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Coarctation of the aorta

Coarctation of the aorta refers to a narrowing of the aortic lumen. It can be primarily divided into two types

  1. infantile (pre-ductal) form 
  2. adult (juxta-ductal, post-ductal or middle aortic) form 

An infantile coarctation is characterised by diffuse hypoplasia or narrowing of the aorta from just distal to brachiocephalic artery to the level of ductus arteriosus, typically with a more discrete area of constriction just proximal to the ductus but distal to the origin of the left subclavian artery. Therefore the blood supply to the descending aorta is via the patent ductus arteriosus

An adult coarctation in contrast is characterised by a short segment abrupt stenosis of the post-ductal aorta. It is due to thickening of the aortic media and typically occurs just distal to the ligamentum arteriosum (remnant of the ductus arteriosus).  

Epidemiology

Coarctations account for between 5-8 % of all congenital heart defects. They are more frequent in males : M:F ratio of ~ 2-3:1

Pathology

Associations

As is the case with many congenital abnormalities, coarctation of the aorta is associated with other anomalies. 

Radiographic features

Plain film - chest radiograph
  • figure of 3 sign - contour abnormality of the aorta
  • inferior rib notching - Roesler sign
    • secondary to dilated intercostal collateral vessels
    • seen only in long standing cases, and therefore not seen in infancy
    • seen in 70% of cases presenting in older children or adults
    • if unilaterally seen on the left, then this suggests an associated aberrant right subclavian artery arising after the coarctation
    • if unilaterally seen on the right, then the origin of the left subclavian artery is distal to the coarctation
    • most often involves 4th-8th ribs
    • occasionally involves 3rd and 9th ribs
    • does not involve 1st and 2nd ribs (the associated arteries are branches of the costocervical trunk, and thus proximal to coarctation)
  • may also show evidence of left ventricular hypertrophy
Antenatal ultrasound

Useful in assessing for infantile coarctations. The suprasternal notch - long axis views are particularly considered helpful. The fetal right ventricle can be appear enlarged in severe coarctations although this alone is not a specific feature. Occasionally an aortic arch view may directly show a narrowing.

Angiography - CTA / MRA / DSA

All modalities are capable of delineating the coarctation as well as collateral vessels, most common collateral pathway being subclavian artery to internal mammary artery to intercostal arteries (resulting in inferior rib notching) to post-coarctation part of descending thoracic aorta.

Treatment and prognosis

Urgency of treatment depends on the presence of congestive cardiac failure. This is usually the case in severe coarctations found in infancy. In less severe cases, elective treatment when the child is older (typically ~ 2 years of age) is preferred 3

Treatment can be either primary surgical repair with excision of the coarctation and end-to-end anastomosis, or balloon angioplasty.

Complications

Differential diagnosis


Related articles

Congenital heart disease

There is more than one way to present the variety of congenital heart diseases. Whichever way they are categorised, it is helpful to have a working understanding of normal and fetal circulation, as well as an understanding of the segmental approach to imaging in congenital heart disease.

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