The aorta consists of thoracic and abdominal components. There are 5 segments of the thoracic aorta. The aortic root is a short segment that includes the aortic valve, the annulus, and the sinuses of Valsalva. The ascending aorta extends from the root to the origin of the right brachiocephalic artery. The proximal aortic arch is the segment from the origin of the right brachiocephalic artery to the left subclavian artery. The posterior aortic arch (the aortic isthmus) extends from the origin of the left subclavian artery to the ligamentum arteriosum. This portion of the arch is often slightly narrower than the descending aorta. The descending thoracic aorta begins at the ligamentum arteriosum and ends at the diaphragm. The proximal aspect of the descending aorta is sometimes slightly prominent relative to the adjacent segments. Mild localized bulging of the posterior aortic arch or the superior aspect of the descending aorta is termed the aortic spindle. The abdominal aorta consists of suprarenal and infrarenal segments.
The most common vascular rings are double aortic arch and right aortic arch with an aberrant left subclavian artery. Unusual arch anomalies that can cause a complete vascular ring include circumflex aorta, right aortic arch with mirror image branching and a left-sided ligamentum arteriosum, and left aortic arch with an aberrant right subclavian artery and a right-sided ligamentum arteriosum (Table 12-1).1
Table 12–1.Vascular Rings |Favorite Table|Download (.pdf) Table 12–1. Vascular Rings
|Double aortic arch ||Bilateral patent arches |
|Atretic left arch |
|Atretic right arch (rare) |
|Left aortic arch ||Aberrant right subclavian, right ligamentum |
|Circumflex left arch, right ligamentum |
|Right aortic arch ||Aberrant left subclavian, left ligamentum |
|Circumflex right arch, left ligamentum |
|Mirror image branching, left ligamentum to aorta |
|Cervical aortic arch ||Contralateral ligamentum |
The most important determinants of the clinical presentation of a vascular ring are the severity of tracheal compression and the occurrence of associated anomalies such as a congenital heart lesion. Some patients present in the neonatal period with life-threatening respiratory distress. At the other end of the spectrum are patients who remain asymptomatic into adulthood, with the lesion discovered incidentally. Symptoms are present during infancy in most patients with double aortic arch or right aortic arch with a left ductus arteriosus. Pulmonary artery sling (origin of the left pulmonary artery from the right pulmonary artery) is another great vessel anomaly that, although not a vascular ring, is usually symptomatic during infancy.
The most common clinical manifestations of a vascular ring are stridor and wheezing. The stridor is most severe during inspiration. Severely affected infants tend to hold their neck hyperextended. Physical activity may exacerbate the respiratory symptoms. These patients are prone to recurrent lower respiratory tract infections. Dysphagia is a less consistent finding in patients with an arch anomaly. ...