A Retrotracheal Right Subclavian Artery in Association with a Vertebral Artery and Thyroidea Ima

The retro-oesophageal right subclavian artery is an anatomical abnormality encountered by anatomists and pathologists and, more recently, interventional cardiologists and thoracic surgeons with an incidence of 0.2-2% in the population. We report a case of a retrotracheal right subclavian artery which originated distally along the left aortic arch and coursed between the trachea and the oesophagus. Additionally, the aortic arch gave rise to a common trunk, which subsequently bifurcated to yield to a right vertebral artery and a left thyroidea ima, replacing the left inferior thyroid artery. Consequently the right and the left recurrent laryngeal nerves were found to recur normally. The possible embryonic development of these branching patterns and their clinical significance is discussed.