Hypoplastic Left Heart Syndrome (HLHS)

Hypoplastic left heart syndrome is a condition children are born with where the left ventricle of the heart does not develop properly so is much smaller than usual. The mitral valve between the left ventricle and the upper left atrium is often closed or very small.

In addition, the main blood vessel that carries blood from the heart to the rest of the body (aorta) is also smaller than usual. This means that the heart is unable to pump blood around the body effectively.