Atrioventricular Canal Defects
What are Atrioventricular Canal Defects?
Atrioventricular canal defects also called atrioventricular septal defects (AVSDs) occur when the central part of the heart does not form correctly. They occur frequently in babies with Down’s syndrome but also in otherwise normal babies.
There can be a hole between the two top chambers of the heart called a primum atrial septal defect, a second hole between the two pumping chambers of the heart called an inlet ventricular septal defect and abnormal development of the two inlet valves of the heart where they are suspended over the central part of the heart.
Symptoms of Atrioventricular Canal Defects
The holes in the heart result in excess blood flow to the lungs which can cause breathlessness, difficulty with feeding and gaining weight, and increased rates of chest infections. Abnormal formation of the inlet valves can result in a leaky (regurgitant) left-sided inlet valve (mitral valve).
Treatment of Atrioventricular Canal Defects
Surgery to repair these abnormalities involves closing the holes inside the heart with patches and repairing the inlet valve on the left side of the heart that forms with 3 leaflets instead of the normal 2 leaflets. About 10-15% of babies and children born with one of these abnormalities will require further surgery later in life due to abnormalities of the left inlet valve and narrowing of the outlet of the left side of the heart which can develop subsequently.