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MR IMAGING OF RIGHT AORTIC ARCH WITH ANOMALOUS
SUBAORTIC LEFT BRACHIOCEPHALIC VEIN AND
ABERRANT LEFT SUBCLAVIAN ARTERY: CASE REPORT
Tsung-Hsien Yen1, Chien-Ming Cheng2
1Department
of Radiology, Fong-Yuan Hospital, Department Of Health Executive Yuan, Taiwan
of Cardiology, Fong-Yuan Hospital, Department Of Health Executive Yuan, Taiwan
2Department
ABSTRACT
Congenital abnormalities of the aortic arch, which is associated with various cardiac anomalies,
represent less than 1% of all congenital cardiac defects. Right aortic arch associated with aberrant
left subclavian artery and subaortic left brachiocephalic vein is extremely rare. Here we report a
case of this anomaly, which was well demonstrated by MR imaging and MR angiography, in an
81-year-old elderly male. Intermittent dysphagia lusoria was noted. Besides, this aberrant left
subclavian artery originated from the diverticulum of Kommerell of the aortic arch, and engorged
azygous vein and arch were also revealed. However, there was no chromosome 22 abnormality in
this patient.
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Keywords: cardiovacular MR, right aortic arch, anomalous subaortic brachiocephalic vein
INTRODUCTION
Right aortic arch associated with aberrant left subclavian artery and subaortic left brachiocephalic
vein is extremely rare. Here we report a case of this anomaly, which was well demonstrated by
MR imaging and angiography, in an 81-year-old elderly male. Besides, the aberrant left
subclavian artery originated from the diverticulum of Kommerell over the aortic arch, and
engorged azygous arch were also revealed. However, there was no chromosome 22 abnormality
in this patient.
CASE REPORT
An 81-year-old elderly male received cardiac MR examination for physical checkup in our
institution. Sometimes intermittent difficulty in deglutition was told. Otherwise, no specific
symptom was noted. Cardiac MR imaging and angiography was subsequently performed on a 1.5
tesla scanner (Signa EXCITE, GE Medical Systems, Milwaukee, Wis) with eight-channel cardiac
array coil and vectorcardiographic (VCG) gating. In the double inversion recovery (DIR), axial
T1-wighted images (Fig. 1), it disclosed a right-sided aortic arch with aberrant left subclavian
artery from a diverticulum of Kommerell (retroesophageal diverticulum), which located posterior
to the esophagus at the level of the fourth thoracic vertebra. Besides, anomalous subaortic left
brachiocephalic vein and engorged azygous arch (Fig. 2) were also depicted. During steady-state
free precession (SSFP) cine imaging, preserved ejection fraction of the both ventricles were noted,
except mild aortic regurgitation. In the phase contrast, velocity-encoding images, single E wave
was revealed through both the mitral and tricuspid valves in the flow patterns (not shown), grade
III diastolic dysfunction was suspected.
Contrast-enhanced MR angiography (MRA) images were obtained in the sagittal plane, then for
three-dimensional volume-rendering (VR) reconstruction. At MRA (Fig. 3), the left common
carotid artery (CCA) arise from the ascending aorta as the first branch, followed by right CCA and
right subclavian artery (SA), and finally the aberrant left SA courses posterior to the esophagus as
the last branch. It also confirmed the subaortic course of the left brachiocephalic vein. Furthermore,
chromosome study was approved by the patient along with informed consent. There was no
chromosome abnormality in this patient, esp. at chromosome 22.
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Fig. 3. Contrast-enhanced MRA with 3-D VR reconstruction. The left common carotid artery (CCA) arose
from the ascending aorta as the first branch, followed by right CCA and right subclavian artery (SA), and
the aberrant left SA (arrowhead) as the last branch. The diverticulum of Kommerell (retroesophageal
diverticulum) (asterisks) at the origin of aberrant left SA was well demonstrated. Anomalous subaortic
course of the left brachiocephalic vein (arrows) was also confirmed.
DISCUSSION
Right aortic arch is a kind of congenital aortic anomalies, which occurs in approximately 0.1%
of general adult population [1]. Secondary to interruption of left arch at different segments,
there are three major types of right arch anomalies: mirror image, aberrant left SA and isolated
left SA [2]. The aberrant left SA, either arising as the fourth (last) branch of the right-sided
aortic arch or from a diverticulum of Kommerell (retroesophageal diverticulum), accounts for
half (0.05%) of the right aortic arch variants [3].
Deletion of chromosome 22q11 is frequently associated with anomalies of the aortic arch,
aortic branches, ductus arteriosus, and pulmonary arteries [4]. Aortic arch anomalies are
associated with a chromosome 22q11 deletion in approximately 20-24% of patients [5].
Fortunately, there was no chromosome abnormality in this elderly patient.
Most patients of right aortic arch with aberrant left SA are asymptomatic [6]. Right aortic arch
with aberrant left SA results from the interruption of the left fourth primitive pharyngeal arch
between the left CCA and SA, with concomitant persistence of the right fourth arch [5]. From
the right aortic arch, left CCA arise from the ascending aorta as the first branch, followed by
right CCA and right SA, and finally the aberrant left SA courses posterior to the esophagus as
the last branch. Sometime the retroesophageal course of the aberrant SA may cause posterior
esophageal compression and present with dysphagia (classically termed as dysphagia lusoria)
[7].
Anomalous subaortic position of the left brachiocephalic (innominate) vein was first described
120 years ago [8]. It extends from the junction of the left internal jugular vein and the left
subclavian vein, runs beneath and behind the aortic arch, then joins with the right
brachiocephalic vein above the opening of the azygous arch to form the superior vena cava
(SVC). The incidence of an anomalous brachiocephalic vein with congenital heart disease was
about 0.2-1.7% in reported literatures [9-11]. Suppose that two-twenty-first (2/21) ratio in
anomalous brachiocephalic vein combined with right aortic arch and aberrant left subclavian
artery [11], it represented less than 0.005% (0.0048%) in prevalence of the adult population.
The exact cause of an anomalous brachiocephalic vein remains unknown. Disturbance of the
ventral precardinal vein, either due to fails to underdevelopment, regression or imbalanced
pressure of the surrounding great arteries, results in anomalous brachiocephalic vein [11-13].
Cardiac MR imaging provides great anatomic and functional information for the investigation
of congenital cardiovascular disease, either in child or adult [14,15]. By variable imaging
techniques, including cine imaging, phase-contrast velocity mapping and contrast-enhanced
MR angiography, it depicts not only structural abnormalities but also hemodynamic change
encountered. It becomes a promising, non-invasive and non-radiation method to evaluate the
congenital cardiovascular disease.
In conclusion, MRA has utility for the diagnosis and follow-up of aberrant left subclavian
artery associated with right-sided thoracic aortic arch, being a non-invasive imaging modality
with no ionizing radiation or exposure to iodinated contrast media.
Fig. 1. Sequential Double-IR axial images. The aorta (A) descends on the right side of chest. The aberrant left
subclavian artery (arrowheads), passing behind the esophagus, originates from a retroesophageal diverticulum
(diverticulum of Kommerell) (asterisk) on the descending aorta. Sub- and retroaortic position of the
anomalous left brachiocephalic vein (arrows) was also identified.
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Fig. 2. Sequential MR angiographic images. The anomalous left brachiocephalic vein (arrows), runs beneath
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arch (arrowhead) to form the superior vena cava (S). Engorged azygous arch was also noted.
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