Incomplete double aortic arch

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Incomplete double aortic arch is a rare vascular ring anomaly wherein a segment of the minor aortic arch, usually the left, is atretic.

Clinical presentation

As in the case of other vascular rings, this anomaly can cause :

  • stridor
  • wheezing
  • dysphagia

Some patients may reach adulthood without symptoms.

Pathology

This anomaly forms when a segment of the left arch in the embryologic double aortic arch undergoes atresia rather than complete involution. The atretic segment tends to be almost always distal to the left subclavian artery . The atretic distal left arch persists as a fibrous cord (retro-esophageal ligamentum arteriosum) tethering the anterior left arch with the descending aortic diverticulum.

Classification

There are four subtypes of double aortic arch with left arch atresia according to the Shuford and Sybers classification :

  • subtype 1
    • atresia occurs distal to the left ductus arteriosus
    • only the fibrous cord that represents the remnant of the atretic left arch inserts in the diverticulum and forms a complete ring
  • subtype 2
    • atresia occurs between the left subclavian artery and ductus arteriosus
    • both the fibrous portion of the atretic left arch and left ductus insert in the diverticulum
  • subtype 3
    • the atretic segment lies between the left common carotid and left subclavian arteries
  • subtype 4
    • the atretic zone is proximal to the left common carotid artery

Radiographic features

CT and MRI features of an incomplete double aortic arch with distal left arch atresia that differentiate it from a right aortic arch with mirror image branching include :

  • symmetric appearance of the subclavian and common carotid arteries originating from the right arch and incomplete left aortic arch
  • relatively more posterior positioning of the incomplete left arch (compared with the left innominate artery)
  • presence of a descending aortic diverticulum

Treatment and prognosis

The fibrous cord (retro-esophageal ligamentum arteriosum) that represents the remnant of the atretic distal left aortic arch (and potentially the left ductus) must be surgically transected in symptomatic patients.

Differential diagnosis

See also