Considerations in Critical-Care and Anesthetic Management of Adult Patients Living With Fontan Circulation

The Fontan procedure is a staged palliation for various complex congenital cardiac lesions, including tricuspid atresia, pulmonary atresia, hypoplastic left heart syndrome, and double-inlet left ventricle, all of which involve a functional single-ventricle physiology. The complexity of the patients’ original anatomy combined with the anatomic and physiologic consequences of the Fontan circulation creates challenges. Teens and adults living with Fontan palliation will need perioperative support for noncardiac surgery, peripartum management for labour and delivery, interventions related to their structural heart disease, electrophysiology procedures, pacemakers, cardioversions, cardiac surgery, transplantation, and advanced mechanical support. This review focuses on the anesthetic and intensive care unit (ICU) management of these patients during their perioperative journey, with an emphasis on the continuity of preintervention planning, referral pathways, and postintervention ICU management. Requests for recipes and doses of medications are frequent; however, as in normal anesthesia and ICU practice, the method of anesthesia and dosing are dependent on the presenting medical/surgical conditions and the underlying anatomy and physiologic reserve. A patient with Fontan palliation in their early 20s attending school full-time with a cavopulmonary connection is likely to have more reserve than a patient in their late 40s with an atriopulmonary Fontan at home waiting for a heart transplant. Each case will require an anesthetic and critical care plan tailored to the situation. The critical care environment is a natural extension of the anesthetic management of a patient, with complex considerations for a patient with Fontan palliation.     

Effects of aerobic exercise training in children after the Fontan operation

It was demonstrated that patients who have undergone the Fontan operation can safely undertake exercise training and that this results in an improvement in aerobic capacity. These findings suggest that aerobic training could be useful in the long-term management of these patients to optimize their cardiovascular fitness for more active lives.     

Fontan Circulation: Success or Failure?

Fontan surgery represents a milestone in the evolution of congenital heart disease management. It achieved the seemingly improbable (ie, restoration of a noncyanotic state by entirely bypassing the subpulmonary ventricle). In so doing, it has allowed a generation of children who may have otherwise succumbed to their severe congenital heart defect to survive to adulthood. Perfect univentricular physiology is, however, an elusive goal. The Fontan circulation inherently represents a hemodynamic compromise that results in a catalog of potential multiorgan complications. In this review, we explore current knowledge regarding pathophysiology of the failing Fontan, its varied clinical manifestations, and potential therapeutic options. Failure of the Fontan circulation is broadly divided into 3 overlapping categories: ventricular dysfunction, systemic complications of Fontan physiology, and chronic Fontan failure. As long as the Fontan operation continues to serve as the paradigm of care for patients with univentricular hearts, efforts must be directed toward supporting this dynamic circulation that progressively declines in efficiency with age. Continued research in therapies is needed for univentricular dysfunction and systemic complications of Fontan palliation, including potential uses of mechanical support as a bridge to transplantation or as a neosubpulmonary ventricle. Fontan patients remain a major challenge to the medical and surgical community as a whole. Multicentre and multidisciplinary efforts to improve the density and depth of experiences might lead to a better appreciation for, and management of, Fontan failure and its ramifications.     

"Taking in the waist": adjusting the size of a stented fontan fenestration

Early spontaneous closure of a fenestration following Fontan palliation may complicate the postoperative management of such patients. The creation of a fenestration in the catheterization laboratory with an intravascular stent may improve these patients' hemodynamic status. The aim of this study is to present a new technique to reduce the diameter of stented Fontan fenestrations in those patients in whom the stent diameter is functionally made too large.     

Diagnostic assessment before Fontan operation in patients with bidirectional cavopulmonary anastomosis: are noninvasive methods sufficient?

OBJECTIVES: This study was designed to determine if a subset of patients who have undergone bidirectional cavopulmonary anastomosis could be identified in which catheterization was of little benefit before completion of the Fontan procedure. BACKGROUND: Diagnostic evaluation before Fontan procedure has typically included cardiac catheterization. However, the overall management strategy for patients with functional single ventricle has evolved to include staging bidirectional cavopulmonary anastomosis in most, and it has become uncommon to exclude patients from Fontan based on catheterization data. METHODS: Patients who underwent bidirectional cavopulmonary anastomosis and had complete echocardiograms and catheterizations within three months of each other between January 1992 and October 1997 were evaluated with a series of clinical and echocardiographic characteristics to identify a subset in whom catheterization was predicted to be of little added value ("no-cath" group). The predictive value and sensitivity of these criteria in excluding patients who required additional intervention, were excluded from Fontan, or died within 30 days of Fontan was determined. RESULTS: A total of 99 patients who underwent bidirectional cavopulmonary anastomosis at 6.7 months (range 2.9 months to 14 years) were studied; 46 met criteria for the "no-cath" group. Noninvasive criteria stratified all patients who died (n = 5) or did not proceed to Fontan (n = 1) and 9 of 11 who required additional interventions to the "cath" group. Thus, the negative predictive value of these criteria was 93%. CONCLUSIONS: Our data suggest that catheterization before Fontan could be avoided in a large percentage of patients without adversely affecting outcome; prospective evaluation of this strategy is warranted.     

Three-dimensional echocardiographic evaluation of the Fontan conduit for thrombus

Introduction: Total caval pulmonary connection (Fontan circuit) is the final common pathway for the palliation of single ventricle congenital heart disease. Flow within the Fontan circuit results in an environment that is prone to thrombus formation putting the patient at risk for pulmonary and/or systemic embolus. To prevent these problems, patients are placed on antithrombotic therapy and periodically evaluated for thrombus within the conduit. Two‐dimensional (2D) echocardiography, although commonly used to evaluate these patients, has been shown to have limited ability in accurately identifying thrombi within the Fontan conduit. The diagnosis of intracardiac thrombi has been augmented by three‐dimensional (3D) echocardiography and the patients in this series were evaluated with 3D imaging (3D transthoracic echocardiography and/or 3D transesophageal echocardiography) to determine if thrombi could be detected or excluded within the Fontan conduit. To the author's knowledge, this constitutes the first case series describing the use of 3D echocardiography to evaluate the Fontan conduit for thrombus. Methods: The four patients described in this case series underwent 3D echocardiography to evaluate the Fontan conduit for a suspected or potential thrombus. Results: The Fontan conduit was imaged and thrombi were felt to be documented or excluded in all four patients with 3D echocardiography. Conclusions: Three‐dimensional echocardiography may enhance the ability to detect or exclude thrombi within the Fontan conduit. Further studies are needed to determine if this will prove to be an effective and reliable technique in evaluating the Fontan conduit for thrombus. (Echocardiography 2012;29:363‐368)     

The Fontan Circulation: From Ideal to Failing Hemodynamics and Drug Therapies for Optimization

Fontan palliation results in a hemodynamically complex circulation with multisystem consequences, which in the long term adversely affect many body processes. Systemic venous hypertension, nonpulsatile low-shear pulmonary blood flow, and low cardiac output are the 3 main characteristics of a Fontan circulation, leading to unavoidable slowly progressive failure. An appreciation of how the hemodynamics of a Fontan circulation change with time and relate to the various modes of Fontan circulatory failure is important. Accurate hemodynamic assessment aid this understanding and may permit early identification of potentially treatable drivers of decline. While no evidence-based or guideline-directed pharmacologic management strategy has been established in Fontan patients, understanding the hemodynamics of Fontan circulation failure will assist in the rational selection of potentially helpful drug therapies for individual patients. In this review, we present hemodynamic concepts of the optimal Fontan physiology and Fontan circulatory failure, review practical aspects of invasive hemodynamic assessment, and discuss the role of drug therapies in increasing systemic venous blood flow return and decreasing ventricular filling pressures in Fontan circulation. Often complementary to catheter-based or surgical interventions, pharmacologic management aims at preserving patency of the circuit, adequate systolic and diastolic ventricular function, atrioventricular valve function, an unobstructed ventricular outflow tract, and pulmonary vascular integrity in order to maintain an acceptable cardiac output.     

Long term negative pressure ventilation: Rescue for the failing fontan?

Current treatment strategies for single ventricle patients include non-intervention strategy, surgical palliation or primary transplantation. Surgical palliation includes a staged operative course culminating in the Fontan operation. With progress in surgical techniques, the survival has been improving. However, almost all of these Fontan patients will demonstrate pathophysiologic changes that ultimately constitute "Fontan failure physiology". This article reviews the pathophysiologic changes, current approach to management of these patients and proposes a novel way of reversing some of the pathophysiologic changes by utilization of negative pressure ventilation.     

Correction of tricuspid atresia.

Although Fontan and Baudet in 1971 described a physiological correction procedure for tricuspid atresia, very few successful operations have been reported. Two patients corrected 20 and 10 months ago at the Brompton Hospital are presented. These two patients exhibit many of the problems in the management of tricuspid atresia. The first patient aged 20 had undergone three previous palliative operations, a Blalock-Taussig shunt, a Glenn procedure, and an infundibular resection, and therefore presented a number of operative problems. In contrast the second patient, aged 8, whose condition had deteriorated considerably over the previous year, had had no previous surgical treatment. At operation he was found, in addition, to have a partial atrioventricular canal. Details of the operative procedures and the patients' postoperative course are described. The criteria for selection of patients for the Fontan operation are discussed as are the possible long-term hazards of homograft failure, atrial dysrhythmias, and hepatic dysfunction. The successful outcome of these two patients suggests that palliative surgery in infancy should allow for this form of correction in later life.     

Correction of tricuspid atresia.

Although Fontan and Baudet in 1971 described a physiological correction procedure for tricuspid atresia, very few successful operations have been reported. Two patients corrected 20 and 10 months ago at the Brompton Hospital are presented. These two patients exhibit many of the problems in the management of tricuspid atresia. The first patient aged 20 had undergone three previous palliative operations, a Blalock-Taussig shunt, a Glenn procedure, and an infundibular resection, and therefore presented a number of operative problems. In contrast the second patient, aged 8, whose condition had deteriorated considerably over the previous year, had had no previous surgical treatment. At operation he was found, in addition, to have a partial atrioventricular canal. Details of the operative procedures and the patients' postoperative course are described. The criteria for selection of patients for the Fontan operation are discussed as are the possible long-term hazards of homograft failure, atrial dysrhythmias, and hepatic dysfunction. The successful outcome of these two patients suggests that palliative surgery in infancy should allow for this form of correction in later life.     

Clinical Approaches to the Patient with a Failing Fontan Procedure

The Fontan operation has been nothing short of revolutionary in its influence on the modern management of patients born with functionally univentricular hearts. The vast majority of these individuals are now surviving well into adulthood. In the 45 years since its introduction, however, there has been increasing recognition of Fontan survivors as a vulnerable population with an altered physiology that has remarkably broad, adverse impact on their long-term health. In this review, the authors discuss the varied manifestations, both cardiac and extracardiac, of the failing Fontan circulation and potential therapeutic options. In addition, a general clinical approach to the patient presenting with Fontan failure is proposed. Ultimately, the key to improving our care and understanding of the Fontan population lies in multi-institutional collaboration and partnership between subspecialty cardiologists and specialists in other organ systems.     

Fontan-Associated Liver Disease: Evidence for Early Surveillance of Liver Health in Pediatric Fontan Patients

The growing awareness of Fontan-associated liver disease (FALD) in adults with Fontan physiology has provided the impetus to better understand the natural history of FALD and develop a reliable noninvasive method to diagnose and monitor liver health in this population. Biochemical and imaging tests have been investigated to determine their association with liver pathology. The congestive hepatopathy that develops after the Fontan procedure has made interpreting these tests challenging. We have reviewed and summarized the current understanding and ongoing challenges with respect noninvasive measures of liver health in Fontan patients including biochemical tests, elastography, hepatic ultrasound, cross-sectional imaging, and hemodynamics and how they relate to liver pathology. It has been demonstrated from biopsy data that liver disease is universal and progressive in Fontan patients. Traditional biochemical tests, elastography, and imaging methods are often abnormal in Fontan patients but do not reliably indicate significant liver pathology. Although a reliable means for surveillance of FALD remains elusive, this continues to be an active area of investigation, with promising recent developments. Therapeutic options for FALD are limited, with cardiac transplant as the only option that can stabilize FALD pathology and improve symptomatology. Given the limited therapeutic options and the prevalence of liver disease in Fontan patients, there is a compelling case for early routine surveillance of liver health and promotion of global liver health.     

Impact of exercise training on muscle function and ergoreflex in Fontan patients: a pilot study

BACKGROUND: Several studies have demonstrated persistent reduced exercise capacity in Fontan patients even after surgical intervention. The purpose of this study was to evaluate if the skeletal muscle function of these patients is abnormal, if it correlates with exercise tolerance and if it can be improved by exercise training. METHODS: We evaluated the functional capacity of seven patients who underwent Fontan procedure (age:16+/-5 years, mean+/-SD) and seven healthy children (19+/-7 years) paired for age, sex, height and weight. Evaluation included pulmonary evaluation, neuromuscular function and exercise tolerance. Secondly, an 8-week exercise training program was performed by five of these patients. RESULTS: The ergoreflex contribution to absolute diastolic blood pressure was higher (12.5+/-4.8 vs. 5.6+/-4.2 mmHg; p=0.04) in Fontan patients vs. healthy subjects whereas a trend was encountered regarding the ergoreflex contribution to absolute systolic blood pressure (9.0+/-7.0 vs. 0.4+/-9.0 mmHg; p=0.09). Furthermore, time to fatigue of the non-dominant forearm muscles was shorter in Fontan patients vs. healthy subjects (431+/-290 vs. 847+/-347 s; p=0.03). Following exercise training, there was a significant reduction of the ergoreflex contribution to absolute values of systolic blood pressure (9.8+/-0.9 vs. 0.3+/-2.7 mmHg; p<0.05). There was an association between muscle strength and VO2 peak in Fontan patients (upper limb: r=0.895; p<0.01; lower limb: r=0.838; p<0.05, respectively). CONCLUSIONS: Skeletal muscle function in Fontan patients is abnormal which may have an impact in the reduced exercise tolerance encountered in these patients. Exercise training may have beneficial impacts on the skeletal muscle function in this population.     

Contemporary Provider Management Practices and Attitudes Toward Referral for Advanced Heart Failure Therapies in Fontan Patients Across North America

Background: To date, no reports have described clinicians’ management practices for patients with Fontan circulatory failure or their understanding of risk factors for mortality and transplant outcomes in these patients.Methods and Results: A cross-sectional survey of caregivers across North America was conducted from February to September 2020. Responses were compared by primary specialty (heart failure/transplant vs non-heart failure/transplant), years of experience (early, mid, and late career), and Fontan center volume (low, medium, and high). Of 400 responses, the majority were from general cardiologists (111, 28%) followed by heart failure/transplant specialists (93, 23%). Although most agreed that patients with Fontan physiology will have signs/symptoms of heart failure (369 [93%]) and eventuate in heart transplant (286 [72%]), many disagreed (180 [45%]) that routine evaluation by a transplant cardiologist is needed without symptoms. Transplant providers were more likely than non-transplant providers to suggest referral for manifestations of Fontan circulatory failure such as protein-losing enteropathy, plastic bronchitis, liver fibrosis/cirrhosis, and worsening valve regurgitation. Non-transplant providers were more likely to suggest that protein-losing enteropathy, plastic bronchitis, and Fontan-associated liver disease lead to inferior outcomes after transplantation. Early career and transplant providers more favorably viewed ventricular assist device use for Fontan patients failing traditional heart failure therapy (P < .05 for all).Conclusions: There is significant variation in the management of Fontan patients, including heterogeneous timing of referral of such patients to the heart failure/transplant team, which may have implications for future outcomes.     

The utility of cardiac magnetic resonance imaging in post‐Fontan surveillance

Objective: Gated cardiac MRI offers the most detailed and accurate noninvasive method of assessing cardiac anatomy, particularly in patients with complex congenital heart disease. The proposed benefits of using cMRI as a routine screening tool in the Fontan population include early recognition of asymptomatic, postoperative anatomic and physiologic changes. In 2011, we therefore instituted at our center a recommended practice of cMRI screening in patients with Fontan physiology at 3 and 8 years postFontan operation. The purpose of this study was to determine the impact of this standardized practice of cMRI screening on the clinical management of a Fontan population.
Design: We retrospectively reviewed charts from our institutional Fontan database to determine which patients were eligible for cMRI under the current guidelines and who underwent imaging from November 2002 to June 2015. We reviewed the frequency of cMRI and number of changes in management based on the results. Statistical significance was determined using a chi-square test.
Results: There were 141 cMRIs performed on 121 patients who met inclusion criteria. The odds of a change in management were significantly greater after clinically indicated cMRI compared to screening cMRI (OR = 3.79, 95% CI: 1.48-9.66, P = .004). There were near significant odds of change in management if the cMRI occurred <8 years after Fontan regardless of whether it was for screening or clinically indicated purposes (OR = 2.43, 95% CI: 0.97-6.08, P = .052). The most frequent change in management was referral for catheterization with pulmonary artery angioplasty.
Conclusions: There is an important role for cMRI in routine surveillance of post-Fontan patients. Screening cMRI performed less than 8 years after Fontan palliation offers increased utility compared to studies performed later. The optimal timing of such imaging after Fontan palliation remains unclear.     

Is it necessary to routinely fenestrate an extracardiac fontan?

OBJECTIVES: This study was conducted to assess the need for, and use of, fenestration of an extracardiac conduit Fontan. BACKGROUND: Fenestration of a Fontan connection has been proposed as a means of improving outcomes of single ventricle palliation. The benefit of fenestration is likely to be greatest in the early postoperative period when patients may experience increased pulmonary vascular resistance and decreased ventricular function due to the effects of cardiopulmonary bypass, aortic cross-clamping and positive pressure ventilation. However, there are potential drawbacks to fenestration. The utility of fenestration with extracardiac Fontan operation has not been determined. METHODS: Since 1992, 81 patients have undergone a modification of the Fontan procedure in which an extracardiac inferior cavopulmonary conduit is used in combination with a previously staged bidirectional Glenn anastomosis. We conducted a retrospective review of these patients. RESULTS: Fenestration was performed selectively in 32 patients (39%), including only 2 of the last 38 (5%). In seven patients, a fenestration was placed or clipped in the early postoperative period without cardiopulmonary bypass. There were two operative deaths. Prolonged (>2 weeks) pleural drainage occurred in 13 patients, 8 with fenestration and 5 without. In addition to undergoing earlier Fontan in our experience, patients who had a fenestration placed had significantly higher preoperative pulmonary vascular resistance, significantly higher common atrial pressure after Fontan and significantly lower post-Fontan systemic arterial oxygen saturation. Fontan pressure did not differ between nonfenestrated and fenestrated patients. At follow-up ranging to five years, there were two late deaths and no patients developed protein losing enteropathy. CONCLUSIONS: Fenestration is not necessary in most Fontan patients when an extracardiac conduit technique is performed as described in this article, and therefore, should not be performed routinely with the extracardiac conduit Fontan. The need for fenestration should be assessed after cardiopulmonary bypass when hemodynamics can be evaluated accurately. Fenestration can be placed and revised easily without bypass and with minimal intervention in patients with an extracardiac conduit Fontan.     

Influence of ventricular morphology on outcome after the Fontan procedure

The modified Fontan procedure has gained wide acceptance in the treatment of various congenital heart defects. Determination of risk factors for mortality remains an important issue for optimizing patient selection for the Fontan procedure. Conflicting results have been reported about whether ventricular morphology is a risk factor in these patients. Survival free of Fontan takedown or cardiac transplantation was assessed in the first 500 patients undergoing the Fontan procedure at our institution. This survival was correlated with ventricular morphology as evaluated by angiography. Both multivariate and univariate analyses indicated ventricular morphology was predictive of early survival free of Fontan takedown or cardiac transplantation following the procedure. However, there was no statistical evidence for ventricular morphology being a risk factor for mortality in patients alive 6 months after the procedure. Ventricular morphology is a risk factor for early survival in patients undergoing a Fontan procedure, with left ventricular morphology associated with a better early survival than right ventricular morphology.     

Prevalence of "silent" pulmonary emboli in adults after the Fontan operation

OBJECTIVES: The study was done to determine the prevalence of pulmonary emboli (PE) in asymptomatic adult Fontan patients and to identify the risk factors associated with PE. BACKGROUND: Right atrial thrombi and systemic thromboembolic complications have been reported after the Fontan procedure. However, the frequency of silent PE in this patient population is not known. METHODS: All consecutive adult Fontan patients attending the adult congenital clinic over a six-month period underwent ventilation-perfusion (VQ) scanning and blood testing for thrombophilia tendency. If the VQ scan showed an intermediate or high probability for PE, a computerized tomography (CT) pulmonary angiogram was performed to confirm the presence of PE. RESULTS: Thirty patients (mean age 26 +/- 7 years, 57% men) were included in this study. Five (17%) adult Fontan patients had an intermediate or high probability for PE on VQ scan, all of which were confirmed on CT pulmonary angiography. No patient had a thrombophilia tendency. Pulmonary emboli were not present in any patients (30%) taking warfarin. Late age at time of Fontan operation (19 +/- 6 years vs. 11 +/- 6 years, p = 0.012) and type of Fontan anatomy (p = 0.001) were associated with increased risk of silent PE. CONCLUSIONS: Seventeen percent of adult patients with Fontan procedure have clinically silent PE. The long-term hemodynamic implications of this with respect to Fontan attrition over time are unknown. Large randomized prospective studies looking at anticoagulation therapy in all Fontan patients are urgently needed.     

Hepatic and Renal Consequences of Single-Ventricle Physiology Palliated With the Fontan Operation

Over time, long-term survival has dramatically increased for patients with complex congenital heart disease who undergo the Fontan operation. With this increased survival, it has become apparent that such a circulation has important consequences for other organ systems, particularly the liver and kidney. The adverse milieu created by chronic venous hypertension, low cardiac output, and an inflammatory state contribute to the pathologic changes observed in the liver and kidneys over the long term in Fontan patients. The clinical importance of these hepatic and renal comorbidities have only recently begun to be recognized in the context of increasing life expectancy in this population. The objectives of this review are to provide an overview of the pathophysiology of the Fontan circulation and how liver and kidney disease evolve in this setting; to summarize the current evidence base as it relates to the diagnostic approach to liver and kidney disease in Fontan patients; and to discuss the therapeutic approaches to Fontan- associated liver and kidney disease. Given that this is a very active area of research in congenital heart disease, we have identified knowledge gaps and priority research areas to improve the care of Fontan patients. These include establishing the optimal diagnostic tests to detect and track liver and kidney disease change over time, determining which treatable risk factors contribute to the development of liver and kidney disease, and evaluating therapies to prevent or slow progression of liver and kidney disease.     

Liver Nodules after the Fontan Operation: Role of Magnetic Resonance Elastography

Hepatic dysfunction after the Fontan surgical palliation runs an indolent course. Moreover, there is no standard method of evaluating hepatic dysfunction. Magnetic resonance elastography has emerged as an advanced screening tool for preclinical detection of hepatic fibrosis and cirrhosis. We describe the case of a patient who had undergone Fontan palliation, and then developed liver nodules and elevated tumor markers 18 years later. Her case illustrates the challenges in diagnostic management of hepatic dysfunction and the potential role of magnetic resonance elastography in monitoring these patients.