The smaller left arch passes anteriorly and to the left of the trachea in the usual position. It is often joined by the ligamentum arteriosum (or patent ductus arteriosus) where it forms the descending aorta. The left arch gives first origin to the left common carotid artery and then the left subclavian artery. The right aortic arch is completing the vascular ring by passing to the right and then behind the esophagus and trachea to join the usually left-sided descending aorta. The first vessel coming off the right arch is usually the right common carotid artery followed by the right subclavian artery. Double aortic arch with left dominant arch:
In this less common condition, as the name indicates, the left arch is the larger of the two aortic arches. The origins of the arm and head vessels are identical to the anatomy of double aortic arch with right dominant arch
Balanced or codominant double aortic arch:
In this rare condition both aortic arches are of the same diameter. Treatment
Surgical correction is indicated in all double aortic arch patients with obstructive symptoms (stridor, wheezing, pulmonary infections, poor feeding with choking). If symptoms are absent a conservative approach (watchful waiting) can be reasonable. Children with very mild symptoms may outgrow their symptoms but need regular follow-up. Anesthesia and intraoperative monitoring
The procedure is performed in general anesthesia. It is useful to place pulse oximeter probes on both hands and one foot so that test occlusion of one arch or its branches will allow confirmation of the anatomy.
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.