Present at birth, an atrioventricular canal defect is a combination of heart problems that may affect your baby and cause a hole in the center of the heart. Atrioventricular canal defect is also called endocardial cushion defect or atrioventricular septal defect. Although the cause is unknown, AV canal defects are more common in babies who have Down syndrome. An untreated defect can cause lung problems but early monitoring and treatment can help your child live a normal life.

Wellness & Prevention

An atrioventricular canal defect happens in the first eight weeks of pregnancy as the heart develops from a hollow tube and grows partitions that become the four chambers. If the structure doesn’t form properly, an AV defect can occur and heart function may be compromised. An atrioventricular canal defect is a complex problem that can involve more than one abnormality including:

  • Atrial septal defect: An atrial septal defect is an opening in the wall between the upper chambers (atria) of the heart.
  • Ventricular septal defect: A ventricular septal defect is an opening in the wall between the lower chambers (ventricles) of the heart.
  • Abnormal valves: Deviations in the mitral and/or tricuspid valves that separate the chambers of the heart can affect how the heart works.

A hole or improperly shaped valve allows oxygenated blood to mix with oxygen-depleted blood returning from the body or permits blood to flow or leak backward into the aorta. More blood than normal can pass through one side of the heart, causing the other side to become enlarged, and the lungs have to work harder to process more blood at one time. Your child may breathe faster than normal because of the extra blood in the lungs under higher pressure.

The risk of developing an atrioventricular canal defect may be higher in pregnant women who have rubella (German measles) early in the pregnancy, diabetes, Down syndrome, use tobacco or alcohol or take certain medications. Having a parent who had a congenital heart defect may also increase the baby’s risk.

Left untreated, atrioventricular canal defect can cause congestive heart failure and high blood pressure in the lungs. Eventually, the blood vessels in the lungs thicken, putting your child at risk for disease and irreversible damage. As pressure in the heart is affected, your child’s bloodstream may not contain enough oxygen and your child’s skin, lips and nail beds may turn blue.

Many pediatric cardiac surgeons recommend treatment before the baby turns 1 year old to surgically repair the hole and valves if necessary. Atrioventricular canal defect symptoms can affect children differently but symptoms become noticeable during infancy and may include:

  • Trouble breathing or rapid, heavy breathing
  • Sweating
  • Poor weight gain and growth
  • A blue or purple color in the lips, skin and nails
  • Pale, cool skin
  • Heart murmur
  • Tiredness
  • Disinterest in feeding, trouble feeding or tired while feeding

AV canal defect symptoms may resemble other conditions. Talk to your child’s doctor and see a pediatric cardiologist if any abnormalities are detected.


Your child’s doctor is often the first medical professional to notice atrioventricular canal defect. During a physical exam, he may hear a heart murmur caused by abnormal blood flow in the heart and recommend seeing a pediatric cardiologist. There are several different ways that cardiologists diagnosis atrioventricular canal defect.

  • Chest X-ray: An X-ray produces an image of tissue, organs and bones in the child’s chest.
  • Electrocardiogram (ECG or EKG): Electrocardiograms record the electrical activity in the heart, showing abnormal rhythms and stress on the heart.
  • Echocardiogram: Using an ultrasound, an echocardiogram creates an image of the heart and assesses the structure and function of the heart, measuring the hole in the heart and showing how much blood flows through opening and the pattern of the flow.
  • Cardiac catheterization: A tiny catheter can be inserted through a larger blood vessel, often in the groin, and threaded into the heart to take blood pressure and oxygen measurements throughout the heart and in the aorta and pulmonary artery.


Treatment plans can vary based on your child’s age, health, medical history, the level of atrioventricular canal defect and the prognosis. Your pediatric cardiologist may manage your child’s condition initially with medication to help the heart and lungs function better and recommending high-calorie formula or breast milk or supplemental tube feedings to help you baby get adequate nutrition until the defect can be repaired.

To repair atrioventricular canal defect, a pediatric cardiac surgeon places a permanent patch over the hole during surgery and heart tissue grows over the patch. Surgery may also be performed to separate or replace improperly formed valves.


After resting and recuperating, your child should go on to live a healthy life with no activity restrictions. Ongoing care may be recommended to ensure your child’s heart and lungs continue to function well.