Atrioventricular canal defect is a combination of several abnormalities in the heart present at birth (congenital abnormalities). This defect, which is sometimes called endocardial cushion defect or atrioventricular septal defect, occurs when there's a hole between the chambers of the heart and problems with the valves that regulate blood flow in the heart.
Atrioventricular canal defect allows extra blood to circulate to the lungs. Ensuing problems overwork the heart and cause it to enlarge.
Atrioventricular canal defect is often associated with Down syndrome. If left untreated, atrioventricular canal defect may cause heart failure and high blood pressure in the lungs. To fix this defect, doctors often recommend surgery during the first year of life to close the hole and reconstruct the valves.
There are two common types of atrioventricular canal defect — partial and complete. The partial form involves only the two upper chambers of the heart. The complete form allows blood to travel freely among all four chambers of the heart. In either type, extra blood circulates in the lungs.
Signs and symptoms of complete atrioventricular canal defect usually develop in the first several weeks of life. They include:
If your baby has complete atrioventricular canal defect, he or she may also develop signs and symptoms of heart failure, including:
Signs and symptoms of a partial atrioventricular canal defect may not appear until early adulthood. When they do become noticeable, signs and symptoms may be related to complications that develop as a result of the defect, and may include:
Contact your doctor if you or your child develops any of the following signs or symptoms. These could be indications of heart failure or another complication of atrioventricular canal defect:
Some babies with the partial form of atrioventricular canal defect may not have any signs or symptoms for weeks, months or even years, depending on the severity of the defect. But, anytime the signs or symptoms above start to appear, seek medical care.
Atrioventricular canal defect occurs during fetal growth when your baby's heart is developing. While some factors, such as Down syndrome, may increase the risk of atrioventricular canal defect, in most cases the cause is unknown.
Your heart is divided into four chambers, two on the right and two on the left. In performing its basic job — pumping blood throughout your body — your heart uses its left and right sides for different tasks. The right side moves blood into vessels that lead to your lungs. In your lungs, oxygen enriches your blood, which circulates to your heart's left side. The left side of your heart pumps blood into a large vessel called the aorta, which circulates blood to the rest of your body. Valves control the flow of blood into and out of the chambers of your heart. These valves open to allow blood to move to the next chamber or to one of the arteries, and they close to keep blood from flowing backward.
In partial atrioventricular canal defect, a hole exists in the wall (septum) that separates the upper chambers (atria) of the heart. Also, the mitral valve between the upper and lower left chambers often has a defect called a cleft that causes it to leak (mitral valve regurgitation).
In complete atrioventricular canal defect, there's a large hole in the center of the heart where the walls between the upper chambers (atria) and lower chambers (ventricles) meet. Instead of two separate valves — one on the right (tricuspid) and one on the left (mitral) — one large common valve exists between the upper and lower chambers. And, this valve may not close tightly.
Oxygen-rich and oxygen-poor blood mix through the hole in the septum, and the abnormal valves leak blood into the heart's lower chambers (ventricles). These problems make the heart work harder, causing it to enlarge.
It's possible your doctor may diagnose your baby's atrioventricular canal defect while you're pregnant.
If your baby has a partial atrioventricular canal defect, his or her doctor may not detect that anything's wrong right away. However, if your baby has a complete atrioventricular canal defect, signs and symptoms usually become noticeable within the first few weeks of life.
Tests that help diagnose an atrioventricular canal defect include:
Treating an atrioventricular canal defect helps your child avoid potential complications, such as:
Although treatment greatly improves the outlook for children with atrioventricular canal defect, some who have corrective surgery may still be at risk of the following associated conditions later in life:
Common signs and symptoms of these complications include shortness of breath, fatigue and a rapid, fluttering heartbeat, among others. In some cases, such as a leaky heart valve, a second surgery may be needed.
In most cases, atrioventricular canal defect can't be prevented. If you have a family history of heart defects or if you already have a child with a congenital heart defect, talk with a genetic counselor and a cardiologist before getting pregnant again.
Caring for a child with a congenital heart defect can be scary and challenging. Here are some strategies that may help make it easier:
Although every circumstance is different, remember that many children with congenital heart defects grow up to lead healthy lives.
Although the exact cause of atrioventricular canal defect is unknown, several factors may increase the risk of a congenital heart defect, such as: