Aberrant Right Subclavian Artery: A Rare Cause of Dysphagia

Abstract

Aberrant right subclavian artery (also known as Arteria Lusoria) is the most common congenital anomaly of the aortic arch occurring in 0.5% to 1.8% of the population based on cadaveric studies. Normally during embryogenesis, regression of the distal right dorsal aorta occurs leading to the right 4th aortic branch and 7th intersegmental artery becoming the right subclavian artery. Aberrant right subclavian artery is caused by the involution of the right 4th aortic branch and proximal right dorsal aorta with a persistent distal right dorsal aorta and 7th intersegmental artery forming the right subclavian artery. This causes the right subclavian artery to originate left of the midline occasionally causing compression. The retroesophageal course of the right subclavian artery behind the esophagus, although usually asymptomatic, may cause compression and a type of dysphagia known as dysphagia lursoria. A 50 year old female with a medical history of von Willebrand disease, hypertension, asthma, and peripheral neuropathy presents with a complaint of several weeks of progressive dysphagia associated with heaviness in her chest. Her dysphagia began with solid foods and progressed to include liquids. Three days prior to presentation, she could not tolerate any solids or liquids by mouth and would have immediate regurgitation. The patient admits to about 20 lbs weight loss in the past two months. EGD and Esophageal Manometry was normal. Barium Esophagram showed mild extrinsic mass effect on the posterior aspect of the upper esophagus. CT neck angiography revealed a congenitally anomalous aortic arch with a retroesophageal aberrant right subclavian artery reaching as far superiorly as the T1 vertebral body. Various proposed mechanisms of why dysphagia develops in older adults include age related increased esophageal rigidity, right subclavian aneurysm formation, and elongation of the aorta. Barium swallow remains an effective tool for initial evaluation usually showing a characteristic diagonal impression in the esophagus at the level of 3rd-4th vertebra. EGD may reveal a pulsating mass at around the same level. Esophageal manometry may reveal a high-pressure zone 25-30cm from the nose. Angiography of the aortic arch or endoscopic ultrasound may be used for definitive diagnosis. Initial treatment should be conservative management using prokinetic or antireflux drugs. Surgical treatment may be attempted in those who do not respond to conservative management.1720_A Figure 1. CT neck angiography revealed a congenitally anomalous aortic arch with a retroesophageal aberrant right subclavian artery reaching as far superiorly as the T1 vertebral body.1720_B Figure 2. Esophageal Manometry: Normal manometry. Normal LES with normal relaxation. 100% swallows peristaltic. Barium Esophagram: No evidence of an intrinsic mass, polyp, diverticulum, or stricture. There is mild extrinsic mass effect on the posterior aspect of the upper esophagus however this caused no limitation of contrast passage.1720_C Figure 3. A) Embryonic pharyngeal arch arteries. Normal Right Subclavian Artery: Right 4th Aortic Arch to Right Dorsal Aorta to Right 7th Intersegmental Artery B) Abnormal obliteration of 4th Aortic Arch with remnant of Right Dorsal Aorta and Right 7th Intersegmental Artery forming an Aberrant Right Subclavian Artery C) Aberrant Right Subclavian Artery crossing midline causing impingement of the esophagus