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.
     Exam:  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.

View CXR from 5 months ago (CXR #1).


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

View CXR from 1 week ago (CXR #2).


     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.

View these CXR's again.
CXR #1


CXR #2


     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.

View current CXR (#3).


     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.

View Barium Swallow.


     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 Ring Teaching Points
     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.

References
     1.  Parrish DA, Seilheimer DK, Pulmonology: 
considerations for pediatric cardiology.  In:  Garson A 
Jr, Bricker JT, McNamara DG.  The Science and 
Practice of Pediatric Cardiology.  Philadelphia, Lea and 
Febiger, 1990, pp. 2508-2509.
     2.  Morrow WR, Huhta JC.  Aortic arch and 
pulmonary artery anomalies.  In:  Garson A  Jr, Bricker 
JT, McNamara DG. The Science and Practice of 
Pediatric Cardiology.  Philadelphia, Lea and Febiger, 
1990, pp. 1425-1426.
     3.  Weinberg PM.  Aortic arch anomalies. In:   
Emmanouilides GC, Reimenschneider TA, Allen HD, 
Gutgesell HP.  Heart Diseases in Infants, Children, and 
Adolescents.  Baltimore, Williams and Wilkins, 1995, 
pp. 824-825.
     4.  Mandell VS, Braverman RM.  Vascular rings and 
slings.  In: Fyler DC.  Nadas' Pediatric Cardiology.  
Philadelphia, Hanley and Belfus, Inc., 1992, pp.
722-724.
     5.  Morrow WR.  Aortic arch and pulmonary artery 
abnormalities.  In:  Oski FA, DeAngelis CD, Feigin RD, 
McMillan JA, Warshaw JB (eds).  Principles and 
Practice of Pediatrics.  Philadelphia, J.B. Lippincott, 
1994, pp. 1588-1589.