Non-perfused elements of other types of vascular rings (e.g. left arch with atretic (closed) end) or the ligamentum arteriosum might be difficult to visualize by echocardiography. Computed tomography (CT):
Computed tomography after application of contrast media is usually diagnostically accurate. It shows the relationship of the arches to the trachea and bronchi. Magnetic resonance imaging (MRI):
Magnetic resonance imaging provides excellent images of the trachea and surrounding vascular structures and has the advantage of not using radiation for imaging compared to Computed tomography. Cardiac catherization/aortography:
Today patients with double aortic arch usually only undergo cardiac catherization to evaluate the hemodynamics and anatomy of associated congenital cardiac defects. Through a catheter in the ascending aorta contrast media is injected and the resulting aortography may be used to delineate the anatomy of the double aortic arch including sites of narrowing in the left aortic arch. Aortography can also be used to visualize the origin of all head and arm vessels originating from the two arches. Classification
Double aortic arch is a subtype of complete vascular ring. There are three types of double aortic arch:

Right dominant arch (about 70% of surgical cases)
Balanced or codominant (about 5%): both arches are of equal size
Left dominant (about 25%)Double aortic arch with right dominant arch:
Normally there is only one (left) aortic arch. In patients with double aortic arch the ascending aorta arises normally from the left ventricle but then divides into two arches, a left and a right aortic arch which join posteriorly to become the descending aorta.
In certain patients it may take several months (up to 1–2 years) for the obstructive respiratory symptoms (wheezing) to disappear. Signs and symptoms
Symptoms are caused by vascular compression of the airway, esophagus or both. Presentation is often within the first month (neonatal period) and usually within the first 6 months of life. Starting at birth an inspiratory and expiratory stridor (high pitch noise from turbulent airflow in trachea) may be present often in combination with an expiratory wheeze. The severity of the stridor may depend on the patient’s body position. It can be worse when the baby is lying on their back rather than their side. Sometimes the stridor can be relieved by extending the neck (lifting the chin up). Parents may notice that the baby’s cry is hoarse and the breathing noisy. Frequently a persistent cough is present. When the airway obstruction is significant there may be episodes of severe cyanosis (“blue baby”) that can lead to unconsciousness. Recurrent respiratory infections are common and secondary pulmonary secretions can further increase the airway obstruction.Secondary to compression of the esophagus babies often feed poorly. They may have difficulties in swallowing liquids with choking or regurgitating and increased respiratory obstruction during feeding. Older patients might refuse to take solid food, although most infants with severe symptoms nowadays are operated upon before they are offered solid food.Occasionally patients with double aortic arches present late (during later childhood or adulthood). Symptoms may mimic asthma. Causes
Little is known regarding the exact causes of aortic arch anomalies.