Right Aortic Arch
General Considerations
- Most are asymptomatic
- Unless they cause encircling vascular ring like pulmonary sling
- Can be complex lesions requiring multiple projections
Left Aortic Arch With Anomalous Right Subclavian Artery (RSCA)
- Occurs in less than 1% of people
- RSCA passes posterior to esophagus
- Pushes trachea and esophagus forward
- Produces oblique shadow above aortic arch on frontal film
- Origin of RSCA may be dilated
- Diverticulum of Kommerell technically was defined with a right aortic arch and anomalous left subclavian artery (LSCA)
Right Aortic Arch
- Types
- At least five different types
- Only two of importance
- Mirror Image Type — Type I
- Aberrant left subclavian — Type II
General considerations
- Recognized by leftward displacement of barium-filled esophagus
- Of air-filled trachea
- Aortic knob is absent from left side
- Aorta descends on right
- Para-aortic stripe returns to left side of spine just above diaphragm
- Mirror-image type almost always has associated congenital heart disease (CHD)
- Usually Tetralogy of Fallot
- Aberrant Left Subclavian type rarely has associated CHD
- Most common variety of right arch
Type 1—Mirror Image Type
- Secondary to interruption of left arch just distal to ductus arteriosus
- Associated with congenital heart disease 98% of time
- Imaging Findings
- No posterior impression on trachea or barium-filled esophagus
- Heart is usually abnormal in size or shape
- Aorta descends on right
Type ll—Aberrant Left Subclavian
- Secondary to interruption of left aortic arch between LCC and LSC arteries
- Associated with cardiac defects 5-10% of the time
- Tetralogy of Fallot most often (71%)
- ASD or VSD next most often (21%)
- Coarctation of aorta rarely (7%)
- Anomalous left subclavian artery (retroesophageal and retrotracheal)
- Aorta descends on right
- Imaging Findings Right Aortic Arch with Aberrant LSCA
- Posterior impression on trachea and barium-filled esophagus
- Heart is usually normal in size and shape
- Aorta descends on right
- If there is a mirror-image right aortic arch, then
- 90% will have Tetralogy of Fallot
- 6% with Truncus Arteriosus
- 5% with Tricuspid Atresia
- If the person has the following lesions, then the association with a mirror-image arch is
- Truncus arteriosus 33%
- Tetralogy of Fallot 25%
- Transposition 10%
- Tricuspid atresia 5%
- VSD 2%
Double Aortic Arch
General considerations
- Most common vascular ring
- Rarely associated with congenital heart disease
- Vascular ring produces tracheal and/or esophageal compression
- Caused by persistence of R and L IV branchial arches
- Passes on both sides of trachea
- Joins posteriorly behind esophagus
- Right arch is larger and higher
- Left arch is smaller and lower
- Barium swallow shows bilateral impressions on frontal view
- Posterior impression on lateral view
- Angiogram is characteristic
- Clinical
- Symptoms may begin at birth and include
- Tracheal compression, or
- Difficulty swallowing
- Anatomy
- Right arch supplies RSCA and RCC
- Left arch supplies LCC and LSCA
- Double Aortic Arch Imaging Findings
- Right arch is higher and larger
- Left arch is lower and smaller
- Produces reverse S on esophagram on AP
- On lateral, arches are posterior to esophagus and anterior to trachea
Cervical Aortic Arch
- General
- Rare
- Usually asymptomatic
- May present as pulsating supraclavicular mass
- May produce vascular ring and compress airway
- Embryogenesis uncertain
- Over 80% are right-sided
- Imaging Findings–Right-sided lesions
- Right-sided cervical aortic arches
- Right apical mass-like density
- Absence of aortic knob on left
- Aorta descends on the left
- Displace the trachea and esophagus forward
- Branching may be normal or mirror-image
- Imaging Findings–Left-sided lesions
- Left-sided cervical aortic arches
- Aortic knob at apex of lung
- Descend on the left
- Do not displace the trachea or esophagus forward
