Atrioventricular Canal Defect | Frequently Asked Questions

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Why is atrioventricular (AV) canal defect a concern?

If it’s not treated, AV canal can cause many problems involving the heart and lungs. When there are holes in the heart, blood flow follows the path of least resistance, which usually means that excess blood flows to the right side of the heart and out the pulmonary artery to the lungs. In children with atrioventricular canal defect, the extra volume of blood handled by the right side of the heart and the lungs can be quite significant, sometimes as much as three times the normal amount.

This extra blood flow through the lung blood vessels often results in higher blood pressure in the lungs and the right side of the heart. Over time, the increased flow of blood and the higher pressure can lead to pathologic changes in the lung blood vessels. Over the long term, these changes in the lung blood vessels can become difficult to treat and irreversible.

What are the effects of AV canal?

As the heart is pumping more blood than normal to the lungs, this adds to the amount of work the right ventricle and the heart as a whole have to do. The heart can become larger or dilated over time, and more muscular than normal. Sometimes, as the heart becomes larger, the atrioventricular valve becomes more leaky, which makes the heart less efficient.

Because blood is pumped at high pressure through the septal openings, the lining of the right and left ventricles can become irritated and inflamed. Bacteria in the bloodstream will sometimes infect this injured area, causing a serious illness known as bacterial endocarditis.

Will my child be OK?

Open-heart surgery at Boston Children’s Hospital has one of the highest success rates in the U.S. among large pediatric cardiac centers. In particular, the methods used to repair AV canal have improved greatly in the past two decades, and the operation has a high likelihood of success.

Complications after surgery are not common, but may include:

  • Residual septal defects can occur, although often these are inconsequential.
  • The AV valves, both tricuspid and mitral, can remain leaky, or sometimes the valve openings are narrow (stenotic).
  • The exit or outflow from the left ventricle may become narrow.
  • Abnormally high pulmonary vascular resistance that was present before surgery may still be elevated, and some may have higher than normal blood pressure in the lungs.
  • The heart’s electrical system may have problems.

What is my child’s long-term outlook?

Many children who've had an AV-canal repair will live healthy lives. Activity levels, appetite and growth typically return to normal in most children. Some children will still have some degree of mitral- or tricuspid-valve abnormality or leakage after surgery, which may require another operation in the future. AV canal patients will need lifelong monitoring (some will need medication), since they will always be at some risk for arrhythmias, infections, heart failure or stroke.

Your cardiologist will help you create a long-term care program as your baby matures into childhood, the teen years and even adulthood. Most people who’ve had congenital-heart-disease repair will have an ongoing relationship with their cardiologist. We will prevent and treat complications, and will advise on daily life issues, such as activity levels, nutrition and any precautions related to becoming pregnant.

Children with Down syndrome will benefit from special programs that not only enhance mental and physical development, but also understand the implications of the heart issues that children with Down syndrome often cope with. Your child's doctor can help you locate such programs in your community.

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

Boston Children's Hospital 300 Longwood Avenue, Boston, MA 02115 617-355-6000 | 800-355-7944

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