J Cardiol 2004 Mar; 43（3）: 147 – 150

Cardiovascular Imaging In-a-Month
Chest Roentogenogram Mimicking Double Aortic Arch in a 30-YearOld Female With Effort Dyspnea and Dysphagia●Shie OHGI, MD
Hisao

ITO, MD, FJCC

Katsuhiko

ISOGAMI, MD＊1

Takayuki

KANNO, MD＊2

CASE
A 30-year-old female was generally healthy, but sometimes experienced low gradeintermittent effort dyspnea with wheezing and mild dysphagia when swallowing alarge piece of solid food. Physical examination revealed no abnormalities, and herblood pressure was 130/82 mmHg. Electrocardiography and echocardiography
revealed no abnormalities. Chest roentgenography（Fig. 1）and swallow esophagography（Fig. 2）
were performed.

Fig. 1Fig. 2──────────────────────────────────────────────
宮城県立循環器・呼吸器病センター 放射線科〔黄木詩恵，伊藤久雄〕，＊ 1 呼吸器外科〔磯上勝彦〕，＊ 2 循環器科〔菅野孝幸〕:〒 989−4501 宮城県栗原郡瀬峰町大里字富根岸 55−2
Departments of Diagnostic Radiology, ＊ 1Respiratory Surgery and ＊ 2Cardiology, Miyagi Cardiovascular and Respiratory Center, Miyagi
Address of correspondence : ITO H, MD, FJCC, Department of Diagnostic Radiology, Miyagi Cardiovascular and Respiratory Center,
Tominegishi 55−2, Osato, Semine-machi, Kurihara-gun, Miyagi 989−4501
Manuscript received September 5, 2003 ; revised September 29, 2003 ; accepted October 11, 2003

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Ohgi, Ito, Isogami et al

Points for Diagnosis
Chest roentogenography（Fig. 1）suggested mild
enlargement of the right lower cardiac margin, andshowed two nodular shadows in the bilateral upper
mediastinum, which were considered to be aortic
knobs. In addition, the margin of the right aortic
knob was apparently connected to the longitudinal
stripe line parallel to the right border of the thoracic
spine, which suggested the margin of the descending thoracic aorta on the right. However, no intracardiac defects were revealed by echocardiography.
We thought that chest roentogenography showed
the silhouette of a double aortic arch, and that vascular ring in association with double aortic arch had
caused the esophago-respiratory symptoms,
although we could not confirm tracheal or esophageal narrowing on the chest roentogenogram.
Furthermore, we found right and left esophageal
impressions on swallow esophagography（Fig. 2）
in association with the double aortic arch, whereas
the right esophageal impression was located at theaortic knob（short arrow）and just inferior to theright aortic knob（middle arrow）.
In contrast, cross-sectional and coronal spiralcomputed tomography（CT）with contrast medium
image disclosed unanticipated radiological featuresof right aortic knob and left mediastinal round nodule of 3 cm in diameter（Figs. 3, 4）.
Three-dimensional CT angiography（ Fig. 5）
demonstrated the nature of the thoracic vascularanomalies prior to angiographic examination, as
right aortic arch with mirror image branching, andaortic diverticulum（asterisk）which was located at
the proximal portion of the descending thoracic
aorta. Digital subtraction angiography of the posteroanterior projection（Fig. 6）confirmed right aortic arch with mirror image branching, but we could
see only a small part of the aortic diverticulum,
because of overlapping by the ascending thoracic
aorta and left common carotid artery.
Right aortic arch with mirror image branchinghas been classified into two types（ Type A andType B）1）caused by the different breaking point of

the left aortic arch of the hypothetical double aortic arch 2）. The break of the aortic arch is intimately associated with the origin of the ductus arteriosus and intracardiac anatomy. Interruption of theleft arch posterior to the left ductus arteriosus leads
to a right aortic arch with mirror image branchingand ductus arteriosus originating from the left
innominate or left subclavian artery. This type ofthoracic vascular anomaly（Type A）is commonlyencountered, and is not associated with vascularring, but cardiac anomalies such as tetralogy of
Fallot or truncus arteriosus. On the other hand,interruption of the left arch between the left subclavian artery and left ductus arteriosus leads to a rightaortic arch with mirror image branching and ductus
arteriosus derived from the aortic diverticulum of
the proximal descending thoracic aorta. This typeof thoracic vascular anomaly（ Type B）is rarely
encountered and is not associated with intracardiac
defects, but vascular ring.
The thoracic vascular anomalies of the present
patient are eventually considered to be Type B rightaortic arch with mirror image branching. This combination of Type B right aortic arch with mirror
image branching and mediastinal nodule isextremely rare.
Diagnosis : Right aortic arch with mirror imagebranching（Type B）causing vascular ring, and left
upper mediastinal nodule
Key Words : Aorta（right aortic arch, vascular ring）;
Computed tomography（three-dimensional CT angiography）; Neoplasms
References1）Garti IJ, Aygen MM, Vidne B, Levy MJ : Right aortic archwith mirror-image branching causing vascular ring : A newclassification of the right aortic arch patterns. Br J Radiol
1973 ; 46 : 115−1192）Edwards JE : Anomalies of derivatives of aortic arch system. Med Clin North Am 1948 ; 32 : 925−949

J Cardiol 2004 Mar; 43（3）: 147 – 150

Cardiovascular Imaging In-a-MonthFig. 3

Fig. 4J Cardiol 2004 Mar; 43（3）: 147 – 150

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Ohgi, Ito, Isogami et al

Fig. 6

Fig. 1 Chest radiogram demonstrating two nodular
shadows in the bilateral upper mediastinum
The right nodular shadow（arrow）is a right aortic
knob, whereas the left nodular shadow（arrowhead）isa left upper mediastinal nodule.
Fig. 2 Swallow esophagogram, posteroanterior projection, showing esophageal impressions
The esophageal impressions located on the right（short and middle arrows）are caused by right aortic
knob and aortic diverticulum, and on the left（longarrow）by left mediastinal nodule, respectively.
Fig. 3 Cross-sectional computed tomographic scan at theupper mediastinal level
The right aortic arch compresses the trachea withresultant narrowing of the lumen. The round medi-

astinal nodule（arrow）, aortic diverticulum（asterisk）
and the left brachiocephalic artery（arrowhead）arevisible. The esophagus（ small black circle）is surrounded by trachea, aortic diverticulum and mediastinal nodule.
SVC ＝ superior vena cava ; AA ＝ ascending thoracic
aorta ; DA ＝ descending thoracic aorta ; T ＝ trachea.
Fig. 4 Coronal computed tomographic scan, multiplanarreconstruction, at the level of the posterior mediastinum
The round mediastinal nodule（arrowheads）is locatedjust above the left main pulmonary artery. The aortic
diverticulum（asterisk）is seen.
P ＝ pulmonary artery ; B ＝ left main bronchus.
Other abbreviation as in Fig. 3.
Fig. 5 Three-dimensional computed tomography
angiogram, left posterocranial projection, demonstrating right aortic arch with mirror image
branching
The aortic diverticulum（asterisk）is situated at theproximal portion of the right-sided descending thoracic aorta. The ligamentum arteriosus, which is acomponent of the vascular ring, is supposed to belocated between the aortic diverticulum and the pulmonary artery.
LCCA ＝ left common carotid artery ; LSA ＝ leftsubclavian artery ; LBCA ＝ left brachiocephalicartery ; RCCA ＝ right common carotid artery ;RSA ＝ right subclavian artery ; PA ＝ pulmonary
artery ; LA ＝ left atrium. Other abbreviations as inFig. 3.
Fig. 6 Digital subtraction angiogram, posteroanterior
projection, showing right aortic arch with mirror
image branching
The first branch of the thoracic aorta is the left brachiocephalic artery, which is divided into two branches of the left common carotid artery and left subclavian artery. The second and third branches are theright common carotid artery and right subclavian
artery, respectively. Opacification of the medistinal
nodule is barely visible, whereas the outer margin（arrowheads）is noted. The aortic diverticulum（arrow）overlaps the ascending thoracic aorta and left
brachiocephalic artery, but a small part of the aortic
diverticulum without overlapping is visible.
Abbreviations as in Figs. 3, 5.

J Cardiol 2004 Mar; 43（3）: 147 – 150