Overview
Definition
A vascular ring is a congenital malformation in which the esophagus and trachea are encircled by an aberrant aorta.
Anatomical recreation of a vascular ring compared to normal anatomy
Double aortic arch causes compression of the trachea and esophagus. Vascular rings often compress the trachea leading to a degree of tracheomalacia.
Embryology
- 4th–5th week of gestation: Mesenchymal cells migrate from the neural crest and paraxial mesoderm → proliferate and form 4 bulges located above heart and liver → branchial arches I–VI
- Each branchial arch has its own artery originating in the aortic root and leading to 2 paired dorsal aortae, which merge caudally into the descending aorta.
- 1st and 2nd aortic arches:
- Mostly degenerate
- 1st arch → maxillary artery
- 2nd arch → stapedial artery
- 3rd aortic arch:
- Proximal sections → common carotid artery
- Distal sections → internal carotid artery together with parts of dorsal aorta
- 4th aortic arch:
- Left → defined aortic arch
- Right → proximal section of right subclavian artery
- 5th aortic arch doesn’t develop.
- 6th aortic arch = pulmonary arch
- Left → ductus arteriosus
- Right → truncus pulmonalis and proximal part of pulmonary artery
- By the time the 6th arch develops, the 1st and 2nd arches have already disappeared.
Embryological formation of the aortic arch and associated blood vessel: The vasculature that will become the aortic arch and all of its associated vessels begins as 6 paired sets of aortic arches, each associated with a branchial arch (A).
Image by Lecturio.
Embryological formation of the aortic arch and associated blood vessel: Involution of some arches and incorporation and growth of others creates the adult structures of the aortic arch and pulmonary arteries (B).
Image by Lecturio.
Embryological formation of the aortic arch and associated blood vessel: In the adult conformation, the aortic arch courses right to left, passing posteriorly to the esophagus and trachea (C).
Image by Lecturio.
Anatomy
Although the clinical symptoms and treatment approach are the same, there are multiple ways in which the development of the aortic arch can give rise to a vascular ring. Each variant is unique in its anatomy and embryological origin.
- Double aortic arch (DAA)
- Failure of right-sided arch to regress while left-sided arch persists
- Right-sided arch passes posteriorly to esophagus, where it joins left-sided aortic arch.
- Left-sided aortic arch passes anterior to trachea.
- Result: ring of blood vessels around trachea and esophagus
- Right aortic arch with aberrant left subclavian artery and left-sided ductus/ligamentum arteriosus
- Aortic arch is right-sided.
- Ductus arteriosus (DA) arises from the base of the aberrant left subclavian artery.
- DA connects to pulmonary artery by tracking anteriorly and to the left of the trachea and esophagus.
- The right-sided aortic arch, the left subclavian artery, and the aberrant ductus arteriosus form the vascular ring around the esophagus and trachea.
Epidemiology
- 1%–3% of all congenital cardiac malformations
- Male:female ratio, 2:1
- Incidence of various forms:
- 55% attributable to DAA
- 35% attributable to right aortic arches, aberrant left subclavian artery, and left-sided ductus arteriosus
- 10% all other forms
- 10%–25% of cases are associated with underlying cardiac anomaly:
- Transposition of great vessels (TGV)
- Ventricular septal defect (VSD)
- Patent ductus arteriosus (PDA)
- Tetralogy of Fallot (TOF)
- Coarctation of aorta (CoA)
- Associated with:
- Trisomy 21 (Down’s syndrome)
- DiGeorge syndrome
- CHARGE syndrome (Coloboma of the eye, Heart defects, Atresia of the nasal choanae, Retardation of growth and/or development, Genital and/or urinary abnormalities, and Ear abnormalities and deafness)
- Increased risk in infants conceived by in vitro fertilization (IVF)
Pathophysiology and Clinical Presentation
Pathophysiology
- Vascular ring encircles trachea and esophagus.
- Direct pressure of blood vessels on trachea and esophagus can be sufficient to cause symptoms.
- Activities that increase cardiac demand (e.g., feeding, crying) cause engorgement of blood vessels and worsen symptoms.
Clinical presentation
The severity of symptoms depends on the degree of compression of the trachea/esophagus.
- Severe compression: noisy breathing or apnea within first few weeks of life
- Mild compression:
- Persistent cough
- Recurrent lung infection
- Vomiting
- Choking
- Difficulty swallowing
- May also be picked up incidentally when scanning for other associated cardiac anomalies
Diagnosis and Management
Physical examination
Examination may be normal, but usually in infants:
- Nonpositional stridor (classic finding)
- Inspiratory stridor
- Bronchial breath sounds
- Crackles
- Respiratory distress
- Failure to thrive
Imaging
- Echocardiography:
- 1st-line imaging
- Assesses nature of vascular ring and extent of compression
- Associated cardiac anomaly
- Computed tomography (CT) and magnetic resonance imaging (MRI): Best methods to delineate anatomy, location, and extent of compression
CT axial image demonstrates a double aortic arch and encircling of the trachea.
Image: “Detection of airway anomalies in pediatric patients with cardiovascular anomalies with low dose prospective ECG-gated dual-source CT” by Jiao H, Xu Z, Wu L, Cheng Z, Ji X, Zhong H, Meng C. License: CC BY 4.0- Chest X-ray:
- Loss of aortic knob
- Lateral/posterior indentation of trachea
- Bronchoscopy: Pulsating mass at level of carina
Management
- Definitive management is surgical therapy, which is indicated for:
- Symptomatic patients
- Concomitant heart defect
- Surgery involves resection and division of vascular ring.
- Reimplantation of key vessels is rarely necessary.
- Excellent prognosis post surgery
Differential Diagnosis
- Laryngomalacia/tracheomalacia: Newborns present with stridor very similar to that of DAA. Stridor is mainly inspiratory. Laryngoscopy confirms collapse of larynx.
- Subglottic stenosis: Congenital forms result in narrowing of subglottic region of trachea, resulting in symptoms very similar to DAA. Laryngoscopy assesses narrowing.
- Bronchiolitis: Infants present with lower respiratory symptoms (e.g., dyspnea, wheezing, and crackles). These infants usually have a history of upper respiratory tract infection and usually respond to supplemental oxygen and suctioning of secretions.
- Gastroesophageal reflux disease (GERD): Acid reflux into esophagus in infancy and childhood may present with intermittent cough and wheezing. May be accompanied by lack of weight gain and increased irritability.
References
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