Embryologically, the aorta's right sided 4th arch failed to regress which resulted in this double aortic arch. This forms a vascular ring around the patient's trachea and esophagus.  Depending on how tight the "ring" is, symptoms in infancy are related to respiratory compression, compared to a later presentation in childhood or adulthood of swallowing difficulty.  When imaged by echo, the 4 head and neck vessels can be visualized individually rather than the usual branching pattern of the innominate artery.