Coarctation of the Aorta
- Coarctation of the aorta (CoA) is a narrowing of the descending aorta typically at the aortic isthmus, the region of insertion of the ductus arteriosus just distal to the left subclavian artery.
- The lesion is congenital in etiology. Rare cases of acquired coarctation have been reported.
- Types include discrete juxtaductal (pre- and postductal), aortic arch hypoplasia, and complex with other cardiac lesions.
- CoA causes outflow obstruction and hypertension (HTN) proximal to the site of coarctation with resultant left ventricular pressure overload, myocardial hypertrophy, and possible congestive heart failure.
- The clinical manifestations of CoA vary in different age groups: in infants, can present as heart failure and shock, whereas in the adults, usually presents as asymptomatic HTN
- Treatment is usually surgical.
- Neonatal coarctations are often missed because a patent ductus arteriosus (PDA), which can obscure the anatomy. Also, the flow across the PDA makes it difficult to obtain an accurate Doppler gradient across the aortic isthmus during echocardiography.
- Upper extremity HTN and delayed femoral arterial pulses may not be present soon after birth and may be difficult to assess in neonates.
- This condition is a common cause of neonatal shock and death, especially if critical coarctation is present. Therefore, immediate medical and surgical intervention must be provided.
- Uncorrected coarctation or restenosis carries a high risk of death from rupture or dissection of the aorta during pregnancy.
- Even with correction, there is a higher incidence of miscarriage and preeclampsia during pregnancy.
- Predominant age: infants and children
- 4 in 10,000 live births
- Accounts for 4–6% of all congenital heart defects
- Sex predilection: male > female (59% vs. 41%)
- Mostly sporadic, with rare familial occurrences
Etiology and Pathophysiology
- Two theories include reduced antegrade intrauterine blood flow causing underdevelopment of the fetal aortic arch and the migration or extension of ductal tissue into the wall of the fetal thoracic aorta.
- As the PDA and foramen ovale close, the gradient across the coarctation increases leading to an increase in left ventricular pressure load and to the development of collateral blood vessels.
- Histologic findings demonstrate medial thickening, cystic medial necrosis, and intimal hyperplasia at the coarctation site.
- A genetic predisposition is suggested by reports of coarctation occurring in family members and by its association with Turner syndrome.
- There is an increased familial risk for congenital left heart abnormalities such as bicuspid aortic valve (BAV), aortic stenosis, and hypoplastic left heart syndrome.
- BAV is commonly associated with CoA and is present in more than half of CoA patients.
- There is a 5–15% incidence with Turner syndrome.
- NOTCH1 gene mutations have been identified in patients with left-sided obstructive lesions such as CoA.
- Male gender
- Family history of left ventricular outflow tract obstruction
- Turner syndrome
Commonly Associated Conditions
- CoA is commonly associated with another cardiac lesion. The frequency of these lesions differs based on the age of the population studied.
- Infants: Approximately 1/3 of patients have other complex cardiac defects, including hypoplastic left heart syndrome, atrioventricular (AV) canal defect, D-transposition of the great arteries (d-TGA), ventricular septal defect (VSD), aortic and subaortic stenosis.
- Adults: The most common cardiac association is BAV (60%). Other less common findings include VSD (13%) and PDA (7%).
- Noncardiac conditions: intracranial aneurysm (10%), Turner syndrome, intercostal aneurysm, neurofibromatosis I, PHACE syndrome, and Williams syndrome
- Other indications for fetal echocardiography include conditions with >2% absolute risk for CHD such as maternal diabetes mellitus, conception via assisted reproductive technology, and CHD in a first-degree relative (1).
- Prenatal diagnosis of CoA is challenging because only a small percentage of cardiac output flows through defect, and the PDA can make the aortic isthmus appear larger than it truly is.
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