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

Treatment of Left Aortic Arch with Aberrant Right Subclavian Artery

Treatment for a left aortic arch with aberrant right subclavian artery (ARSA) coursing posterior to the esophagus should be based on symptoms and anatomical measurements, with surgical intervention recommended when the diverticulum orifice is >3.0 cm or the combined diameter of the diverticulum and adjacent descending aorta is >5.0 cm. 1, 2

Diagnostic Evaluation

When ARSA is discovered:

• Dedicated imaging (CT or MRI) to assess for thoracic aortic aneurysm is reasonable if not already performed 1
• Evaluate for presence of Kommerell's diverticulum (present in 20-60% of ARSA cases) 1, 2
• Assess for symptoms:
  • Dysphagia (especially with solid foods) - "dysphagia lusoria"
  • Respiratory symptoms
  • Recurrent laryngeal nerve palsy 2

Treatment Algorithm

Asymptomatic Patients:

1. No intervention needed if:

   • No Kommerell's diverticulum
   • Diverticulum orifice <3.0 cm
   • Combined diameter of diverticulum and adjacent descending aorta <5.0 cm 1

2. Regular surveillance with cardiovascular imaging to monitor for:

   • Development of symptoms
   • Aneurysmal dilatation
   • Enlargement of Kommerell's diverticulum 2, 3

   Key measurement: Cross-sectional ARSA diameter 1 cm distal to the ostium (shows most significant growth in patients who eventually require intervention) 3

Symptomatic Patients:

1. Urgent referral to cardiovascular surgeon or interventional radiologist 2

2. Surgical intervention recommended when:

   • Diverticulum orifice >3.0 cm, OR
   • Combined diameter of diverticulum and adjacent descending aorta >5.0 cm, OR
   • Presence of significant symptoms (dysphagia, respiratory symptoms) 1, 2

Surgical Approaches

Three main approaches are available, with selection based on patient anatomy and comorbidities:

1. Open Surgical Repair:

   • Resection of aneurysmal segment of subclavian artery (diverticulum) and adjacent aorta
   • Graft replacement
   • Subclavian-carotid transposition or carotid-subclavian bypass for revascularization 2, 4

2. Endovascular Approach:

   • Thoracic endovascular aortic repair (TEVAR)
   • Exclusion of the right subclavian artery origin and adjacent aorta using an aortic endograft 2, 4

3. Hybrid Approach (most common, used in 54% of cases in one study):

   • Combines open and endovascular techniques
   • Typically involves right carotid-subclavian bypass or transposition followed by TEVAR 2, 3

Important Surgical Considerations

• Assess for nonrecurrent right laryngeal nerve (may be present with ARSA), which increases risk of nerve injury during surgery 2
• Individualized therapy planning in specialized centers is vital for optimal outcomes 4
• Technical success rates of 100% have been reported with appropriate surgical planning 4

Post-Operative Care

• Regular cardiovascular imaging to monitor for:

  • Recurrent symptoms
  • Endoleaks (if endovascular approach was used)
  • Aneurysmal progression 2

• Potential complications to monitor:

  • Vascular access issues
  • Horner syndrome after subclavian-carotid transposition
  • Type II endoleaks requiring additional intervention 4

The decision to intervene should be guided by symptoms and anatomical measurements, with the primary goal of preventing aneurysm rupture and alleviating compressive symptoms. Surgical outcomes are generally excellent with appropriate patient selection and technique.