Aortic Arch Anomalies

• General
  
  
  • Most are asymptomatic
    • Unless they cause encircling vascular ring like pulmonary sling
  • Can be complex lesions requiring multiple projections
    • MRI or CT
  
  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 is most commonly seen 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 arteriosis
  • 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

Mirror-image right aortic arch. This contrast-enhanced axial CT scan at the level of the aortic arch
demonstrates a right sided-aortic arch. There is no retrotracheal, retroesophageal
aberrant left subclavian artery. This is the mirror-image variety
with a high association with congenital heart disease..
For a larger photo of the same image, click on this link

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

  • Origin of RSCA may be dilated
    • Diverticulum of Kommerell technically was defined with a right aortic arch and anomalous left subclavian artery (LSCA)

• If there is a mirror-image right aortic arch, then

  • 90% will have Tetralogy of Fallot

  • 6% with Truncus Arteriosis

  • 5% with Tricuspid Atresia

• If the person has the following lesions, then the association with a mirror-image arch is

  • Truncus arteriosis                    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

  • Imaging Findings -- Double Aortic Arch

    • 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

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