Atrioventricular Canal Defect | Overview

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What is atrioventricular canal defect?

An atrioventricular (AV) canal defect is a combination of several closely-associated heart problems that result in a large defect in the center of the heart. Also known as atrioventricular septal defect or endocardial cushion defect, the condition is congenital, which means it is present at birth, and occurs in two out of every 10,000 newborns. It is often associated with Down syndrome.

Atrioventricular Canal Defect in Children

When the heart is properly divided, blood from the lungs does not mix with blood from the body; however with an AV canal, blood moves freely among the four heart chambers. If left untreated, AV canal can cause many problems involving the heart and lungs.

What are the defects associated with AV canal?

Like many congenital heart conditions, AV canal defect isn’t actually a single defect but rather a group of closely-associated defects in various combinations and with varying degrees of severity:

Atrial septal defect

The wall of tissue (septum) that separates the two upper heart chambers (left and right atria) has a hole. Atrial septal defect allows oxygen-rich (red) blood to pass from the left atrium through the hole, and then mix with oxygen-poor (blue) blood in the right atrium.

Ventricular septal defect

The wall of muscle tissue (septum) that separates the two lower chambers of the heart (left and right ventricles) has a hole. Atrial septal defect allows oxygen-rich (red) blood to pass from the left ventricle through the opening, and then mix with oxygen-poor (blue) blood in the right ventricle.

Abnormalities of the atrioventricular (AV) valves (mitral and tricuspid)

The valves that separate the upper heart chambers (atria) from the lower chambers (ventricles) are abnormally formed. Often this results in one large “common” valve rather than two separate valves.

Care for atrioventricular canal defect

At Boston Children’s Hospital our Cardiac Surgery team treats some of the most complex pediatric heart conditions in the world, with overall success rates approaching 98 percent — among the highest in the nation among large pediatric cardiac centers. In particular, the methods used to repair an AV canal defect have improved greatly in the past two decades, and the operation has a high likelihood of success.

We are grateful to have been ranked #1 on U.S. News & World Report's list of the best children's hospitals in the nation for the third year in a row, an honor we could not have achieved without the patients and families who inspire us to do our very best for them. Thanks to you, Boston Children's is a place where we can write the greatest children's stories ever told.”
- Sandra L. Fenwick, President and CEO

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