What is the recommended management for a left aortic arch with an aberrant right subclavian artery (ARSA) coursing posterior to the esophagus?

Management of Left Aortic Arch with Aberrant Right Subclavian Artery

For a left aortic arch with aberrant right subclavian artery (ARSA) coursing posterior to the esophagus, management should be guided by symptoms and anatomic measurements, with surgical or endovascular intervention recommended when the Kommerell's diverticulum orifice is >3.0 cm, the combined diameter of the diverticulum and adjacent descending aorta is >5.0 cm, or when the patient is symptomatic. 1

Initial Evaluation

• Dedicated thoracic aortic imaging with CT or MRI is reasonable for all patients discovered to have an ARSA, as this anomaly is associated with thoracic aortic aneurysm (TAA) in 2-8% of cases 1
• Assess for symptoms of compression, which may include dysphagia (dysphagia lusoria), respiratory symptoms, or recurrent laryngeal nerve palsy due to the aberrant vessel coursing behind the esophagus 1
• Evaluate for the presence of Kommerell's diverticulum, a persistent remnant of the fourth primitive dorsal aortic arch that may be present in 20-60% of patients with an aberrant subclavian artery 1

Measurement Criteria

• Two key diameter measurements should be obtained using cross-sectional imaging 1:
  • The diverticulum orifice (measured radially and longitudinally at the aortic wall)
  • The combined diameter of the diverticulum and adjacent descending thoracic aorta (measured from the tip of the diverticulum to the opposite aortic wall)

Management Algorithm

Asymptomatic Patients:

• If Kommerell's diverticulum is absent or small (<3.0 cm orifice and combined diameter with adjacent aorta <5.0 cm):

  • Surveillance with periodic imaging is appropriate 1, 2
  • No immediate intervention required 3

• If Kommerell's diverticulum meets size criteria (orifice >3.0 cm or combined diameter with adjacent aorta >5.0 cm):

  • Repair may be reasonable depending on patient anatomy and comorbidities 1
  • The risk of rupture or dissection has been reported to be as high as 50% in case series, although high-quality data on natural history are limited 1

Symptomatic Patients:

• For patients with symptoms of compression (dysphagia, respiratory symptoms, recurrent laryngeal nerve palsy):
  • Surgical or endovascular intervention is indicated regardless of size 4, 2
  • Symptoms are the primary indication for intervention in many cases 3

Intervention Options

• Surgical approaches:

  • Open repair with division of the aberrant vessel and reimplantation to prevent subclavian steal syndrome 5
  • Excision of Kommerell's diverticulum when present (particularly recommended for large diverticula) 4

• Endovascular approaches:

  • May be appropriate depending on patient anatomy and comorbidities 1
  • Hybrid procedures involving right carotid-subclavian bypass or transposition and thoracic endovascular aortic repair (TEVAR) 3

• Choice of approach:

  • Should be based on patient-specific factors including anatomy, comorbidities, and institutional expertise 1

Follow-up for Non-Surgical Cases

• Regular surveillance imaging is recommended for patients who do not undergo immediate intervention 2
• Monitor for:
  • Growth of the Kommerell's diverticulum (particularly at 1 cm distal to the vessel ostium, which may show the most significant change) 3
  • Development or worsening of symptoms 2
  • Associated aortic pathology 1

Important Considerations

• Left aortic arch with ARSA is the most common aortic arch anomaly, occurring in approximately 1% of the population 1
• While many cases are asymptomatic and found incidentally, the potential for serious complications including rupture, dissection, or compression symptoms necessitates appropriate evaluation and management 1, 2
• The 2022 ACC/AHA guidelines and 2024 ESC guidelines provide consistent recommendations regarding size criteria for intervention 1