Atrioventricular Canal Defect


Atrioventricular canal defect (also known as atrioventricular septal defect or endocardial cushion defect) occurs when large hole in center of a child’s heart connects all 4 chambers. Normally, heart chambers are divided so that the oxygen-rich blood from the lungs does not mix and extra blood gets pumped into lung arteries. This extra blood makes the heart and lungs have to work harder.  Often there is an abnormal valve on the left side of the heart.

In most children the cause isn’t known, although canal defects are often associated with Down syndrome.

Patients can be seen by Texas Children's experts in Heart Center.

Symptoms & Types

In some cases, doctors may diagnose atrioventricular canal defect while a women is pregnant.

Usually, symptoms will not occur until several weeks after birth. Infants with canal defect have trouble breathing and their bodies may not grow normally.

Diagnosis & Tests

Tests that help diagnose an atrioventricular canal defect include:

  • Physical exam: A doctor will look for trouble breathing and usually listen for a heart murmur — a “whooshing” sound caused by improper blood flow in the heart.
  • Echocardiogram:  Using sound waves that bounce off the heart to create video images, this test allows the doctor to see if there is a hole in the wall between the heart chambers. This test can also show whether the blood is moving through the hole, mixing the allowing oxygen-rich and oxygen-poor blood.
  • Cardiac catheterization: This diagnostic tool involves threading a long, thin tube (called a catheter) through an artery or vein in the leg or arm and into the heart. A dye is injected through the catheter to make the heart structures visible on X-ray pictures.

Treatment & Care

Texas Children’s Heart Center typically performs surgery in the first few months after birth to correct a complete canal defect. The hole may be closed with 1 or 2 patches, and the valve is repaired.

Volumes & Outcomes