Abstract
A 47 year-old man presented to the clinic with a 2-year history of intermittent headaches, dizziness, blurry vision, and hearing loss in his left ear. Although symptoms were increasing in frequency, they were not precipitated by any upper extremity effort. Physical examination revealed a normal neuromotor response and equal pulses and blood pressures in both arms. The patient gave written consent for publication of all details of his case, including the radiologic images. Computed tomography angiography demonstrated a right-sided aortic arch (RAA; A) with unconventional origins of the great vessels: the left common carotid, the right common carotid, and right subclavian arteries. The origin of the left subclavian artery (LSA) was congenitally atretic and reconstituted just proximal to the left vertebral artery (B). The lower attenuation of contrast in the LSA and vertebral arteries compared with the arch vessels suggested a subclavian steal phenomenon, later confirmed by retrograde flow in the left vertebral artery on ultrasound imaging. The isolated LSA (ILSA; C) showed prominent left inferior thyroid collateralization to the thyrocervical trunk (Cover). All of these findings were consistent with an RAA with ILSA. RAA is a rare congenital anomaly occurring in ∼0.05% of the population.1Turkvatan A. Buyukbayraktar F. Olcer T. Cumhur T. Congenital anomalies of the aortic arch: evaluation with the use of multidetector computed tomography.Korean J Radiol. 2009; 10: 176-184Crossref PubMed Scopus (79) Google Scholar The RAA is further classified into three subtypes: RAA with aberrant LSA, RAA with mirror image, and RAA with ILSA. Of these, the RAA with ILSA is the most rare, accounting for only 0.8% of these anomalies.2Stewart J.R. Kincaid O.W. Edwards J.E. An atlas of vascular rings and related malformations of the aortic arch system. Charles C. Thompson, Springfield, IL1964: 12-131Google Scholar The ILSA receives its blood supply through retrograde flow from the left vertebral artery, potentially causing a subclavian steal syndrome with vertebrobasilar insufficiency.3Luetmer P.H. Miller G.M. Right aortic arch with isolation of the left subclavian artery: case report and review of the literature.Mayo Clin Proc. 1990; 65: 407-413Abstract Full Text Full Text PDF PubMed Scopus (87) Google Scholar Case reports show that this entity usually presents in the fourth or fifth decade of life, despite being a congenital abnormality, due to lack of compensation for the steal syndrome later in life.3Luetmer P.H. Miller G.M. Right aortic arch with isolation of the left subclavian artery: case report and review of the literature.Mayo Clin Proc. 1990; 65: 407-413Abstract Full Text Full Text PDF PubMed Scopus (87) Google Scholar Our patient had symptoms highly suggestive of vertebrobasilar insufficiency, and thus, we advised him to undergo a left carotid-to-LSA bypass. The patient chose to have close follow-up given that his symptoms were not yet interfering with his activities of daily living.
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