The Norwood procedure is an open-heart surgery performed on newborns whose hearts developed with only one working pumping chamber instead of the usual two. It is most commonly done for babies born with hypoplastic left heart syndrome (HLHS), a condition where the left side of the heart is too small to pump blood to the body. The surgery is typically performed in the first weeks of life and is the first of three operations the child will need.
Why the Surgery Is Needed
In a healthy heart, the right side pumps blood to the lungs and the left side pumps oxygen-rich blood out to the body. In a baby with HLHS, the left side never fully developed in the womb, so it can’t do its job. Without intervention, the baby’s body has no reliable way to receive oxygenated blood.
HLHS is the most common reason for a Norwood procedure, but it’s not the only one. Babies born with other forms of single-ventricle heart disease, where only one pumping chamber works well enough to sustain circulation, may also need this surgery. The goal in every case is the same: reroute the plumbing of the heart so that the single working ventricle can pump blood to both the lungs and the body.
Keeping the Baby Stable Before Surgery
Before the Norwood can be performed, the baby depends on a small blood vessel called the ductus arteriosus, which naturally connects the lung artery to the body’s main artery. This vessel is open in all babies at birth but normally closes within days. For a baby with HLHS, that closure would be fatal, because it’s the only path keeping oxygenated blood flowing to the body.
To prevent the vessel from closing, doctors give the baby a continuous IV medication (a form of prostaglandin) that keeps it open. This medication typically works within 30 minutes to two hours. It buys critical time, stabilizing the infant until surgery can be scheduled in those first weeks of life.
What the Surgery Does
The Norwood procedure is not a cure. It is a palliative surgery, meaning it doesn’t fix the underlying anatomy but instead reconfigures the heart so the baby can survive and grow. The core of the operation involves rebuilding the main artery leaving the heart (the aorta) so that the right ventricle, the one working chamber, can pump blood to the entire body. Surgeons also create a new pathway to send some blood to the lungs to pick up oxygen.
That pathway to the lungs is created using a small tube called a shunt, and there are two main options. One approach connects an artery in the upper chest to the lung artery, providing a constant trickle of blood to the lungs during every heartbeat. The other approach connects the right ventricle directly to the lung artery through a small tube, which only delivers blood to the lungs when the heart contracts. Each has tradeoffs.
Shunt Options and Tradeoffs
A large trial published in the New England Journal of Medicine compared the two shunt types in 549 infants across 15 North American centers. The shunt connecting the ventricle directly to the lung artery showed a possible early survival advantage: babies in that group had a lower rate of cardiac arrest during the initial hospital stay. However, by the time researchers looked at outcomes beyond 12 months, the survival difference between the two groups was no longer statistically significant. The ventricle-to-lung shunt seemed to help more in the short term, while the artery-to-lung shunt appeared to carry slightly less risk later on.
Interestingly, the advantage of the ventricle-to-lung shunt was most apparent at lower-volume surgical centers. At hospitals performing a high number of these surgeries, the outcomes were similar regardless of which shunt was used. This is one reason the choice of surgical center matters as much as the choice of technique.
The Three-Stage Surgical Plan
The Norwood is only the beginning. Because one ventricle is doing double duty, the heart is working harder than it should. Two additional surgeries gradually separate the lung circulation from the body circulation, reducing the workload on that single ventricle over time.
- Stage 1 (Norwood procedure): Performed in the first weeks of life. Rebuilds the aorta and creates a temporary shunt to the lungs.
- Stage 2 (Glenn or hemi-Fontan): Usually performed within six months of birth. Redirects blood returning from the upper body so it flows directly to the lungs without passing through the heart first.
- Stage 3 (Fontan procedure): Performed between roughly 18 months and 3 years of age. Completes the separation by routing blood from the lower body directly to the lungs as well.
After all three stages, the single ventricle only needs to pump blood to the body. Blood returning from the body flows passively to the lungs under its own pressure, without the heart needing to push it there. This is not a normal circulatory system, but it can support a child through growth and into adulthood.
Survival and the Interstage Period
Survival after the Norwood procedure has improved significantly over the past two decades, though it remains one of the highest-risk operations in pediatric heart surgery. Estimated one-year survival is around 80%, and five-year survival is approximately 73%. The period between the Norwood and the second surgery, often called the interstage period, carries the greatest risk. During these months the baby is at home with a heart that is still working in an unstable configuration, relying on a temporary shunt.
Many pediatric heart centers now run interstage home monitoring programs. Parents are trained to track the baby’s oxygen levels, weight gain, and feeding patterns daily, and a specialized team reviews that data regularly. These programs have helped reduce unexpected deaths between stages by catching warning signs early.
What Recovery Looks Like
After the Norwood, babies spend weeks in the cardiac intensive care unit. The early days focus on stabilizing blood pressure, oxygen levels, and the balance of blood flow between the lungs and the body. Feeding is a major milestone: babies with single-ventricle hearts often tire easily during feeding, and some need supplemental tube feeding to get enough calories for growth.
Discharge depends on the baby reaching several benchmarks, including stable oxygen levels, adequate weight gain, and the ability to feed reliably. Parents are typically taught how to use a pulse oximeter at home, how to recognize signs of distress, and what feeding volumes to expect before the team feels comfortable sending the baby home. The road between discharge and the second surgery requires close follow-up, usually with visits every one to two weeks.
Long-Term Outlook
Children who complete all three stages live with what doctors call Fontan circulation. It works, but it places lifelong demands on the body. The single ventricle can weaken over decades, and the passive flow of blood to the lungs creates its own set of complications affecting the liver, kidneys, and lymphatic system over time. Many Fontan patients live into their 30s, 40s, and beyond, but they require ongoing cardiac care throughout their lives.
Activity levels vary. Some children participate in sports with modifications, while others face more significant limitations. Developmental delays, particularly in motor skills and learning, are more common in children who have undergone the Norwood pathway, partly because of the cumulative effect of multiple open-heart surgeries and time on bypass in infancy. Early intervention services, including physical therapy and developmental support, are a routine part of care for these children.