Atrioventricular septal defects (AVSD) in children involves the lung overfilling with blood, potentially causing leakage.
This defect refers to any abnormal development of the endocardial cushions. These cushions control the separation of the parts of the heart near the tricuspid and mitral valves. It is also referred to as an atrioventricular canal defect or an AV canal defect.
AVSD is a fairly common defect, accounting for about 5% of all congenital heart defects. AVSD is the most common heart defect to occur in children with Down syndrome. It can also occur with other types of congenital heart diseases like coarctation of the aorta or tetralogy of Fallot.
The defect involves atria and ventricles that have not separated into their own chambers and mitral and tricuspid valves that have also not separated. As a result, there is a large hole between the two atria and the two ventricles, and one single atrioventricular valve instead of separate mitral and tricuspid valves.
AVSD is usually divided into three types: complete, partial, or transitional. A complete AVSD, which is the most severe type, involves defects in all the parts of the heart controlled by the endocardial cushions. This means there are holes in the atrial septum and the ventricular septum, which results in an undivided AV valve.
Depending on the type of AVSD, the already oxygenated blood may be recirculated to the lungs, which is inefficient. The left ventricle also tends to have to work harder, which increases pressure to the lungs. This can cause the lungs to overfill with blood, potentially causing it to leak into the air around the lungs. This pulmonary edema can lead to congestive heart failure.
How is AVSD diagnosed?
The condition is usually identified through a heart murmur. Diagnosis is confirmed by doing an echocardiogram, and possibly a chest X-ray or electrocardiogram.
Children with this defect are often diagnosed within a week or two of birth. They are managed with drugs, and rarely with pulmonary artery banding, until they are old enough for corrective surgery. Surgery can use patches to close the holes in the atrial septum or the ventricular septum, and reconstruct the atrioventricular valve.
What is the long-term outlook for children with AVSD?
The outlook is very good in these children following surgery. A leaky mitral valve is a rare complication that may require re-operation.