Atrioventricular Canal Defect
Information on Kids Health
An atrioventricular canal defect (AV canal) is a complex defect that results in a large hole in the center of the heart. It involves three abnormalities:
- Atrial Septal Defect (ASD-Primun Defect)
- Ventricular Septal Defect (VSD)
- A malformed left atrioventricular valve (the valve that separates the left atrium from the left ventricle)
Concerns and Symptoms
AV canal causes oxygen-rich blood from the left side of the heart to flow through the openings and mix with oxygen-poor blood in the right side of the heart. The right side of the heart and the lungs must then handle more blood than normal.
Over time, the increased pressure in the right side of the heart and the lungs begins to push oxygen-poor blood back to the left side of the heart, where it can be circulated through the body. In addition, the malfunctioning mitral valve allows oxygen-rich blood to flow backward into the left atrium, instead of through the left ventricle and aorta, and out to the rest of the body. When the body does not receive enough oxygen in the circulating blood, the child can become cyanotic, or blue.
Children with an AV canal defect usually show symptoms in infancy. Symptoms include fatigue, rapid or heavy breathing, rapid heart rate, difficulty feeding and poor weight gain.
Surgery is required to repair an AV canal defect. The operation is performed under general anesthesia, which means the child will be asleep during surgery. First the surgeon makes a vertical incision in the front of the chest, opens the breastbone and exposes the heart. Blood from the heart is redirected to a bypass machine. The bypass machine does the job of the heart and lungs during the operation.
The surgeon then opens the heart and identifies the ventricular defect. He cuts a small piece of Gore-Tex in the size and shape of the defect and uses this as a patch. He then reconstructs the malformed mitral valve so it can function properly. Finally, he repairs the atrial septal defect with small a piece of the pericardium - the sac that surrounds the heart.
After the defects are repaired and the heart closed, the surgeon shuts down the heart-lung bypass machine, and the heart starts beating again. The surgeon then closes the breastbone and chest incision, and applies bandages to the incision site.