Dayton Children’s Hospital

AV Canal Defect

What is AV canal defect?

Babies who have an AV canal defect, also known as atrioventricular septal defect (AVSD), are born with abnormal holes between the heart chambers. In some cases, the heart valves that control the flow of blood between the upper and lower chambers are also not formed correctly. Blood flows freely between the left and the right side of the heart and too much blood flows to the lungs.

Babies may have either of two types of AV canal defect:

  1. Complete AV canal defect: In babies with this type, the defect allows blood to flow between all four chambers through one large opening in the center of the heart. There is also one common valve in the center of the heart instead of one on each side.
  2. Partial or incomplete AV canal defect: In babies with this type of defect, there is usually a hole between the two upper heart chambers (atria) or the two lower heart chambers (ventricles). There are usually two heart valves instead of one common valve, but one of them (most often the mitral valve) does not close completely, so blood leaks backward from the ventricles to the atria.

How is AV canal defect diagnosed?

Your doctor may diagnose this condition during your pregnancy after abnormalities are seen on an ultrasound. If an AV canal defect is suspected, a fetal echocardiogram (an ultrasound that allows your doctor to take a closer look at your baby’s heart) can confirm the diagnosis.

Babies who have a complete AV canal defect not diagnosed during pregnancy usually develop signs within the first few weeks after birth. The signs may include:

  • Difficulty breathing
  • Trouble feeding
  • Poor growth
  • Pounding heart
  • Fatigue
  • Irritability

Because the severity of the condition varies, babies with a partial AV canal defect may not be diagnosed during infancy.

While examining your baby, your doctor will first listen for a heart murmur with a stethoscope. If your doctor hears a murmur or if your baby is showing some signs of an AV canal defect, tests can confirm the diagnosis. The most common test is an echocardiogram (a painless test that uses sound waves to create a moving picture of the heart), but a chest X-ray, EKG or cardiac catheterization may also be used.

How is an AV canal defect treated?

Babies with an AV canal defect usually require surgery to repair the holes in the heart and to separate the single common valve into two distinct valves (one on each side of the heart). In addition, the mitral valve may need to be repaired.

The age at which your baby’s surgery will be done depends on your baby’s overall health and the specific structure of the defect. If possible, doctors will arrange for surgery before there is permanent damage to the lungs, but this could be at any time between 3 months and 3 years of age.

How will an AV canal defect affect my baby during and after surgery?

During surgery, your baby will be given general anesthesia, which means the baby will be comfortable and sleeping. After surgery, your baby will need to stay in a cardiac intensive care unit (CICU) for the first few days and may be connected to several tubes and wires to allow your baby’s doctor to best monitor the baby’s condition. Pain control will be used to make sure your baby is comfortable.

Most of the tubes and wires will be disconnected before your baby leaves the CICU, after which he or she will spend several more days in the hospital in a step down unit.

Surgery is not a cure for AV canal defect, so your baby will need continuous monitoring by a cardiologist and may continue to have complications. The most common complication is a leaky mitral valve, which may require additional surgery.