surgical planning.

Surgical division of the vascular ring is indicated in any patient who is symptomatic with airway or esophageal compression

Copyrighted:- Radiology Cases in Pediatric Emergency Medicine Volume 6, Case 20 Loren Yamamoto, MD, MPH, Professor of Pediatrics, University of Hawaii John A. Burns School of Medicine.Loreny@hawaii.edu