Learn more about treatments for the congenital heart defect called hypoplastic left heart syndrome (HLHS), including the Norwood procedure, bidirectional Glenn shunt procedure and Fontan procedure.

Published: November 23, 2018 | Updated: October 7, 2019

One of the rarest and most complicated heart defects found in babies is hypoplastic left heart syndrome (HLHS) in which a critical underdevelopment of the left side of the heart leaves the right side doing most of the work.

“With hypoplastic left heart syndrome, the left side of the heart can’t effectively pump blood to the body,” said Joshua Sparks, M.D., medical director of the Pediatric Advanced Heart Failure and Transplant Program team at Norton Children’s Hospital and pediatric cardiologist with UofL Physicians.

The result for infants with HLHS is that oxygen-rich and oxygen-poor blood mix in their heart. They experience trouble breathing and rapid heartbeat. Because of poor circulation, their extremities are cold and the skin, lips and nail beds take on a blue color.

It’s widely unknown why defects such as HLHS occur, but suspected causes include genetics, certain medications taken during pregnancy, drug and alcohol use while pregnant and viral infections.

Although HLHS treatment isn’t exactly the same for each child, many undergo a series of surgical procedures. The timetable for these procedures can vary based on growth, overall wellness and organ development. The surgical procedures include:

Norwood procedure

• Typically done in the first week of a baby’s life.
• Cardiothoracic surgeons create a new aorta to connect to the right ventricle.
• A tube is placed from either the aorta or the right ventricle and connected to the blood vessels supplying the lungs, also known as the pulmonary arteries.
• All of this allows the right ventricle to pump blood to both the lungs and the rest of the body.

Bidirectional Glenn shunt procedure

• Typically performed when the infant is 4 to 6 months old.
• Cardiothoracic surgeons create a direct connection between the pulmonary artery and the blood vessels that return oxygen-poor blood from the upper part of the body to the heart. This vessel is known as the superior vena cava.
• It reduces the work of the right ventricle by allowing blood returning from the body to flow directly to the lungs.

Fontan procedure

• Typically performed when an infant is 2 to 4 years old.
• Cardiothoracic surgeons connect the pulmonary artery and the blood vessels that return oxygen-poor blood from the lower part of the body to the heart, also known as the inferior vena cava. This allows the rest of the blood coming back from the body to go to the lungs.
• Once this procedure is complete, oxygen-rich and oxygen-poor blood no longer mix in the heart and an infant’s skin will no longer look bluish.

These surgeries don’t cure HLHS. The child will need regular follow-up visits with a pediatric cardiologist to monitor progress. When the child becomes an adult, a congenital heart defect specialist will continue to provide care.

In some cases, if the HLHS is very complex or the heart becomes weak after any of the surgeries, a heart transplant may be needed.