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Mirror-Image Right Aortic Arch

 

Aortic Anomalies
Right Aortic Arch

  • 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 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 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

  • 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