Atrioventricular Septal Defect
(Atrioventricular Canal Defect; Endocardial Cushion Defect)
The heart has four chambers. A wall divides the chambers inside the heart. This helps to keep blood flowing through the heart in the right direction.
An atrioventricular septal defect (AVSD) is a problem with how this area develops. It can lead to one or more holes in the wall between the right and left chambers. It can also lead to defects in the two heart valves between the upper and lower chambers. There are different types of AVSD:
- Complete AVSD:
- A hole develops in wall where all four chambers meet
- Only one large heart valve forms instead of two smaller ones
- Partial AVSD:
- A hole only develops between the upper or lower chambers
- There are two heart valves but one does not work well
AVSD can make it harder for blood to flow through the heart. It can also lower the amount of oxygen going out to the body in the blood. It will also make it hard to move blood flow through the lungs. This can lead to a backup of fluid in the lungs and lung damage. AVSD also puts extra strain in the heart. It can lead to heart failure .
An AVSD happens as a fetus grows. It is not always known why this happens. Some things that may play a role are:
- Changes in certain genes—may happen on their own or may be passed down from a parent
- Illness during the mother’s pregnancy
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The chances of having a baby with an AVSD are higher for mothers who:
- Have diabetes
- Used tobacco during pregnancy
AVSDs are also common in people with other genetic problems, such as Down syndrome .
AVSD may not cause problems at birth. It may be a few weeks before symptoms start. For partial AVSD, symptoms may not start until after infancy.
Problems may be:
- Cool feeling to the hands and feet
- Tiring easily
- Feeding problems
- Failure to gain weight
- Weight loss
- Breathing problems
- Fast heart beat
Sometimes, AVSD is be found before birth. during an ultrasound. A fetal echocardiogram may also be done to get more detail.
If the AVSD is not found before birth, it may not be noticed until symptoms start. The doctor will ask about your baby’s symptoms and health history. AVSD may cause a heart murmur that can be heard during a physical exam.
Tests may be:
Surgery is almost always needed to repair AVSD. Without treatment, AVSD can lead to heart failure and severe lung damage.
Surgery is often delayed until a baby is 3 to 6 months of age. This allows the baby time to grow. Until then, stress on the baby's heart and lungs will be managed. The baby will be closely monitored.
There are no known methods to prevent AVSD.
Medicine cannot treat AVSD. It can ease stress on the heart and manage symptoms for a time. Medicine may be used to:
- Relax the blood vessels
- Help the heart pump more effectively
- Lessen the work load on the heart
- Remove excess fluid from the body
- Lower blood pressure
The goal of surgery is to close the hole before there is too much heart and lung damage. One or two patches may be placed over the hole in the wall. Over time, the heart lining will grow over it.
The surgery may also need to correct damaged valves. Some options are:
- A single valve may be split into two separate valves
- Two valves may be present but need repair to work better
Babies with AVSD may have slower growth and a harder time eating. A high calorie diet may be needed. These babies also have a higher risk of severe infections and will need to be monitored.
Some children will have activity limits as they get older. This is more common if valves cannot be fully repaired and blood flow is still mixed.
Long Term Care
Lifetime monitoring will be needed. Problems can happen as a child gets older. Monitoring can help find problems before they happen. This may involve:
- A yearly exam with a heart specialist
- Regular tests of heart function
- Changes to the child's treatment plan
- Atrioventricular (AV) canal defect. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/atrioventricular-av-canal-defect.
- Atrioventricular septal defect. Merck Manual Professional Version website. Available at: https://www.merckmanuals.com/professional/pediatrics/congenital-cardiovascular-anomalies/atrioventricular-septal-defect.
- Complete atrioventricular canal defect (CAVC). American Heart Association website. Available at: https://www.heart.org/en/health-topics/congenital-heart-defects/about-congenital-heart-defects/complete-atrioventricular-canal-defect-cavc.
- Facts about atrioventricular septal defect (AVSD). Centers for Disease Control and Prevention website. Available at: https://www.cdc.gov/ncbddd/heartdefects/avsd.html.
- Kari Kuenn, MD
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