Ostium Secundum Atrial Septal Defects Workup

Updated: Sep 12, 2019
  • Author: Ira H Gessner, MD; Chief Editor: Syamasundar Rao Patnana, MD  more...
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Workup

Laboratory Studies

No specific laboratory blood tests are necessary in the evaluation of patients with an ostium secundum atrial septal defect.

A small degree of right-to-left shunt may occur with a large atrial septal defect. This may be detected by observing a mild decrease in cutaneous oxygen saturation to 93-95%. Although this may increase hemoglobin and hematocrit minimally, it is insufficient to cause clinical cyanosis.

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Electrocardiography

An ECG demonstrates sinus rhythm, often with evidence of right atrial enlargement manifested by tall, peaked P waves (usually best seen in leads II and V2) and prolongation of the PR interval. The QRS axis is slightly directed to the right (+100º), and the precordial leads reveal right ventricular enlargement of the so-called volume overload type that is characterized by an rSR' pattern in leads V3 R and V1 with normal T waves.

The QRS duration may be mildly prolonged because of right ventricular dilation. This mimics the finding in right ventricular conduction delay.

A significant proportion (20-40%) of children with secundum atrial septal defect may not have abnormal ECG findings. [14]

Uncommonly, a patient with a secundum atrial septal defect may demonstrate a superior QRS axis with right ventricular enlargement, mimicking findings observed in the ECG of a patient with an ostium primum atrial septal defect (see Ostium Primum Atrial Septal Defects).

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Imaging Studies

Routine chest radiography is not essential in the evaluation of a child with a suspected secundum atrial septal defect. They demonstrate increased pulmonary arterial vascularity with a prominent pulmonic trunk, right atrial enlargement, no evidence of left atrial enlargement, and right ventricular dilation.

Echocardiography is essential in the evaluation of a child with a suspected atrial septal defect. The right atrium and right ventricle are dilated; paradoxical motion of the ventricular septum is usually present.

Note the following:

  • Two-dimensional imaging from the subcostal position best reveals the defect in the atrial septum. The diameter of the defect can be measured, multiple defects can be identified, and associated anomalies can be evaluated. Some investigators use 3-dimensional echocardiography to provide an accurate assessment of the exact shape of the defect because this can be important in device closure of atrial septal defects.

  • Color Doppler studies provide direct, simulated visualization of flow from the left atrium to the right atrium. This flow is not turbulent when the defect is large enough to be clinically apparent because its size eliminates the pressure difference between the atria.

  • Complete echocardiographic examination must also identify normality of the coronary sinus, normal entrance of the pulmonary veins, an intact primum portion of the atrial septum, and normal mitral valve function. Left ventricular contractility may appear abnormal due to the dilated right ventricle. This corrects rapidly after atrial septal defect closure. [15, 16, 17]

  • Transesophageal echocardiography may be necessary in some patients because of large body size or other impediments to adequate transthoracic visualization. Transesophageal echocardiography is also used during interventional catheterization to close a secundum atrial septal defect by guiding device placement. [18]

Magnetic resonance imaging is not indicated in the evaluation of a child with a suspected secundum atrial septal defect and does not add significantly to echocardiography findings.

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Procedures

Cardiac catheterization is not indicated in the routine evaluation of a child with a suspected secundum atrial septal defect. However, it is an integral part of transcatheter occlusion of the ASDs. If concerns about pulmonary hypertension are noted, the pulmonary artery pressure and the reactivity of the pulmonary vascular resistance to vasodilators can be measured at cardiac catheterization.

Additional tests and procedures are necessary only in evaluation of other components of the patient's status, as indicated by complete history and physical examination.

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