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When the Aorta Forms a Vascular Ring Around the Trachea and Oesophagus

Introduction

Double Aortic Arch — DAA — is a congenital abnormality of the aortic arch in which the ascending aorta divides into right and left arches that pass around the trachea and oesophagus before rejoining to form the descending aorta.

Unlike ASD, VSD or PDA, Double Aortic Arch is not primarily a shunt lesion.

It does not usually cause abnormal mixing of oxygenated and deoxygenated blood.

Instead, the two arches form a complete vascular ring around the airway and oesophagus.

The child is therefore usually pink, but may develop serious respiratory and feeding problems because the vascular ring compresses structures lying inside it. (NCBI)

Body

Normal Aortic Arch Anatomy

Normally, blood leaves the left ventricle through:

Left ventricle → Aortic valve → Ascending aorta → Aortic arch → Descending aorta

The normal aortic arch passes predominantly to the left of the trachea.

Three major vessels usually arise from the arch:

  • brachiocephalic artery;
  • left common carotid artery;
  • left subclavian artery.

The arch then continues as the descending thoracic aorta.

What Happens in Double Aortic Arch?

In Double Aortic Arch, the ascending aorta divides into two channels.

One passes:

to the right of the trachea and oesophagus

and the other passes:

to the left.

The two arches then join again posteriorly to form the descending aorta.

The result is effectively:

Ascending aorta → Right arch + Left arch → Descending aorta

with the:

trachea and oesophagus trapped inside the ring. (Children’s Hospital of Philadelphia)

Why is it Called a Vascular Ring?

A vascular ring is an abnormal arrangement of blood vessels or their remnants that encircle the trachea, oesophagus, or both.

Double Aortic Arch creates a complete vascular ring.

This is important because the problem is mechanical compression rather than abnormal intracardiac blood flow. (NCBI)

The trachea can be compressed from the front and sides.

The oesophagus can be compressed posteriorly.

The tighter the ring, the more severe the symptoms.

Why is the Baby Usually Pink?

Blood still follows the normal systemic pathway:

Left ventricle → Aorta → Body

There is normally no obligatory right-to-left shunt.

Systemic arterial blood remains appropriately oxygenated.

The child therefore generally remains acyanotic or pink.

The central problem is:

airway and oesophageal compression

rather than:

abnormal oxygenation.

Embryological Development

The normal aortic arch develops from a complex series of paired embryological arches.

During development, some segments persist while others regress.

The normal adult left aortic arch is produced by selective persistence and regression of these embryological vessels.

In Double Aortic Arch, the right-sided component that would normally regress remains patent.

Both right and left arches therefore persist. (NCBI)

The trachea and oesophagus consequently remain enclosed between them.

Right-Dominant and Left-Dominant Arches

The two arches are not necessarily the same size.

Most commonly, the:

right arch is dominant

and the:

left arch is smaller. (NCBI)

Less commonly:

  • the left arch is dominant;
  • or both arches are approximately equal in size.

This matters surgically because the smaller or non-dominant arch is usually the one divided to release the ring.

Branch Vessels

The head and neck vessels typically arise separately from the two arches.

In a classic Double Aortic Arch:

the right arch supplies the:

  • right common carotid artery;
  • right subclavian artery;

while the left arch supplies the:

  • left common carotid artery;
  • left subclavian artery. (NCBI)

Understanding this anatomy is important before surgery because the surgeon must preserve adequate arterial supply to the head and upper limbs.

The Ductus Arteriosus and Ligamentum Arteriosum

The ductus arteriosus is usually left-sided.

After closure it becomes the:

Ligamentum Arteriosum.

This structure can form an additional component of the vascular ring.

During surgical repair, the ligamentum or patent ductus may therefore also need to be divided to completely release the trachea and oesophagus. (NCBI)

Tracheal Compression

Respiratory symptoms are particularly important in Double Aortic Arch.

The trachea lies within the vascular ring.

Compression can narrow the airway and cause:

  • stridor;
  • noisy breathing;
  • wheezing;
  • persistent cough;
  • recurrent chest infections;
  • increased work of breathing;
  • and episodes of respiratory distress. (NCBI)

Symptoms often begin in infancy because the neonatal and infant airway is small and relatively compliant.

A comparatively modest external compression can therefore produce a significant reduction in airway diameter.

Stridor

Stridor is a harsh respiratory sound caused by turbulent airflow through a narrowed upper or central airway.

In Double Aortic Arch, stridor results from external compression of the trachea.

This can sometimes be mistaken for:

  • laryngomalacia;
  • asthma;
  • recurrent bronchiolitis;
  • or other respiratory disease.

Persistent or unexplained respiratory symptoms in an infant should therefore raise the possibility of external vascular compression.

Tracheomalacia

Longstanding vascular compression can interfere with normal development of the tracheal cartilage.

The trachea may become abnormally soft and prone to collapse.

This is known as:

Tracheomalacia.

Importantly, dividing the vascular ring removes the external compression but does not instantly restore normal strength to the tracheal wall.

Respiratory noise or stridor may therefore persist for some time after successful surgery. (NCBI)

Oesophageal Compression

The oesophagus also lies within the ring.

Compression may cause:

  • difficulty swallowing;
  • choking during feeds;
  • coughing with feeds;
  • vomiting;
  • slow feeding;
  • food refusal;
  • or poor weight gain.

Older children may develop dysphagia, particularly when progressing from liquids to solid foods. (NCBI)

Why Might Liquids Be Easier Than Solids?

Liquids can pass through a partially compressed oesophagus relatively easily.

Solid food requires considerably more space.

Some children therefore appear relatively well while bottle feeding but develop obvious swallowing difficulty when solid food is introduced.

This pattern is particularly useful when considering vascular-ring disorders.

Recurrent Respiratory Infections

Airway compression can impair normal clearance of respiratory secretions.

Swallowing difficulties may also increase the risk of aspiration.

Together, these can contribute to recurrent:

  • bronchitis;
  • pneumonia;
  • persistent cough;
  • and wheezing.

The respiratory symptoms may therefore be the indirect result of both airway compression and abnormal swallowing.

Presentation

Double Aortic Arch tends to present earlier than many other vascular rings.

Symptoms commonly appear in infancy. (NCBI)

Typical features include:

  • stridor;
  • noisy breathing;
  • persistent wheeze;
  • respiratory distress;
  • recurrent chest infections;
  • barking cough;
  • choking;
  • dysphagia;
  • difficulty feeding;
  • and poor weight gain.

Severe airway compression can occasionally cause acute respiratory compromise.

Associated Congenital Heart Disease

Double Aortic Arch can occur as an isolated vascular abnormality.

Associated intracardiac abnormalities are less common but may include:

  • Ventricular Septal Defect;
  • Atrial Septal Defect;
  • Tetralogy of Fallot;
  • Truncus Arteriosus;
  • and Transposition of the Great Arteries. (NCBI)

An echocardiogram is therefore important even when the principal symptoms arise from airway compression.

Diagnosis

Diagnosis requires defining both:

the vascular anatomy

and

the effect on the trachea and oesophagus.

Echocardiography

Echocardiography can demonstrate:

  • aortic arch sidedness;
  • the presence of two arches;
  • intracardiac abnormalities;
  • ventricular function;
  • and associated congenital cardiac defects.

However, echocardiography may not always show the complete relationship between the vascular ring, trachea and oesophagus.

CT Angiography

CT angiography is particularly valuable because it can show:

  • both aortic arches;
  • which arch is dominant;
  • branch vessel origins;
  • descending aorta;
  • relationship to the trachea;
  • degree of airway compression;
  • and associated vascular abnormalities. (NCBI)

Modern CT imaging can produce detailed three-dimensional reconstructions that are extremely useful for operative planning.

Cardiac MRI

MRI can also define the arch anatomy without ionising radiation.

It can demonstrate:

  • vascular relationships;
  • flow;
  • branch vessel anatomy;
  • and associated cardiac lesions.

Its use depends partly upon the age and stability of the child and whether sedation or anaesthesia would be necessary.

Bronchoscopy

Bronchoscopy allows direct assessment of the airway.

It can demonstrate:

Bronchoscopy can be particularly useful when respiratory symptoms persist after vascular-ring repair.

Barium Swallow

Historically, a barium swallow was commonly used to demonstrate external compression of the oesophagus.

The study may show characteristic indentations created by the surrounding vascular structures.

CT and MRI now provide much more detailed anatomical information, although oesophageal studies can still have a role in selected patients. (Children’s Hospital of Philadelphia)

Treatment

Symptomatic Double Aortic Arch is treated surgically.

The objective is:

to open the vascular ring and relieve compression of the trachea and oesophagus. (Children’s Hospital of Philadelphia)

This is fundamentally different from intracardiac congenital cardiac surgery.

The circulation itself usually does not need to be rerouted.

One component of the ring simply needs to be divided safely.

Surgical Repair

The surgeon first establishes:

which arch is dominant

and

which arch can be safely divided.

The smaller non-dominant arch is usually selected.

A common approach is through a:

left posterolateral thoracotomy. (NCBI)

Division of the Non-Dominant Arch

The non-dominant arch is carefully dissected.

Before division, the surgeon must confirm that interruption of that segment will not compromise:

  • cerebral blood flow;
  • upper-limb perfusion;
  • or descending aortic flow.

The smaller arch is then:

clamped, divided and oversewn.

This breaks the vascular ring.

The trachea and oesophagus are no longer completely encircled.

Division of the Ligamentum Arteriosum

The ligamentum arteriosum or residual ductus is also usually divided when it contributes to completion of the ring. (NCBI)

This is essential because simply dividing one arch while leaving another constricting structure intact may fail to fully release the airway and oesophagus.

Mobilising the Oesophagus and Trachea

The surrounding tissue may also need to be divided or mobilised.

The objective is to ensure that neither the oesophagus nor trachea remains tethered within the previous vascular ring.

Relief of compression should be anatomical rather than simply division of one visible vessel.

Cardiopulmonary Bypass

Unlike many congenital heart operations, uncomplicated Double Aortic Arch repair is usually performed without cardiopulmonary bypass.

The operation is generally carried out through a thoracotomy.

Cardiopulmonary bypass may be required only if there are additional complex cardiovascular abnormalities requiring repair.

Thoracoscopic Repair

Selected vascular rings can also be divided using minimally invasive thoracoscopic techniques.

Video-assisted approaches have been used successfully in specialised centres. (NCBI)

The underlying principle remains the same:

identify the ring → divide the non-essential component → release the trachea and oesophagus.

Anaesthetic and Theatre Considerations

Double Aortic Arch creates a different anaesthetic problem from most congenital cardiac defects.

The principal concern may be the airway rather than the circulation.

Important considerations include:

  • degree of tracheal compression;
  • presence of tracheomalacia;
  • dynamic airway collapse;
  • previous episodes of respiratory distress;
  • positioning;
  • induction of anaesthesia;
  • and positive-pressure ventilation.

A spontaneously breathing child may maintain airway patency differently from an anaesthetised and paralysed child.

Severe fixed or dynamic tracheal compression therefore deserves careful preoperative assessment.

Induction of Anaesthesia

Loss of airway tone following induction can potentially worsen dynamic airway collapse.

In a child with severe compression, anaesthetic planning should therefore take account of:

  • location of narrowing;
  • severity of compression;
  • ability to ventilate beyond the obstruction;
  • bronchoscopy availability;
  • and the surgical team’s ability to gain rapid access to the ring.

These cases are primarily airway and thoracic vascular procedures rather than routine “pink baby” intracardiac operations.

Recurrent Laryngeal Nerve

The recurrent laryngeal nerves travel in close relationship to the aortic arch and great vessels.

Careful surgical dissection is therefore required.

Injury may produce:

  • vocal cord weakness;
  • hoarse cry;
  • swallowing difficulty;
  • or aspiration.

Vocal cord paresis or paralysis is a recognised complication of vascular-ring surgery. (NCBI)

Thoracic Duct

The thoracic duct also lies within the operative region.

Damage can produce leakage of lymphatic fluid into the chest.

This is known as:

Chylothorax.

It is another recognised complication following vascular-ring surgery. (NCBI)

After Surgery

Many children improve considerably following division of the ring.

Feeding symptoms can improve as oesophageal compression resolves.

Respiratory improvement may be slower.

This is particularly true where longstanding compression has resulted in tracheomalacia.

The operation removes the external pressure.

The airway may still require time to regain structural stability. (NCBI)

Persistent Stridor After Repair

Persistent stridor does not necessarily mean that the vascular ring has been inadequately divided.

Possible explanations include:

  • residual tracheomalacia;
  • fixed tracheal stenosis;
  • bronchomalacia;
  • residual vascular compression;
  • or recurrent laryngeal nerve dysfunction.

Persistent symptoms therefore require reassessment rather than automatically assuming recurrence of the original ring.

Long-Term Outcome

The overall prognosis following successful surgical division is generally very good. (NCBI)

Most children experience substantial improvement in:

  • breathing;
  • feeding;
  • growth;
  • and recurrent respiratory symptoms.

Those with significant tracheomalacia or associated airway abnormalities may require longer-term respiratory follow-up.

Double Aortic Arch Versus Other Vascular Rings

Double Aortic Arch is only one form of vascular ring.

Others include:

  • right aortic arch with aberrant left subclavian artery and left ligamentum;
  • circumflex aortic arch;
  • selected arch anomalies with an aberrant subclavian artery.

A pulmonary artery sling can also cause severe airway compression, although anatomically it is better described as a vascular sling rather than a true complete vascular ring. (NCBI)

Double Aortic Arch in One Sentence

Double Aortic Arch is a congenital persistence of both right and left aortic arches, forming a complete vascular ring around the trachea and oesophagus and causing symptoms principally through compression rather than abnormal blood oxygenation.

The most important question is therefore not:

“How much blood is shunting?”

but:

“How tightly is the vascular ring compressing the airway and oesophagus?”

Key Points

Double Aortic Arch is usually a Pink Baby lesion because systemic oxygenation is normally preserved.

It is not primarily a left-to-right or right-to-left shunt.

The ascending aorta divides into:

right and left arches

which pass around the:

trachea and oesophagus

before rejoining as the descending aorta. (Children’s Hospital of Philadelphia)

The result is a complete vascular ring.

The right arch is usually dominant. (NCBI)

Symptoms are principally due to:

  • tracheal compression;
  • oesophageal compression;
  • and secondary tracheomalacia.

Typical symptoms include:

  • stridor;
  • wheeze;
  • recurrent respiratory infections;
  • choking;
  • dysphagia;
  • and feeding difficulties. (NCBI)

CT angiography is particularly useful for defining the vascular and airway anatomy.

Surgical treatment usually involves:

division of the smaller non-dominant arch

and

division of the ligamentum arteriosum or ductus where necessary. (NCBI)

Cardiopulmonary bypass is usually not required for an isolated repair.

Respiratory symptoms may persist temporarily after successful surgery because of pre-existing tracheomalacia.

Glossary of Terms

Aortic Arch

The curved portion of the aorta connecting the ascending and descending aorta.

Aortic Arch Dominance

The relative size and importance of one arch compared with the other in Double Aortic Arch.

The right arch is most commonly dominant.

Aortic Arch Sidedness

The relationship of the aortic arch to the trachea and main bronchus.

A normal arch is usually left-sided.

Barium Swallow

An imaging test in which contrast material is swallowed to outline the oesophagus.

External vascular compression may produce characteristic indentations.

Bronchoscopy

Direct visual examination of the trachea and bronchi using a bronchoscope.

It can assess compression and tracheomalacia.

Chylothorax

Accumulation of lymphatic fluid within the pleural cavity, usually following damage to the thoracic duct.

Complete Vascular Ring

A vascular abnormality that completely encircles the trachea and oesophagus.

Double Aortic Arch is a classic example.

CT Angiography — CTA

CT imaging performed with vascular contrast to define blood vessels and their relationship to surrounding structures.

Descending Aorta

The portion of the aorta travelling downwards through the thorax after the aortic arch.

Double Aortic Arch — DAA

A congenital abnormality in which both right and left aortic arches persist and surround the trachea and oesophagus.

Dysphagia

Difficulty swallowing.

It may result from oesophageal compression by a vascular ring.

Ligamentum Arteriosum

The fibrous remnant of the foetal ductus arteriosus.

It can contribute to completion of a vascular ring.

Non-Dominant Arch

The smaller of the two aortic arches in Double Aortic Arch.

It is usually the arch selected for surgical division.

Oesophageal Compression

External narrowing of the oesophagus caused by surrounding vascular structures.

It can cause feeding difficulty and dysphagia.

Patent Ductus Arteriosus — PDA

Persistence after birth of the foetal connection between the pulmonary artery and aorta.

The ductus or its ligamentous remnant may form part of some vascular rings.

Pink Baby

An informal teaching term describing congenital cardiovascular disease in which systemic oxygenation remains sufficient to avoid central cyanosis.

Posterolateral Thoracotomy

A surgical incision through the side and back of the chest providing access to thoracic structures.

It is commonly used for Double Aortic Arch repair.

Pulmonary Artery Sling

An abnormal origin and course of the left pulmonary artery in which it passes between the trachea and oesophagus, potentially producing severe airway compression.

Recurrent Laryngeal Nerve

A branch of the vagus nerve supplying muscles controlling the vocal cords.

It travels close to the great vessels and can be vulnerable during vascular-ring surgery.

Stridor

A harsh respiratory sound caused by turbulent airflow through a narrowed airway.

Thoracic Duct

The major lymphatic vessel within the thorax.

Damage during thoracic surgery can cause chylothorax.

Trachea

The main airway connecting the larynx with the bronchi.

Tracheal Compression

External narrowing of the trachea.

In Double Aortic Arch it occurs because the airway lies within the vascular ring.

Tracheomalacia

Weakness of the tracheal wall that allows excessive dynamic airway collapse.

It can develop following prolonged vascular compression.

Vascular Ring

An abnormal arrangement of cardiovascular structures that surrounds and compresses the trachea, oesophagus, or both.

Video-Assisted Thoracoscopic Surgery — VATS

A minimally invasive thoracic surgical technique performed using a camera and instruments passed through small chest incisions.