Surgical Approach to Coarctation of the Aorta and Interrupted Aortic Arch Workup

Updated: Mar 30, 2015
  • Author: Dale K Mueller, MD; Chief Editor: Jonah Odim, MD, PhD, MBA  more...
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Workup

Laboratory Studies

Arterial blood gas

ABG analysis may be ordered to look for acidosis, which is common in severe coarctation in a newborn. The results of ABG analysis are nonspecific.

Electrocardiography

Another nonspecific but noninvasive examination, ECG may reflect signs of right, left, or biventricular hypertrophy, or they findings may be entirely normal in older children and adults.

Left ventricular hypertrophy with strain is a common late finding in severe coarctation.

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Imaging Studies

Chest radiography

Chest radiography may reveal little more than left ventricular hypertrophy in a mild case of coarctation. However, several other findings are considered pathognomonic of coarctation.

The classic sign of rib notching, which Meckel first described in 1827. This sign may be clearly evident on posteroanterior radiographs. The notching, a result of dilated intercostal arteries eroding the lower edge of the rib, may be absent in older patients who have not developed collaterals. It is usually absent in young patients (usually < 5-6 y) who have not had time to develop clinically significant collaterals.

The reverse-3 sign is another classic radiologic finding in coarctation. Observed en face, the upper part of the 3 is formed by the dilated proximal segment coming down into the coarcted segment, whereas the bottom portion of the 3 is formed by the coarcted segment exiting into the normal distal segment of the aorta.

Chest computed tomography scanning

CT scanning of the chest may be useful in evaluating complex abnormalities and in making the diagnosis in adults.

Angiography

Angiography was considered the criterion standard. However, CT and MRI have replaced angiography as their resolution has improved. See the image below.

Aortic coarctation visualized by aortic angiograph Aortic coarctation visualized by aortic angiography.

Magnetic resonance imaging

MRI is similar to CT scanning in that it is most helpful in assessing complex abnormalities. The resolution of MRI is better than that of CT scanning; however, the long exposure times necessary for MRI make it a more difficult to perform in infants than a 30-second rapid spiral chest CT scan. See the image below.

Aortic coarctation visualized by MRI. Aortic coarctation visualized by MRI.

The risks associated with the sedation necessary for adequate imaging likely outweigh any additional benefit.

Echocardiography

Echocardiography has gained favor in relatively recent years because its resolution has dramatically increased and its processing power has been improved.

Two-dimensional echocardiography can demonstrate the site of coarctation and helps in evaluating for other cardiac anomalies. Color Doppler flow can suggest the magnitude of pressure gradients.

Because of its portability, accuracy, and noninvasive nature, echocardiography is the diagnostic test of choice in neonates. Neonates seldom require angiographic study, except in rare cases when the area cannot be visualized well and when the abnormality cannot be effectively ruled out.

Advances in transesophageal echocardiography have made it the diagnostic test of choice during surgery, and it provides an excellent noninvasive means for postoperative follow-up care.

The most important disadvantage of echocardiography is a consequence of its noninvasive nature. Because the pressure gradients are not measured directly, they may not be as accurate as angiographically determined gradients.

Intravascular ultrasonography

IVUS is an imaging technique recently used in the diagnosis and treatment of coarctation. Capabilities include measurement of the diameter of the aorta, coarctation, and length of the lesion. This information guides the selection and deployment of stents. It also provides a means by which the endovascular repair can be followed. [16]

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Diagnostic Procedures

Cardiac catheterization

This invasive examination is not typically considered necessary because coarctation rarely involves the coronary arteries. Patients with coarctation are at risk for coronary disease later in life because of the latent effects of hypertension; therefore, cardiac catheterization may be useful in a patient examined for recoarctation at an older age.

Angiography and aortography

Considered the most objective method of analysis, angiography and aortography have many benefits; however, less invasive diagnostic techniques have largely replaced these studies.

Angiography and aortography reflect the location and extent of the coarctation, it delineates any great-vessel involvement, it facilitates the evaluation of any associated cardiac defects, and it allows for the direct measurement of pressure gradients.

Angiography and aortography are particularly useful in evaluating recurrent coarctation because balloon angioplasty can be performed at the time of the procedure if necessary.

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Histologic Findings

Ductal tissue stains lighter than aortic tissue because of its low elastin levels. In a normal aorta, the inner one third of the elastic lamellae of the aorta merges into the internal elastic lamina of the ductus, whereas the outer two thirds should merge into the adventitia.

In coarctation, ductal tissue often encircles the lumen of the aorta. As the ductus attempts to close soon after birth, ductal tissue encroaching on the aorta constricts as well, narrowing the aortic lumen.

This ectopic tissue growth is not present in all patients. This observation led to the proposal that coarctation is not a result of abnormal tissue growth, but rather, a result of abnormal fetal blood-flow patterns. [17]

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