Overview of Norwood Procedure
The Norwood procedure is a groundbreaking surgical technique, named after William Norwood, a well-respected heart surgeon. This procedure has brought hope to babies born with a severe heart condition known as hypoplastic left heart syndrome (HLHS). Before this procedure was developed in the 1980s, babies with HLHS had poor chances of survival as there were no effective treatment options. However, the Norwood procedure turned things around, significantly improving their survival rate. It’s now a common operation for this condition, with a 2018 report showing that over 2000 Norwood procedures were carried out in about 100 medical facilities worldwide.
The first Norwood procedures were done at Boston Children’s Hospital. Over time, adjustments have been made to the procedure to make it better and safer, showing the progress in surgical techniques. One ongoing debate about this procedure is choosing the right type of shunt (a tube to redirect blood flow) to maintain blood flow to the lungs. There are two main types of shunts considered: the modified Blalock-Taussig-Thomas (mBTT) and the right ventricle to pulmonary artery (RV-PA) Sano shunts. To determine which shunt gives the best results, a study was conducted called the Single Ventricle Reconstruction (SVR) trial. Interestingly, the study found no significant difference in the outcomes between the two types of shunts, reminding doctors of the complexity of making this kind of decision.
Thanks to the Norwood procedure, patients have the possibility of receiving further surgeries to improve their condition. These additional procedures include the superior cavopulmonary connection and Fontan procedures. The hope is that these procedures can improve the patient’s ability to live a long, quality life.
Anatomy and Physiology of Norwood Procedure
HLHS, or hypoplastic left heart syndrome, is a common type of heart defect seen in babies who undergo a surgery called the Norwood procedure. This syndrome means that the left side of the heart doesn’t develop as it should. This leads to problems with pumping blood to the rest of the body. Sometimes, a baby with HLHS also has other heart-related issues such as a small aorta or a narrowed one.
In a normally developed heart, oxygenated (fresh) and deoxygenated (used) blood are separated. In HLHS, however, the blood gets mixed up, which can cause health problems. In such a case, the right side of the heart has to do the extra work of pumping blood both to the lungs and the rest of the body.
There are different forms of HLHS, classified by the conditions of two heart valves: the mitral and aortic valves. It is also often associated with other congenital heart diseases. Sometimes, other forms of heart disease in newborns may also require the Norwood procedure.
The main goal of the surgery for HLHS is not to cure the condition but to stabilize and maintain a steady flow of blood in both systemic (body) and pulmonary (lung) circulation. The Norwood procedure is typically the first step in this process and is usually carried out within the first week of the baby’s life. More surgeries follow later, at around 4 to 6 months and again at 3 to 5 years of age. These surgeries are meant to support the heart until the patient can receive a heart transplant.
Right after birth, babies with HLHS usually need to start medication to keep a specific pathway in the heart open and ensure blood keeps flowing to the body. Depending on the condition of the baby’s heart, they may also need a procedure to ensure that blood is combining properly. Babies diagnosed with HLHS before birth should be delivered at a specialized center prepared for these complex cases. This group of infants may need immediate treatment after birth and generally have a higher risk of serious health problems or life-threatening situations. If the return flow of blood to the lungs is blocked, these infants urgently need surgery.
Why do People Need Norwood Procedure
People born with a certain heart condition called single ventricle congenital heart disease are at serious risk if they don’t get surgery. This heart condition can cause severe heart failure and eventually death if untreated. There’s a surgical operation, known as the Norwood procedure, that is very helpful for newborn babies with this condition and other similar heart issues.
Some of the heart problems this procedure can help with include double-inlet left ventricle, hypoplastic right heart syndrome, and tricuspid atresia. Babies who have these conditions and are at risk of their heart not being able to pump enough blood to support their body’s needs may benefit from a Norwood procedure. In some situations, doctors might decide to do a Norwood procedure on a newborn if they are uncertain whether the baby’s heart could adequately function with two separate pumping chambers, or ventricles. By doing this, doctors provide a chance for the baby’s heart to grow normally and possibly be fixed completely when they are a bit older.
It’s very important that the baby is stabilized right after birth because the Norwood procedure involves a technique called cardiopulmonary bypass that temporarily takes over the heart and lung functions during the surgery. This process involves some risk and can cause health complications. To improve the baby’s health condition before the operation, doctors may perform a simple procedure called a balloon atrial septostomy. This procedure makes sure the heart’s upper chambers mix and balance out the blood pressure properly. It’s essential that a newborn who needs a Norwood procedure is taken care of at a special hospital that is equipped to handle these complex heart conditions.
When a Person Should Avoid Norwood Procedure
There are a few situations that might make the Norwood procedure, which is a type of heart surgery, not the best choice for a newborn. These could involve issues like poor heart function, being born very prematurely or at low birth weight, having certain genetic disorders, unusually severe bleeding inside the brain, or other serious health issues not related to the heart.
Before going ahead with the surgery, it’s important for families to understand that the Norwood procedure is high risk, and it’s only the first step in a longer process that may lead to a heart transplant in the future. This means they’ll need to provide dedicated, ongoing care and be ready for their child to have more surgeries and treatments down the line. Some families choose to focus on making their child comfortable rather than opting for surgery. If a diagnosis of HLHS, which means the left side of the heart is underdeveloped, is made before the baby is born, families can take the time to understand what this means and think through their options.
There are other options available for newborns with HLHS. One of them is a hybrid stage 1 palliative procedure, which includes making a small hole in the wall between the two upper chambers of the heart (atrial septostomy), keeping a blood vessel called the ductus arteriosus open (patent ductus arteriosus stenting), and limiting blood flow to the lungs (bilateral pulmonary artery band placement). Other options could involve a heart transplant shortly after birth or focusing on care that makes the child comfortable. Trying to treat HLHS before the baby is born is being explored but it’s still experimental. It is important to understand that despite these alternatives, the risk of a newborn with HLHS dying within the first week can be high, although this is rare.
Equipment used for Norwood Procedure
The Norwood procedure is a type of heart surgery meant to deal with congenital, or birth defects, in a baby’s heart. It’s essential that this surgery is done in a specialized workspace which is equipped for dealing with early-age heart conditions. In this space, there are tools along with able-bodied staff who are skilled in dealing with newborns having heart issues.
The machinery and equipment needed to perform the Norwood surgery go beyond the average, including:
- A cardiopulmonary bypass pump, which is a machine that takes over the work of circulating and oxygenating the blood in the body. The circuit and cannulas (small tubes used for administering or drawing fluids) used need to be suited for the patient’s age.
- A cardioplegia solution, which is a special fluid used to protect the heart during surgery.
- An echocardiography machine that includes two types of probes, transesophageal and epicardial. This machine uses sound waves to make images of the heart to guide the surgeon during the procedure.
- Clean drapes, gowns, and other supplies to maintain a sterile environment.
- Surgical instruments, like a sternotomy saw for cutting through the chest bone, knives, clamps, and fine stitch material called sutures.
- Conduit material, which is used to create the planned shunt, or passage, needed in the surgery.
- Patch material to fix the aorta, the main blood vessel branching off the heart.
Who is needed to perform Norwood Procedure?
The Norwood procedure, a type of heart surgery, involves a team of specialized medical professionals. This team often includes a heart surgeon who specifically treats birth defects, a pediatric cardiac anesthesiologist who makes sure children are safely put to sleep for the surgery, a surgical assistant, nurses or surgical technicians who assist in the operating room, a pediatric perfusionist whose job is to monitor and manage the heart-lung machine during surgery, and a pediatric cardiologist who may also use an echocardiography machine to take pictures of the heart.
After the surgery, the patient is transferred to a specific intensive care unit (ICU) where pediatric specialists and nurses are experienced in caring for newborns with a special type of heart condition where only one chamber of the heart is fully functional. These professionals understand the unique care these patients need and help them recover and grow stronger after their surgery.
Preparing for Norwood Procedure
Before a Norwood procedure (a type of heart surgery), your doctor will examine all your important test results, especially those from a transthoracic echocardiogram – which is like an ultrasound for your heart. They will pay close attention to various parts of your heart like the ascending aorta (the large blood vessel that carries blood from your heart to the rest of your body), the performance of your heart chambers, how your heart valves are functioning, and the structure of your aortic arch (the curve of the main artery) and isthmus (a narrow passage connecting two larger areas).
Your doctor will also need to ensure there is a balance in blood flow between your body (systemic circulation or Qs) and your lungs (pulmonary circulation or Qp). Ideally, these two blood flows should be equal, and the level of oxygen in your blood should be between 75% to 85%. Limiting extra oxygen and support for breathing is important – too much blood in the lungs can decrease the overall blood flow from your heart. To maintain an open path for blood, an infusion of a medication called Prostaglandin E1 is usually given.
How is Norwood Procedure performed
The Norwood procedure is a heart operation aiming to ensure a good mix of blood in the heart’s chambers, make sure blood flows well through the main artery (the aorta), supply a steady stream of blood to the lungs, avoid flooding the lungs with too much blood, and keep the blood vessels of the lungs healthy. This operation involves creating a shunt or passageway to establish blood flow to the lungs. Two main options for this shunt are the mBTT shunt and the Sano shunt.
Before this surgery begins, babies are given medication to make them sleep during the procedure. The doctors closely watch the baby’s health by monitoring their blood pressure and oxygen levels in their brain. The best way to access the veins varies from hospital to hospital. Because babies are small, it sometimes isn’t possible to use typical heart ultrasound imaging through the esophagus; in this case, it becomes necessary to plan to use this ultrasound technique via the surface of the heart once the heart-lung machine is started up. The usual point of entry for this surgery on babies in need of heart-lung bypass is through a sternotomy which means a cut made in the sternum which is the long flat bone in the center of the chest.
Different hospitals use different techniques to protect the baby’s brain during surgery- some prefer a method called antegrade cerebral perfusion or deep hypothermic circulatory arrest (DHCA) when the surgery involves the aorta.
Once the protective covering of the heart, the pericardium, is opened, a common way to insert the cannulas, which are thin tubes to carry the blood to and from the heart-lung machine, is via the right atrium vein and artery in a right subclavian (under the collarbone). The baby is then cooled to 18 degrees Celsius to prepare for the DHCA. After this, the doctors close-off a large open vessel that usually closes after birth (the patent ductus arteriosus). The doctors then stop the heart and perform an atrial septectomy which is a procedure to create a hole in the wall between the two upper chambers of the heart, under DHCA.
The aorta is then reconstructed with a patch while the blood flow to the brain is maintained but at a low rate via the graft on the right subclavian artery. Following this, the doctors join the upper aorta and the main pulmonary artery together in a procedure known as a Damus-Kaye-Stansel procedure. After this, normal blood flow is resumed after the heart is warmed again. The final step connects the graft to the lung’ artery to complete the mBTT shunt.
If the Sano shunt is used, a small cut is made in the right lower chamber of the heart, and the “Sano” tube is attached at the base and other end attached to the lung artery at where it splits into two. After the surgery, lines for monitoring, chest drainage tubes, and temporary pacing wires for heart rate control are inserted. Some centers may leave the chest open, with plans for delayed closing.
The choice of shunt varies. A clinical trial called SVR compared both shunts in over 500 patients and found that patients with Sano shunt had a better survival rate without needing a heart transplant. However, they also had more unplanned procedures and complications. Overall the survival rate remained similar for both groups after 1, 3, 6, and 12 years follow-up.
Possible Complications of Norwood Procedure
Patients with a heart condition called single ventricle physiology need specialized care after surgery, ideally from medical centers with experience in this area. There has been a rise in surgical interventions like the Norwood procedure for newborns with this heart condition. However, the reduction in overall death rates has been small, falling from 25% in 1998 to 21% in 2005.
The most dangerous time for these patients is the two days after the Norwood procedure. There is a risk of developing a major complication, such as bleeding, irregular heart rhythms, weak heartbeat, leaky heart valves, twisted blood vessels in the lungs, poor heart function, seizures, stroke, blood clot in the shunt (tubing used during the surgery), voice box dysfunction, infection, heart stopping, or death.
The biggest risks factors for dying after the Norwood procedure include being born early or with low birth weight, having genetic syndromes, and other physical anomalies. These can also result in longer stays on a breathing machine and in the hospital. Even though these patients have similar rates of needing ECMO (a machine to pump and oxygenate blood) and reoperation, they show higher rates of dying in the hospital.
Complications after the Norwood procedure have been tallied over the long term, at one, three, and six years after surgery. Interestingly, heart function and problems didn’t vary much between different types of shunts used during surgery. After the 6 year mark, an estimated 20% of patients may experience a blood clot, 15% may have seizures, and 7% may have a stroke. Irregular heart rhythms were also common, regardless of shunt type.
For newborns who can’t undergo the second surgery after the Norwood procedure, risks include weakened heart function and leaky heart valves. Other risk factors found in a previous study included being born early, longer periods on bypass during the surgery, and needing ECMO, which may either lead to death or a heart transplant. Certain anatomical subtypes may also increase risk after the Norwood procedure.
For patients with a single ventricle undergoing sequenced operations to repair the heart, the biggest risk of death is after the first stage: the Norwood procedure. The death rates are notably higher after the Norwood procedure compared to the following surgeries. Interestingly, up to 15% of newborns can die after being discharged from the Norwood procedure and while waiting for their second stage operation.
What Else Should I Know About Norwood Procedure?
The Norwood procedure is a type of surgery used to treat infants born with a condition where they only have one working ventricle in their heart, which is known as single ventricle heart disease. Despite it being a common strategy to improve these infants’ conditions in stages, about 15% of infants sadly still pass away after undergoing this surgery, no matter what type of shunt (tube that helps direct the flow of blood) is used.
The risk of death between all three stages of the treatment tends to be highest following this first stage — the Norwood procedure. However, the situation used to be much worse; before Dr. Norwood developed his innovative method, nearly all newborn infants with a heart condition called Hypoplastic Left Heart Syndrome (HLHS) faced almost certain death.
Thanks to Dr. Norwood’s pioneering work, there has been a monumental shift in how we approach treatment for newborns with severe heart disease. This shift has allowed for palliative surgeries (surgeries aimed at relieving symptoms rather than curing the disease) to be carried out on thousands of newborns, allowing many of them to survive into their teenage years and adulthood. Many of these patients eventually receive a heart transplant.
