What is hypoplastic left heart syndrome (HLHS)?
Hypoplastic left heart syndrome (HLHS) is a severe congenital heart defect in which the left side of the heart is underdeveloped.
In a normal heart, the heart’s left side has the job of pumping oxygenated blood into the aorta, the large artery that carries blood to the body. In a child with HLHS:
- The mitral valve, which separates the two left chambers of the heart, is too small or completely closed (atretic).
- The left ventricle (the lower, pumping chamber) is very small.
- The aortic valve, which separates the left ventricle and the aorta, is too small or completely closed (atretic).
In addition to the most common form of HLHS shown in the animation below, there are a number of complex cardiac conditions with variations in the structures as described. In these children, where one ventricle is also small (sometimes called “HLHS variants”) the treatment strategy is similar to those with the more typical HLHS, which is shown in the animations below.
Treatment for hypoplastic left heart syndrome
Hypoplastic left heart syndrome is most often fatal without early intervention. Compared to 25 years ago, there are now many different options for treatment of this complex heart condition; an individualized approach is taken for each and every child. Your doctor will explain each individual option, and why one particular approach might be recommended for your child.
Typically, your child will require open heart surgery to re-direct the oxygen-rich (“red”) blood and oxygen-poor (“blue”) blood. After these operations:
- The right side of the heart will do what is usually the job of the left side — pumping oxygenated blood to the body.
- The deoxygenated blood will flow from the veins to the lungs without passing through the heart.
The series of three reconstructive operations to repair HLHS — the Norwood, Glenn and Fontan procedures — is known as “Staged Reconstruction.”
Frequent surveillance in infancy and early childhood is important to minimize risk factors for the eventual Fontan operation. Your child will also need a customized series of diagnostic tests between the planned stages of surgery, and throughout childhood. Additional surgical or catheter therapies, or in rare cases heart transplantation, may also be recommended.