Atrial septal defect (Secundum)
Because atrial septal defects can be associated with other types of congenital heart
disease, it is imperative that a complete and thorough echocardiographic examination be
performed.
Secundum atrial defects are well defined on echo from subcostal view and the defect can be
sized. With use of color Doppler flow mapping, a qualitative assessment of shunting and its
direction can be obtained.
The four-chamber apical view can assess the shunt-volume effects on size and wall thickness
of the right ventricle, but is less reliable for accurately measuring the defect. The
parasternal ventricular short axis view may show a flattened interventricular septum during
diastole due to right ventricular volume overload. TEE can be extremely useful in diagnosis
and management since it accurately displays the region of the atrial fossa where the
secundum defects occur and can determine eligibility for catheter-guided closure.
Apical 4-chamber view shows the shunt from left atrium to right atrium.
NM SPECT perfusion imaging reveals marked dilation of the RV in the short axis
view (above) and the horizontal long axis view (below).
Long axis view of the ventricles shows the enlarged right ventricle
and should raise suspicion for a left to right atrial shunt, anomalous pulmonmary venous
drainage, or severe tricuspid regurgitation.
Short axis view of the left ventricle shows the right ventricular
enlargement indicating RV volume overload and flattening of the interventricular septum.
Apical 4 chamber view shows the relative enlargement of the right
ventricle compared to the left which should raise suspicions of a left to right shunt. The
echo drop-out at the atrial fossa requires interrogation by color doppler.
Color doppler apical 4-chamber view shows the shunt from left atrium
to right atrium.
Pulsed-wave doppler sampling at the right side of the 2nd ASD defect show a
continuous left to right atrium flow with velocity of up to 1 m/s.
Agitated saline injected intravenously acts as a contrast solution.
Here it is evident that a negative effect of non-contrast flow is visible through the
secundum ASD from left atrium to right atrium.