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Fontan Procedure

Usually, the heart has two lower chambers called ventricles. The right ventricle pumps blood to the lungs, and the left ventricle pumps blood to the body. One chamber has to do all the work in children with single ventricle heart conditions. This can overwork the heart and make it hard for the body to get enough oxygen.

The Fontan procedure is the last of three surgeries that help blood flow directly to the lungs without going through the heart. This separates oxygen-poor (blue blood) blood from oxygen-rich (red blood) blood, so the body gets more oxygen and the heart does not have to work as hard.

In a normal heart, each ventricle has its own job. The right ventricle pumps oxygen-poor blood (blue blood) from the heart to the lungs. The left ventricle pumps oxygen-rich blood (red blood) to the body. In children with single ventricle heart defects, one ventricle must pump blood to both the lungs and the body. This means red and blue blood mix in the heart, causing a lower level of oxygen in the body.

After the Fontan procedure, blood from the lower body flows to the lungs instead of to the heart. The heart then pumps only oxygen-rich blood to the body, separating the blue (oxygen-poor) and red (oxygen-rich) blood. This improves oxygen levels and helps the body function more normally.

Types of Fontan Procedures

Two main types of Fontan procedures are used:

1. Extracardiac conduit. In this approach, a Gore-Tex tube is placed outside the heart to direct blood flow from the lower part of the body to the lungs. This type of procedure doesn't involve working directly on the heart, so there is a lower chance of problems. It is often chosen because it's simpler and has a lower risk of causing arrhythmias, or abnormal heart rhythms.
2. Lateral tunnel. In this approach, doctors create a tunnel inside the heart to reroute blood from the lower body to the lungs. While it changes the heart, this method lets the tunnel grow with the child. That makes it a better choice for some kids. But it may have a slightly higher risk of arrhythmias than the extracardiac conduit.

Doctors will choose the best approach based on your baby's heart and function, the surgeon's experience and the specific needs of the heart condition.

What Conditions Are Treated by a Fontan Procedure?

Fontan procedure can treat many types of single ventricle defects. Single ventricle defects are rare. They occur in about 5 out of every 100,000 births. Before the Fontan procedure, most children with single ventricle defects would not survive.

The Fontan surgery is a procedure used to treat single ventricle heart disease. Single ventricle heart disease refers to a group of congenital (present at birth) heart defects where only one of the heart’s two ventricles, or pumping chambers, works properly. A few examples of these heart defects are:

Hypoplastic left heart syndrome (HLHS): HLHS is a type of heart defect where the left side of the heart doesn't develop properly, and the left ventricle is too small. The mitral and aortic valves on the left side of the heart may also be small, or not develop at all (called atresia). Because of this, the heart has trouble pumping oxygen-rich blood to the body. HLHS is life-threatening shortly after birth, since the body doesn't get enough oxygen or blood flow. Babies with this syndrome cannot survive without heart surgery.

Tricuspid atresia: The tricuspid valve in the heart controls blood flow between the right atrium (upper chamber) and the right ventricle (lower chamber). It opens to let blood flow from the upper chamber to the lower chamber. Then it closes to prevent blood from flowing backward. If the tricuspid valve doesn't develop properly, it can cause problems with how the heart pumps blood. In this condition, the right ventricle is usually too small to be functional. There is no way to restore the function of the tricuspid valve.

Pulmonary atresia: In pulmonary atresia, the valve that controls blood flow from the heart to the lungs doesn't form properly. This stops blood from reaching the lungs to get oxygen. Not all cases of pulmonary atresia require the Fontan surgery to thrive. However, in more severe cases, the right ventricle is too small. The Fontan procedure can be the only option for these patients.

Double inlet left ventricle (DILV): DILV is a condition where the right ventricle usually doesn’t form correctly. This is because the tricuspid and mitral valves enter the left ventricle (as opposed to one going to each pumping chamber). Children with this condition usually need a Fontan procedure.

What Happens Before a Fontan Procedure?

The Fontan procedure is the third step in a series of surgeries. Each surgery is considered a stage. Each stage changes your baby's blood flow so the body can get more oxygen. These stages help lower the stress on the heart.

Stage 1

The first surgery, or stage, is done when the baby is a newborn, usually in the first week of its life.

In some cases, the first surgery may be the Norwood procedure, which is used to treat children with HLHS. The Norwood procedure helps reroute the blood flow to make sure the baby’s body gets enough oxygen until the next stage of treatment.

For other types of single ventricle heart disease, doctors may perform a shunt surgery or pulmonary artery banding.

In a shunt surgery, a small tube called a shunt is placed to increase blood flow to the lungs. It's a temporary fix to help the baby survive until it's old enough for more surgeries.

Pulmonary artery banding is a procedure where a band is placed around the artery that carries blood from the heart to the lungs. This helps prevent too much blood from flooding the lungs, which could cause other problems.

New research is making the first stage of the Fontan procedure less invasive. This non-surgical approach uses thin instruments, called catheters, to guide tools through blood vessels to access the heart. These new methods use stents, balloons, or flow-restricting devices, and could reduce recovery time and lower the risks of open-heart surgery. These new options offer hope for a less invasive way to help children with single ventricle heart conditions.

Stage 2—Glenn Procedure

The Glenn procedure replaces the temporary shunt that was placed in stage one. This surgery is typically done when the baby is between 4 and 6 months old. It is a key step toward the final Fontan procedure, which will fully separate the oxygen-rich and oxygen-poor blood.

During stage two, doctors connect the superior vena cava, a large vein that transports blood from the upper body, directly to the lungs. This bypasses the heart and reduces the work it has to do each heartbeat to a more normal level. It allows oxygen-poor blood from the upper body to flow straight to the lungs, where it can pick up oxygen.

Preparing for the Fontan Procedure

Before the Fontan procedure, doctors will carefully evaluate your child's health to ensure they are ready for surgery.

One of the most critical aspects of preparation is monitoring your child’s growth and nutrition. Babies with heart conditions often have higher calorie needs because their heart works harder, and they may struggle to gain weight. Your doctor may recommend adding extra calories to formula or breast milk to help meet these increased nutritional needs. Making sure your baby is growing and gaining weight is essential for a successful surgery and recovery.

This preparation also includes several tests, which may include:

• Echocardiogram. This ultrasound of the heart allows doctors to see how well the heart is working. It helps check the heart's structure and function and how blood flows through it.
• Cardiac MRI or CT scan. These scans give doctors a detailed picture of the heart and blood vessels to help plan the surgery.
• Electrocardiogram (ECG). An ECG measures the electrical activity of the heart and helps find any irregular heart rhythms.
• Blood tests. These are done to check overall health, including kidney and liver function, and to ensure the body is ready for surgery.
• Oxygen levels (pulse oximetry). A small sensor is placed on the skin to measure how much oxygen is in the blood.
• Heart catheterization (sometimes needed). Doctors use a catheter (a thin tube) to get a closer look at the heart's blood flow and pressure. This involves putting the tube into a blood vessel and guiding it to the heart to take measurements.

During this time, your child's doctors also will talk with you about any medications your child may need to take before the surgery.

What Happens During a Fontan Procedure?

The Fontan procedure is typically done when the child is around 3 years old. During the surgery, doctors take the large vein that carries blue blood from the lower body (called the inferior vena cava) and reroute it directly to the lungs, bypassing the heart. This can be done by using a small tube (conduit) outside the heart or creating a tunnel inside the heart. This new Fontan circulation now allows all of the body’s blue blood to go straight to the lungs to pick up oxygen. This makes it easier for the heart to pump red blood to the rest of the body.