The Fontan procedure is a specialized heart surgery that transforms how blood flows through the body in children born with only one working heart pumping chamber. This surgical approach has revolutionized care for babies who would not have survived past early childhood just a few decades ago, allowing many to grow into adulthood with active lives.

How Surgery Helps When Only One Heart Chamber Works

In a normally developing heart, two lower chambers called ventricles work together as separate pumps. The right ventricle sends oxygen-poor blood to the lungs to pick up oxygen, while the left ventricle pumps oxygen-rich blood throughout the body. However, some babies are born with congenital heart defects where only one ventricle develops properly or one of the main heart valves does not form correctly. This means one ventricle must do double duty—pumping blood both to the lungs and to the rest of the body.^[1]

This arrangement causes several problems. When a single ventricle handles all the pumping work, oxygen-rich blood and oxygen-poor blood mix together inside the heart. As a result, the body receives blood that does not contain enough oxygen to support normal growth and development. Additionally, the ventricle that is working overtime becomes strained from the excessive workload, which can lead to heart muscle weakness over time.^[2]

The goal of the Fontan procedure is to improve blood flow so that the body receives properly oxygenated blood while reducing the burden on the single working ventricle. After this surgery, oxygen-poor blood from the lower part of the body travels directly to the lungs without passing through the heart first. This means the single ventricle only needs to pump oxygen-rich blood to the body, no longer wasting effort on sending blood to the lungs. The separation of these two types of blood ensures the body receives the oxygen it needs for healthy function.^[4]

The Fontan procedure is not a cure for single ventricle heart defects. Rather, it is a palliative treatment, which means it helps manage symptoms and improve quality of life without completely fixing the underlying problem. Children who undergo this surgery will need specialized medical care for the rest of their lives.^[3]

Which Children Need This Surgery

The Fontan procedure is designed for children born with conditions called single ventricle heart defects, where only one of the heart’s two pumping chambers functions properly. These conditions occur in approximately 1 in 10,000 live births, making them relatively rare but serious heart problems.^[17]

Several different heart conditions may require the Fontan procedure. The most common is hypoplastic left heart syndrome, where the left side of the heart is severely underdeveloped. Other conditions include tricuspid atresia, where the valve between the right atrium and right ventricle is missing or not formed properly; pulmonary atresia, where the valve that controls blood flow from the heart to the lungs is blocked; and double inlet left ventricle, where both upper chambers of the heart connect to the same ventricle. Children with severe Ebstein’s anomaly, unbalanced atrioventricular canal defects, and heterotaxy syndrome (where internal organs are in abnormal positions) may also need this surgery.^[2]

Not every child with a single ventricle defect is a suitable candidate for the Fontan procedure. Healthcare providers must carefully evaluate whether a child meets specific requirements before proceeding. For instance, the working ventricle must be strong enough to pump blood effectively throughout the body. The lungs also need to be healthy enough to receive blood that flows passively, without the force of a pumping heart chamber behind it. Children whose heart or lung function is too weak may not benefit from this surgery.^[2]

Most children who undergo the Fontan procedure are between 2 and 5 years old, though the typical age range is 18 to 36 months. However, some children may have the surgery as early as before age 2 or as late as 15 years old, depending on their individual medical circumstances and how their earlier surgeries have performed.^[1][3]

The Staged Surgical Approach

The Fontan procedure is usually the third and final surgery in a series of operations performed during childhood. Because newborns and infants are very small and their bodies are still developing, surgeons cannot perform the complete Fontan reconstruction all at once. Instead, they use a staged approach, performing different procedures at different ages to gradually redirect blood flow in a way the child’s body can tolerate.^[5]

The first operation typically occurs within days of birth. This initial surgery, often called the Norwood procedure, ensures that the newborn has adequate blood flow to stay alive until the next stage. During this operation, the surgeon may combine the pulmonary artery and aorta to create a larger blood vessel for getting blood to the body. An artificial tube or shunt may be placed to allow blood to reach the lungs. Some surgeons also remove the wall between the left and right atrium to allow oxygenated and deoxygenated blood to mix in the upper chambers of the heart. Alternative first-stage procedures include the Blalock-Taussig-Thomas shunt, which directs blood from a major artery to a pulmonary artery, or a pulmonary artery band, which reduces the amount of blood flowing to the lungs while increasing flow to the body.^[2][5]

The second operation usually takes place when the baby is around 4 to 6 months old. This procedure, known as the Glenn procedure or hemi-Fontan, redirects oxygen-poor blood from the upper body directly to the lungs. The surgeon disconnects the superior vena cava, the large vein that carries blood returning from the head, arms, and upper chest, from the heart and connects it to the pulmonary artery instead. After this surgery, blood from the upper body flows directly to the lungs without passing through the heart first, while blood from the lower body still flows through the heart.^[2][5]

The Fontan procedure completes this staged reconstruction by redirecting blood from the lower body to the lungs as well. This final stage establishes what doctors call Fontan circulation, where all oxygen-poor blood bypasses the heart and goes straight to the lungs through passive blood flow rather than through active pumping.^[6]

What Happens During the Fontan Surgery

The Fontan procedure is an open-heart surgery, meaning the chest is opened and the heart is directly accessed during the operation. The surgery typically lasts several hours and requires the child to be placed on a heart-lung bypass machine, which temporarily takes over the work of the heart and lungs while the surgeon operates.^[1]

During the procedure, the surgeon disconnects the inferior vena cava—the large vein that brings oxygen-poor blood from the lower body—from the heart. Instead of allowing this blood to flow into the heart chambers, the surgeon redirects it to the pulmonary artery using a tube called a conduit. From the pulmonary artery, the blood flows into the lungs where it picks up oxygen. The newly oxygenated blood then returns to the heart, where the single working ventricle pumps it out to the body.^[1]

There are two main types of Fontan procedures based on how this redirection is accomplished. In the extracardiac conduit approach, a Gore-Tex tube is placed outside the heart to direct blood flow from the inferior vena cava to the lungs. This method does not involve working directly inside the heart, which reduces the risk of certain complications like abnormal heart rhythms. Because the conduit is placed outside the heart, this approach is often considered simpler and safer. However, the tube cannot grow as the child grows, which may require additional procedures later in life.^[4][7]

In the lateral tunnel technique, surgeons create a tunnel inside the heart itself to reroute blood from the lower body to the lungs. While this method involves more complex work within the heart, the tunnel can expand somewhat as the child grows, making it potentially more suitable for very young children. However, the lateral tunnel approach may carry a slightly higher risk of developing abnormal heart rhythms compared to the extracardiac conduit method.^[4][7]

Many surgeons create a small hole called a fenestration between the conduit and the right atrium during the Fontan procedure. This hole allows some blood to continue flowing back to the heart, acting as a pressure relief valve. The fenestration prevents too much blood from flowing to the lungs all at once, giving the lungs time to adjust to the new circulation pattern. This temporary hole can be closed later through a cardiac catheterization procedure, which is a less invasive technique that uses thin tubes inserted through blood vessels to reach the heart.^[1]

Recovery After Surgery

After the Fontan procedure, children typically spend 1 to 2 weeks in the hospital recovering. During this critical period, they receive round-the-clock monitoring and care from specialized medical teams. Healthcare providers watch closely for any complications and ensure the child’s heart and lungs are adjusting to the new blood flow pattern.^[1]

Children receive various medications after surgery to help the heart work more efficiently and improve blood flow. Some of these medicines help prevent blood clots, which can form more easily in Fontan circulation because blood moves more slowly through the system without being actively pumped. Other medications may help the heart muscle contract more effectively or prevent fluid buildup in the lungs and other tissues. Many of these medications will need to be continued at home, and some children may need to take certain medicines for the rest of their lives.^[1]

Before a child is ready to go home, the medical team teaches parents how to care for their child. This education includes how to give medications correctly, what symptoms to watch for that might indicate problems, and when to contact the doctor. Children are generally ready to go home when they are eating well, growing appropriately, and gaining weight at a healthy pace.^[1]

Following discharge from the hospital, children need regular follow-up appointments with a pediatric cardiologist, a doctor who specializes in children’s heart conditions. These visits typically occur frequently at first and then gradually become less frequent as the child’s condition stabilizes. During these appointments, the cardiologist performs various tests to monitor heart function, including electrocardiograms (EKG), which measure the heart’s electrical activity; echocardiograms, which use sound waves to create moving pictures of the heart; and blood tests to check for various indicators of health. Some children will need periodic cardiac catheterization procedures to assess how well the Fontan circulation is working and to make small adjustments if needed.^[1]

Most people who have had the Fontan procedure can expect to live 30 years or more after surgery, with many surviving well into adulthood. An estimated 50,000 to 80,000 people worldwide are currently living with Fontan circulation. Each year, approximately 1,000 Fontan procedures are performed in the United States alone.^[2]

Long-Term Management and Complications

The Fontan procedure significantly improves survival and quality of life for children with single ventricle heart defects, but it is important to understand that it is not a cure. People living with Fontan circulation face unique challenges throughout their lives because their hearts work differently from normal hearts. The single ventricle must pump blood to the entire body, and blood flows to the lungs passively without a pumping chamber to move it along. This unusual circulation pattern can lead to various complications over time.^[3]

One common issue is the development of abnormal heart rhythms, called arrhythmias. These may feel like skipped heartbeats or a racing heart. Arrhythmias occur because scar tissue from previous surgeries can interfere with the heart’s normal electrical signals. Some patients may require medications to control these rhythm problems, while others might need a pacemaker or implantable cardioverter defibrillator to help regulate the heartbeat.^[10]

Blood clots represent another significant concern for people with Fontan circulation. Because blood moves more slowly through the system, particularly in the connections between the veins and the pulmonary arteries, it has more time to clot. These clots can be dangerous if they break loose and travel to the lungs or other organs. Many Fontan patients take blood-thinning medications to reduce this risk.^[10]

The liver often experiences problems in Fontan patients because the circulation pattern causes increased pressure in the veins, including those that drain the liver. Over time, this elevated pressure can lead to liver congestion and potentially cirrhosis, a condition where healthy liver tissue is gradually replaced with scar tissue. Regular monitoring of liver function through blood tests and imaging studies helps doctors detect these changes early.^[10][13]

Some people with Fontan circulation develop a condition called protein-losing enteropathy, where the intestines lose protein into the digestive tract. This leads to low protein levels in the blood, which can cause swelling, fluid accumulation, and nutritional problems. Treatment may involve dietary changes and medications, though some cases can be difficult to manage.^[10]

Heart failure can occur if the single ventricle becomes weakened over time from the constant workload. Symptoms include fatigue, shortness of breath, decreased ability to exercise, and fluid retention. Medications can help manage these symptoms, but in severe cases, a heart transplant may be necessary.^[10]

Kidney function can also decline in Fontan patients due to reduced blood flow and changes in blood pressure. Regular blood tests help monitor kidney health, and doctors work to prevent further deterioration through careful management of medications and blood pressure control.^[13]

Living with Fontan Circulation

Many children with Fontan circulation thrive and live active, fulfilling lives, though they may need to make some adjustments compared to their peers. Understanding how to maintain health while living with this unique physiology is essential for long-term wellbeing.^[13]

Regular physical activity is strongly encouraged for people with Fontan circulation. Exercise helps strengthen both the heart muscle and the breathing muscles, which work together to move blood through the body in Fontan circulation. When these muscles are stronger, blood flows more efficiently throughout the system. While some individuals may need to exercise at their own pace and avoid certain very strenuous activities, most can participate in regular moderate exercise. The specific types and intensity of exercise should be discussed with a cardiologist who can provide guidance based on individual heart function.^[13][19]

Research has shown that adults with Fontan circulation who engage in regular physical activity report better quality of life and have improved health status compared to those who are less active. Starting regular exercise habits in childhood helps establish patterns that continue into adulthood, contributing to better long-term outcomes.^[19]

Dental health requires special attention in Fontan patients. Bacteria that normally live in the mouth can enter the bloodstream during dental procedures and potentially cause infections in the heart. Excellent dental hygiene—including regular brushing, flossing, and at least annual dental visits—is crucial. Some patients may need to take antibiotics before dental procedures to prevent infection, and this should be discussed with both the cardiologist and dentist.^[13]

For women with Fontan circulation, pregnancy planning is an important consideration. While pregnancy is possible for many women with Fontan circulation, it is considered higher risk and requires careful planning and monitoring. Some methods of birth control are safer than others for women with heart conditions. Generally, progesterone-only birth control methods are preferred because they carry a lower risk of blood clots compared to estrogen-containing methods. Women should discuss family planning with their cardiologist before attempting pregnancy, as some women with particularly weak heart function or other complications may be advised against pregnancy.^[13]

Patients with Fontan circulation should learn to recognize symptoms that might indicate complications. New or worsening fatigue, shortness of breath, swelling in the legs or abdomen, decreased exercise tolerance, or bluish discoloration of the lips or fingernails should prompt contact with the healthcare provider. Regular follow-up appointments, even when feeling well, are essential for detecting problems early before they become severe.^[13]

Specialized Fontan Clinics and Comprehensive Care

Because people with Fontan circulation can develop problems affecting multiple organ systems beyond the heart, many specialized medical centers have established dedicated Fontan clinics. These clinics provide a coordinated, multispecialty approach to care that addresses all aspects of health affected by Fontan circulation.^[8]

In a Fontan clinic, patients are seen by multiple specialists during a single visit rather than having to schedule separate appointments with different doctors at different times. The team typically includes pediatric or adult cardiologists who specialize in congenital heart disease, along with specialists in liver disease, kidney disease, lung disease, and other areas as needed. Social workers and behavioral health specialists may also be available to help with educational planning, including developing individualized education plans at school, and to provide emotional support for patients and families.^[8]

These comprehensive clinics emphasize regular screening and continuous monitoring to identify potential complications before they become severe. This proactive approach can lead to earlier intervention and better long-term outcomes. For example, routine liver imaging can detect early signs of liver disease that may not yet be causing symptoms, allowing doctors to implement strategies to slow progression.^[8]

Some Fontan clinics are involved in cutting-edge research to develop better treatments for complications. For instance, some centers are pioneering the use of remote monitoring devices that can track pressures in the Fontan circulation from home, potentially allowing earlier detection of problems without requiring frequent hospital visits. Other research focuses on new surgical techniques or medications that might improve outcomes for Fontan patients.^[8][12]

Most common treatment methods

• Staged surgical reconstruction
  • Norwood procedure or other first-stage operations performed within days of birth to ensure adequate blood flow until the next surgery
  • Glenn or hemi-Fontan procedure at 4 to 6 months of age to redirect blood from the upper body directly to the lungs
  • Fontan completion at 18 months to 5 years of age to complete the redirection of all oxygen-poor blood to the lungs
  • Two main types: extracardiac conduit (tube placed outside the heart) and lateral tunnel (pathway created inside the heart)
  • Fenestration (small hole) may be created during surgery and closed later through cardiac catheterization
• Medications for ongoing management
  • Blood-thinning medications to prevent blood clots in the slower-moving Fontan circulation
  • Heart medications to help the single ventricle pump more effectively and manage heart failure symptoms
  • Medications to control abnormal heart rhythms (arrhythmias)
  • Diuretics to reduce fluid buildup in the lungs and body tissues
• Cardiac procedures and interventions
  • Regular cardiac catheterization to assess how well the Fontan circulation is working and make minor adjustments
  • Closure of fenestration through catheterization after the lungs have adjusted to new blood flow
  • Pacemaker or implantable cardioverter defibrillator placement for severe heart rhythm problems
• Monitoring and diagnostic testing
  • Regular electrocardiograms (EKG) to check heart electrical activity and detect rhythm problems
  • Echocardiograms to visualize heart structure and function with ultrasound
  • Blood tests to monitor organ function, especially liver and kidney health
  • Imaging studies to assess liver health and detect early signs of cirrhosis
• Lifestyle modifications and supportive care
  • Regular moderate exercise programs to strengthen heart and breathing muscles
  • Excellent dental hygiene and preventive antibiotics before dental procedures to prevent heart infections
  • Specialized birth control counseling for women, with preference for progesterone-only methods
  • Nutritional support and dietary modifications for complications like protein-losing enteropathy
• Advanced interventions for complications
  • Thoracic duct decompression surgery for severe protein-losing enteropathy as an alternative to heart surgery
  • Heart transplantation for severe heart failure when the single ventricle becomes too weak
  • Combined heart-liver transplantation in some cases where both organs have failed
  • Remote monitoring devices to track Fontan circulation pressures from home in research settings