Congenital Aortic Anomalies

Eric J. Crotty, MD

DIFFERENTIAL DIAGNOSIS

Common

Left Aortic Arch with Aberrant Right Subclavian Artery
Aortic Coarctation
Double Aortic Arch

Less Common

Right Aortic Arch with Aberrant Left Subclavian Artery
Right Aortic Arch with Mirror-Image Branching

Rare but Important

Interrupted Aortic Arch
Cervical Aortic Arch
Persistent 5th Aortic Arch
Pulmonary Sling

ESSENTIAL INFORMATION

Helpful Clues for Common Diagnoses

Left Aortic Arch with Aberrant Right Subclavian Artery
- Right subclavian artery has separate origin as last vessel from arch or proximal descending aorta
- No diverticulum at origin of aberrant right subclavian artery
- Patients usually asymptomatic as no vascular ring is present
- Radiograph may show left aortic arch and impression on posterior wall of trachea
- Esophagram, AP view
- Impression on left side of barium column, which continues obliquely superiorly and to right
- Esophagram, lateral view
  - Posterior indentation on barium column on lateral view
- CT and MR will show aberrant right subclavian artery coursing posterior to esophagus and superiorly to right
Aortic Coarctation
- Focal narrowing of upper thoracic aorta at level of insertion of ductus arteriosus
  - Less commonly long segment or may be associated with diffuse tubular hypoplasia of aortic arch and isthmus
- Cardiomegaly and increased pulmonary vascularity with edema may be present in infants
- “3” sign may be present
- Notching of undersurface of ribs may develop in longstanding severe cases
- Collateral flow best identified by CTA and MRA; can be quantified by MR
Double Aortic Arch
- Both limbs usually complete, but 1 side may be atretic (30%)
  - Atretic limb remains in fibrous continuity with descending aorta
- Although variable, right limb is usually larger (dominant) and higher in position than left
- Most commonly: Left arch anterior and left of trachea, right arch posterior and right of esophagus
  - Limbs join posteriorly to form left-sided descending aorta
- Symptoms usually present early
- Radiograph may show dominant arch and compression on both sides of trachea
- Esophagram, AP view
  - Compression on both sides of esophagus
- Esophagram, lateral view
- Posterior impression
- CT and MR demonstrate relative sizes of limbs and degree of associated tracheal narrowing
- Rarely associated with intracardiac defects

Helpful Clues for Less Common Diagnoses

Right Aortic Arch and Aberrant Left Subclavian Artery
- Left subclavian artery has separate origin
  - Last vessel from arch or proximal descending aorta
- May be associated with diverticulum of Kommerell
- Radiograph may show right aortic arch and impression on posterior wall of trachea
- Esophagram, AP view
  - Impression on right side of barium column which continues obliquely superiorly to left
- Esophagram, lateral view
  - Posterior indentation on esophagus
- CT and MR will show aberrant left subclavian artery coursing posterior to esophagus and superiorly to left
- Vascular ring completed by left ligamentum arteriosum to left pulmonary artery
- Low association (10%) with intracardiac defects
Right Aortic Arch with Mirror-Image Branching
- 3 vessels arise from right aortic arch in following order
  - Left innominate artery coursing anterior to trachea
  - Right carotid artery
  - Right subclavian artery
- Impression on right side of trachea and right arch are visible on frontal chest radiograph
- Lateral chest radiograph does not show impression on posterior wall of trachea
- Esophagram, AP view
  - Shows corresponding impression on right wall of esophagus
- Esophagram, lateral view
  - No impression on posterior wall of esophagus
- High association (90%) with intracardiac defects
  - Tetralogy of Fallot, truncus arteriosus, and double-outlet right ventricle most common defects

Helpful Clues for Rare Diagnoses

Interrupted Aortic Arch
- Interruption may occur at different sites along arch
  - Most common site is between origins of left carotid artery and left subclavian artery (2/3 of cases)
- Postnatally, blood supply to lower half of body requires patent ductus arteriosus
Cervical Aortic Arch
- Arch found above level of clavicle
  - May reach level of C2 vertebra
- Usually right arch
- May have associated symptomatic vascular ring
Persistent 5th Aortic Arch
- Both arches appear on same side of trachea with superior-inferior relationship
- Both arches may be patent or superior arch may be interrupted with patent inferior arch
Pulmonary Sling
- Origin of left pulmonary artery has distal origin from main pulmonary artery and courses sharply to left
- Passes between trachea and esophagus
- Associated with long-segment tracheal narrowing
  - Narrowing due to complete tracheal rings and anomalous tracheal branching

Image Gallery

Anteroposterior esophagram shows a left aortic arch displacing the esophagus to the right

. There is a filling defect in the contrast column running obliquely and superiorly to the right

Lateral esophagram shows a posterior impression on the esophagus

. The findings on the AP and lateral views are consistent with a left aortic arch with an aberrant right subclavian artery.

(Left) Coronal T1WI MR shows a left-sided aortic arch

with an aberrant right subclavian artery

. Because the ligamentum arteriosum is on the left side, there is no vascular ring, and the patients are often asymptomatic. Pressure on the esophagus may cause dysphagia. (Right) Posterior 3D reconstruction shows the aberrant subclavian artery