EUS Diagnosis of Aberrant Right Subclavian Artery (arsa)

Abstract

Background: Aberrant right subclavian artery (ARSA) is the most common congenital anomaly of the aortic arch occurring in 0.4-2.0% of the general population. Instead of arising from the brachiocephalic artery, the ARSA arises as the last branch from the aortic arch. ARSA is usually asymptomatic and found incidentally on imaging studies as it courses between the esophagus and spine (80%), between the esophagus and trachea (15%) or anterior to the trachea (5%). Aim: Determine the prevalence of ARSA in patients undergoing upper EUS and describe the EUS characteristics of ARSA. Methods: Retrospective review of 6040 upper EUS exams from 07/01/00 to 12/01/04. Results: 26 of 7180 (0.37%: 95% CI [0.22%, 0.50%]) patients (9 males, 17 females; mean age 56 years (range 23-81 years) undergoing upper EUS were found to have an ARSA. The indications for EUS were esophageal or gastric cancer (n=6), biliary disease (n=7), chronic pancreatitis (n=3), pancreatic cancer (n=3), pancreatic cyst (n=1), mediastinal mass (n=3), insulinoma (n=1), plasmacytoma (n=1) and abdominal pain (n=1). In all 26 patients, radial imaging identified a well-defined, anechoic tubular structure originating from the descending thoracic aorta passing between the esophagus and spine. In all 10 patients undergoing linear imaging, the abnormal anatomy was detected and the vascular nature confirmed by Doppler. In the one patient, both radial and linear imaging identified unsuspected aneurysmal dilatation of the ARSA; a rare condition referred to as Kommerell's Diverticulum (KD). The presence of co-morbidities precluded surgical repair despite the presence of dysphagia and risk of severe complications associated with KD. None of the other 23 patients had symptoms to suggest an ARSA. Interestingly, of the 13 patients who had CT prior to EUS, only 4 were initially reported to have ARSA. However, later review of the CTs verified an ARSA in all 13 patients. Of the two patients that underwent a barium swallow, only one suggested an ARSA. Conclusion: This report highlights the utility of both radial and linear EUS imaging in identifying previously unsuspected ARSA and associated anomalies. Background: Aberrant right subclavian artery (ARSA) is the most common congenital anomaly of the aortic arch occurring in 0.4-2.0% of the general population. Instead of arising from the brachiocephalic artery, the ARSA arises as the last branch from the aortic arch. ARSA is usually asymptomatic and found incidentally on imaging studies as it courses between the esophagus and spine (80%), between the esophagus and trachea (15%) or anterior to the trachea (5%). Aim: Determine the prevalence of ARSA in patients undergoing upper EUS and describe the EUS characteristics of ARSA. Methods: Retrospective review of 6040 upper EUS exams from 07/01/00 to 12/01/04. Results: 26 of 7180 (0.37%: 95% CI [0.22%, 0.50%]) patients (9 males, 17 females; mean age 56 years (range 23-81 years) undergoing upper EUS were found to have an ARSA. The indications for EUS were esophageal or gastric cancer (n=6), biliary disease (n=7), chronic pancreatitis (n=3), pancreatic cancer (n=3), pancreatic cyst (n=1), mediastinal mass (n=3), insulinoma (n=1), plasmacytoma (n=1) and abdominal pain (n=1). In all 26 patients, radial imaging identified a well-defined, anechoic tubular structure originating from the descending thoracic aorta passing between the esophagus and spine. In all 10 patients undergoing linear imaging, the abnormal anatomy was detected and the vascular nature confirmed by Doppler. In the one patient, both radial and linear imaging identified unsuspected aneurysmal dilatation of the ARSA; a rare condition referred to as Kommerell's Diverticulum (KD). The presence of co-morbidities precluded surgical repair despite the presence of dysphagia and risk of severe complications associated with KD. None of the other 23 patients had symptoms to suggest an ARSA. Interestingly, of the 13 patients who had CT prior to EUS, only 4 were initially reported to have ARSA. However, later review of the CTs verified an ARSA in all 13 patients. Of the two patients that underwent a barium swallow, only one suggested an ARSA. Conclusion: This report highlights the utility of both radial and linear EUS imaging in identifying previously unsuspected ARSA and associated anomalies.