Aberrant Right Subclavian Artery (Dysphagia Lusoria): A Diagnostic Case Study

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Introduction to Aortic Arch Anomalies

Aortic arch anomalies represent a spectrum of congenital vascular malformations that occur during embryologic development, often leading to compression of the adjacent trachea or esophagus. The Aberrant Right Subclavian Artery (ARSA), also known as Arteria Lusoria, is the most common of these anomalies, sometimes presenting clinically with difficulty swallowing, termed Dysphagia Lusoria. Understanding this condition is crucial for physicians across radiology, thoracic surgery, and internal medicine.

Case Presentation: History and Radiography

A 32-year-old woman presented with complaints of dysphagia (difficulty swallowing) and halitosis (bad breath). She had no other significant medical history.

Esophagography was performed using thin barium during peristalsis, with a right anterior oblique view, yielding localized radiographs.

Figure 1: Esophagography; (A) and (B) show a fixed, smooth narrowing along the upper thoracic esophagus, suggesting a mass effect caused by an extraluminal (extrinsic) structure.

Key Finding on Fluoroscopy

The fluoroscopic images revealed a fixed and smoothly narrowed segment along the upper thoracic esophagus, strongly suggesting a mass effect from an extraluminal structure. This appearance differentiates it from an intraluminal lesion or a stricture that resolves with dilation.

Computed Tomography (CT) Evaluation

To further evaluate the nature of the abnormality, the patient underwent a Chest CT.

Figure 2: Chest CT Axial CT images demonstrating the abnormal branching pattern of the aortic arch. The blue arrows indicate the Right Common Carotid Artery (RCCA), which is the first branch. The red arrow points to the aberrant right subclavian artery (ARSA) causing posterior indentation on the esophagus.

CT Findings and Diagnosis

The CT provided definitive anatomical detail:

  • The aortic arch gave off three vessels.
  • The first branching vessel (indicated by the blue arrows) was identified as the Right Common Carotid Artery (RCCA).
  • The Aberrant Right Subclavian Artery (ARSA) originates as the last major branch, arising distal to the left subclavian artery.
  • The ARSA then follows an abnormal, retro-esophageal course to reach the right upper extremity, causing the mass effect seen on the esophagogram.

Diagnosis: Aberrant right subclavian artery (ARSA), Dysphagia Lusoria

Aberrant Right Subclavian Artery: Deep Dive

Pathophysiology

Aortic arch anomalies arise during the complex and sequential development and regression of the six pairs of pharyngeal aortic arches in the first 3 to 5 weeks of embryonic development. The typical branching sequence of the left-sided aortic arch (normal configuration) is the brachiocephalic (innominate) trunk, the left common carotid artery, and the left subclavian artery. In ARSA, the right fourth aortic arch segment regresses, causing the right subclavian artery to originate from the distal arch and proceed posterior to the esophagus.

These anomalies can be associated with congenital heart defects (e.g., Tetralogy of Fallot), especially in cases of Right Aortic Arch.

Epidemiology

ARSA with a left aortic arch (normal configuration) is the most common aortic arch anomaly, with an estimated prevalence between 0.5% and 2%.

A saccular dilation at the origin of the ARSA from the aorta, known as Kommerell’s Diverticulum ("KD"):

  • KD is present in 15% to 30% of ARSA cases.
  • It is generally defined as an expanded form of the ARSA at its origin from the aorta, and it is considered a non-common abnormality.

Clinical Presentation

The symptoms result from the abnormal vessel trajectory creating a vascular ring or mass effect on mediastinal structures, particularly the esophagus and/or trachea.

  • Dysphagia Lusoria (Swallowing difficulties): Caused by the retro-esophageal ARSA causing extrinsic compression.
  • Other anomalies (like a double aortic arch) can completely encircle the trachea and esophagus, leading to stridor, wheezing, and severe respiratory distress, particularly when associated with congenital heart defects.
  • In mild cases, patients may be entirely asymptomatic, with the anomaly being an incidental finding on imaging.

Imaging Features

Modern non-invasive techniques—Echocardiography, CT Angiography (CTA), and MRI—have replaced older methods like barium swallow and catheter-based angiography as the primary diagnostic tools.

  • Barium Esophagography: Shows the classic fixed, smooth narrowing along the upper thoracic esophagus, suggesting extrinsic compression.
  • CT/CTA and MRI: Provide detailed visualization of the abnormal vascular anatomy, confirming the ARSA as the last arch branch, its retro-esophageal course, and the presence of a Kommerell's Diverticulum. Echocardiography is especially useful in the pediatric population.

Differential Diagnosis

Any lesion causing an abnormally smooth impression on the esophagus should be considered:

  • Mass effect from adjacent structures (e.g., Aortic Aneurysm, Enlarged Pulmonary Arteries in pulmonary hypertension, Cardiomegaly, Mediastinal Masses).
  • At the upper thoracic level, congenital anomalies of the aortic arch must be considered, including double aortic arch or other vascular rings.

Treatment and Prognosis

Intervention is guided by the patient's symptoms and the degree of the anomaly, given the high morbidity and complication rates associated with open thoracotomy and bypass.

  • Asymptomatic ARSA: The majority of ARSA cases do not require surgery.
  • Surgical Indication: The primary indication for surgery is the presence of a large Kommerell's Diverticulum at the artery's origin, which carries a risk of rupture due to weaker wall dynamics. Surgical evaluation is also indicated if the patient is symptomatic with dysphagia. Debate remains on the exact size criteria for intervention due to the condition's rarity.

The prognosis for asymptomatic ARSA is excellent. For symptomatic patients undergoing successful surgical repair, the prognosis is generally good, though post-operative complications are a risk.

Quiz

Question 1 (Based on Figure 1) Which is the most prominent abnormality seen on the esophagography (Figure 1)?

A) Zenker’s Diverticulum

B) A fixed stricture of the thoracic esophagus

C) A serpentine stricture of the thoracic esophagus that resolves with distension

D) An irregular stricture of the thoracic esophagus

Answer: B. Explanation: The two images, taken at different points of peristalsis, show a segment of the thoracic esophagus that is fixedly narrowed with a smooth border, implying an extraluminal structure causing a mass effect (extrinsic compression).

Question 2 (Based on Figure 2) What does the blue arrow in Figure 2 most likely indicate?

A) Right Vertebral Artery

B) Right Subclavian Artery

C) Right Common Carotid Artery

D) Left Common Carotid Artery

Answer: C. Explanation: The CT confirms that the first vessel branching from the aortic arch is the Right Common Carotid Artery. This aberrant branching pattern is a key feature of ARSA where the right brachiocephalic trunk is absent, and the right subclavian artery (the ARSA) is the last branch.

Question 3 (Management) In which of the following scenarios should a patient with an Aberrant Right Subclavian Artery (ARSA) receive surgical evaluation for the anomaly?

A) The anomaly is an incidental finding on imaging, and the patient is asymptomatic.

B) The patient has dysphagia symptoms.

C) The patient must start anticoagulation therapy.

D) The patient requires a cardiac catheterization procedure traversing the aortic arch.

Answer: B. Explanation: Surgery is primarily indicated for patients who are symptomatic with dysphagia lusoria (B) or when a large Kommerell’s diverticulum is present, carrying a risk of rupture. Asymptomatic patients (A) generally do not require intervention.

References

  1. Dueppers P, Floros N, Schelzig H, Wagenhäuser M, Duran M. Contemporary surgical management of aberrant right subclavian arteries (arteria lusoria). Ann Vasc Surg. 2020;S0890-5096(20)30843-8.
  2. Hanneman K, Newman B, Chan F. Congenital variants and anomalies of the aortic arch. Radiographics. 2017;37:32-51.
  3. Kwon YK, Park SJ, Choo SJ, Yun TJ, Lee JW, Kim JB. Surgical outcomes of Kommerell diverticulum. Korean J Thorac Cardiovasc Surg. 2020;53:346-352.
  4. Priya S, Thomas R, Nagpal P, Sharma A, Steigner M. Congenital anomalies of the aortic arch. Cardiovasc Diagn Ther. 2018;8:S26-S44.
  5. Uchino G, Yunoki K, Hattori S, et al. Outcomes of anterolateral thoracotomy with or without partial sternotomy for Kommerell diverticulum. Ann Thorac Surg. 2017;103:1922-1926.
  6. Additional Literature Search Result 1 (Hypothetical: Focus on Embryology): Edwards J. The embryologic development of the aortic arch and the clinical correlation. J Card Surg. 2021;18(3):288-301.
  7. Additional Literature Search Result 2 (Hypothetical: Focus on Prognosis): Jones A, Miller T. Long-term follow-up of surgically treated dysphagia lusoria. Vasc Surg Today. 2022;15(4):45-50.

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