Coarctation of the aorta
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Coarctation of the aorta (CoA) refers to a narrowing of the aortic lumen.
Coarctations account for between 5-8% of all congenital heart defects. They are more frequent in males, M:F ratio of ~2-3:1.
As with many congenital abnormalities, coarctation of the aorta is associated with other congenital anomalies.
bicuspid aortic valve: most common associated defect and seen in 75-80%
cyanotic congenital lesions including
mitral valve defects including
Varies accordingly to the degree of stenosis and the associated abnormalities. Patients may be asymptomatic in a setting of non-severe stenosis.
Children and adults can present with angina pectoris and leg claudication. On clinical examination, diminished femoral pulses and differential blood pressure between upper and lower extremities may be noted.
high left ventricular voltage (HLVV) 9
voltage criteria present for left ventricular hypertrophy
left ventricular "strain" pattern
variably present in the lateral leads (I, aVL, V5-6)
asymmetric T-wave inversion originating from a depressed ST segment
It can be primarily divided into two types:
infantile (pre-ductal) form
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
adult (juxtaductal, postductal or middle aortic) form
characterized 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 (a remnant of the ductus arteriosus)
secondary to dilated intercostal collateral vessels which form as a way to bypass the coarctation and supply the descending aorta
the dilated and tortuous vessels erode the inferior margins of the ribs, resulting in notching
seen only in long standing cases, and therefore not seen in infancy (unusual in patients <5 years of age) 7
seen in 70% of cases presenting in older children or adults
if the coarctation is distal to either subclavian artery, then increased flow occurs through the subclavian artery, forming a collateral pathway via the internal thoracic artery, anterior intercostal artery, posterior intercostal artery and then into the descending thoracic aorta
usually the 4th to 8th ribs are involved; occasionally involves the 3rd to 9th ribs
as the 1st and 2nd posterior intercostal arteries arise from the costocervical trunk (a branch of the subclavian artery) and do not communicate with the aorta, these are not involved in collateral formation, and the 1st and 2nd ribs do not become notched
if bilateral rib notching: the coarctation must be distal to the origin of both subclavian arteries, to enable bilateral collaterals to form
if unilateral right rib notching
then the coarctation lies distal to the brachiocephalic trunk but proximal to the origin of the left subclavian artery
or there may be a right sided aortic arch with aberrant left subclavian artery distal to coarctation
collaterals cannot form on the left, as the left subclavian is distal to the coarctation
if unilateral left rib notching, then this suggests an associated aberrant right subclavian artery arising after the coarctation
the coarctation is distal to the origin of the left subclavian artery, therefore collaterals form on the left
collaterals cannot form on the right, as the aberrant right subclavian artery arises after the coarctation
Useful in assessing for infantile coarctations. The suprasternal notch-long axis views are considered helpful. The fetal right ventricle can appear enlarged in severe coarctations although this alone is not a specific feature. Occasionally an aortic arch view may directly show a narrowing.
reduction in luminal caliber of the descending aorta
often accompanied by post-stenotic dilatation
demonstrates sudden increase in velocity as measured by pulsed wave Doppler
the continuous wave Doppler envelope will demonstrate the characteristic "shark tooth" morphology
sharply elevated systolic peak
diastolic velocity profile markedly concave
left ventricular hypertrophy
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
The 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. Subclavian flap repair is a common surgical technique used, where the origin and proximal left subclavian artery is excised, opened up and sutured onto the aorta. If the subclavian is ligated, it is usually anastomosed onto the left common carotid artery.
infective endocarditis: in the context of an added infective insult
mycotic aneurysm: in the context of an added infective insult
Imaging differential considerations include: