Aortic coarctation pathophysiology

An aortic coarctation results from both, congenital and acquired means. Factors directly influencing the pathophysiology include defect location and sites of secondary dilation.

Coarctation of the aorta can be:

• Congenital coarctation resulting from an infolding of the aortic media that incorportaes ductal tissue, forming a ridge that eccentrically narrows the lumen of the vessel. Subsequent intimal proliferation on the ridge leads to progressive narrowing of the vessel lumen. There is a dilatation before and after the narrowing, giving the aorta an hourglass appearance. The exact etiology of the aortic abnormality remains unclear but likely involves a defect in the vascular wall of the aorta due to reduced antegrade intrauterine blood flow or to constriction of ductal tissue extending into the thoracic aorta.
• Acquired coarctation occurring in systemic arteritides such as Takayasu arteritis. Additionally it may occur in rare cases of severe atherosclerosis.

• 95% of the lesions are located distal to the left subclavian artery and proximal to the ductus arteriosus (preductal coarctation) or just at or distal to the ductus (postductal coarctation).
• 5% of coarctations are located proximal to the left subclavian artery, or rarely in the abdominal aorta.
• In some cases, coarctation presents as a long segment or a tubular hypoplasia.
• The stenosis is caused by an infolding of the left posterolateral aspect of the aortic wall resulting in an eccentric narrowing.

• Aorta proximal to the coarct
• Aorta distal to the coarctation
• Left subclavian artery
• The narrowing progresses throughout life, and extensive collaterals develop from the subclavian (predominantly) and axillary arteries through:

1. Internal mammary artery
2. Scapular artery
3. Intercostal arteries
4. Epigastric arteries
5. Anterior spinal arteries

• Aortic coarctation, like many congenital heart diseases, is more common in patients with other genetic conditions.
• As many as 10-25% of patients with Turner syndrome have an accompanying coarctation of the aorta.

Images courtesy of Professor Peter Anderson DVM PhD and published with permission © PEIR, University of Alabama at Birmingham, Department of Pathology

• It is commonly associated with bicuspid aortic valve.
• There is 5 fold increase in the intracranial aneurysm in patient with coarctation.

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