About Hypoplastic Left Heart Syndrome (HLHS)

HLHS: A Child's Perspective

Hypoplastic left heart syndrome (HLHS) is a rare, complex heart defect that is present at birth (congenital). HLHS affects approximately 1,000 newborns every year in the United States. HLHS occurs during fetal growth when the baby's heart is developing. The cause is unknown and it cannot be prevented.

In HLHS, the left side of a child's heart — the left ventricle, ascending aorta and left heart valves — is severely underdeveloped. The result is a heart with only a single functional ventricular chamber — the right ventricle — and a small ascending aorta. In a properly developed heart, the right side pumps blood to the lungs, while the left side pumps blood to the rest of the body. In newborns and children with HLHS, the right side of the heart is forced to pump blood to both the lungs and the rest of the body.

HLHS treatment generally requires a series of surgeries. Though post-surgical outlook is good, and many people with HLHS live nearly normal lives, there is always the chance that a heart transplant may be needed in the future. Because the right side of the heart is not meant to support the entire body, the strain on the heart can lead to declines in its pumping ability over time, making a transplant necessary.

Although every circumstance is different, many children with HLHS grow up to lead healthy lives.