May also be called: Endocardial Cushion Defect; ECD; Atrioventricular Canal Defect

An atrioventricular septal defect is an abnormal heart condition caused by a poorly formed central area of the heart. Atrioventricular septal defects are congenital, meaning they are present at birth.

More to Know

The heart consists of four chambers — the left atrium and left ventricle, and the right atrium and right ventricle. The chambers are separated by a wall of tissue called the septum. Two valves — the mitral and tricuspid valves — separate the atria (plural of atrium) from the ventricles.

With atrioventricular septal defects, the tissues that form the septum don't grow completely while a baby is in the womb, leaving one or more holes between the atria or the ventricles. In some cases, instead of two separate valves, there is only one large common valve, which may be malformed (formed incorrectly).

The causes of atrioventricular septal defects aren't fully understood, but they're commonly seen in children with Down syndrome. The defects can make the heart have to work harder to pump blood and cause symptoms like difficulty feeding, failure to gain weight, lung congestion, and a bluish tint to the skin (called cyanosis).

Atrioventricular septal defects are usually corrected through surgery while a child is still an infant.

Keep in Mind

If left untreated, an atrioventricular septal defect can cause complications (including heart failure) and may be life threatening. Once surgery has been done to correct the defect, however, most kids lead a normal life.

All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts.