Interrupted Aortic Arch Workup

Updated: Mar 29, 2016
  • Author: Alvin J Chin, MD; Chief Editor: Syamasundar Rao Patnana, MD  more...
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Workup

Laboratory Studies

The most helpful blood test in interrupted aortic arch (IAA) is the arterial blood gas (ABG) study to confirm the presence of metabolic acidosis.

A serum calcium measurement is occasionally informative because many patients with interrupted aortic arch have DiGeorge syndrome, including the hypoparathyroidism phenotype.

Fluorescent in situ hybridization (FISH) can reveal the typical 22q11.2 deletion [49] seen in 85-90% of patients with DiGeorge syndrome.

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Imaging Studies

Two-dimensional echocardiography and Doppler analysis

Two-dimensional echocardiography is diagnostic for interrupted aortic arch (IAA). In addition, it can usually provide at least indirect evidence for the presence or absence of aberrant right subclavian artery. Occasionally, the presence of an isolated right subclavian artery can be detected. A suprasternal frontal sweep followed by left oblique and sagittal cuts is recommended.

Color-flow Doppler analysis may assist in the ultrasonographic tracing of such vessels by rapidly distinguishing them from venous structures. Furthermore, in the patient whose ductus arteriosus has markedly reduced in size, 2-dimensional and Doppler analysis can be used to monitor the effect of exogenous prostaglandin E1 on this structure.

The size and anatomic type of the ventricular septal defect (VSD) can also be identified. In the setting of a large VSD, additional small VSDs can be missed, just as with cardiac catheterization. The most important contribution of 2-dimensional echocardiography to the preoperative characterization of patients with interrupted aortic arch is the display of the aortic outflow region. The presence of thymus can be ascertained as well.

Echocardiography also demonstrates the site of arch interruption, the size and anatomic type of the ventricular septal defect, the morphology of the aortic valve, and the anatomic severity of subaortic hypoplasia. [50] Aortic valve and subaortic abnormalities are present in 50-80% of patients with interrupted aortic arch.

Chest radiography

Chest radiography findings vary. The cardiothymic silhouette may be normal or enlarged Patients with DiGeorge syndrome may have an absent thymus.

Pulmonary vascularity may be normal or increased.

Electrocardiography

Common electrocardiography (ECG) findings include right ventricular hypertrophy and ST-T wave abnormalities. Occasionally, QT prolongation is evident because of DiGeorge syndrome–related hypocalcemia.

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Procedures

Cardiac catheterization

Cardiac catheterization reveals the site of arch interruption, the size and anatomic type of ventricular septal defect, and the anatomic severity of subaortic hypoplasia. Cardiac catheterization also reveals whether the right subclavian artery is aberrant.

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