Hypoplastic left heart syndrome (HLHS)

What is hypoplastic left heart syndrome (HLHS)?

Hypoplastic left heart syndrome is a type of single ventricle defect that is present at birth. In a child with hypoplastic left heart syndrome, the left ventricle, a pumping chamber, is too small to pump blood with oxygen to the body. Only the right ventricle (pumping chamber) is able to pump blood to the body. In addition, the first part of the main blood vessel between the heart and the body (aorta) is very small. As a result, your child’s organs and body don’t get the blood and oxygen they need to function properly.

These parts of the left side of the heart are too small or underdeveloped:

• Left ventricle - The chamber that pumps blood out to the body

• Mitral valve - The valve that controls blood flow between the two left chambers (atrium and ventricle)

• Aortic valve - The valve that regulates blood flow from the heart to the rest of the body

• Aorta - The first part of the large artery arising from the heart

What are the signs and symptoms of hypoplastic left heart syndrome (HLHS)?

• Pale or blue skin (cyanosis) from low oxygen levels

• Heavy, rapid breathing

• Fast heart rate

• Cold feet

• Weak pulse throughout the body

An infant with hypoplastic left heart syndrome may appear healthy at first. Symptoms typically appear within the first hours or days of life as oxygen levels and blood circulation drop.

How is hypoplastic left heart syndrome (HLHS) diagnosed?

Doctors at our Fetal Heart Program diagnose hypoplastic left heart syndrome during pregnancy. Sometimes, the condition is caught after birth when your newborn undergoes health screenings that detect low levels of oxygen in the blood.

To make a diagnosis and determine the severity of the heart defects, we use the latest cardiac imaging, including:

• Chest X-ray

• Echocardiogram

• Electrocardiogram (EKG)

What causes hypoplastic left heart syndrome (HLHS)?

Hypoplastic left heart syndrome happens for unknown reasons as a baby develops in the womb. Heart defects aren’t the result of anything a woman does – or doesn’t do – during pregnancy.

How is hypoplastic left heart syndrome (HLHS) treated?

Newborns with hypoplastic left heart syndrome need immediate care soon after birth. We partner with your maternity hospital to start therapies and quickly bring your baby to our pediatric cardiac intensive care unit (CICU). Here, your baby is in the expert hands of a pediatric heart team with deep experience treating this uncommon heart condition.

Our surgical treatments provide a different way for your child’s heart to circulate blood, ensuring their body gets the oxygen it needs. But even after these surgeries, your child will always have just one working pumping chamber.

Treatment for hypoplastic left heart syndrome involves a series of three separate open-heart surgeries:

• Norwood procedure - Soon after birth, our heart surgeons reconstruct the aorta so that blood flows from the heart to the body. We also create a pathway for blood to flow to the lungs to get oxygen.

  • Sano shunt - A Sano shunt is a small plastic tube that allows the heart to pump blood to the lungs to pick up oxygen. The shunt connects the right ventricle (pumping chamber) of a baby’s heart to the lung artery. Our heart surgeons place the shunt during a heart surgery called the Norwood procedure.

• Glenn procedure - When your baby is 4 to 6 months old, our heart surgeons make a connection between the superior vena cava (a large blood vessel) and blood vessels in the lungs. This allows blood from the upper body to reach the lungs to get oxygen.

• Fontan procedure - When your child is 18 to 36 months of age, our heart surgeons make a connection to bring blood flow from the lower body to the pulmonary artery in the heart. After this procedure, all blood in the body goes directly to the lungs for oxygen without passing through the heart.

Children’s Health is among a select few pediatric hospitals in the country with a dedicated Fontan Program for children with hypoplastic left heart syndrome. We offer all the care your child needs to enjoy their healthiest life possible.