Abnormal branching pattern of the aortic arch Abnormal branching pattern of left aortic arch 2017-05-27T17:24:29Z A deviance from the norm of the origin or course of the right brachiocephalic artery, the left common carotid artery, the left subclavian artery or the proximal vertebral arteries, whereby the aortic arch descends on the left as normal (as opposed to right aortic arch).