Vascular Ring Double Aortic Arch

The term "vascular ring" (VR) refers to the structures that encircle and compress the esophagus and trachea, causing respiratory and gastrointestinal symptoms. VRs are divided into 2 broad categories: complete or incomplete (see Image. Vascular Ring). Complete VRs encircle the trachea and esophagus entirely. These include a double aortic arch (DAA) and a right aortic arch (RAA) with an aberrant (retro-esophageal) left subclavian artery (see Image. Double Aortic Arch and Right Aortic Arch With Aberrant [Retroesophageal] Left Subclavian Artery). These are the most common types of vascular rings. Incomplete VRs do not completely encircle the trachea and esophagus, although some compress either the trachea or esophagus; it usually includes an aberrant innominate artery, an aberrant right subclavian artery, and a pulmonary artery sling.

An arch-sidedness is defined by the position of the aortic arch in relation to the trachea and the bronchi. A left aortic arch would be towards the left of the trachea and run over the left bronchus, whereas an RAA would be towards the right of the trachea and run over the right bronchus. A DAA is when 2 transverse aortic arches run over the trachea and both bronchi. Normally, the arch-sidedness is towards the left, and no arterial duct is behind the trachea or esophagus. In cases of the vascular ring, there is a patent vessel, an atretic vessel, or its remnants circling the trachea or esophagus.

DAA can be further divided into 3 main types. The dominant RAA with a smaller LAA (80%) is the most common. The dominant LAA is found in 10% of the cases, and equal aortic arches are found in the other 10%. Depending on the site of the regression of the fourth aortic arch, RAA can be divided into 2 parts. If regression is proximal to the left subclavian artery, it is called RAA with an aberrant (retro esophageal) left subclavian artery. If regression is distal, it is called RAA with mirror image branching. Around 50% of cases of the right-sided aortic arch are associated with an aberrant (retro-esophageal) left subclavian artery. This often has a Kommerell diverticulum named after the radiologist Dr Burckhard Komerell, who reported this finding in 1936. Kommerell diverticulum is an outpouching of the distal aorta and usually originates from the left arch.

Pulmonary artery sling occurs when the left pulmonary artery originates from the right pulmonary artery, which crosses between the trachea and esophagus before entering the left lung, thus compressing the trachea. This is the only VR type with an indentation in the anterior esophagus on barium swallow. Anomalous innominate artery originates later from the transverse arch and then crosses the trachea, causing anterior tracheal compression.

According to the International Congenital Heart Surgery Nomenclature and Database Committee, the classification system for vascular rings is as follows:

A. Complete vascular rings

1. Double aortic arch

I. Dominant right arch

II. Dominant left arch

III. Equal arches/balanced arches

1. Right aortic arch

I. RAA+ aberrant left subclavian artery (ALSA)

II. RAA with mirror imaging

B. Incomplete aortic arch

1. Innominate artery compression syndrome

2. Pulmonary artery sling

3. Aberrant right subclavian artery (ARSA)