What Is the Norwood Procedure?

Medically Reviewed by Dany Paul Baby, MD on April 27, 2022

Babies born with heart problems often require immediate care to save their lives. One of the most complex heart issues in newborns is hypoplastic left heart syndrome. Any baby born with this condition will need surgery to reconstruct their hearts within the first few days of life. The operation for this situation is called a Norwood procedure.

The Norwood procedure is the first in a series of operations performed to correct a condition called hypoplastic left heart syndrome (HLHS). The condition is a congenital heart defect that causes half of a baby's heart to develop improperly before birth. The underdeveloped heart cannot pump enough blood to the rest of the body. 

The Norwood procedure reconstructs the heart so that blood can get to the baby’s vital organs. 

Doctors perform the Norwood procedure in infants a few days after birth. Without the surgery, HLHS is fatal.

HLHS is a very rare form of congenital heart defect,  which means it is something babies develop before birth. Most cases of HLHS have no known cause, and there is no way to prevent it. Only about 960 babies are born with HLHS in the United States each year.

Human hearts have four chambers, two on the right and two on the left. The right side receives deoxygenated blood and pushes it to the lungs to get fresh oxygen. The oxygenated blood enters the left side of the heart, which then pumps oxygen-rich blood to the rest of your body.

Babies born with HLHS have hearts that did not develop typically in the womb. The left half of the heart is too small. In addition, the connections between the two halves of the heart are too small or completely closed.

The underdeveloped portions of the heart cannot get oxygenated blood to the rest of the body. Instead, the right side of the heart has to pump blood to the lungs and the rest of the body at the same time. The result is dangerously low oxygenated bloodflow to vital organs. Without treatment, babies with HLHS will die within a few weeks of birth.

In many cases, doctors diagnose HLHS during routine prenatal ultrasounds. That allows parents and doctors to plan for treatment right after the baby is born. If you know your baby has HLHS, your doctor may recommend planning your delivery at a hospital with a pediatric cardiologist available facilities to manage the condition. 

If ultrasounds don’t reveal HLHS, parents and doctors may not realize anything is wrong right away. It can take several days for symptoms to start. Symptoms include:

  • Bluish tint to the skin
  • Cold hands and feet
  • Lethargy
  • Low output of urine
  • Metabolic acidosis
  • Poor suckling and feeding
  • Pounding heart
  • Problems breathing 
  • Weak pulse

If your baby has these symptoms, your doctor may use testing such as EKG, X-rays, or cardiac catheterization to diagnose HLHS.

One hypoplastic left heart syndrome treatment is a Norwood procedure. The purpose of the Norwood operation is to reconstruct the heart so it can work more effectively. First, doctors make it possible for the right side of the heart to pump oxygenated blood to both the lungs and the rest of the body. Then, they combine the main pulmonary artery and aorta so they carry blood to the body. They disconnect the branching pulmonary arteries that typically carry blood to the lungs. They then place a shunt between the main branch of the pulmonary artery and the lungs to carry blood to the lungs.

The Norwood procedure stabilizes the baby’s heart function for the short term. Babies can go home within a few weeks of the initial operation. They may need medication and attentive care for the next few months. Your doctor can tell you what your baby will need after the first surgery. As the baby grows, doctors will do two other operations to improve how blood circulates in the body.

The second operation is called a Hemi-Fontan procedure or a Glenn procedure. Babies typically have this surgery when they are between 3 and 6 months old.

For this operation, doctors disconnect the vena cava, which is a large vein that carries deoxygenated blood from the upper body back to the heart. They will reconnect the vein to the pulmonary artery instead of the heart itself. After this operation, deoxygenated blood will go directly to the lungs instead of passing through the heart first.

The final operation is called the Fontan procedure. Doctors usually perform this operation when a child is between 1.5 and 3 years old.

In the Fontan procedure, doctors disconnect the inferior vena cava, which is a large vein that carries deoxygenated blood from the lower body into the heart. They then connect it directly to the pulmonary artery, much as they did with the superior vena cava in the Glenn procedure. Once this operation is complete, all of the child’s deoxygenated blood goes to the lungs without passing through the heart.

The most critical period for babies with HLHS is the time between the Norwood and Glenn procedures. Their health may be fragile, and they will need extensive follow-up care for the next several months. 

Experts estimate that 75% of babies recover from the Norwood procedure and survive until they can have the second stage of reconstructive surgery. Survival rates for children who undergo the Glenn and Fontan procedures are 90%.

All children born with HLHS will need lifelong care. Some people with HLHS lead relatively normal lives with few striations. Other people have abnormal heart rhythms or low oxygen levels that restrict their activities. Some develop weak or leaking blood vessels later in life. They will need to see a cardiologist regularly to manage any complications that arise.

If your child has HLHS, talk to your doctor about what treatment they need. They can direct you to experts who will provide the best care for your baby. 

Show Sources


Children’s Hospital of Philadelphia: “Hypoplastic Left Heart Syndrome (HLHS).” “Staged Reconstruction Heart Surgery.”

Cleveland Clinic: “Heart.”

Genetic and Rare Disease Information Center: “Hypoplastic left heart syndrome.”

University of California San Fransisco: “Norwood Procedure.”

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