Abnormalities seen in the four-chamber view

In the four-chamber view, the loss of off-setting of the atrioventricular valves indicates a common atrioventricular valve; there is a single valve opening into both ventricular chambers. A complete AVSD consists of both atrial and ventricular components and in a typical AVSD both ventricles are equal in size.

Prevalence

This defect is found in about 1 in 5,000 live births.

Other abnormalities

Regardless of the size of the atrial or ventricular components, AVSD seen in the setting of normal atrial situs is commonly associated with extracardiac defects and chromosomal anomalies, mainly trisomies 21 and 18, found in more than 80% of cases. In AVSD with atrial isomerism, the fetal karyotype is usually normal.

Prognosis

The prognosis is mainly dependent on the presence or absence of other abnormalities. In cases of isolated AVSD, survival after postnatal surgery is more than 95% and long-term outcome is good.

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