Atrioventricular Septal Defect (AVSD)

(also called complete AV Canal, Atrio-Ventricular Canal)

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During heart development, a septum or partition and two valves form that separate the upper atrium from the lower ventricle and also separate the heart into four chambers. When the septum does not develop properly, an atrioventricular septal defect occurs. There are several types of AV canal defects, the most severe being the Complete AV Septal Defect, where there is only one common AV valve over a large hole between all four chambers of the heart. All four chambers mix blood and there is typically a large amount of blood going to the lungs. Both ventricles have to pump harder and pulmonary hypertension (high blood pressure in the lungs) develops over time.  Heart failure and poor growth are common findings.

Surgical correction:  Closure of ASD, closure of VSD, and separation of left and right AV valves.  This partition is usually done with a piece of the child’s own pericardium, a thin sack of tissue that naturally surrounds the heart.  The difficult portion of the surgery is dividing the 2 AV valves into two separate valves that have minimal leakage.