Right Aortic Arch With an Aberrant Left Subclavian Artery Causing Tracheoesophageal Compression

Abstract

Right-sided aortic arch (RAA), a congenital malformation of the great vessels of the thorax, can cause symptoms from the compression of the trachea and/or esophagus. Most cases are diagnosed during childhood.1,2 There are a few reports in the literature about symptomatic RAA presented in adulthood. We report a case of a 19-year-old man with a RAA who presented with dyspnea on exertion, dysphagia, and a characteristic bronchoscopic image. CASE REPORT A 19-year-old man, nonsmoker, was admitted with gradually worsening dyspnea on exertion and dysphagia of 3 years’ duration. Physical examination was unremarkable. His chest x-ray revealed a right aortic knob without other abnormalities. The contrast-enhanced computed tomography (CT) scan of the chest demonstrated a RAA and the compression of the posterior wall of the lower part of the trachea and the right main bronchus, the latter from the right-sided descending aorta. The CT scan also revealed an anomalous origin and retroesophageal course of the left subclavian artery that caused compression of the middle part of the esophagus (Fig. 1).FIGURE 1.: Computed tomography scan of the chest, which shows the compression of the trachea by the right aortic arch and the coma-like appearance of its lumen as well as the compression of the esophagus by the left subclavian artery (arrow).Flexible bronchoscopy revealed a coma-shaped and stenosed lower third of the trachea, proximal to the origin of the right main bronchus, from an extrinsic pulsatile compression of its posterior wall (Fig. 2). Another site of stenosis was also observed at the orifice of the apical segmental bronchus of the right upper lobe by an extrinsic compression of its posterior wall. Single-contrast esophagography revealed stenosis at the middle third of the esophagus, from an extrinsic compression, with prestenotic dilatation.FIGURE 2.: Bronchoscopic image of the lower portion of the trachea reveals the characteristic coma-like appearance of its lumen by an extrinsic pulsatile compression.The patient’s symptoms were attributed to the RAA malformation, and a surgical correction of the anomaly was recommended. The patient refused therapeutic intervention, because he was informed of the benign nature of his disease. DISCUSSION Congenital malformations of the aortic arch arise from disorders in the formation of the primitive double aortic arch.3 A RAA with an aberrant origin of the left subclavian artery is 1 of these malformations that can cause symptoms during infancy as a result of the formation of a vascular “ring.” The usual symptoms and signs are stridor, apnea, dysphagia, recurrent respiratory track infections, and respiratory distress.4 When these appear in adulthood, they can mimic asthma or other obstructive airway diseases.5 In normal individuals, the left aortic arch passes in front and to the left of the trachea, and the ligamentum arteriosum connects the descending aorta to the pulmonary trunk. The left subclavian artery has a normal course at the left of the trachea. In our case, the aortic arch was cited posteriorly and on the right of the trachea. The left subclavian artery had an aberrant origin from the distal aortic arch and a retroesophageal course, passing between the esophagus and the thoracic vertebrae. The vascular “ring” was consisted by the right-sided aortic arch, the descending aorta, the left subclavian artery, the pulmonary trunk, and the ligamentum arteriosum. When the ligamentum arteriosum is sort or taut, compression of the trachea and esophagus can occur.1 In infants, the diagnoses of vascular abnormalities of the chest that cause airway obstruction can be made by using barium esophagography, bronchoscopy, CT scan, angiography, and magnetic resonance imaging (MRI).4,6 Backer et al. postulated that barium esophagography is the best diagnostic examination for infants with vascular “ring” anomalies.4 MRI is a noninvasive technique that can depict the anatomic abnormalities of the vessels of the chest and is also indicated in such cases.6 In our patient, the presence of RAA on the chest radiograph suggested that his symptoms were likely to be the result of this anomaly. It was confirmed by CT scan, single-contrast esophagography, and bronchoscopy. In patients with symptomatic RAA, bronchoscopy can assess the location and degree of the compression. During corrective surgery, bronchoscopy is essential to ensure that the correction of the airway compression has been achieved by operative manipulations.2 Chapotte and coworkers, in a retrospective study, also emphasized the importance of fiberoptic bronchoscopy in the assessment of airway compression in children resulting from vascular “rings” and concluded that bronchoscopy is a well-tolerated procedure, which optimizes the preoperative assessment of children with congenital heart disease.7