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.
Complete atrioventricular canal defect
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:
Partial atrioventricular canal defect
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:
When to see a doctor
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.
The normal-functioning heart
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.
What happens in atrioventricular canal defect
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.
Although the exact cause of atrioventricular canal defect is unknown, several factors may increase the risk of a congenital heart defect, such as:
Treating an atrioventricular canal defect helps your child avoid potential complications, such as:
Complications later in life
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.
You’re likely to first mention your concerns to your child’s doctor or, in the case of a partial defect that’s gone unnoticed into adulthood, your primary care physician. However, you or your child may then be referred to a doctor who specializes in disorders of the heart (cardiologist).
Because appointments can be brief, and there’s often a lot of ground to cover, it’s a good idea to arrive well prepared. Here’s some information to help you get ready for your appointment, and what to expect from your doctor.
What you can do
Preparing a list of questions can help you make the most of your time with your doctor, and ensure that you cover all of the points that are important to you. For atrioventricular canal defect, some basic questions to ask your doctor include:
In addition to the questions that you’ve prepared to ask your doctor, don’t hesitate to ask questions during your appointment anytime you don’t understand something.
What to expect from your doctor
Your doctor or your child’s doctor is likely to ask you a number of questions, such as:
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:
Surgery is necessary to fix both complete and partial atrioventricular canal defects. During the procedure, the hole in the septum is closed using one or two patches. The patches remain in the heart permanently, becoming part of the septum as the heart’s lining grows over it. The surgeon also separates the one large heart valve between the upper and lower chambers into two separate valves.
For a partial atrioventricular canal defect, the surgery also involves repair of the mitral valve so it will close tightly. If repair isn’t possible, the valve may need to be replaced instead.
If your baby has complete atrioventricular canal defect, the surgery also includes separation of the single valve into two valves, one on the left side and one on the right side of the repaired septum. If reconstruction of the single valve into two valves isn’t possible, heart valve replacement may be necessary.
If the atrioventricular canal defect has been successfully repaired with surgery, your child will likely lead a normal life, often with no activity restrictions.
However, your child will need lifelong follow-up care with a heart doctor (cardiologist) who specializes in congenital heart disease. The recommendation for follow-up is usually once a year, unless you have lingering problems, such as a leaky heart valve. In that case, follow-up will be more frequent.
Your child may also need to take preventive antibiotics before certain dental procedures and other surgical procedures if he or she is at risk of severe complications of endocarditis, a bacterial infection of the lining of the heart. Typically, this is when your child has some remaining defects after surgery, has received an artificial valve or has had repair with artificial (prosthetic) material.
Many people who have corrective surgery for atrioventricular canal defect don’t need additional surgery. However, some complications, such as heart valve leaks, may require treatment.
When an atrioventricular canal defect has been surgically corrected before any permanent lung damage has occurred, women can generally expect to have normal pregnancies. Pregnancy is not recommended, however, if serious heart or lung damage occurred before surgery. An evaluation by a cardiologist is advised before women with repaired or unrepaired atrioventricular canal defect attempt pregnancy.
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.
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.