Overview of the management and prognosis of patients with Fontan circulation

INTRODUCTION — The Fontan operation is a palliative surgical procedure performed in patients with a functional or anatomic single ventricle (also known as univentricular heart) [1,2]. The Fontan operation was originally described for patients with tricuspid atresia in 1971 [3]. During the past 50 years, the types of malformations for which the Fontan operation is utilized has expanded considerably, and it has become the most common operation performed for patients with any type of single ventricle [4]. Following the Fontan procedure, patients face substantial morbidity and mortality risk and require lifelong follow-up with a cardiologist experienced in the care of patients with complex congenital heart disease (eg, pediatric cardiologist or adult congenital heart disease specialist).

This topic will discuss management of patients who have undergone a Fontan procedure. Lesions for which a Fontan may be performed are discussed in separate topic reviews. Complications in patients with Fontan circulation are discussed separately. (See "Management of complications in patients with Fontan circulation".)

BACKGROUND OF FONTAN PROCEDURE

Lesions treated and rationale — The Fontan procedure is typically performed in patients with anatomic or functional single ventricle, defined as presence of only one well-developed ventricle with the rudimentary ventricle (if present) less than 30 percent of its expected volume. Depending on the underlying anatomy, the predominant chamber could be either a left or right ventricle, both right and left ventricles, or in rare cases indeterminate. Lesions for which a Fontan may be performed include:

●Hypoplastic left heart syndrome. (See "Hypoplastic left heart syndrome: Anatomy, clinical features, and diagnosis".)

●Tricuspid atresia. (See "Tricuspid valve atresia".)

●Pulmonary atresia with intact ventricular septum. (See "Pulmonary atresia with intact ventricular septum (PA/IVS)".)

●Double-inlet left ventricle.

●Unbalanced atrioventricular canal defects. (See "Management and outcome of atrioventricular (AV) canal defects".)

●Rarely, a Fontan operation may be performed for patients with other conditions such as Ebstein anomaly, double-outlet right ventricle, congenitally corrected transposition of the great arteries, or other anatomic variants in which there is significant hypoplasia of either ventricle.

The single functional ventricle must supply blood to the higher resistance systemic circulation, as well as provide blood flow to the lower resistance pulmonary circulation in order to support long-term survival. This balance of the circulations occurs spontaneously only rarely, and surgical modification of the circulation is usually required.

The Fontan procedure, in its varied forms, effectively diverts systemic venous return to the lungs without a pump. Pulmonary blood flow is driven by central venous pressure and is augmented by changes in intrathoracic pressure, active relaxation of the systemic ventricle (drawing blood forward), and the peripheral skeletal muscle pump [5]. For this circulation to be effective, the patient must have a low pulmonary arteriolar resistance, relatively normal systolic and diastolic function of the single ventricle, and sufficiently large pulmonary arteries to minimize mechanical resistance [6,7].

The worldwide population of patients with Fontan circulation was estimated to be 50,000 to 70,000 patients as of 2018, with 40 percent of patients over 18 years of age [1,8]. In the United States, about 1000 Fontan operations are performed annually [9].

Criteria for Fontan procedure — Accepted contemporary criteria for the Fontan procedure are similar to the requirements for an "ideal Fontan candidate" originally specified by Dr. Fontan and colleagues [3], although some criteria such as age and pulmonary artery anatomy requirements have been liberalized; others, such as pulmonary vascular resistance, have become more stringent [10].

Common criteria for the Fontan procedure include the following:

●Age. The Fontan operation is currently typically performed in those between two and five years of age, with a weight of around 10 to 15 kg, depending on the specific clinical presentation, surgical history, and center preference. While some centers perform the Fontan procedure in those between two and three years of age in an attempt to limit the amount of time the patient is cyanosed, others wait until there is physiologic need (eg, decreasing oxygen saturations, symptoms), often between three and five years of age [11]. Although the Fontan operation in early childhood is preferred, it is also an option in carefully selected adults with functional single ventricle [12]. The current flexibility in age criteria contrasts with the original commandments, which specified ages 4 to 15 years [3].

●Sinus rhythm.

●Normal drainage of the venae cavae. While normal drainage of the venae cavae was one of the original commandments, modifications of the Fontan procedure have been published for use in patients with an interrupted inferior vena cava. The most popular of these is the Kawashima procedure [13]. In patients with bilateral superior vena cavae, bilateral Glenn anastomosis can also be performed.

●Normal right atrial volume.

●Low pulmonary artery pressure (<15 mmHg).

●Low pulmonary resistance (<4 Woods units/m²).

●Adequate pulmonary artery size (pulmonary-artery-to-aorta ratio >0.75).

●Normal ventricular function.

●No/minimal atrioventricular valve regurgitation.

●Normal pulmonary artery anatomy without distortion.

Technical surgical issues

Common surgeries prior to the Fontan procedure — When evaluating a patient who has had a Fontan procedure, a detailed surgical history is critically important, including a review of all past operative notes, as this enhances insight into the specific physiology of the individual Fontan patient. The unfenestrated Fontan procedure returns the patient to near normal oxygen saturations by fully separating the pulmonary and systemic circulations and aims to return the systemic ventricle to a near-normal workload. The vast majority of patients (particularly those having the Fontan procedure since 1990) will have had at least one prior palliative procedure. The following are surgeries that patients may have received prior to the Fontan procedure:

●Bidirectional cavopulmonary anastomosis (bidirectional Glenn connection (figure 1)). (See "Hypoplastic left heart syndrome: Management and outcome", section on 'Stage II: Cavopulmonary shunt'.)

●Systemic-pulmonary shunts (eg, Blalock-Thomas-Taussig shunt [also commonly called Blalock-Taussig shunt], central shunts [eg, Potts, Waterston, Mee]) (figure 2A-C).

●Atrial septectomy or septostomy.

●Norwood operation (performed for hypoplastic left heart syndrome and other patients with left ventricular hypoplasia) (figure 3). This includes staged reconstruction to allow unobstructed flow from the systemic right ventricle to aortic arch and coronary arteries; thus, the stages include aortic arch repair, relief of obstruction to pulmonary venous return (if present), and shunt placement from either right ventricle to pulmonary artery or a modified Blalock-Thomas-Taussig shunt. (See "Hypoplastic left heart syndrome: Management and outcome", section on 'Stage I procedures'.)

●Damus-Kaye-Stansel (DKS) procedure (generally performed at the time of cavopulmonary connection for variants of hypoplastic left heart syndrome and other forms of single-ventricle physiology with transposed great arteries and/or systemic outflow obstruction). The DKS procedure involves a direct connection of the ascending aorta and main pulmonary artery, with the intent of having both outflows directed to the systemic circulation, as a method for mitigating the risk of systemic ventricular outflow tract obstruction. A separate conduit or shunt is then placed to provide blood flow to the pulmonary circulation. (See "Hypoplastic left heart syndrome: Management and outcome", section on 'Surgical management'.)

●Starnes procedure (performed for severe Ebstein anomaly; the procedure includes patch closure of the tricuspid valve annulus, atrial septectomy, and placement of a systemic-pulmonary shunt). (See "Ebstein anomaly: Clinical manifestations and diagnosis".)

●Pulmonary arterial banding.

Surgical technique — The most prevalent forms of the Fontan procedure seen in pediatric and adult cardiology clinics are the atriopulmonary (or "classic") connection and cavopulmonary connection (figure 4). The atriopulmonary connection has been abandoned in favor of cavopulmonary connections that avoid progressive atrial dilation and associated complications such as arrhythmias and thrombus formation [1].

●In the atriopulmonary Fontan, the right atrial appendage is directly anastomosed to the main pulmonary artery, providing a pathway for blood from the inferior and superior venae cavae to get to the pulmonary circulation (figure 4). The atrial septum is left intact (or repaired), and there should be no shunting between the right (deoxygenated blood) and the left atrium (oxygenated blood).

●The cavopulmonary connection was first described by de Leval in 1988 and uses either an intraatrial conduit in the form of a lateral tunnel (incorporating part of the native right atrium in the pathway) or extracardiac conduit (figure 4) [14,15]; the latter was described by Marcelletti [16]. This completes the "total cavopulmonary connection" and can be done as the initial operation in combination with or after a bidirectional Glenn anastomosis.

•Since the year 2000, the majority of patients undergoing a Fontan procedure have had a nonvalved extracardiac conduit placed [1,4,11]; the surgical procedure and material used for the conduit vary among institutions. These extracardiac conduits typically vary in diameter (from 18 to 22 mm) and are placed in the pericardial space. This type of connection is generally preferred since it minimizes native atrial tissue in the Fontan pathway.

•An intraatrial conduit may still be used when pulmonary venous or other anomalies complicate the use of an extracardiac conduit.

Indications for reoperation (including conversion surgery and other types of reoperation) are discussed separately. (See "Management of complications in patients with Fontan circulation", section on 'Indications for reintervention'.)

Fenestration — In selected cases, a fenestration in the Fontan is either left or created, functioning as a small residual atrial septal defect. This allows a small right-to-left shunt to persist between the Fontan connection and the left atrium. Given the potential benefits and risks of fenestration, some centers have moved toward using fenestration only in "high-risk" patients [17-19]. This commonly includes patients with mildly elevated pulmonary pressure or vascular resistance, those with abnormal pulmonary artery anatomy, and patients with other risks for protein-losing enteropathy (PLE). The decision remains largely center specific. Management of patients with PLE is discussed separately. (See "Management of complications in patients with Fontan circulation", section on 'Protein-losing enteropathy'.)

A fenestration eases the transition to the Fontan circulation for patients by providing a consistent source of systemic ventricular preload. Secondary benefits of fenestration include reported decreased duration of postoperative pleural effusions and diminished postoperative hospital length of stay [20,21].

Potential risks of fenestration include paradoxical embolization due to the right-to-left shunt, (thus, anticoagulation is suggested for Fontan patients with fenestration), desaturation from right-to-left shunting, and the potential need for future percutaneous procedures to close the fenestration.

Spontaneous fenestration closure occurs frequently. If the patient has acceptable post-Fontan-procedure hemodynamics, spontaneous fenestration closure may not result in any sequelae and may be found during routine follow-up.

Fontan "physiology" — Following Fontan procedure, since there is no ventricular pump to propel blood into the pulmonary arterial circulation, systemic venous pressures become elevated compared with those of a normal biventricular circulation (figure 5) [22]. Thus, individuals with Fontan circulation may have heart failure signs and symptoms in the presence of preserved ventricular function, as well as those associated with systolic and/or diastolic dysfunction [1]. Many of the complications seen post-Fontan procedure are directly or indirectly related to this chronic elevation of central venous pressure. Cardiac output is also typically lower than normal in individuals with two-ventricle circulation, particularly during physical exertion. (See "Management of complications in patients with Fontan circulation".)

Patients with Fontan circulation generally have mild systemic arterial oxygen desaturation at rest on room air (oxygen saturation most commonly 90 to 95 percent) for a number of reasons [1]. After a cavopulmonary Fontan procedure, deoxygenated coronary sinus blood is typically left draining into the atrial chamber, which connects directly to the systemic ventricle and systemic circulation. Also, ventilation-perfusion mismatch is caused by pulmonary arterial blood flow with low kinetic energy gravitating to lower lung segments, while upper segments receive greater aeration.

Some patients are left with fenestrations that allow right-to-left shunting and decrease oxygen saturation. Intra- or extracardiac communications (eg, veno-venous collaterals and pulmonary arteriovenous fistula) between the systemic venous and lower-pressure pulmonary venous chambers may develop over time. Some patients with Fontan circulation have marked arterial oxygen desaturation (<90 percent) at rest, as discussed separately. (See 'Surgical technique' above and "Management of complications in patients with Fontan circulation", section on 'Cyanosis and shunts'.)

LONG-TERM FOLLOW-UP

Follow-up recommendations — Patients with prior Fontan operation require lifelong follow-up with a cardiologist experienced in the care of patients with complex congenital heart disease (eg, pediatric cardiologist or adult congenital heart disease specialist) [1,2]. Annual clinical evaluation by a specialist is recommended at a minimum. Patients after the Fontan operation are among the most challenging that congenital cardiologists manage due to the high level of complexity of issues involved and substantial risk for morbidity and mortality. Patients with complications following Fontan operation require more frequent follow-up; the frequency of follow-up and monitoring is individualized. The medical care team should include a primary care provider and, if the patient does not live close to a congenital heart disease center, ideally also should include a local cardiologist to provide combined care with a congenital heart disease specialist.

Fontan patients are best considered as having a condition with systemic and cardiac manifestations. Specialized care of the patient following Fontan operation should include [1]:

●Clinical assessment by a congenital cardiologist every 6 to 12 months, depending on comorbid conditions.

●Regular laboratory testing including hematology, B-type natriuretic peptide (BNP) or N-terminal pro-BNP (NT-proBNP), renal function (including urine for protein content), liver function (including liver function tests [LFTs], platelet count, international normalized ratio [INR], and alpha-fetoprotein), electrolyte assessment, serum albumin, and total protein (to screen for protein-losing enteropathy [PLE]). Frequency depends on the time since the Fontan operation. American Heart Association (AHA) guidelines suggest testing every three to four years in patients <12 years old, every one to three years in adolescence, and every one to two years in adulthood. (See "Management of complications in patients with Fontan circulation", section on 'Protein-losing enteropathy'.)

●Annual electrocardiogram (ECG) is recommended to evaluate heart rhythm.

If symptoms, tachycardia, or an abnormal ECG develop, further arrhythmia assessment may include Holter monitoring, event monitoring, prolonged rhythm assessment, or exercise ECG to assess heart rate response and heart rhythm with exercise.

●Annual chest radiography is generally suggested. The heart size and pulmonary vascularity should be normal in patients following Fontan operation. Pleural effusions suggest PLE or other hemodynamic abnormality. (See "Management of complications in patients with Fontan circulation", section on 'Heart failure' and "Management of complications in patients with Fontan circulation", section on 'Protein-losing enteropathy'.)

●Cardiopulmonary exercise testing is performed regularly (every one to three years, depending upon the age of the patient [1]) to identify changes in exercise capacity, arrhythmias, or desaturation with exercise that may prompt further evaluation.

●Overnight oximetry may be performed to screen for obstructive sleep apnea, as this condition is common in adolescent and adult patients with Fontan circulation.

●Cardiac imaging:

•Annual comprehensive transthoracic echocardiography (TTE) is recommended and should be performed by staff with expertise in congenital heart disease to assess ventricular function, valve function, and the Fontan connection.

•Transesophageal echocardiography (TEE; or cross-sectional imaging) may be performed if right atrial or Fontan thrombus is suspected, and provides improved visualization of the entire Fontan pathway. TEE examination may help to assess the presence or absence of a Fontan fenestration and the gradient across the fenestration if present and not seen on TTE. TEE is recommended prior to cardioversion in patients following Fontan regardless of anticoagulation status. Given the risk associated with a TEE procedure and sedation for the procedure, TEE should be performed only when needed and by staff with expertise in complex congenital heart disease. In some centers a cardiac anesthesiologist provides sedation for high-risk patients.

•Cardiovascular magnetic resonance (CMR) imaging/computed tomography (CT) – If echocardiography images are inadequate or inconclusive, additional imaging with cardiac CT or CMR is performed on an individual basis by staff with expertise in congenital heart disease. AHA guidelines suggest that CMR could be performed as often as every two to three years in Fontan patients, although many congenital centers do not utilize CMR this frequently.

•Cardiac catheterization is indicated to investigate unexplained volume retention, fatigue, exercise limitation, arrhythmias, cyanosis, hemoptysis, PLE, failing Fontan physiology, and features of Fontan-associated liver disease [2]. AHA guidelines suggest performing a cardiac catheterization at minimum every 10 years after the Fontan operation. Exercise during cardiac catheterization may enhance assessment of abnormal hemodynamics and provide incremental diagnostic information [23,24].

●Abdominal imaging – Patients with Fontan-associated liver disease with cirrhosis or marked fibrosis need regular abdominal imaging to assess liver disease, spleen size, ascites, and to assess for hepatocellular carcinoma.

Findings requiring further evaluation — Symptoms, signs, and laboratory tests may alert the clinician to complications following Fontan procedure. Acute decompensation can occur in patients post-Fontan and generally is precipitated by a tachy- or bradyarrhythmia or Fontan pathway thrombosis. When patients present with acute symptoms, Fontan pathway obstruction or stenosis should be sought.

Important hemodynamic issues contributing to chronic morbidity and mortality in patients with Fontan operation include progressive symptoms, decline in systemic ventricular function, greater ventricular volumes, valve regurgitation, a rise in pulmonary vascular resistance, atrial enlargement, atrial arrhythmias, pulmonary venous obstruction, and chronic systemic venous hypertension, which can lead to hepatic congestion and dysfunction [25]. Echocardiography-derived circumferential strain and CMR-derived ventricular end-diastolic volume index are associated with transplant-free survival in patients after Fontan operation and have higher discriminative ability than clinical variables [26].

Symptoms — New symptoms and signs that warrant investigation after Fontan operation include palpitations/arrhythmias, syncope or near-syncope, dyspnea, fatigue, exercise intolerance, poor somatic growth, diarrhea, and edema or ascites. Such symptoms may be related to heart failure (due to Fontan circulation, ventricular dysfunction, arrhythmias, valve dysfunction, or volume-loading shunts), PLE, liver disease, or more complex conditions.

Physical examination findings — The physical examination is helpful in identifying complications following Fontan procedure.

Since patients with Fontan circulation are at risk for impaired physical development, patient growth (including height and weight), pubertal development, and muscle mass should be evaluated. Mild jugular venous distention (usually nonpulsatile) is common after the cavopulmonary Fontan procedure, and prominent A waves can often be seen in atriopulmonary Fontan procedure. However, marked jugular venous distension and hepatomegaly should raise concern for Fontan obstruction.

Prior shunts may affect the physical examination. In patients with prior Blalock-Thomas-Taussig (subclavian artery to pulmonary artery) shunt (figure 2A), falsely low or absent ipsilateral upper-extremity blood pressure readings may be obtained, particularly in the setting of a classic Blalock-Thomas-Taussig shunt. In patients with a history of a Glenn operation (figure 1), Fontan obstruction may manifest as hepatic distension and later peripheral edema, without jugular venous distention.

Cyanosis should be assessed following Fontan procedure. Patients with Fontan operation are not expected to be significantly cyanotic (<90 percent) unless they have a Fontan fenestration or veno-venous collaterals. Cyanosis may worsen with physical activity. Cyanotic patients who have not received intentional fenestration should be referred for cardiac catheterization to determine the cause of cyanosis. (See "Management of complications in patients with Fontan circulation", section on 'Cyanosis and shunts'.)

The presence of edema or ascites should prompt assessment for cardiac dysfunction, Fontan obstruction, PLE, or liver disease. Lower extremity venous insufficiency is commonly seen during late follow-up, particularly those with prior multiple cardiac catheterizations and/or a history of deep vein thrombosis. Identification of those at greatest risk for local trauma and bleeding from the peripheral varicosities is important to securing good outcomes.

Laboratory findings — Low serum albumin or total protein should prompt evaluation for PLE or other causes of protein loss. Patients with evidence of kidney disease (elevated creatinine, cystatin-C, and/or reduced glomerular filtration rate), PLE, or liver disease (abnormal LFTs, thrombocytopenia, elevated INR) should receive further evaluation and referral to nephrology and gastrointestinal/hepatology specialists with experience treating patients with complications following Fontan operation. (See "Management of complications in patients with Fontan circulation", section on 'Renal complications' and "Management of complications in patients with Fontan circulation", section on 'Liver disease' and "Management of complications in patients with Fontan circulation", section on 'Arrhythmias' and "Management of complications in patients with Fontan circulation", section on 'Protein-losing enteropathy'.)

Imaging findings — Echocardiography may identify systemic ventricular dysfunction. This is typically assessed using a combination of qualitative and quantitative measures. Changes in ventricular function should prompt consideration for further evaluation (eg, catheterization or advanced imaging) and addition of heart failure therapies. (See "Management of complications in patients with Fontan circulation", section on 'Heart failure'.)

Atrioventricular and semilunar valve disease are also assessed routinely by TTE, and the presence of severe valve disease may prompt further intervention. (See "Management of complications in patients with Fontan circulation", section on 'Atrioventricular valve regurgitation'.)

Intracardiac thrombus is sought routinely, especially those with arrhythmias and/or atriopulmonary Fontan procedure with associated right atrial dilation. (See "Management of complications in patients with Fontan circulation", section on 'Thrombosis'.)

Aortic dilation may be noted in select patient populations following Fontan procedure.

Echocardiography with Doppler and other imaging modalities may identify obstruction at any point in the Fontan circuit. If suspected, cardiac catheterization will be required to confirm and determine best treatment options. Since echocardiography and other imaging may miss Fontan obstruction, cardiac catheterization is the diagnostic test of choice when obstruction is suspected. (See "Management of complications in patients with Fontan circulation", section on 'Cardiovascular complications'.)

MANAGEMENT

Management of complications — Prevention and management of complications in patients with Fontan circulation (including use of antithrombotic agents, given the risk of thrombus and thromboembolism) are discussed separately. (See "Management of complications in patients with Fontan circulation".)

Management of noncardiac surgery — Patients with Fontan circulation are at increased risk of anesthetic and perioperative complications, including death. Elective noncardiac surgical procedures should be performed at experienced centers, and an experienced multidisciplinary team should manage Fontan patients. The highest-risk patients appear to be those with ventricular dysfunction, protein-losing enteropathy, and Fontan-associated liver disease [27,28]. (See "Management of cardiac risk for noncardiac surgery" and "Anesthesia for adults with congenital heart disease undergoing noncardiac surgery".)

Endocarditis prophylaxis — Endocarditis prophylaxis is routinely recommended for patients at the highest risk of adverse effects from endocarditis; this includes patients with Fontan circulation, given the presence of a prosthetic conduit and passive flow [2]. (See "Prevention of endocarditis: Antibiotic prophylaxis and other measures".)

Antibiotic prophylaxis is suggested for patients with Fontan operation for all designated relevant procedures; these include dental procedures that involve manipulation of gingival tissue, the periapical region of teeth, and perforation of the oral mucosa. (See "Prevention of endocarditis: Antibiotic prophylaxis and other measures".)

Exercise — A significant (eg, 16 to 19 percent) increase in peak oxygen consumption has been reported after completion of the Fontan procedure [29,30]. Despite this improvement, post-Fontan-procedure patients remain limited in their physical abilities, with maximum oxygen consumption ranging from 48 to 65 percent of predicted values for age- and sex-matched peers [31-33]. The majority of children with Fontan circulation do not achieve normal physical activity levels [34], which may be due to multiple physical, social, and psychological factors. Physiologic causes of restricted exercise capacity in this population include cardiovascular, pulmonary, and muscular limitations. Cardiovascular impairments include failure to increase stroke volume with activity (related to reduced preload from failure to adequately increase pulmonary blood flow) [31,35,36], chronotropic incompetence, reduced arterial blood saturation (which may worsen with exercise) [31,37,38], and abnormal ventriculovascular coupling. Patients with Fontan circulation commonly have restrictive lung disease. Peak oxygen consumption is also affected by muscle mass [39]; 25 percent of Fontan patients have severely reduced muscle mass. (See "Management of complications in patients with Fontan circulation", section on 'Cardiovascular complications' and "Management of complications in patients with Fontan circulation", section on 'Respiratory complications'.)

We suggest periodic cardiopulmonary exercise testing in patients following Fontan operation to exclude chronotropic incompetence, desaturation, or arrhythmias with exercise, and to assess whether exercise limitation is cardiac or pulmonary [40]. A regular exercise program is often suggested for patients following Fontan to reduce deconditioning, and some patients may benefit from a cardiac rehabilitation program [41]. (See "Management of complications in patients with Fontan circulation", section on 'Cardiovascular complications' and "Management of complications in patients with Fontan circulation", section on 'Respiratory complications'.)

Oscillatory ventilation refers to regular oscillations in minute ventilation during cardiopulmonary exercise testing. Oscillatory ventilation has been found to predict mortality and arrhythmias independent of other known predictors in adults with heart failure. This is a relatively frequent occurrence in patients post-Fontan procedure and carries poor prognosis [42].

Patients with Fontan circulation should be encouraged to participate in an active lifestyle, including routine symptom-limited aerobic activity [43,44]. Competitive and isometric sports participation is generally discouraged, but recreational sports are encouraged. High-intensity resistance training can result in increased peak oxygen consumption, increased muscle strength, and total muscle mass.

The 2015 American College of Cardiology/American Heart Association (ACC/AHA) Eligibility and Disqualification Recommendations for Competitive Athletes with Cardiovascular Abnormalities provide a guideline for the Fontan patient interested in competitive sports participation [45]. These guidelines do not necessarily apply to noncompetitive sports activities. Patients are recommended to undergo full evaluation before competitive sports participation, including clinical assessment, ECG, imaging assessment of ventricular function (eg, echocardiography or magnetic resonance imaging), and cardiopulmonary exercise testing. The specific sports-based recommendations for Fontan patients include:

●Athletes without ventricular dysfunction, arrhythmias, or outflow tract obstruction "may be considered" for participation in moderate- to high-intensity sports. This is dependent on the athlete completing an exercise test with no exercise-induced arrhythmias, hypotension, or other concerning clinical symptoms [45].

●Athletes with reduced ventricular function (ie, ejection fraction <40 percent), outflow tract obstruction, or recurrent or uncontrolled arrhythmias are recommended to be restricted from sports, with the possible exception of class IA sports (these include golf, riflery, curling, bowling, yoga, and cricket).

Reproductive issues — Patients with prior Fontan procedure who are contemplating pregnancy should undergo preconception assessment and counseling by an adult congenital heart disease specialist, including a comprehensive prepregnancy cardiovascular evaluation to identify residua following Fontan operation that may adversely affect pregnancy outcome. A review of patient medications should be performed, including discussion of need and options for anticoagulation and discontinuation of medications that are harmful during pregnancy such as angiotensin converting enzyme inhibitors, angiotensin receptor blockers, angiotensin-neprilysin inhibitor, and direct oral anticoagulants. Prepregnancy counseling should also include a discussion about overall prognosis following Fontan procedure as well as genetic consultation. (See "Use of anticoagulants during pregnancy and postpartum" and "Management of heart failure during pregnancy".)

Patients with poor functional capacity, a history of heart failure or ventricular function <40 percent, arrhythmias, protein-losing enteropathy, intracardiac thrombi, Fontan-associated liver disease, or cyanosis (room air saturation <90 percent) are discouraged from proceeding with pregnancy due to the risk of pregnancy-related complications and adverse fetal outcome [46].

Any pregnancy in a patient with prior Fontan operation is considered high risk. Successful pregnancy has been reported in Fontan patients, but complications are common and include atrial arrhythmias, thrombotic and bleeding events, ventricular dysfunction, and edema. There is an increased risk for spontaneous abortion and premature birth, as well as intrauterine growth restriction [47-52]. Postpartum hemorrhage is also well documented in up to 50 percent of pregnancies. Management of heart failure during pregnancy is discussed separately. (See "Management of heart failure during pregnancy".)

A literature review reported rates of complications during 25 completed (>20 weeks gestation) pregnancies among women with Fontan repair for various types of functional single ventricle [51]:

●Maternal arrhythmias occurred in four pregnancies, heart failure in one pregnancy, and cardiovascular events (myocardial infarction, stroke, cardiovascular mortality) in none.

●With respect to the fetus, preterm delivery occurred in seven pregnancies, fetal mortality in no pregnancies, perinatal mortality in one pregnancy and recurrent congenital heart disease (of any type) in one pregnancy.

Contraception in women with congenital heart disease is discussed separately. (See "Pregnancy in women with congenital heart disease: General principles", section on 'Contraception'.)

Heart or multiorgan transplant — An important part of the ultimate care of patients with Fontan palliation is discussion and evaluation for heart or multiorgan transplant as an ultimate treatment option. The timing of this evaluation should be individualized, but the prospect of transplant should be introduced early in the course of care, particularly for patients with multiorgan disease. This may require referral to a center with expertise in complex congenital heart disease transplantation and multiorgan transplant.

Social work — Social work assessment and support are beneficial for many patients and their families and caregivers following Fontan procedure. Regular follow-up with a social worker is recommended.

Palliative care — While survival in patients with Fontan circulation has improved, many patients continue to face shortened life expectancy, and death is not always preceded by a period of decline [1]. Thus, palliative care is important for patients with Fontan circulation, including timely discussion of end-of-life matters and advanced care planning (including encouraging completion of advance directives) in an age- and development-appropriate manner [1]. A patient's primary care physician may provide palliative care, with consultation with palliative care specialists as needed to optimally address the patient's symptoms, as well as the patient's and family's concerns. (See "Overview of comprehensive patient assessment in palliative care" and "Palliative care for patients with advanced heart failure: Indications and systems of care" and "Palliative care for patients with advanced heart failure: Decision support and management of symptoms".)

PROGNOSIS AFTER FONTAN PROCEDURE — Operative and long-term survival after Fontan procedure have steadily improved [1,53]. Postoperative 15- to 20-year survival rates after Fontan procedure range from 60 to 85 percent [25,54,55]. Patients currently undergoing Fontan procedure are predicted to have a 30-year survival rate of approximately 85 percent [1].

Mortality has been shown to correlate with underlying diagnosis, but many other factors contribute:

●In a study of 261 patients born before 1985, the actuarial event-free survival was 75 and 68 percent at 10 and 20 years post-Fontan procedure, respectively. Patients who survived the initial operation had an 83 percent survival rate at 20 years. Predictors of all-cause mortality or transplantation included a history of hypoplastic left heart syndrome, elevated right atrial/central venous pressures, and a history of protein-losing enteropathy [25]. (See "Hypoplastic left heart syndrome: Management and outcome", section on 'Outcome'.)

●In a study of 216 patients who had Fontan operations for tricuspid atresia, the cumulative survival rate was 79 percent with a median of 13 years of follow-up [53]. (See "Tricuspid valve atresia".)

Survival for patients with hypoplastic left heart syndrome who undergo a Fontan operation ranges from 72 to 85 percent at 10 years [25,56,57]. However, when taking into account the other surgeries required for these infants, the overall survival of any infant with hypoplastic left heart syndrome through all of their initial surgeries is only 50 to 70 percent at 10 years. This low overall survival rate is related to other patient-specific factors including genetic factors, gestational age, and location of delivery [11,58]. Mortality occurring between surgical stages (known as interstage mortality) contributes substantially to overall mortality [59].

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Congenital heart disease in adults" and "Society guideline links: Arrhythmias in adults".)

SUMMARY AND RECOMMENDATIONS

●The Fontan procedure was developed to divert systemic venous return to the lungs in patients with an anatomic or functional single ventricle. For this circulation to be effective, the patients must have a low pulmonary arteriolar resistance, relatively normal systolic and diastolic function of the single ventricle, and sufficiently large pulmonary arteries to minimize mechanical resistance. (See 'Lesions treated and rationale' above and 'Criteria for Fontan procedure' above.)

●Lesions treated by the Fontan procedure include hypoplastic left heart syndrome, tricuspid atresia, pulmonary atresia with intact ventricular septum, double-inlet left ventricle, and unbalanced atrioventricular canal defects. (See 'Lesions treated and rationale' above.)

●The most common forms of Fontan procedure are the atriopulmonary connection (no longer being routinely performed due to associated complications) and the cavopulmonary connection. A cavopulmonary connection with an extracardiac conduit has been the dominant Fontan procedure since the year 2000. (See 'Surgical technique' above.)

●Following Fontan procedure, systemic venous pressures are elevated compared with those with a normal biventricular circulation (figure 5), which leads to many of the complications seen post-Fontan procedure. (See 'Fontan "physiology"' above and "Management of complications in patients with Fontan circulation".)

●Patients with prior Fontan operation require lifelong follow-up with a cardiologist experienced in the care of patients with complex congenital heart disease. (See 'Long-term follow-up' above.)

●Patients with Fontan circulation have restricted exercise capacity that may be due to cardiovascular, pulmonary, and muscular limitations. We suggest periodic cardiopulmonary exercise testing in patients following Fontan operation to exclude chronotropic incompetence, desaturation, or arrhythmias with exercise, and to assess whether exercise limitation is cardiac or pulmonary. Patients with Fontan circulation should be encouraged to participate in an active lifestyle, including routine symptom-limited aerobic activity. (See 'Exercise' above.)

●Pregnancy in a patient with prior Fontan operation is considered high risk. Patients with prior Fontan procedure who are contemplating pregnancy should undergo comprehensive preconception assessment and counseling by an adult congenital heart disease specialist. These patients are advised to avoid pregnancy when they have any complications associated with the Fontan procedure. (See 'Reproductive issues' above.)

●Palliative care is important for patients with Fontan circulation, including timely discussion of transplant timing, end-of-life matters, and advanced care planning (including encouraging completion of advance directives) in an age- and development-appropriate manner. (See 'Palliative care' above.)

●Operative and long-term survival after Fontan procedure have steadily improved. Patients currently undergoing Fontan procedure are predicted to have a 30-year survival rate of approximately 85 percent. (See 'Prognosis after Fontan procedure' above.)