VASCULAR RINGS AND SLINGS U1 L2

What is a vascular ring?

An anomaly of the aortic arch that encircles the trachea and esophagus.

What can happen to the components of a vascular ring?

The components may be:

1. Patent

2. Atretic

3. Remnants

How common are vascular rings?

They are very rare and make up approximately 1–3% of cardiovascular anomalies.

Are vascular rings usually isolated or associated with other defects?

They are usually isolated.

List the 2 most common defects associated with vascular rings.

• VSD

• Tetralogy of Fallot

What is the etiology of vascular rings?

The etiology is unknown.

What genetic deletion is most commonly associated with vascular rings?

22q11 deletion

How many paired embryologic arches form portions of the cardiovascular vessels?

6 paired arches.

List the 3 structures that the 6 paired arches help form.

• Cardiovascular vessels

• Ascending aorta

• Pulmonary arteries

What structures are located between the ductus and descending aorta during development?

The dorsal aortas

What normally happens to the right aorta during development?

The right aorta regresses, and the left arch is formed.

List the 3 normal brachiocephalic branches of a left aortic arch.

• Innominate artery

• Left common carotid artery

• Left subclavian artery

Into which 2 arteries does the innominate artery normally bifurcate?

• Right common carotid artery

• Right subclavian artery

What direction should the innominate artery course to confirm a normal left aortic arch?

Rightward

List the 3 types of vascular rings.

• Double aortic arch

• Right arch with mirror-image branching

• Right aortic arch with an aberrant left subclavian artery

When does the clinical presentation of vascular rings usually develop?

Early

What determines the severity of symptoms from a vascular ring?

The degree of compression by the abnormal vessel on the trachea, bronchus, or esophagus.

List the 6 symptoms of a vascular ring.

• Breathing difficulty

• Wheezing

• Stridor

• Cough

• Recurrent respiratory infections

• Dysphagia

List the 3 things that may aggravate the symptoms of a vascular ring.

• Crying

• Physical exertion

• Respiratory infection

Why may an infant with a vascular ring initially gain weight appropriately?

The infant may tolerate liquid formula without difficulty.

What may happen when an infant with a vascular ring advances to solid foods?

Symptoms may become more evident.

List the 2 additional symptoms that may occur as symptoms become more evident.

• Apnea

• Cyanosis

What embryologic structure remains in a double aortic arch?

The right dorsal aorta remains.

Where are the 2 arches positioned in a double aortic arch?

• One arch is to the right of the trachea and esophagus.

• The other arch is to the left

Where do the 2 arches join in a double aortic arch?

They join posteriorly at the descending aorta

Which arteries arise from each arch in a double aortic arch?

Each arch gives rise to the common carotid and subclavian arteries.

How many ductus arteriosus may be present with a double aortic arch?

There may be 2 ductus arteriosus, one from each subclavian artery.

What structures does a double aortic arch encircle?

• Esophagus

• Trachea

What is the most common vascular ring?

Double aortic arch.

In what percentage of double aortic arch cases is the right arch larger and positioned higher than the left?

75% of cases.

What pathway does the right arch take when there is a left descending aorta and left ductus?

The right arch curves leftward posterior to the esophagus and trachea.

What completes the vascular ring in a right arch with a left descending aorta and left ductus?

The ligament attachment to the left pulmonary artery.

What is the first branch of a right aortic arch with mirror-image branching?

The left innominate artery.

What is the branching order in a right aortic arch with mirror-image branching?

• Left innominate artery

• Right carotid artery

• Right subclavian artery

• Left ductus ligament

What embryologic change results in a right aortic arch with mirror-image branching?

Regression of the left dorsal aorta.

In what direction does the first brachiocephalic branch course with a right aortic arch?

Leftward

What embryologic change causes a right arch with an aberrant left subclavian artery?

Regression of the left arch segment.

Where does the left subclavian artery originate in a right arch with an aberrant left subclavian?

It originates as the last branch from the aortic arch.

What path does the aberrant left subclavian artery take?

It courses behind the esophagus to the left arm.

What is a diverticulum of Kommerell, and how often is it present?

It is a dilation at the base of the left subclavian artery and occurs in about 60% of patients.

Where does the left ductal ligament attach with a right arch and aberrant left subclavian artery?

It attaches the aorta to the left pulmonary artery.

What structures are compressed by the vascular ring in a right arch with an aberrant left subclavian artery?

• Esophagus

• Trachea

What is the big echo finding for a right arch with an aberrant left subclavian artery?

The innominate artery immediately courses to the left but does not branch.

List the 6 other imaging modalities that may be used to evaluate vascular rings.

• Chest radiographs

• Barium contrast esophagrams

• Bronchoscopy

• X-ray angiography

• Computed tomography

• MRI

What can limit echocardiographic evaluation of a vascular ring?

The airway may obstruct the echo view.

What type of sweeps should be used when evaluating vascular rings by echo?

Longer sweeps.

How should the patient’s neck be positioned when evaluating vascular rings?

Hyperextend the neck by placing a rolled towel or pillow underneath the patient's shoulders.

What is the normal suprasternal-notch view used to evaluate?

The morphologic features of the aortic arch.

How is the innominate artery evaluated from the suprasternal-notch short-axis view?

Use a superior sweep to identify the innominate artery and follow it until it splits in the neck.

What is the normal course and branching pattern of the innominate artery?

It should course to the patient's right and split into:

1. Carotid artery

2. Subclavian artery

What does it indicate if the innominate artery courses toward the patient’s left side?

A right aortic arch.

What is the differential diagnosis for a vascular ring?

Other vascular rings.

How are vascular rings treated?

They require surgical division of the ring

What is a pulmonary artery sling?

An anomalous left pulmonary artery that arises from the proximal right pulmonary artery branch.

Where does the left pulmonary artery course in a pulmonary artery sling?

It courses between the esophagus and trachea.

What structure is compressed by a pulmonary artery sling?

The trachea, but not the esophagus.

What syndrome is associated with a pulmonary artery sling?

Mowatt-Wilson syndrome

What embryologic abnormality is hypothesized to cause a pulmonary artery sling?

The left arch fails to develop its connections to the left lung.

Where is the ductus positioned in a pulmonary artery sling?

To the left of the trachea, connecting to the descending aorta

What causes the symptoms of a pulmonary artery sling?

Tracheal compression.

List the 5 symptoms of a pulmonary artery sling.

• Respiratory distress

• Stridor

• Cyanosis

• Wheezing

• Retractions

What happens to the airway in a pulmonary artery sling?

Airway narrowing occurs, leading to respiratory stridor and distress.

When does a pulmonary artery sling typically become symptomatic?

It is typically severe and manifests during the newborn period.

How does the left pulmonary artery typically appear in a pulmonary artery sling?

The left pulmonary artery is smaller.

What 2 hemodynamic consequences can result from the smaller left pulmonary artery?

• Decreased left-lung perfusion

• Pulmonary hypertension

Can a pulmonary artery sling be diagnosed by echocardiography?

Yes

What suprasternal view is used to evaluate a pulmonary artery sling?

The suprasternal-notch transverse, or crab, view

What should be seen in the crab view with a pulmonary artery sling?

The left pulmonary artery arises from the right pulmonary artery and courses leftward behind the trachea toward the left lung.

What additional echo window can be used to evaluate a pulmonary artery sling?

The high parasternal short-axis window.

Which 2 imaging modalities are most likely to diagnose a pulmonary artery sling?

• Computed tomography

• MRI

List the 6 cardiac defects associated with a pulmonary artery sling.

• Patent ductus arteriosus

• Atrial septal defect

• Ventricular septal defect

• Pulmonary atresia

• Left superior vena cava

• Single ventricle

List the 3 common extracardiac abnormalities associated with a pulmonary artery sling.

• Tracheal stenosis

• Complete tracheal rings

• Tracheoesophageal fistula

What causes tracheal compression in innominate artery compression syndrome?

The innominate artery passes anterior to the trachea, causing the trachea to become compressed and narrowed.

How common is innominate artery compression syndrome, and is it usually associated with CHD?

It is extremely rare and is rarely associated with congenital heart disease.

List the 3 symptoms that may occur with innominate artery compression syndrome.

• Severe apnea

• Syncope

• Difficulty feeding

What abnormality is associated with innominate artery compression syndrome?

Esophageal atresia

List the 3 methods used to diagnose innominate artery compression syndrome

• MRI

• CT

• Bronchoscopy