Children's Hospital Colorado

Atrioventricular Septal Defect

What is an atrioventricular septal defect?

A complete atrioventricular septal defect (AVSD), or AV canal, is a rare cardiac birth defect. AVSD is the result of incomplete development of the middle of the heart. In these cases, the common atrioventricular valve in the center of the heart fails to separate into two distinct valves (the tricuspid and mitral valves). In addition, the walls that separate the upper and lower chambers of the heart do not grow all the way to meet in the center of the heart. The result is a large hole in the center of the heart.

Who gets ASVD?

This heart defect is common in babies with Down syndrome (approximately 15 to 20% of newborns with Down syndrome have AVSD).

How is ASVD diagnosed?

AVSD in babies may be identified during pregnancy using ultrasound.

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