Chapter 30

    These relatively common anomalies may eventually interfere with the normal dynamics of the esophagus and occasionally the trachea.
    The majority of the vascular rings around these structures, however, are asymptomatic and may be at times associated with other more complex cardiac diseases.

1. Right subdavian artery arising anomaly, where this artery starts after the origin of the left subdavian, as the fourth branch of the aortic artery.    The vessel usually passes behind the esophagus and trachea, and more frequently, courses with no symptoms.
2. Right aortic arch. When the left fourth aortic arch disappears in the embryo between the fifth and sixth week (normally is the right one which disappears), the aortic arch will be rightward of the trachea with esophagus passing over the right bronchus and then behind the esophagus. The majority of these patients are asymptomatic. Few of them may present with dysphagia and/or dyspnea.
3. Double aortic arch. Where both the left and right aortic arch persist in the embryo. This real vascular ring many times produces syptoms of dysphagia and dyspnea with frequent respiratory track infections. In double aortic arch, usually each carotid artery and sublcavian artery arises from its respective arch and no brachiocephalic artery exists.
4. Brachiocephalic artery with anomalous origin. More often the origin of this artery is abnormally displaced toward the left, passing in front of the trachea which may compress the structure and produce dyspnea.
5. Left carotid anomalous origin. Where its origin is abnormally displaced toward the right, may produce compressive subocclusion of the trachea.
6. Interruption of the aortic arch. Many variants are described as protrayed in the illustration in this chapter. The lack of continuity between the aortic arch and the descending aorta constitutes the main anomaly but PDA exists in many of these patients connecting the pulmonary artery with the descending aorta. VSD is also present in the majority of the cases. Not infrequently, complete transposition or both arteries arising from right ventricle can be encountered.

    There will be a difference in arterial blood saturation between the inferior and superior part of the patient's body, with differential cyanosis.
    Right ventricular volume overload with pulmonary hypertension develops with time.
    Many different anomalies in origin of the aortic arch branches may frequently co-exist with this malformation.