Hypoplastic left heart syndrome (HLHS) is a rare, complex, single ventricle and congenital (present at birth) heart defect. It occurs when the fetal heart doesn’t develop correctly. In hypoplastic left heart syndrome, most of the structures on the left side of the heart are small and underdeveloped.

The degree of underdevelopment differs from child to child. The structures affected usually include the following:

• Mitral valve: The valve that controls blood flow between the left atrium and left ventricle in the heart.
• Left ventricle: The lower left-hand chamber of the heart. It receives oxygen-rich (red) blood from the left atrium and pumps it into the aorta, which takes the blood to the body. The left ventricle must be strong to pump enough blood to the body.
• Aortic valve: The valve that regulates blood flow from the heart into the aorta.
• Aorta: The largest artery in the body. It is the primary blood vessel leading from the heart to the body.

When these structures on the left side of the heart are small and underdeveloped, the heart cannot provide enough blood flow to meet the body's needs. For this reason, an infant with hypoplastic left heart syndrome will not live long without surgical intervention.

 To restore proper blood flow to the rest of the body, your child will need to undergo a series of three open heart surgeries. Your child's cardiologist and cardiac surgeon will explain the risks and benefits to you. The options include the following:

• This staged reconstruction will turn the heart's right ventricle into the main pumping chamber and reroute blood flow through several surgically created connections. The three operations include:

• The Norwood procedure: Usually occurs within a week of birth.
• The Glenn procedure: Usually performed about six months after birth, following the Norwood procedure.
• The Fontan procedure: The final surgery, usually performed between the ages of 18 months and 3 years.

Heart transplantation: If the heart becomes too weak after the surgeries, or if the HLHS is very complex, a heart transplant may be necessary. 

Interstage home monitoring program: For children undergoing single ventricle surgical treatment, the time between the Norwood and Glenn procedures, commonly known as the “interstage period,” is a critical stage in their care. Our Interstage Home Monitoring Team equips families with a comprehensive home monitoring plan, tracking tools and direct access to interstage team members to ensure proper support.

Fontan Survivorship Program: Although life expectancy and outcomes after the Fontan procedure have improved, some patients may develop health problems later in life. Our Fontan Survivorship Program is staffed by a team of experts trained to provide the best possible care for children and adults who have had the Fontan procedure. 

Care close to home: The Herma Heart Institute has 10 clinic locations. These clinics can be found in Wisconsin and upper Michigan.

Lifelong support: We provide care to our patients in all ages and stages of life — from before birth through adulthood. Your fetal heart doctor can care for your child through their childhood. As they age, they can transition into our Adult Congenital Heart Disease Program.

Commitment to innovation: Our team is leading the way in congenital heart disease research. We are working to discover breakthrough treatments and procedures to improve outcomes.

Support beyond the clinic: We know that our heart families need support that extends beyond the clinic. That’s why we invest in programs that help children thrive and get them back to being kids sooner:

• Neurodevelopmental Follow-Up Program
• Educational Achievement Partnership Program