Right Aortic Arch

In this abnormality, the aorta curves to the right and, if it descends on the right side of the vertebral column, is usually associated with other cardiac malformations. It is found in 20% of cases of tetralogy of Fallot and is also common in truncus arteriosus. A right aortic arch without other cardiac anomalies is not associated with symptoms. It can often be visualized on the chest roentgenogram. The trachea is deviated slightly to the left of the midline rather than to the right, as in the presence of a normal left arch. On a barium esophagogram, the esophagus is indented on its right border at the level of the aortic arch.

Vascular Rings

Congenital abnormalities of the aortic arch and its major branches result in the formation of vascular rings around the trachea and esophagus with varying degrees of compression (Table 426-1). The origin of these lesions can best be appreciated by reviewing the embryology of the aortic arch (Fig. 414-1). The most common anomalies include (1) double aortic arch (Fig. 426-1A), (2) right aortic arch with a left ligamentum arteriosum, (3) anomalous innominate artery arising farther to the left on the arch than usual, (4) anomalous left carotid artery arising farther to the right than usual and passing anterior to the trachea, and (5) anomalous left pulmonary artery (vascular sling). In the latter anomaly, the abnormal vessel arises from an elongated main pulmonary artery or from the right pulmonary artery. It courses between and compresses the trachea and the esophagus. Associated congenital heart disease may be present in 5-50% of patients, depending on the vascular anomaly.

Table 426-1 VASCULAR RINGS

Figure 426-1 Double aortic arch. A, Small anterior segment of the double aortic arch (most common type). B, Operative procedure for release of the vascular ring.

Diagnosis

Standard roentgenographic examination is not usually helpful, however, in the past, performing a barium esophagogram was the standard method of diagnosis (Fig. 426-2). Echocardiography in combination with either MRI or CT will usually define the lesion. Cardiac catheterization is reserved for cases with associated anomalies or in rare cases where these other modalities are not diagnostic. Bronchoscopy may be helpful in more severe cases to determine the extent of airway narrowing.

Figure 426-2 Double aortic arch in an infant aged 5 mo. A, Anteroposterior view. The barium-filled esophagus is constricted on both sides. B, Lateral view. The esophagus is displaced forward. The anterior arch was the smaller and was divided at surgery.

Anomalous Origin of the Left Coronary Artery from the Pulmonary Artery (Alcapa)

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