What is it?
First performed in 1971 by Frances Fontan and Eugene Baudet, the Fontan procedure is a surgical procedure performed for single ventricle physiology. Patients with single ventricle physiology have hearts with only one effective pumping chamber that delivers blood to both the body and the lungs. Because there is only one ventricle instead of two, blood without oxygen mixes with oxygenated blood in this single chamber, so the oxygen content of the blood going to the body is considerably lower than normal. Uncorrected, this leads to long term cyanosis (or blueness), and associated issues such as exercise intolerance, elevated blood pressures in the lungs, abnormally high red blood cell counts and bleeding disorders, to name a few. The Fontan operation allows for separation of the two circulations by re-routing under-oxygenated blood from the body directly to the blood vessels that lead to the lungs, thereby allowing the single ventricle to pump only oxygenated blood to the body. This creates a more normal circulation, and reduces the complications described above.
The first Fontan operations involved directly connecting the right atrium (the heart chamber that receives all of the blood without oxygen back from the body) to the pulmonary artery (the vessel that directs blood flow to the lungs). This was called a right atrium to pulmonary artery Fontan (or a Classic Fontan). Over the years, modifications of the operation have developed in order to exclude the right atrium from the circuit, since it was found that over time this chamber became very stretched out and enlarged, leading to problems with abnormal heart rhythms and blood clots. The two types of Fontan operations done today are the lateral tunnel Fontan and the extracardiac Fontan, and are usually performed at around 4 years of age. The Glenn shunt may precedes this, and is usually done at around 6-12 months. Many patients with the "classic" type of Fontan operation have undergone conversion to either the lateral tunnel or (more commonly) the extracardiac Fontan in order to decrease the complications associated with the older operation.
How is the Fontan circulation different from normal circulation?
Normally, the heart has two lower pumping chambers, the right ventricle and the left ventricle. The right ventricle receives blood depleted of oxygen back from the body, and pumps this blood to the lungs to collect more oxygen. The left ventricle receives blood rich with oxygen and pumps this out to the body to be used by the tissues and organs. In the Fontan circulation, no pumping chamber to the lungs exists. The blood flows passively to the lungs, aided by the pressure changes caused by normal breathing and the development of higher pressures in the veins leading to the Fontan connection. The Fontan connection consists of either a tube inside the right atrium (lateral tunnel) or a tube outside of the right atrium (extracardiac) that connects the large veins from the lower body and upper body directly to the pulmonary arteries (leading blood to the lungs).
Are there any long term consequences related to having higher pressure in the veins?
Yes, some of these can include varicose veins in the lower legs, and congestion in the liver. The latter issue is followed very closely by adult congenital heart specialists, and if present, can often be helped by medications. In some cases, long-term congestion of the veins in the liver can lead to liver damage, so this is an important part of lifelong cardiac surveillance, and a major focus of current research into therapies to prevent these liver changes.
Are there any other complications or long term consequences of having a Fontan Operation?
Some patients can develop irregular heart rhythms, or arrhythmias, that may require treatment with medications. At times, a pacemaker is needed to help correct slow heart rhythms or to allow for medication treatment of faster heart rhythms. Patients can have trouble with fluid retention in the lower legs or, more commonly, the abdomen. In rare instances, arrhythmias and swelling can lead to a condition called PLE (protein losing enteropathy), a serious condition that may require hospitalization to treat. Finally, the single ventricle may over time experience a decrease in function, requiring medications and possibly heart transplantation.
Is exercise permitted with a Fontan?
Regular exercise is not only permitted, but encouraged. Most patients who have undergone a Fontan operation can engage in low to moderate levels of aerobic exercise such as walking, jogging, cycling, yoga, swimming and elliptical training without restriction. Light weight lifting is also acceptable, with focus on higher repetitions and lower weights. Heavy weight lifting and/or straining should be avoided, as should high level contact sports. As with all exercise, you should make sure to warm up and cool down appropriately, stay well hydrated and go at a pace that is comfortable for you. Listen to your body, and stop if you experience any symptoms that concern you such as extreme fatigue, abnormally high heart rates that don't slow down when you do, excessive breathlessness, or dizziness.
Can I have children if I've had a Fontan?
For both men and women with Fontan procedures (single ventricle physiology), there is a higher risk of passing congenital heart disease on to their biological offspring. The risk for this is estimated to be between 4-15%, and tends to be in the higher range if the parent with a single ventricle/Fontan is the mother.
Pregnancy in women who have undergone the Fontan operation is a complex topic and highly individualized. Many women with the Fontan operation have had safe and successful pregnancies and have delivered healthy babies. However the physical changes of pregnancy imposed upon the unique circulation and heart function of the Fontan patient makes any pregnancy, however uncomplicated, a high risk endeavor. Women wishing to start a family should discuss this topic with their adult congenital heart disease team long before they actually plan to get pregnant. In this way, tests can be performed that will help your doctor to determine if a pregnancy can safely be undertaken with minimal risks for complications such as heart arrhythmias and heart failure and minimal risks to the fetus related to medications, etc. Once pregnancy occurs, it is extremely important that you see your adult congenital heart disease (ACHD) team at least once per trimester and also that you are followed by an appropriately trained high risk obstetrician. It is also recommended that a fetal echocardiogram be obtained at 18-22 weeks of pregnancy, to screen for congenital heart disease in the baby, and this applies regardless of which parent has the Fontan (risk of genetic transmission to one's offspring is approximately 4-15% above the general population).
Contraception is also an important topic to discuss with your ACHD team. Some patients should avoid certain types of oral contraceptives, particularly those containing estrogen. Many forms of non-estrogen containing birth control methods exist, and can be discussed in coordination with your gynecologist. Procedures such as sterilization, hysterectomy or uterine ablation need to be coordinated with your gynecologic and ACHD teams as well.
Unless it is an emergency, non-cardiac surgery in the patient with a prior Fontan procedure should be performed in a regional center specializing in congenital cardiology, with experienced surgeons and cardiac anesthesiologists, and should be closely coordinated with the patient's ACHD team.
Additional things to know
Patients who have undergone the Fontan operation require lifelong care at a specialized Adult Congenital Heart Disease facility. It is very important that you work with your team to learn the details of your heart condition and prior operations, understand the medications you may be taking, and carry information about your heart condition with you at all times, either in the form of the Adult Congenital Heart Association Health Passport, paper records, or PDF files stored on a small flash drive. This will better enable outside medical personnel to treat you appropriately and connect with your primary team should you find yourself with a medical issue while in unfamiliar surroundings.