Babies with the congenital heart defect hypoplastic left heart syndrome receive specialized care from our expert team.

Babies with hypoplastic left heart syndrome (HLHS) — a rare, complex heart defect that is present at birth — need comprehensive care from an experienced team to meet their unique needs throughout their treatment.

Our Approach to Treating HLHS

The team in the Johns Hopkins All Children’s Heart Institute in St. Petersburg, Florida, includes specialized pediatric cardiologists, heart surgeons, fetal heart specialists, cardiac critical care physicians and others to provide your baby with expert, compassionate care from diagnosis and treatment, to follow up care into adulthood. 

In hypoplastic left heart syndrome (HLHS), the left side of the heart is critically underdeveloped and cannot effectively pump blood to the body, leaving the right side of the heart to pump blood to both the lungs and the rest of the body. In HLHS the left lower chamber may be too small, or it may not have developed at all. The valves on the left side of the heart also do not work properly, and the main artery leaving the heart is smaller than normal.

All babies are also born with a patent ductus arteriosus, which is an opening between the pulmonary artery and the aorta that allows blood to flow directly from the heart to the lungs. This typically closes after birth but babies with HLHS are given medication to prevent this closure because the PDA helps provide additional blood flow to help keep them stable before surgery. 

Hypoplastic left heart syndrome may be diagnosed before your baby is born with a fetal echocardiogram. A fetal echocardiogram is a type of ultrasound used to take pictures of a baby’s heart before birth to diagnose various types of congenital heart defects. If your primary obstetrician has a concern about your baby’s heart after an ultrasound, you may be referred to a specialist for a fetal echocardiogram.

At Johns Hopkins All Children’s Hospital, our Fetal Heart Program team provides expert diagnosis using fetal echocardiogram as well as management before birth of congenital heart defects like hypoplastic left heart syndrome.

Sometimes babies are diagnosed after birth. Babies with HLHS are usually seriously ill right after birth and will have lower oxygen levels. Babies will have an echocardiogram to confirm a diagnosis of HLHS. An echocardiogram is a type of ultrasound that takes moving images of your baby’s heart.

Treatment for hypoplastic left heart syndrome

All babies with HLHS will require three surgeries done at different times. This is referred to as “staged reconstruction.” The surgeries done to repair HLHS are the Norwood procedure, the Glenn procedure, and the Fontan procedure. These surgeries are performed by our board-certified heart surgeons. Learn more about the heart surgery team.

Norwood procedure

The first surgery is the Norwood procedure, which is done within the first week of life. In babies with HLHS, the left ventricle and aorta are too small to pump blood to the body. The Norwood procedure is done so the right ventricle can pump blood to the body. This involves rebuilding the aorta by joining it with the bottom part of the pulmonary artery and placing a shunt that will take blood to the lungs.

Your baby’s oxygen levels after the Norwood procedure will still be lower than normal, but the procedure helps to stabilize their oxygen levels. The goal for patients after the Norwood procedure is to be able to eat well enough to gain weight.

Some babies may have difficulty eating and may need a feeding tube to help them get enough calories to grow. If this is needed, your baby’s care team will discuss with you the type of feeding tube that best meets your child’s needs and how to care for them with the tube at home. After the Norwood procedure, your baby will see our team for follow-up visits typically every two weeks until their second surgery.

Glenn procedure

The Glenn procedure is the second surgery done to repair HLHS. This surgery is typically done when patients are 4-6 months of age. Before surgery your baby will have a cardiac MRI or catheterization procedure so that doctors can examine how your baby’s heart is functioning to make sure they are ready for surgery. For the catheterization procedure, a long, thin tube called a catheter is guided through the blood vessels to examine the heart. These procedures are performed by the team in our Interventional Cardiology Program.

For the Glenn procedure, the surgeon will disconnect the superior vena cava (which usually carries blood back to the heart from the head, arms, and upper body) from the heart and connect it to the branch pulmonary arteries so that blood will now flow from the upper body directly to the lungs. This makes it so the single ventricle does not have to work as hard. During the Glenn procedure, the surgeon will also remove the shunt that was placed during the Norwood procedure.

While babies will continue to have abnormal oxygen levels, the Glenn procedure further stabilizes the way blood flows to the lungs.

Fontan procedure

The third surgery done to repair HLHS is the Fontan procedure, which is usually done when the child is a little older, between 2-5 years old, depending on your child’s individual condition. Similar to before the Glenn procedure, a catheterization procedure will be performed so that doctors can make sure that your child is a good candidate for the operation.

For the Fontan procedure the surgeon will connect the inferior vena cava (a vein that carries blood from the abdomen and lower body back to the heart, so that it can go to the lungs for oxygen) to the pulmonary artery using a tube. The surgeon will also often create a small hole between the tube and the right atrium, called a fenestration, so that some blood still flows back to the heart, to help moderate pressure in the lungs. The Fontan procedure is done so that the single ventricle only pumps oxygenated blood to the body, so that blood with oxygen and blood without oxygen no longer mixes as it flows through the body.

Caring for your baby between surgeries

After each surgery, your baby will be cared for by the team in the cardiovascular intensive care unit (CVICU). The CVICU team includes pediatric cardiologists, heart surgeons, cardiac critical care physicians, respiratory therapists and other pediatric experts who care for our patients after surgery.

The highest risk time at home is between the first and second surgery. Your baby will be monitored by the team in our Cardiac High Risk Monitoring Program during this period. The program provides seamless coordination of care and a consistent point of contact for your family during this time.

We provide families with education and technology so that they can track their baby’s health and progress between visits, allowing our team to receive real-time updates about your baby’s vital signs such as oxygen levels, feedings, and other important information. Families also have access to the team through a 24-hour dedicated phone line for any questions or concerns that may arise. Learn more about the Cardiac High Risk Monitoring Program.

Follow-up care

After their third surgery, children with HLHS will continue to follow up with a cardiologist throughout their life. The Fontan procedure is done to improve your child’s oxygen levels as much as possible, but the way blood flows through the body will still be abnormal. Their oxygen levels will need to be monitored throughout their life, and children with HLHS may experience complications later in life.

They will often remain on medication throughout their life, and they may later need additional surgeries, including heart transplantation in some cases. Other long-term complications may include issues with the liver or swelling or the buildup of fluid in the abdomen or extremities. Johns Hopkins All Children’s Hospital has a Fontan clinic to provide specialized care for children who have had this procedure.

Patients are also recommended to have developmental evaluations between ages 9-12 months and may need care from other specialists later. Our team can refer your child to other specialists throughout Johns Hopkins All Children’s as needed.

Pediatric patients can also continue to receive care from our experts as adults in the Adult Congenital Heart Disease Program. Adults who were treated for HLHS as children benefit from seeing a provider who is familiar with the Fontan procedure in particular and understands how congenital heart defects can impact health long term.