Pediatric Unbalanced Atrioventricular Septal Defects Workup

Updated: Jan 04, 2016
  • Author: Mark A Law, MD; Chief Editor: Howard S Weber, MD, FSCAI  more...
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Laboratory Studies

A CBC count with special attention to the peripheral smear to exclude Howell-Jolly bodies should be obtained in patients with heterotaxy syndrome. Howell-Jolly bodies may be noted in patients with functional asplenia.

Chromosome testing may be performed, although findings are usually normal, unless the patient has Down syndrome.



Electrocardiography often reveals left axis deviation, initial counterclockwise frontal loop, and RV hypertrophy, as depicted below.

ECG of a 3-month-old female with a left ventricula ECG of a 3-month-old female with a left ventricular (LV)–dominant atrioventricular (AV) canal. The ECG reveals left axis deviation with an initial counterclockwise frontal loop.

In patients with heterotaxy, P-wave axis may assist in determining the location of the sinus node.


Imaging Studies

Chest radiography

Chest radiography may reveal abdominal situs inversus with heterotaxy. Abnormalities of bronchial anatomy may be evident in the setting of asplenia or polysplenia.

Generally, chest radiography reveals cardiomegaly with increased pulmonary vascular markings. If significant subpulmonic obstruction is present, pulmonary markings may be decreased.

Two-dimensional echocardiography and Doppler analysis

Doppler-echocardiography is definitive and is the method of choice in making the diagnosis of unbalanced atrioventricular (AV) septal defect (see image below). Cardiac anatomy, hemodynamics, and ventricular function can be noninvasively assessed in detail. Doppler-echocardiography alone can generally provide sufficient anatomic and functional information before repair and/or palliation. [3, 10, 11, 12]

Echocardiogram image revealing a left ventricular Echocardiogram image revealing a left ventricular dominant atrioventricular (AV) canal defect.

The initial Doppler-echocardiogram should focus on the following:

  • Atrial and visceral situs

  • Presence and size of atrial-level defect and shunt (Common atria may be observed.)

  • Presence and size of ventricular-level defect and shunt

  • Anatomy of the atrioventricular valve (AVV), including annulus size, leaflet morphology, chordal attachments, and papillary muscle architecture. (Assess the proportion of the AVV overlying each ventricle from the subcostal short-axis view as well as the degree of AVV regurgitation.) See video below. [13]

    Echocardiogram clip demonstrating common atrioventricular (AV) valve regurgitation in a patient with a left-ventricular (LV)–dominant AV canal defect.
  • Relative chamber sizes and functions

  • Relationship and sizes of the great arteries

  • Detailed attention to the anatomy of the left ventricular (LV) and right ventricular (RV) outflow tracts and the presence of obstruction

  • Systemic and pulmonary venous connections

  • Hypoplasia of aortic arch and/or status of ductus arteriosus

  • Presence or absence of RV and/or pulmonary artery (PA) hypertension

The greatest clinical challenge for the cardiologist is to determine the feasibility of the 2-ventricular repair in borderline cases. This depends on relative ventricular sizes, AVV structure and function, size of the ventricular septal defect (VSD), size of the LV outflow tract, and aortic arch hypoplasia. Note the following:

  • No strict quantitative guidelines exist; qualitative and/or clinical impressions often provide accurate guidance in the feasibility of a 2-ventricular repair.

  • PA banding in infancy protects the pulmonary vascular bed and allows additional time before a commitment needs to be made for either a univentricular or biventricular repair. Additionally, many perform primary repair if a biventricular approach is considered, again to avoid the deleterious hypertrophy that can occur after PA banding.

  • Three-dimensional echocardiography may be useful in providing more detailed information about ventricular potential in borderline cases and has been described in evaluating the anatomy in AV septal defects and AVV regurgitation. [14, 15]

Abdominal ultrasonography

This study helps detect presence or absence of the spleen.

Magnetic resonance imaging

MRI can be useful in delineating the intracardiac, PA, systemic and pulmonary venosum, and abdominal anatomy in patients with heterotaxy syndrome. MRI may also be useful in providing more detailed quantitative information about ventricular potential in borderline cases.



Cardiac catheterization and angiography

Note the following:

  • Invasive studies are not always needed before surgical repair and/or palliation if all the anatomic and functional data can be obtained using echocardiography.

  • Catheterization may be helpful in borderline cases to assist with decision making about whether to proceed with univentricular or biventricular repair.

  • Catheterization may assist with defining systemic venous and pulmonary venous anatomy more completely.

  • If single-ventricular repair is chosen, catheterization is often used prior to creation of the bidirectional Glenn anastomosis to assess the pulmonary artery architecture and pressures (see image below). Catheterization may also be obtained prior to completion of a Fontan repair to assess systemic and PA structure and hemodynamics.

    Catheterization in a patient with a left ventricul Catheterization in a patient with a left ventricular (LV)–dominant atrioventricular (AV) canal defect. The catheter is positioned in the pulmonary artery demonstrating pulmonary artery band and branch pulmonary arteries.