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Atrioventricular Septal Defect

(Atrioventricular Canal Defect; Endocardial Cushion Defect)

How to Say It: A-tree-o-ven-TREAH-q-lar sep-TAL DEE-fect
by Cynthia M. Johnson, MA

Definition

The heart is made up of four chambers. A wall divides the chambers inside the heart. It 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:
    • Hole develops in wall where all four chambers meet
    • Only one large heart valve forms instead of two smaller ones
  • Partial AVSD:
    • Hole only develops between upper or lower chambers, not both
    • 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.

Causes

An AVSD happens as the baby grows in the uterus. It is not always known why a specific area of the heart does not form well when the heart is developing. 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

Ventricular Septal Defect

Ventral septal defect
Copyright © Nucleus Medical Media, Inc.

Risk Factors

The chances of a baby with AVSD are higher for mothers who:

  • Have diabetes
  • Used tobacco during pregnancy

AVSD are also common in people with other genetic problems, such as Down syndrome.

Symptoms

AVSD may not cause problems at birth. It may be a few weeks before symptoms happen. For partial AVSD, symptoms may not appear until after infancy. Others may have severe issues. Symptoms may be:

  • Cool feeling to the hands and feet
  • Tiring easily
  • Feeding problems
  • Failure to gain weight
  • Weight loss
  • Breathing problems
  • Fast heart beat— tachycardia
  • Repeated lung infections

Diagnosis

Some AVSD may be found before birth. It may be noticed 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 develop. The doctor will ask about your baby’s symptoms and health history. AVSD may cause a heart murmur that can be heard during an exam.

Tests may be:

Treatment

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.

Medicines

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

Surgery

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 will need to be split into two separate valves
  • Two valves may be present but need repair to work better

Supportive Care

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. They will be monitored for lung infections.

Some children will need to 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

Prevention

There are no known methods to prevent this health problem.

RESOURCES:

American Heart Association
https://www.heart.org
Family Doctor—American Association of Family Physicians
https://familydoctor.org

CANADIAN RESOURCES:

Canadian Adult Congenital Heart Network
http://www.cachnet.org
Heart and Stroke Foundation
http://www.heartandstroke.ca

References:

Atrioventricular (AV) canal defect. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/atrioventricular-av-canal-defect. Accessed August 27, 2021.
Atrioventricular septal defect. Merck Manual Professional Version website. Available at: https://www.merckmanuals.com/professional/pediatrics/congenital-cardiovascular-anomalies/atrioventricular-septal-defect. Accessed August 27, 2021.
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. Accessed August 27, 2021.
Facts about atrioventricular septal defect (AVSD). Centers for Disease Control and Prevention website. Available at: https://www.cdc.gov/ncbddd/heartdefects/avsd.html. Accessed August 27, 2021.
Last reviewed July 2021 by EBSCO Medical Review Board Kari Kuenn, MD
Last Updated: 8/27/2021