Aortic Arch Anomalies

Scheme of the aortic arches of vertebrates showing the embryonic arterial segments that form the most important arteries. Variations in this developmental pattern may lead to clinically significant anomalies of the aortic arch. Gray's Anatomy (1918) figure 473 (originally from Kollmann). Source: Wikimedia Commons

Anomalies of the aortic arch and related abnormalities are uncommon, accounting for less than 1% of congenital heart disease. These anomalies arise from unusual patterns of development of the aortic arch arteries of the pharyngeal arches, such that there may be persistence of vessels that normally regress, and involution of vessels that normally continue to develop. Thus, aortic arch anomalies are described by the position of the aortic arch (right, left, double, or cervical), and the pattern of branching from the aortic arch. Some of these anomalies create a "vascular ring" around the trachea and esophagus, which can present clinically with respiratory obstruction and dysphagia. Other anomalies may be asymptomatic.

Types

• Double aortic arch
• Right aortic arch with mirror-image (i.e., "normal") branching
• Right aortic arch with abnormal branching
• Left aortic arch with abnormal branching
• Cervical aortic arch

Double Aortic Arch

Double aortic arch results from persistence of both (right and left dorsal aortae). A functioning double aortic arch forms a vascular ring around the trachea and esophagus, which may cause respiratory obstruction and dysphagia. Some cases display partial involution (i.e., atresia) of one of the arches.

Right Aortic Arch

A right-sided aortic arch results from involution of part of left dorsal aorta and persistence of right dorsal aorta. Right aortic arch is usually associated with an abnormal branching pattern.

Right aortic arch with mirror-image branching

This anomaly is usually does not form a vascular ring; however, there is an uncommon variant in which a vascular ring is formed by a retroesophageal right aortic arch and a left ductus arteriosus. Virtually all cases of right aortic arch with mirror-image branching are associated with other heart defects, most commonly Tetralogy of Fallot.

Right aortic arch with abnormal branching

Involution of the left 4th arch, in addition to the left dorsal aorta, results in an abnormal origin of the left subclavian artery.

• Right aortic arch with aberrant left subclavian artery
  

The left subclavian may have an aberrant origin from a right aortic arch (typically distal to the right subclavian artery) and an aberrant course of the artery, usually posterior to the esophagus.

• Right aortic arch with isolated left subclavian artery
  

The left subclavian may become disconnected from the aorta, and be supplied by the left pulmonary artery via the ductus arteriosus. Closure of the ductus arteriosus is likely to cause a congenital subclavian steal syndrome involving the vertebral artery.

Left Aortic Arch with Abnormal Branching

• Left aortic arch with retroesophageal right subclavian artery

Involution of the right 4th aortic arch results in aberrant origin of the right subclavian artery from a left (normal) aortic arch, typically distal to the left subclavian artery. This anomaly is the most common aortic arch anomaly and is usually asymptomatic.

Cervical Aortic Arch

Very rarely, an aortic arch (right or left) may be found in the neck region. The embryology of this anomaly is not known, but the existence of various forms indicates that one embryological defect cannot explain all of the cases of cervical aortic arch. Some cases may involve aortic arch arteries cranial to the 4th aortic arch artery that usually forms the aortic arch.

External Links

McElhinney DB, Goldmuntz E. Abnormalities of the Aortic Arch. Orphanet encyclopedia, June 2004.