Aortic coarctation overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Priyamvada Singh, M.B.B.S.[2], Cafer Zorkun, M.D., Ph.D. [3]; Assistant Editor(s)-In-Chief: Kristin Feeney, B.S.[4]
Overview
Aortic coarctation is a localized narrowing or abrupt constriction of the aortic arch anywhere along its length. It is most common distal to the origin of the left subclavian artery, near the area where the ductus arteriosus (ligamentum arteriosum after its regression) inserts. Less commonly, the obstruction can occur in the abdominal aorta. Coarctation may be associated with bicuspid aortic stenosis. There is a dilation of the aorta immediately above the narrowing, but especially just below. Therefore the latin term "coarctatus", which means contracted or tightened.
Historical perspective
Aortic coarctation has been on historical record since as early as 1760. In the 1900s, researchers such as Bonnett and Johnson would later further classify the anatomical configurations associated with aortic coarctation.
Epidemiology and demographics
Coarctation of the aorta is a common malformation. It occurs in about 7% of patients with congenital heart defects. It is more common in males than females with a ratio of 2:1. Up to 25% of patients with Turner syndrome have coarctation of the aorta. It is commoner in caucasians with approximately 7 times more cases in caucasians versus asian.
Classification
An aortic coarctation can be classified in three ways depending on the anatomical configuration. These include: preductal coarctation, ductal coarctation, and postductal coarctation. All classifications involve narrowings of the aorta that directly impact the aortic hemodynamics.
Risk factors
Although the cause of aortic coarctation is not definitively known, certain factors have been associated with a potential risk increase. These include genetic anomalies such as turner syndrome, familial history, environmental factors (viral infections during pregnancy), and neonatal care.
Causes
Like many congenital heart diseases, the cause of aortic coarctation is not clear. The etiology of coarctation of the aorta may be explained by multifactorial inheritance hypothesis. Clinical studies suggest that genetic, familial influence and environmental factors both play an important role during pregnancy. It has been found to be associated more with patients with turner syndrome. Additional research suggests a possible link between other congenital heart diseases and an aortic coarctation, indicating that those with congenital heart disease are more likely to have an accompanying secondary defect.
Differential diagnosis
A thorough examination is necessary to truly diagnose an aortic coarctation. Conditions with similar symptoms to an aortic coarctation include: aortic stenosis cardiomyopathies (dilated cardiomyopathy and hypertrophic cardiomyopathy), endocardial fibroelastosis, primary hypertension, hypoplastic left heart syndrome viral myocarditis, congenital adrenal hyperplasia, patent ductus arteriosus, polyarteritissepsis, shock
Physical examination
Physical examination acts as an important tool in the diagnosis of coarctation of aorta. Differential hypertension (depending on the location of coarctation)with increased blood pressure in upper limb and hypotension in lower extremities. The difference is usually in systolic blood pressure whereas the diastolic blood pressures are typically similar. Similarly, the pulses in upper extremities are bounding whereas the femoral pulses are often diminished (brachial-femoral delay). There are 3 potential sources of a murmur: multiple arterial collateral (continuous murmur), an associated bicuspid aortic valve (systolic ejection click), and the coarctation itself which can be heard over the left infraclavicular area and under scapula. Murmurs due to associated cardiac abnormalities such as VSD or aortic valve stenosis, may also be detected. Neonates may present with discrepancies in blood pressure and pulses between the limbs, differential cyanosis or reversed differential cyanosis (depending on associated lesions), murmur, congestive heart failure, and shock. Older children and adolescent may be referred due to agitated behavior, headache, vision problem, and hypertension.
Chest Xray
Aortic coarctation on chest Xray presents with irregular notching of the inferior margins of the posterior ribs resulting from collateral flow through dilated and pulsatile intercostal arteries. An inverted "3" sign of the barium-filled esophagus or a "3" sign on a highly penetrated chest radiograph may be visualized. Signs of congestive heart failure - Cardiomegaly, pulmonary edema, prominent pulmonary vasculature.
Echocardiography
Echocardiography is an useful diagnostic tool for coarctation of aorta. The 2 D echocardiography helps in evaluation of the aortic arch to assess the transverse aortic arch, isthmus, severity of coarctation, and other associated cardiac abnormalities.Doppler echocardiography helps to decide the gradient across the coarctation and helps in taking decisions regarding treatment.
Medical therapy
The treatment choice depends on the patients age of presentation, severity, the location of the coarctation and other associated anomalies. For children who present early, the role of medical management is for stablizing the patient for surgery. However, in older kids and adolescent presenting with hypertension treatment is guided towards correction of hypertension and other associated anomalies. Beta blocker is treatment of choice for both pre and post operative hypertension.