What Are Common Vascular Rings and Slings?

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Patient Presentation
A term newborn male was transferred to the regional children’s hospital after having respiratory distress that developed after birth. The patient had a sepsis evaluation and was started on empiric antibiotics. Congenital heart disease was suspected but additional evaluation was not available locally, and the patient was intubated for transfer.

The pertinent physical exam showed an intubated male with normal vital signs who was breathing above the ventilator but in no distress. Growth parameters had a weight of 3.47 kg, length and head circumference were 50%. Ballard assessment showed a 39-week male consistent with pregnancy dating. The heart examination showed normal S1, S2 without murmurs. He had organomegaly and had good peripheral pulses.

The radiologic evaluation included a chest x-ray which showed suspected right-sided tracheal mass. Echocardiogram showed suspected right-side predominant double aortic arch without intracardiac congenital heart anomalies. Computed tomography confirmed the diagnosis of right-side predominant double aortic arch that was “tight.” Timing and approach for the repair was being planned by the cardiovascular surgeons and neonatologists.

Discussion
Vascular rings and slings are not that common a congenital heart problem (about 1% of all congenital heart defects), but do occur and arise from abnormal embryological development of the major vascular structures.
Embryologically the great vessels and their major branches arise from the aortic sac.
The aortic sac forms two horns – a right and a left. These horns then form aortic arches.
The aortic arches with their paired branches then course into the pharyngeal arches.
Initially these aortic/pharyngeal arches have symmetric vascular pairs, but as development progresses they become asymmetric (basically due to structural regression) and normal or abnormal development of the vascular structures occurs.

There are 6 aortic arches and the 4th and 6th are the most important for forming the major vascular structures:

  • 1 – Maxillary artery, regresses early
  • 2 – Hyoid and stapedial artery, regresses early
  • 3 – Carotid arteries
  • 4 – Right arch helps form right proximal subclavian artery. Left arch helps form part of aortic arch.
  • 5 – “…[N]ever forms or incompletely forms and regresses.”
  • 6 – “The right and left arches separate into ventral and dorsal segments. The ventral segments are responsible for the formation of the pulmonary arteries bilaterally. The left ventral arch also contributes to the formation of the pulmonary trunk. The right dorsal arch regresses. The left dorsal arch forms the ductus arteriosus, which later closes and is termed the ligamentum arteriosum.”

If the development is abnormal, the major vessels may form abnormal structures or the vessels may have an abnormal position. These commonly form some type of ring or sling structure that encircles the esophagus or trachea and therefore are called vascular rings or slings. Patients with abnormal structures may present with cough, noisy breathing, stridor, respiratory distress, wheezing, exertional dyspnea, dysphagia, respiratory tract infections and apparent life-threatening events.

Evaluation for patients usually starts with a chest x-ray. Additional imaging usually is with computed-tomography or magnetic resonance imaging and may be helpful for understanding the specific anatomy and relationships of all the adjacent structures. 3D models can be made from this imaging. However, atretic or ligamentous structures may not be enhanced during these modalities and require direct visualization during surgery. Echocardiography may also be helpful for evaluating possible concomitant congenital heart disease. Fetal imaging may also help with diagnosis. While the predominant anatomy helps to classify the major problem, each patient is unique and may have variations of the predominant anatomy.

Learning Point
Dr. Robert Gross from Boston Children’s Hospital performed the first vascular ring surgical repair in 1945. In 1954, the first successful pulmonary artery sling repair was performed by Dr. Willis Potts. One institutional case series of vascular rings and slings from 1947-201 of 373 patients found 41.5% had a double aortic arch, 46.2% had a right aortic arch/left ligamentum and 12.3% had a pulmonary artery sling.

Double aortic arch – the vascular ring is caused by both right and left arch persistence which encircles the esophagus and airway, and then combine to form the dorsal aorta. The “double” can be asymmetric or balanced, but a “right-sided” double aortic arch is more common, than left or balanced. This ring is often more constrictive and patients may present earlier. Usually the smaller arch is surgically divided but other structures may also need to be surgically attended to. For example, in a right-sided double aortic arch, the left aorta is ligated but the ligamentum arteriosum also needs to be ligated otherwise there can still be persistence of the ring. A brief review of the radiographic imaging can be found here

Right aortic arch – the vascular ring is caused by a right aortic arch, retroesophageal left subclavian artery and left ligamentum arteriosum. It is a “looser” ring and may present later. Some patients do not have a full or true vascular ring because of variations. Surgical treatment may include ligation as well as vascular re-implantation. A brief review of the radiographic imaging can be found here

Pulmonary artery sling – this occurs when the left pulmonary artery originates from the right pulmonary artery instead from the main pulmonary artery. The left pulmonary artery takes an aberrant course between the trachea and esophagus instead of anterior to the trachea. This causes the area around the carina to be caught between the aberrant left pulmonary artery posteriorly and the main pulmonary artery anteriorly. These patients may have tracheal stenosis as well as ~75% may have complete cartilaginous tracheal rings. Surgical correction may also include tracheal correction as well. A brief review of the radiographic imaging can be found here

Other “common” vascular anomalies causing similar problems includes:

Left aortic arch with aberrant right subclavian artery – this is not a true vascular ring, but the right subclavian artery arises from the descending thoracic aorta. This is commonly asymptomatic and occurs in 0.5% of people. A brief review of the radiographic imaging can be found here

Innominate artery compression – this is also not a true vascular ring but patients can have significant tracheal compression as the vessel crosses from left to right after branching off the ascending thoracic aorta. A brief review of the radiographic imaging can be found here.

Questions for Further Discussion
1. What are causes of non-cyanotic congenital heart disease? A review can be found here
2. What causes respiratory distress? Especially at birth? A review can be found here
3. What are potential complications of cardiothoracic surgery? A review can be found here

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for this topic: Congenital Heart Defects

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Backer CL, Monge MC, Popescu AR, Eltayeb OM, Rastatter JC, Rigsby CK. Vascular rings. Semin Pediatr Surg. 2016;25(3):165-175. doi:10.1053/j.sempedsurg.2016.02.009

Madueme PC. Computed tomography and magnetic resonance imaging of vascular rings and other things: a pictorial review. Pediatr Radiol. 2022;52(10):1839-1848. doi:10.1007/s00247-022-05366-y

Rahmath MRK, Durward A. Pulmonary artery sling: An overview. Pediatr Pulmonol. 2023;58(5):1299-1309. doi:10.1002/ppul.26345

Rosen RD, Bordoni B. Embryology, Aortic Arch. In: StatPearls. StatPearls Publishing; 2023. Accessed June 20, 2023. http://www.ncbi.nlm.nih.gov/books/NBK553173/

Author
Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa

Published