What is the management approach for a patient with a left-sided aortic arch and a retroesophageal right subclavian artery?

Management of Left-Sided Aortic Arch with Aberrant Right Subclavian Artery

All patients discovered to have an aberrant right subclavian artery (ARSA) require dedicated thoracic aortic imaging with CT or MRI to evaluate for associated thoracic aortic aneurysm, which occurs in 2-8% of these patients. 1

Initial Diagnostic Evaluation

Mandatory Imaging Assessment

• Obtain dedicated CT angiography or MRI of the entire thoracic aorta if the initial imaging study that detected the ARSA did not include complete thoracic aortic visualization 1
• CT angiography is the preferred modality due to superior anatomic detail of vascular structures and their relationship to surrounding tissues 2
• MRI/MRA serves as an excellent alternative when radiation exposure is a concern or iodinated contrast is contraindicated 2

Clinical Symptom Assessment

Evaluate specifically for:

• Dysphagia (difficulty swallowing due to retroesophageal compression) 3
• Respiratory symptoms including dyspnea, wheezing, stridor, or cough from tracheal compression 3, 4
• Recurrent laryngeal nerve palsy manifesting as hoarseness 3
• Upper extremity pulse discrepancies or blood pressure differences between arms 5

Kommerell's Diverticulum Evaluation

• Assess for presence of Kommerell's diverticulum, which occurs in 20-60% of patients with ARSA 3, 2
• This represents a persistent remnant of the fourth primitive dorsal aortic arch 3

Critical Measurement Protocol

Obtain two specific diameter measurements using cross-sectional imaging: 1, 3

1. Diverticulum orifice diameter - measured radially and longitudinally at the aortic wall 1
2. Combined diameter - measured from the tip of the diverticulum to the opposite aortic wall of the adjacent descending thoracic aorta 1

Management Algorithm

Indications for Surgical or Endovascular Intervention

Intervention is recommended when ANY of the following criteria are met: 1, 3

• Kommerell's diverticulum orifice diameter >3.0 cm 1, 3
• Combined diameter of diverticulum and adjacent descending aorta >5.0 cm 1, 3
• Presence of compressive symptoms (dysphagia, respiratory symptoms, or recurrent laryngeal nerve palsy) regardless of size 3

Asymptomatic Patients Below Size Thresholds

• Surveillance imaging with CT or MRI at regular intervals 3
• Monitor for progressive enlargement of the diverticulum or development of symptoms 3
• Maintain awareness that rupture and dissection of Kommerell's diverticulum have been reported in diverticula ranging from 4.0 cm to 10 cm (mean size 5.0 cm) 1

Intervention Approach Selection

Treatment Modality Options

Both open surgical and endovascular approaches can achieve successful repair, with selection based on: 1, 3

• Patient-specific anatomy 3
• Presence and severity of comorbidities 1, 3
• Institutional expertise 3

Open Surgical Techniques

• Primary resection of Kommerell's diverticulum with left subclavian artery transfer to the left carotid artery has demonstrated excellent outcomes in selected patients 4
• Approach typically through left thoracotomy 6, 4
• May require staged procedures depending on anatomic complexity 6

Endovascular Considerations

• Hybrid approaches combining endovascular and open techniques may be appropriate for high-risk patients 3
• Requires adequate proximal and distal landing zones 1

Critical Pitfalls to Avoid

• Do not dismiss this finding as a benign incidental variant - the association with thoracic aortic aneurysm (2-8% of cases) mandates complete aortic evaluation 1
• Do not rely solely on symptom presence - asymptomatic patients with size criteria meeting thresholds still require intervention due to rupture/dissection risk 1
• Do not use imprecise measurements - standardized measurement techniques are essential as Kommerell's diverticulum measurement can be difficult 1
• Do not delay intervention in symptomatic patients - compressive symptoms indicate need for repair regardless of diverticulum size 3