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Cardiac syndromes

Unbalanced Atrioventricular Canal Defects

Atrioventricular canal defects, also known as atrioventricular septal defects and endocardial cushion defects, name a group of congenital abnormalities that share a defect at the atrioventricular septum, a membrane that separates the right atrium and the left ventricle. The canal is an anatomic structure of the septum. The size and location of the defect can lead to a mix of deoxygenated and oxygenated blood, affecting the amount of oxygen carried to the body. Of people with congenital heart disease, up to five percent have an atrioventricular defect; the condition affects an estimated .19 percent of 1,000 newborns.

The condition is classified as partial, complete, or rarely, as intermediate, and is usually characterized by a deformed mitral leaflet and an atrial septal defect (ASD), an abnormal opening between the right and left atria. Newborns, infants and children with this condition appear to be underfed and are small, and the heart is often enlarged. Surgery to repair the defect(s) should occur before two years of age to reduce the risk of pulmonary vascular disease, particularly in people with Down's syndrome.