Melissa Lyle, MD: Hello, everyone. I am Melissa Lyle, cardiology fellow at Mayo Clinic. Today, we will be discussing the management of Fontan patients. I am joined by my colleagues, Dr Alexander Egbe and Dr Sameh Said, who both specialize in this area. Welcome.
Alexander Egbe, MBBS: Thank you.
Sameh Said, MD: Thank you.
Historical Overview of the Fontan Operation
Dr Lyle: Can you give us a brief overview of the Fontan operation?
Dr Said: The Fontan operation was initially designed by Francis Fontan in 1968, and the first publication in 1971 addressed patients who had a single ventricle, whether an anatomical or functional single ventricle. In these patients, pulmonary and systemic circulation run in parallel, [causing the] mixing of arterial and venous blood. That is why their oxygen levels are not normal. The goal of the operation was to separate the circulations completely and achieve adequate tissue oxygenation.
The operation was initially indicated for patients with tricuspid atresia as an example of a single ventricle. However, over the years, the design of the operation and the indication has extended to other examples of single ventricle, like hypoplastic left heart syndrome. The Fontan that was originally described by Francis Fontan connected the right atrium to the pulmonary artery [via] a valved conduit, but this has changed over time because we realized—through lab experiences and follow-up of these patients—that the atrium failed over the years.
The current Fontan design connects the superior and inferior vena cava return directly to the pulmonary artery using an extracardiac conduit with no valves. That is what we call an extracardiac conduit Fontan.
In [an interim era], a conduit was used intra-atrially—for example, a lateral tunnel Fontan. Although this evolved to no longer use any valves in the circulation because they are proven to fail over time, it is still being done in some centers.
Life Expectancy and Fontan-Associated Diseases
Dr Lyle: How many adults currently have a Fontan palliation, and what is the life expectancy in this population?
Dr Egbe: We do not know the number of adults who have Fontan palliation in the United States. A recent study on the prevalence of congenital heart disease estimated about 10,000 to 20,000 US adults currently have Fontan palliation, but this is a very crude estimate.
Life expectancy has improved dramatically in the past 40 years. Data from the Mayo Clinic showed that only about 50% of the initial cohort that had this operation in the 1970s and '80s survived into adulthood. In contrast, recent data from Australia and New Zealand show that nearly 90% of patients undergoing this operation in the current era survive into adulthood. Although survival has improved, the average life expectancy in this population is still low: about 35 to 40 years in contrast to 70 to 80 years in the general population. Patients die young because they are faced with many medical comorbidities, which we commonly refer to as Fontan-associated diseases.
Dr Lyle: You mentioned that lower life expectancy is due to Fontan-associated diseases. What are the two most common Fontan-associated diseases that you encounter?
Dr Egbe: We have been involved in in-depth research on clinical outcomes after a Fontan operation. Data from our center—which is consistent with data from other centers—show that the two most common Fontan-associated diseases are arrhythmia and liver disease.[4,5] Arrhythmia is present in about half of all Fontan patients who are currently being seen in the adult clinic, and the risk is much higher for those with the old-style Fontan known as the atrial pulmonary Fontan. There are surgical [methods] to address this problem, which [Dr Said] will discuss. The next problem is liver disease: about one-fourth of all patients have cirrhosis. This is due to chronic venous congestion, which is inherent in the Fontan hemodynamics.
Dr Said: To echo Dr Egbe, arrhythmia is very common in Fontan patients partly because of the different designs of the Fontan circuit that have been done over the years. Data from our institution and other centers showed that the use of extracardiac conduit and avoiding incisions in the atrium and suture lines in the atrium definitely decreases the risk of arrhythmia.
By 2011, we converted about 70 individuals from an older design Fontan into an extracardiac conduit. The patients had an atrial pulmonary Fontan or other forms of older Fontan. Initially, it was thought that some sort of a pump was needed in the Fontan circuit; it was thought that the atrium would function as this pump. However, over the years, this did not prove to be correct, because the atrium would dilate over time, [causing] energy loss in the circuit [and, in turn,] the arrhythmia. One of the main indications for conversion is to do the arrhythmia surgery, which involves a series of ablation lines in the atrium, reducing the size of the atrium, moving that conduit to the outside the heart in the form of an extracardiac conduit, and implanting an epicardial pacemaker. These are three or four components of the current concept of what we call a Fontan conversion. Again, the risk of arrhythmia is becoming lower with the current use of the extracardiac Fontan.
Improving Survival and Well-being in Fontan Patients
Dr Lyle: What are the most important issues moving forward that could improve survival and well-being in the Fontan population?
Dr Said: Patient selection is very important, because sometimes we have pushed the limits and the indication for the Fontan too far. The original criteria by Fontan and Choussat, what we call the "10 Commandments," are based on the age of the patient, the normal anatomy, the competent AV valve, lower pulmonary artery pressure, etc. This has changed a lot, partly because of improved techniques and perioperative care, but also the indication. The Fontan was not designed for other indications of single ventricle. It was mainly for tricuspid atresia and was extended over time to other morphology.
We still have to be strict, because we forget that the Fontan operation is not a curative operation. There are a lot of data about patients who can survive for a longer period of time with other forms of palliation. We have to understand not everybody has to have the Fontan operation, and some patients are not Fontan candidates. We can try to make them Fontan candidates by repairing or replacing a valve or some other intermediate stage, but it is at the expense of having worse long-term outcomes.
Patient selection is important and, like Dr Egbe said, early detection of these Fontan-associated problems before they occur is also key because data show that patients' who develop cirrhosis have poor long-term outcomes. One-year survival is less than 50%, which is very bad in this group. Better selection and early detection of problems [will help improve] outcomes.
Dr Egbe: From a medical standpoint, it is important to provide optimal care for these patients, ideally using a multidisciplinary team approach. In this model of care, the congenital cardiologist is no longer the sole provider but is instead a coordinator of care, integrating expertise from cardiovascular surgery, electrophysiology, imaging, and hepatology. [Collectively,] these specialties will help provide holistic care for the patient.
The other important [issue to address is] being able to identify very early the patients who have failing Fontan physiology. Patients with Fontan failure due to a target lesion, like arrhythmia, thromboembolism, or Fontan obstruction should be referred for adequate medical or surgical therapy. Patients who have Fontan failure without any target lesion should be referred early for organ transplantation.
Dr Said: The future carries a lot of [advances], and we have already seen some of them, like stem-cell therapy in single ventricles and the use of mechanical circulatory support. Animal experiments have already [aided in the] development of a pump-assist to the Fontan circulation. Even using different materials to do the operation or computational flow models to try to understand which design is better for the patient and the position of the conduit. There is still a lot of work in progress that will probably change the outcomes.
Dr Lyle: Thank you, Dr Said, Dr Egbe for these very important insights and thank you all for joining us on theheart.org on Medscape Cardiology.
Cite this: Hope and Hazards for Patients After Fontan Procedure - Medscape - Oct 20, 2017.