Some people are born with a heart that has only one pumping part that does the job of both pumps, and therefore works harder than where there are two separate pumps. This is known as a univentricular heart, meaning “one ventricle” heart. When there is only one pumping part to the heart, blood that is oxygen-rich mixes with oxygen-poor blood, causing the patient to have cyanosis (“bluish” appearance of skin, nails and tongue). The pump also has to enlarge as it tries to pump blood both into the body and into the lungs. This enlargement is called volume load.

The operation is designed to help the univentricular heart (one pumping chamber heart) work better and to take away cyanosis (bluish appearance).

Originally, the Fontan operation had the following parts:

• All holes in the atrial chambers were closed—so no mixing of oxygen-poor and oxygen-rich blood could occur.
• The heart valve between the right-side atrium and the right ventricle was closed.
• Next, the surgeon stitched the right sided atrium to the lung arteries (pulmonary arteries). This made a pathway for blood to go from the right atrium to the lungs without first going into the right ventricle.

In the modern era, the Fontan operation has two parts:

1. The SVC (vein draining oxygen-poor blood from the upper half of the body) is connected to the lung artery directly. This operation is known as a Glenn operation.
2. The IVC (vein draining oxygen-poor blood from the lower half of the body) is stitched (connected) onto a tube that is placed outside of the heart. The top end of this tube is then stitched to the lung artery.

When these two parts of the operation are completed, the patient now has a completed Fontan.

The surgical success rate is now more than 98%. Once the child has pulled through the early period after the Fontan operation, most children will continue to do well.

With the newer kind of Fontan operation (extracardiac Fontan), we now see that more than 97% of children are still alive 10 years after having the Fontan operation.

At 30 years after the Fontan operation, almost 80% of those who survived the Fontan operation are still alive.

We have discovered that more than half of Fontan patients will have some degree of organ damage within 10 years of having the Fontan.

Liver
The most common organ that is affected by the Fontan operation is the liver. Most patients will show signs that the liver is under strain, also called congestion. Over time, these early changes—which are not harmful—may change into more concerning degrees of liver damage. In patients with severe liver disease, it is important to have regular follow-up with a congenital heart disease expert and also a liver expert.

Kidneys
As many as 40% of patients will have a mild degree of kidney damage as a result of their Fontan. Usually this mild form of kidney damage does not need specific treatment, apart from making sure that the damage does not become worse over time. When the Fontan does not function very well, the kidney damage may become more important and need specific treatment.

Lungs
The lungs are also affected in patients with a Fontan. The muscles that sit around the chest cage are often weakened in Fontan patients, and sometimes the diaphragm may also be weakened. The size of the working parts of the lungs is often smaller than in people with a normal heart. This is called restrictive lung disease.

Small and Large Bowels
The bowels may also be affected in roughly one in 10 Fontan patients. The Fontan, as with the liver, puts pressure back on the bowels, causes irritation of the bowel lining, and in some people causes the bowel to leak proteins into the bowel. This is called protein losing enteropathy (also known as PLE).

You have a higher chance of having a stroke and other blood clots because you have a Fontan. Medical studies have shown that the chances of having a stroke in Fontan patients are usually quite small but are still higher than if you did not have a Fontan.

When you have a Fontan, your blood may be stickier than normal, making it easier to develop a blood clot (which may cause a stroke or mini-stroke). When you have an arrhythmia, an older-style Fontan operation, and/or you have had previous clots, it is especially important to take special precautions over and above those usually followed when you have a Fontan.

Please ask your CHD cardiologist about your specific risks, as this is different in every patient with a Fontan.

Most people with a Fontan will need medications of some sort, so talk to your cardiologist or pharmacist about your needs. The kind of medications that are often used tend to take the strain off the heart by lowering and controlling heart rate and blood pressure (beta blockers and ACE inhibitors). These medications can also prevent stiffening of the heart muscle and blood vessels over time. Diuretic medications such as furosemide and spironolactone are used to control extra fluid accumulation, and therefore prevent swelling of the legs and other parts of the body. Blood-thinning medications such as aspirin or warfarin are most often used, and they are used to prevent life-threatening blood clots. In patients with protein losing enteropathy (this is when protein leaks out into the bowels), medications like sildenafil or steroid medications may be used to improve your condition.

Some people who have had a Fontan will need surgery again as they get older. The surgery may be needed for many reasons to remove blockages of the veins or to help your heart work best. Unfortunately, even after the best medications and surgery, some patients will experience symptoms due to ongoing abnormal vein or heart function. In this case, your cardiology team may discuss the possibility of heart transplantation.

The team usually begins to consider heart transplantation when your heart problem cannot be treated well by surgery but before your other organs show significant damage. If you are referred for consideration for a heart transplant, the heart transplant team will provide you with a comprehensive evaluation of your heart and other organs. At this evaluation, you will receive information about the risks and potential benefits of heart transplantation and be encouraged to ask questions about the procedure. After the evaluation, you, your cardiologist and the heart transplant team will decide if listing for heart transplant is appropriate for you.