Evaluation and Management of the Child and Adult With Fontan Circulation: A Scientific Statement From the American Heart Association

Cardiopulmonary Exercise Test Interpretation Across the Lifespan in Congenital Heart Disease: A Scientific Statement From the American Heart Association

Survivorship from congenital heart disease has improved rapidly secondary to advances in surgical and medical management. Because these patients are living longer, treatment and disease surveillance targets have shifted toward enhancing quality of life and functional status. Cardiopulmonary exercise testing is a valuable tool for assessing functional capacity, evaluating cardiac and pulmonary pathology, and providing guidance on prognosis and interventional recommendations. Despite the extensive evidence supporting the ability of cardiopulmonary exercise testing to quantitatively evaluate cardiovascular function, there remains confusion on how to properly interpret cardiopulmonary exercise testing in patients with congenital heart disease. The purpose of this statement is to provide a lifespan approach to the interpretation of cardiopulmonary exercise testing in patients with congenital heart disease. This is an updated report of the American Heart Association's previous publications on exercise in children. This evidence-based update on the significance of cardiopulmonary exercise testing findings in pediatric, adolescent, and adult patients with various congenital cardiac pathologies and surgically modified physiology is formatted in a way to guide cardiopulmonary exercise testing interpretation practically for the clinicians and exercise physiologists who care for patients with congenital heart disease. Focus is placed on the indications for exercise testing, expected findings, and how exercise testing should guide the management of patients with various congenital heart disease subtypes. Areas for future intervention that could lead to improved care and outcomes for those with congenital heart disease are noted.

Over 100 Fontan Patients on Systemic Ventricular Assist Device Support: An ACTION Update

As the Fontan population grows, understanding successful strategies for ventricular assist device (VAD) support of the failing Fontan circulation is needed. We performed a retrospective analysis of patients with Fontan circulation and systemic VAD support in the Advanced Cardiac Therapies Improving Outcomes Network (ACTION) registry. Competing outcomes and Kaplan-Meier estimated survival methods were used. Between January 2012 and December 2022, 106 Fontan patients underwent VAD implant (median age 10 years, 20% age ≥18 years). At time of implant, 58% were on greater than or equal to 2 inotropes, 26% on extracorporeal membrane oxygenation (ECMO), and 41% intubated. Since 2018, there have been more patients implanted at INTERMACS profile 1 or 2 (88% vs. 71%, p = 0.02) and on inotropic support (95% vs. 76%, p = 0.01). Median duration of VAD support was 113 (interquartile range (IQR): 43-266) days. At 12 months post-VAD implant, 53% were transplanted, 27% were alive on device, 2% had successful recovery, and 18% had died. Overall, 75% experienced greater than or equal to 1 adverse event, with bleeding, infection, and neurologic dysfunction most common. Despite high acuity at the time of VAD implant and high rate of adverse events, the majority of Fontan patients were transplanted or still alive on device at 12 months post-VAD implant.

Native liver T1 mapping on magnetic resonance imaging for an evaluation of congestive liver injury in children with congenital heart disease

Fontan-associated liver disease (FALD) may be caused by chronic liver congestion due to high central venous pressure (CVP). Recently, the usefulness of liver native T1 mapping in magnetic resonance imaging (MRI) in adulthood has been reported. To evaluate the usefulness of native liver T1 mapping in children with congenital heart disease (CHD), we investigated the utility of native liver T1 relaxation time (LT1) in pediatric Fontan patients in comparison to other CHDs. Correlations between LT1 and laboratory biomarkers or hemodynamic data were also assessed. A total of 155 patients with CHD (biventricular repair, n = 42; bidirectional Glenn circulation, n = 38; and Fontan circulation, n = 75) underwent blood tests, cardiac catheterization, and cardiac MRI within 48 h. Both CVP and LT1 levels were higher in Fontan patients than in bidirectional Glenn and biventricular patients. There were significant correlation in the overall population and weak correlation in Fontan patients between CVP and LT1(correlation coefficient 0.644 [0.541-0.728] and 0.244 [0.0179-0.446], P < 0.001 and 0.035, respectively). Among the laboratory data, the multiple linear regression analysis revealed that the fibrosis-4 index and alanine aminotransferase were significantly correlated with LT1 in the overall population (P = 0.008,0.012), and the fibrosis-4 index was correlated with LT1 in Fontan patients (P = 0.019). LT1 might have some role to predict elevated CVP and liver injury in children with CHD.

The molecular mechanisms of cardiac development and related diseases

Cardiac development is a complex and intricate process involving numerous molecular signals and pathways. Researchers have explored cardiac development through a long journey, starting with early studies observing morphological changes and progressing to the exploration of molecular mechanisms using various molecular biology methods. Currently, advancements in stem cell technology and sequencing technology, such as the generation of human pluripotent stem cells and cardiac organoids, multi-omics sequencing, and artificial intelligence (AI) technology, have enabled researchers to understand the molecular mechanisms of cardiac development better. Many molecular signals regulate cardiac development, including various growth and transcription factors and signaling pathways, such as WNT signaling, retinoic acid signaling, and Notch signaling pathways. In addition, cilia, the extracellular matrix, epigenetic modifications, and hypoxia conditions also play important roles in cardiac development. These factors play crucial roles at one or even multiple stages of cardiac development. Recent studies have also identified roles for autophagy, metabolic transition, and macrophages in cardiac development. Deficiencies or abnormal expression of these factors can lead to various types of cardiac development abnormalities. Nowadays, congenital heart disease (CHD) management requires lifelong care, primarily involving surgical and pharmacological treatments. Advances in surgical techniques and the development of clinical genetic testing have enabled earlier diagnosis and treatment of CHD. However, these technologies still have significant limitations. The development of new technologies, such as sequencing and AI technologies, will help us better understand the molecular mechanisms of cardiac development and promote earlier prevention and treatment of CHD in the future.

Peak Oxygen Consumption Scaled to Body Composition Is Associated With Mortality and Morbidity in People With a Fontan Circulation

BACKGROUND

Peak oxygen consumption (peak V ̇ $$ \dot{\mathrm{V}} $$ O2) is traditionally scaled by body mass, but it is most appropriately scaled by fat-free mass. However, it is unknown whether peak V ̇ $$ \dot{\mathrm{V}} $$ O2 scaled by fat-free mass is associated with mortality and morbidity in people with a Fontan circulation. The aim of this study was to assess the associations between different expressions of peak V ̇ $$ \dot{\mathrm{V}} $$ O2 with mortality and morbidity in people with a Fontan circulation.

METHODS AND RESULTS

Eighty-seven participants (aged 24.1±7.3 years; 53% women) with a Fontan circulation completed a cardiopulmonary exercise test and a dual-energy x-ray absorptiometry scan. Cox proportional hazard regressions models assessed the association (hazard ratio [HR]) between different expressions of peak V ̇ $$ \dot{\mathrm{V}} $$ O2 with a composite outcome of Fontan failure (FF). Participants were followed up for a median of 6.5 years (95% CI, 6.4-6.9). Individuals experiencing FF (n=10/87) had a significantly lower absolute peak V ̇ $$ \dot{\mathrm{V}} $$ O2. In univariable models, peak V ̇ $$ \dot{\mathrm{V}} $$ O2 ratio scaled to body mass was not significantly associated with FF (HR, 0.91; P=0.111). However, peak V ̇ $$ \dot{\mathrm{V}} $$ O2 scaled by fat-free mass (HR, 0.90; P=0.020) or lean mass (HR, 0.90; P=0.017) was significantly and inversely associated with FF. These associations remained significant after adjusting for age, sex, and peak respiratory exchange ratio.

CONCLUSIONS

The association between peak V ̇ $$ \dot{\mathrm{V}} $$ O2 and FF is improved when scaled to measures of body composition. Applied clinically, a 1-unit increase in peak V ̇ $$ \dot{\mathrm{V}} $$ O2 scaled to fat-free mass or lean mass is associated with a ≈10% lower risk of FF.

Cardiac MRI Predictors of Arrhythmic Sudden Cardiac Events in Patients With Fontan Circulation

BACKGROUND

Among patients with congenital heart disease, those with single ventricles have the highest risk of early mortality. Sudden cardiac death is an important cause of death in this population. Understanding the risk factors for sudden cardiac events (SCE) in Fontan patients could improve prediction and prevention.

OBJECTIVES

The goal of this study was to determine the prevalence of SCE and risk factors for SCE in the Fontan population.

METHODS

The Fontan Outcomes Registry Using CMR Examinations (FORCE) is an international registry collecting clinical and imaging data on Fontan patients. SCE was defined as: 1) cardiac arrest from a shockable rhythm; 2) need for emergent cardioversion/defibrillation; or 3) documented sustained ventricular tachycardia. Univariate and multivariate Cox proportional hazards regression models estimated hazard ratios for predictors of SCE.

RESULTS

Our sample included 3,132 patients (41% female). The median age at first cardiac magnetic resonance was 14.6 years. SCE was experienced by 3.5% (n = 109) over a median follow-up time of 4.00 years. Of the 109 patients with SCE, 39 (36%) died. On multivariable analysis, NYHA functional class >II (HR: 4.91; P < 0.0001), history of protein-losing enteropathy/plastic bronchitis (HR: 2.37; P = 0.0082), single-ventricle end-diastolic volume index >104 mL/m2 (HR: 3.15; P < 0.0001), and ejection fraction <50% (HR: 1.73; P = 0.0437) were associated with SCE. Kaplan-Meier analysis demonstrated that in patients with none of the above risk factors, the 4-year freedom from SCE was 99.5%.

CONCLUSIONS

SCE occurred in 3.5% of the study population, and one-third of patients who experienced SCE died. Mild ventricular dysfunction and dilatation by cardiac magnetic resonance, NYHA functional class, and history of protein-losing enteropathy/plastic bronchitis were associated with SCE.

Transcatheter Interventions in Adults With Fontan Palliation

The Fontan circuit is associated with chronically elevated systemic venous pressures and decreased cardiac output, often leading to circuit failure. Managing Fontan circuit failure is complex and requires multiple therapeutic options. Transcatheter interventions have emerged as a reliable approach. They can alleviate obstructions and improve cyanosis by enhancing pulmonary blood flow and oxygen saturation. These procedures can also increase cardiac output and reduce systemic venous pressure, contributing to patient stabilization. In addition, they help mitigate volume overload and decrease the risk of bleeding during heart or combined heart and liver transplants. In recent years, percutaneous interventions have rapidly evolved and become a key therapeutic option for addressing various aspects of Fontan circuit failure. These interventions should be considered integral to the management strategy for this specific patient population.

Deterioration in Renal Function in Patients With a Fontan Circulation and Association With Mortality

Background

Renal dysfunction is a well-established risk factor in cardiovascular disease, but little is known about the prevalence and factors associated with deterioration in renal function in patients with a Fontan circulation.

Objectives

The purpose of the study was to investigate the course and factors associated with deterioration in renal function in patients with a Fontan circulation and its association with mortality.

Methods

This is a longitudinal study of patients with a Fontan circulation (n = 82), in which creatinine-based estimated glomerular filtration rate (eGFRcr) was measured over an 11-year time period. Cystatin C and N-terminal prohormone of brain natriuretic peptide (NT-proBNP) levels were measured at baseline. Renal dysfunction was defined as an eGFR <90 ml/min/1.73 m2. Factors associated with annual change in eGFRcr were investigated with linear mixed-effect models and compared with data from a healthy Dutch cohort. The primary endpoint for the survival analyses was all-cause mortality. Associations between repeated eGFRcr levels and the primary endpoint were assessed using a joint model.

Results

The median age at baseline was 20 years (IQR: 14-27 years). Twelve percent of the cohort had renal dysfunction based on eGFRcr and 24% based on cystatin C-based eGFRcys. During follow-up, eGFRcr deteriorated on average by 1.36 ml/min/1.73 m2/year, which is faster than the healthy cohort. Higher baseline NT-proBNP z-scores were associated with a more rapid decline in eGFRcr. A larger decline in eGFRcr was associated with all-cause mortality.

Conclusions

Declines in eGFRcr in patients with Fontan circulation are more rapid than in healthy individuals. Higher baseline NT-proBNP z-scores are associated with a more rapid deterioration of eGFRcr, and eGFRcr deterioration is associated with mortality.

Central Venous Waveform Patterns in the Fontan Circulation Independently Contribute to the Prediction of Composite Survival

It is well appreciated that the Fontan circulation perturbs central venous hemodynamics, with elevated pressure being the clearest change associated with Fontan comorbidities, such as Fontan-associated liver disease (FALD) and protein-losing enteropathy (PLE). Our group has better quantity of these venous perturbations through single- and multi-location analyses of flow waveforms obtained from magnetic resonance imaging of Fontan patients. Here, we determine if such analyses, which yield principal components (PC) that describe flow features, are associated with Fontan survival. Patients with a Fontan circulation (N = 140) that underwent free-breathing and mechanically ventilated cardiac MRI were included in this study. Standard volumetric and functional hemodynamics, as well as flow analysis principal components, were subjected to univariate and bivariate Cox regression analyses to determine composite clinical outcome, including plastic bronchitis, PLE, and referral and receipt of transplant. Unsurprisingly, ventricular function measures of ejection fraction (EF; HR = 0.88, p < 0.0001), indexed end-systolic volume (ESVi; HR 1.02, p < 0.0001), and indexed end-diastolic volume (EDVi; HR = 1.02, p = 0.0007) were found as specific predictors of clinical events, with specificities uniformly > 0.75. Additionally a feature of IVC flow (PC2) indicating increased flow in systole was found as a highly sensitive predictor (HR = 0.851, p = 0.027, sensitivity 0.93). In bivariate prediction, combinations of ventricular function (EF, ESVi, EDVi) with this IVC flow feature yielded best overall prediction of composite outcome. This suggests that central venous waveform analysis relays additional information about Fontan patient survival and that coupling sensitive and specific measures in bivariate analysis is a useful approach for obtaining superior prediction of survival.

Functional Capacity Assessment in Adults After Fontan Palliation: A Cardiopulmonary Exercise Test-Invasive Exercise Hemodynamics Correlation Study

Although cardiopulmonary exercise testing (CPET) parameters have known prognostic value in adults after Fontan palliation, there are limited data correlating treadmill CPET with invasive exercise hemodynamics. Furthermore, the invasive hemodynamic underpinnings of exercise limitations have not been thoroughly investigated. This is a retrospective analysis of 55 adults (age ≥18 years) with prior Fontan palliation who underwent treadmill CPET before invasive exercise hemodynamic testing using a supine cycle protocol between November 2018 and April 2023. The median age was 32.2 (IQR 24.1; 37.2) years. The peak heart rate (HR) was 139.7 ± 28.1 beats per minute and the peak oxygen consumption (VO2) was 19.1 ± 5.7 ml/kg/min (47.4 ± 13.5% predicted). VO2/HR was directly related to exercise stroke volume index (r = 0.50, p = 0.0002), whereas no association was seen with exercise arterio-mixed venous O2 content difference (r = 0.14, p = 0.32). Peak HR was inversely related to exercise pulmonary artery (PA) pressures (r = -0.61, p <0.0001) and PA wedge pressures (PAWP) (r = -0.61, p <0.0001). Moreover, %predicted VO2 was inversely related to exercise PA pressures (r = -0.50, p <0.0001) and PAWP (r = -0.55, p <0.0001). Peak VO2 ≤19.1 ml/kg/min had a sensitivity of 81% and a specificity of 76% (area under the curve 0.82) for predicting a ΔPAWP/ΔQs ratio >2 mmHg/L/min and/or a ΔPA/ΔQp >3 mmHg/L/min, whereas a predicted peak VO2 ≤48% had a sensitivity of 74% and a specificity of 81% (area under the curve 0.79) for the same parameters. In summary, lower peak HR and peak VO2 were associated with higher exercise PAWP and PA pressure. Peak VO2 ≤48% predicted provided the optimal cutoff for predicting increased indexed exercise PAWP or PA pressures; therefore, low peak VO2 should alert clinicians of abnormal underlying hemodynamics.

Biomechanics and clinical implications of Fontan upsizing

BACKGROUND

The Fontan operation, a palliative procedure for single ventricle patients, has evolved to improve outcomes and reduce complications. While extracardiac conduit (ECC) is favored for its simplicity and potential hemodynamic benefits, concerns arise about conduit size adequacy over time. Undersized ECC conduits may cause hemodynamic inefficiencies and long-term complications, while oversizing can lead to flow disturbances, stagnation, and thrombosis, necessitating surgical revision or upsizing to optimize hemodynamics.

OBJECTIVES

The study aimed to predict the impact of upsizing by developing a patient-specific workflow using cardiac magnetic resonance-based imaging and computational fluid dynamics to assess Fontan hemodynamic changes and determine the most optimal conduit size.

METHODS

We simulated upsizing in patient-specific models, computing reduction in power loss (PL), and analyzed pressure gradients, wall shear stress (WSS), and other local flow dynamic parameters such as vorticity and viscous dissipation that influence PL in a Fontan. Additionally, we quantified the impact of upsizing on hepatic flow distribution (HFD).

RESULTS

Across the patient cohort, upsizing resulted in a PL reduction of 16 %-63 %, with the greatest reduction observed in patients with the smallest pre-existing conduit sizes (14 mm). The optimal conduit size for minimizing PL was highly patient-specific. For instance, a 20 mm conduit reduced PL by 63 % in one patient, while another patient showed 16 % reduction with upsizing. Pressure gradients decreased by 15 %-35 %, correlating with the reduction in PL, while WSS decreased consistently with upsizing. Vorticity and viscous dissipation exhibited more variability but followed the overall trend of reduced PL. HFD changes were modest with a maximum variation of 30 %.

CONCLUSIONS

Our findings underscore the importance of individualized approaches in Fontan conduit upsizing. CFD-based quantitative evaluations of PL, pressure gradients, HFD, and WSS can guide optimal conduit sizing, improving long-term outcomes for patients.

Feasibility, classification and potential clinical impact of non-invasive delineation of abdominal lymphatic vessels in patients following TCPC with T2 weighted MRI

Recent research in patients with functionally univentricular hearts (UVH) is focusing on pathologies of the lymphatic vessels. Morphology of the abdominal lymphatic vessels was analyzed by MRI in patients with UVH following total cavopulmonary connection (TCPC) and it was examined, if clinical and laboratory parameters correlate with changes after TCPC. We prospectively examined 33 patients at the age of 19.8 (14.6;30.2) years [median (Q1;Q3)] after TCPC (follow-up 14.3 years (9.7;24.9) with a heavily T2-weighted MRI sequence on a 3.0 T scanner. Examinations in coronal orientation were performed with respiratory gating, slice thickness 0.6 mm, TR 2400 ms, TE 692 ms, FoV 460 mm (covering thoracic and abdominal regions), scan time 14:41 min (13:18;16:30) after a solid meal and a cup of pineapple juice. The findings were classified according to delineation of abdominal lymphatic vessels. Type 1: <3 abdominal vessels (av) definable; type 2: 4-6 av definable; type 3: >6 av and/or oedematous changes or ascites. The results were correlated with parameters obtained at the annual routine check-up. Statistical analysis was performed using U-test and Chi-square test. Fifteen patients (group 1) showed type 3 lymphatic morphologies, two of which had ascites. Eighteen patients (group 2) showed lower grade morphologies (type 1-2). Image quality was rated considering the delineation of the common hepatic duct and did not differ between groups (p = 0.134). "Lymphatic burden" was automatically examined and was indexed to the number of delineated abdominal vessels and showed quantification according to the chosen categories type 1-3. Patients in group 1 were younger at MRI examination (17.4;14.3/18.9 vs. 26.2;18.2/32.3 years, p = 0.03). Superior cavopulmonary connection (SCPC) had been performed earlier in group 1 (9.9;7.9/25.5 vs. 29.2;13.7/66.6 months, p = 0.018). Laboratory examinations in group 1 showed lower levels for Immunoglobulin G (IgG), Lipase, α-Antitrypsin, Cystatin C and TSH. There were no significant differences for total protein, NTproBNP, lymphocytes or platelets. A history of chylothorax was present in 7/15 versus 2/18 p = 0.022. Protein-losing enteropathy (PLE) occurred in 4/15 versus 1/18 (p = 0.092). T2 weighted MRI is feasible for noninvasive delineation of abdominal lymphatic vessel in patients following TCPC. In the long-term follow-up, patients with more pronounced changes of the abdominal lymphatic vessels were younger at SCPC and were more likely to show a history of chylothorax and lower IgG values.

Association between warfarin use and thromboembolic events in patients post-Fontan operation: propensity-score overlap weighting analyses

OBJECTIVES

The appropriate antithrombotic regimen after a Fontan operation is yet to be elucidated. Hence, this study aimed to compare the incidence of thromboembolic events in patients with and without receiving warfarin for thromboprophylaxis in a large post-Fontan population.

METHODS

This retrospective cohort study used data from the Diagnosis Procedure Combination database in Japan between April 2011 and March 2022. We identified all patients who underwent a Fontan operation and excluded those who were born before 2010, died during the hospitalization or received mechanical heart replacement. Propensity score overlap weighting was performed between patients discharged with warfarin (with or without aspirin) and the control group (only aspirin or neither aspirin nor warfarin). Cox and Fine-Gray hazards models compared thromboembolic and bleeding events.

RESULTS

We identified 2007 eligible patients, including 1670 warfarin users and 337 non-users. The mean follow-up duration was 2.1 years. The crude proportions of thromboembolic events were 3.0% and 3.0% and those of bleeding events were 0.4% and 0.3% in the warfarin and control groups, respectively. There was no significant difference in thromboembolic events between the groups (sub-distribution hazard ratio: 0.77; 95% confidence interval 0.39-1.51; P = 0.45) or bleeding events (sub-distribution hazard ratio: 0.78; 95% confidence interval 0.09-7.03; P = 0.83).

CONCLUSIONS

Warfarin use at discharge after a Fontan operation may not be necessary for thromboembolism prophylaxis in paediatric patients, based on large-scale real-world data, with a mean postoperative follow-up duration of 2.1 years. There is room for further studies to reconsider routine warfarin use in patients post-Fontan operation.

Surgical valve replacement in adults late after total cavo-pulmonary connection/Fontan procedure

OBJECTIVES

There is dearth of data on long-term outcomes of systemic semilunar (SS) or atrioventricular (AV) valve operation in adult patients with a Fontan circulation. We describe a single-centre experience of adults who underwent valve surgery late after a Fontan procedure.

METHODS

We retrospectively reviewed all patients with a Fontan circulation who had a reoperation for severe valve disease during adulthood in our centre. Demographic, anatomical, clinical and periprocedural data and long-term outcome were retrospectively retrieved from our dedicated electronic hospital database and examined.

RESULTS

Out of 233 adults with a Fontan operation, 8 (7 males [88%]) had valve surgery during the study period. Indication for surgery was severe symptomatic valve regurgitation in all patients (of the SS valve in seven cases and of the left AV valve in 1). Mechanical prosthesis was implanted in all cases. At a median follow-up of 10 years (interquartile range 5-20), one patient died due to hepatitis C virus infection. All the remaining 7 patients experienced a significant improvement of the New York Heart Association class compared to the pre-operative state (P = 0.015); echocardiography showed stable systemic ventricle ejection fraction in absence of volume overload (50.1 ± 7.9% vs 51.6 ± 8.7%, P = 0.399) and well-functioning prostheses. No patient needed further operation nor heart transplantation.

CONCLUSIONS

Surgical SS valve replacement late after a Fontan operation in highly selected adult patients with valvular regurgitation performed in a tertiary dedicated centre resulted to be safe in our population and conveyed clinical benefit. Close monitoring of all Fontan patients developing valvular dysfunction is warranted, whereas future prospective research may refine selection criteria, optimal timing and outcomes.

Evaluation of diagnostic criteria for mild-to-advanced stages of Fontan-associated liver disease: A nationwide epidemiological survey in Japan

AIM

Fontan-associated liver disease (FALD) is a complication after Fontan surgery, and a common cause of liver tumors and cirrhosis. However, no diagnostic criteria for FALD have been established, leading to an underestimation of its prevalence.

METHODS

We conducted a national survey to elucidate the characteristics of FALD by collecting data from high-volume centers managing patients who had undergone the Fontan surgery in Japan. In total, 1168 patients were enrolled in the study. First, we examined typical liver findings on ultrasonography after the Fontan surgery. Next, we proposed diagnostic criteria for FALD and advanced FALD based on blood tests, imaging, liver tumors, and pathological examinations. We investigated the sensitivity of histologically diagnosed FALD and advanced FALD based on criteria for blood or imaging tests.

RESULTS

Hepatomegaly, hepatic venous dilatation, caudate lobe enlargement, splenomegaly, liver atrophy, ascites, hepatocellular carcinoma, and hepatic tumors other than hepatocellular carcinoma were observed in 37.7%, 29.9%, 18.4%, 33.2%, 3.2%, 6.0%, 0.85%, and 10.0% of patients, respectively. Typical ultrasound findings of FALD included hepatomegaly, hepatic vein dilatation, and splenomegaly, reflecting liver congestion. With the progression of fibrosis, caudate lobe enlargement and splenomegaly became more prominent. Based on these findings, we proposed diagnostic criteria for FALD. Using these criteria, FALD was diagnosed in 1014 (86.8%) of the patients, and all patients with a pathological diagnosis of FALD were successfully identified. Eight patients were found to have pathological cirrhosis, and all were diagnosed with advanced FALD using our criteria based on blood tests or imaging.

CONCLUSION

Our diagnostic criteria facilitate detection of FALD or advanced FALD after the Fontan surgery. The accuracy of these criteria should be further evaluated.

Clinical impact of novel cardiovascular magnetic resonance technology on patients with congenital heart disease: a scientific statement of the Association for European Pediatric and Congenital Cardiology and the European Association of Cardiovascular Imaging of the European Society of Cardiology

Cardiovascular magnetic resonance (CMR) imaging is recommended in patients with congenital heart disease (CHD) in clinical practice guidelines as the imaging standard for a large variety of diseases. As CMR is evolving, novel techniques are becoming available. Some of them are already used clinically, whereas others still need further evaluation. In this statement, the authors give an overview of relevant new CMR techniques for the assessment of CHD. Studies with reference values for these new techniques are listed in the Supplementary data online, supplement.

Lymphatic Disorder Management in Pediatric Patients With Congenital Heart Disease in European Pediatric Cardiology Centers: Current Status, Disparities, and Future Considerations

BACKGROUND

Lymphatic disorders such as protein-losing enteropathy, plastic bronchitis, and chylothorax are important complications of the Fontan circulation and ultimately result in an increased risk of early death. Several European centers are now performing lymphatic procedures. The aim of this study is to map the extent of these lymphatic disorders and treatments provided across European pediatric cardiology centers.

METHODS AND RESULTS

A survey was circulated to 49 European pediatric cardiology centers consisting of 37 questions including a mix of binary, categorical, and continuous variables. Thirty-one centers (63%) participated in the study, performing a median of 250 (interquartile range, 178 - 313) cardiopulmonary bypass procedures per year. Chylothorax emerged as the most prevalent lymphatic disorder followed by protein-losing enteropathy and plastic bronchitis. The most common diagnostic investigation method was noncontrast magnetic resonance lymphangiography (52%). Eleven centers (35%) conducted lymphatic interventions with a median of 3 (interquartile range, 1 - 4) procedures per year and 12 (interquartile range, 5 - 15) interventions in total per center.

CONCLUSIONS

This study confirms the rarity of and variation in treatment approaches for lymphatic disorders across Europe. With at least 11 centers offering lymphatic interventions, the adoption of these procedures is on the rise in Europe. To improve the quality of care and treatment outcomes for these complex patients, it is crucial to consider evidence-based lymphatic diagnostics, interventional lymphatic procedures, and the centralization of services in Europe.

Pregnancy in women with a Fontan circulation: Short and long-term outcomes

BACKGROUND

The Fontan circulation procedure is the palliative surgery of choice for patients with single ventricle physiology, many of whom are now reaching childbearing age due to advances in care. Our study examines the impact of pregnancy on women with Fontan circulation, assessing both short and long-term outcomes.

METHODS

We retrospectively analysed pregnancies in women with Fontan circulation at our centre from 2005 to 2023, including a matched non-pregnant, nulliparous cohort for comparison. Pregnancies lost before 18 weeks were analysed separately.

RESULTS

Among 26 pregnancies in 18 women, preterm births were common (73.1%), with 3 fetal losses and no maternal deaths. Neonatal complications included a 50% incidence of babies small for gestational age (SGA). Cardiac events occurred in 19.2% of pregnancies, primarily supraventricular arrhythmias, and 23% experienced postpartum haemorrhage. Over a median 6.1 [5.2-10.6]-year follow-up, no deaths, heart failure (HF), or Fontan-associated liver disease (FALD) developed, and functional status remained stable.

CONCLUSIONS

Women with a Fontan-type circulation undergoing pregnancy had a few serious maternal cardiac events, though there was a high rate of post-partum haemorrhage. The rates of neonatal complications, particularly related to restricted growth and pre-term birth, were also high. Our findings indicate a generally positive medium-term outlook for these patients, though the impact of pregnancy on long-term survival remains unclear. Careful selection of patients with Fontan circulation during pre-pregnancy counselling may help to reduce complications during and after pregnancy.

MYH6 Variants Are Associated with Atrial Dysfunction in Neonates with Hypoplastic Left Heart Syndrome

Background: MYH6 variants are the most well-known genetic risk factor (10%) for hypoplastic left heart syndrome (HLHS) and are associated with decreased cardiac transplant-free survival. MYH6 encodes for α-myosin heavy chain (α-MHC), a contractile protein expressed in the neonatal atria. We therefore assessed atrial function in HLHS patients with MYH6 variants. Methods: We performed a retrospective, blinded assessment of pre-stage I atrial function using 2D speckle-tracking echocardiography (2D-STE). Variant carriers were control-matched based on AV valve anatomy, sex, and birth year. Studies were obtained postnatally from awake patients prior to surgical intervention. Right atrial (RA) and right ventricular (RV) strain and strain rate (SR) were measured from the apical four-chamber view. Results: A total of 19 HLHS patients with MYH6 variants had echocardiograms available; 18 were matched to two controls each, and one had a single control. RA active strain (ASct) was decreased in variant carriers (-1.41%, IQR -2.13, -0.25) vs. controls (-3.53%, IQR -5.53, -1.28; p = 0.008). No significant differences were identified in RV strain between the groups. RA reservoir strain (ASr) and conduit strain (AScd) positively correlated with heart rate (HR) in MYH6 variant carriers only (ASr R = 0.499, p = 0.029; AScd R = 0.469, p = 0.043). RV global longitudinal strain (GLS) as well as RV systolic strain (VSs) and strain rate (VSRs) correlated with HR in controls only (GLS R = 0.325, p = 0.050; VSs R = 0.419, p = 0.010; VSRs R = 0.410, p = 0.012). Conclusions: We identified functional consequences associated with MYH6 variants, a known risk factor for poor outcomes in HLHS. MYH6 variant carriers exhibit impaired RA contractility despite there being no differences in RV function between variant carriers and controls. MYH6 variants are also associated with an ineffective RA reservoir and conduit function at high heart rates, despite preserved RV diastolic function. RA dysfunction and reduced atrial "kick" may therefore be a significant contributor to RV failure and worse clinical outcomes in HLHS patients with MYH6 variants.

Chemical Cardioversion of Atrial Arrhythmias with Ibutilide in Children and Adults with Congenital Heart Disease

There is a dearth of systematic data on efficacy and safety of ibutilide in children and adults with CHD and also in pediatric age-group patients. To determine the efficacy and safety of ibutilide in these populations, and to characterize the determinants of its efficacy. Patients with CHD and children < 18 years old with structurally normal hearts were recruited between Jan 1, 2010 and Dec 1, 2020. Logistic regression models were used to determine the effect of covariates on odds of successful cardioversion with ibutilide. 53 patients underwent 105 chemical cardioversions (age: 27.5 ± 10.4 years [75% males], 80% atrial flutter) with ibutilide during the study period. The overall rate of successful cardioversion with ibutilide in our cohort was 70.4% (mean ibutilide dose: 1.5 ± 0.65 mg). Presentation in atrial flutter (P = 0.08) and male gender (0.07) showed a trend towards significance. Adverse effects were reported after 8 ibutilide administrations (7.6%, n = 6/8 [75%] female).

Magnetic resonance elastography is useful to determine the severity of liver fibrosis according to liver biopsy in post-fontan patients

OBJECTIVE

The reliability of various modalities for assessing and monitoring Fontan-associated liver disease compared to liver biopsy remains an intriguing subject of inquiry. Our objective was to assess the efficacy of multiple modalities in comparison to liver histology for evaluating liver fibrosis in post-Fontan patients.

METHODS

We conducted a cross-sectional study involving Fontan patients without known liver disease. Eligible patients underwent cardiac and hepatic evaluations, including ultrasound liver elastography, magnetic resonance elastography (MRE) of the liver, computerized tomography (CT) scan of the upper abdomen, echocardiography, cardiac catheterization, and liver biopsy. The severity of liver fibrosis was categorized using the METAVIR score derived from liver biopsy results: F0/F1 indicated no or mild fibrosis, F2 indicated significant fibrosis, F3 indicated advanced fibrosis and F4 indicated cirrhosis.

RESULTS

A total of 38 patients (mean age 21 ± 6.5 years, 52.6% female) were included in the cross-sectional study, with a mean time elapsed since the Fontan operation of 13 years. Parameters obtained from echocardiography, ultrasound liver elastography, and CT scan of the upper abdomen did not exhibit significant differences among the groups. Notably, liver biopsy revealed advanced cirrhosis in 23 out of 38 patients and none were diagnosed with hepatocellular carcinoma. Multivariate logistic regression analysis demonstrated that the factor significantly associated with significant liver fibrosis or cirrhosis in post-Fontan patients was liver stiffness with MRE > 4.4 kPa [OR 13.5 (95% CI 1.2-152.2)].

CONCLUSIONS

Our findings suggest that post-Fontan patients with liver stiffness of MRE > 4.4 kPa should undergo further investigation. These results contribute to understanding the liver fibrosis assessment in post-Fontan patients and highlight the importance of MRE in predicting significant liver disease.

Defining the causes for Fontan circulatory failure in total cavopulmonary connection patients

OBJECTIVES

This study aims to identify the causes of failure in Fontan patients with a total cavopulmonary connection.

METHODS

We conducted a comprehensive review of all patients who underwent a total cavopulmonary connection procedure at our centre between 1988 and 2023, aiming to identify and analyse the factors contributing to Fontan failure (defined as mortality, heart transplantation, Fontan takedown, protein-losing enteropathy, plastic bronchitis or New York Heart Association Functional Classification class III or IV).

RESULTS

The study included 217 patients (median age at time of Fontan completion 3.7 years) with a median follow-up of 12.7 years (interquartile range 7.2-17.7). Systolic ventricular function decreased significantly over time in patients with right ventricular dominant morphology (P = 0.002), while systolic ventricular function remained stable in patients with left ventricular dominant morphology. Fontan failure occurred in 24 patients, with estimated freedom from Fontan failure rates of 97.7% [95% confidence interval (CI), 95-99] at 1 year, 93.9% (95% CI, 89-97) at 15 years and 77.2% (95% CI, 65-86) at 20 years of follow-up. Systolic ventricular dysfunction was the most common cause of failure (29%), followed by atrioventricular valve regurgitation (16.7%), a high pulmonary vascular resistance (16.7%), restrictive pathophysiology (16.7%) and obstruction (12.5%). Patients with right ventricular dominance developed most often systolic ventricular dysfunction, while patients with left ventricular dominant morphology developed most often restrictive pathophysiology or a high pulmonary vascular resistance.

CONCLUSIONS

Approximately 10% of patients experienced Fontan failure within 15 years postoperatively. Patients with right ventricular dominance experienced progressive decline due to systolic dysfunction, while those with left ventricular dominance exhibited failure due to restrictive pathophysiology or high pulmonary vascular resistance.

Associations Between Exercise Capacity and Psychological Functioning in Children and Adolescents with Fontan Circulation

Individuals with Fontan circulation (FC) often have diminished exercise capacity and are at risk for psychological problems. The current study examines associations between exercise capacity and psychological functioning in children and adolescents with FC. A multidisciplinary team evaluated participants in a clinic for pediatric patients with FC. Participants completed cardiopulmonary exercise testing (CPET). Parent and child were administered a psychological questionnaire (BASC-3) to measure child depression, anxiety, and inattention symptoms. Individuals who completed CPET with adequate effort and a psychological measure were eligible for inclusion. Clinical sample (n = 51) was 55% male with a mean age of 13.6 years (SD = 2.5). A majority had hypoplastic left heart syndrome (51%). Parent-report of inattention was negatively correlated with peak VO2 (R =  - .307, 95% CI - .549/ - .018, P = 0.038). Self-report of anxiety was positively correlated with HR recovery at 3 (R = .438, 95% CI .155/.655, P = 0.004) and 8 (R = .432, 95% CI .147/.651, P = 0.004) minutes post exercise. Depression was positively correlated with HR recovery at 3 min for parent-report (R = .294, 95% CI .004/.538, P = 0.047) and 8 min for self-report (R = .410, 95% CI .122/.635, P = 0.007). Greater inattention may have negatively impacted CPET engagement, reflected in lower peak VO2. The more rapid decline from max HR to recovery for those with greater depression and anxiety symptoms was unexpected, perhaps explained by a reduction in anxiety state after exercise or possibly an age effect, as a blunted HR decline has been found in adult cardiac patients with depression/anxiety.

Cardiac Rehabilitation for Fontan Circulation Patients: A Systematic Review, and Meta-Analysis

Background and Objectives: Despite advances in the surgical management of patients with Fontan circulation, their exercise capacity and quality of life remain significantly impaired. Exercise-based cardiac rehabilitation (CR) offers promising improvements in these areas, but the implementation and adherence to these programmes are often inconsistent. This systematic review and meta-analysis aimed to evaluate the safety, efficacy, and optimal exercise modalities for Fontan patients. Materials and Methods: A systematic search of PubMed, Scopus, Web of Science, and Cochrane Library was conducted on 24 August 2023. Studies were screened and assessed for quality using the Cochrane RoB Tool 2 and STROBE checklist. Meta-analysis was performed using a continuous random-effects model to determine the effectiveness of various CR interventions, including aerobic exercise training (AET), resistance training, and inspiratory muscle training (IMT). Results: A total of 26 studies (7 RCTs, 19 cohorts) comprising 22 distinct cohorts were included, with a total sample size of 428 Fontan patients. The interventions ranged from 4 weeks to 24 months and included AET (18 studies), resistance training (11 studies), and IMT (6 studies). The meta-analysis revealed significant improvements in exercise capacity, with a pooled mean difference in peak VO2 of 1.947 (95% CI: 1.491 to 2.402, p < 0.001). Subgroup analyses showed that combined AET and resistance training had the most robust effect, with a mean difference of 2.11 (95% CI: 1.57 to 2.65, p < 0.001). Home-based interventions showed significant benefits, while supervised and hybrid interventions did not show statistically significant differences. Publication bias was identified, particularly in home-based interventions, where smaller studies demonstrated larger effect sizes, as confirmed by Egger's test (Intercept = 2.417, 95% CI: 1.498 to 3.337, p = 0.001). However, no significant bias was detected in supervised or hybrid interventions, which displayed symmetrical distributions in funnel plots and non-significant Egger's test results. Conclusions: CR appears to be an effective intervention for improving exercise capacity in Fontan patients, particularly when combining AET with resistance training. Home-based programmes offer promising results, though the potential for publication bias, especially in smaller studies, warrants cautious interpretation of these findings. Further research is needed to refine protocols, explore long-term outcomes, and determine the underlying mechanisms, particularly for patients with more severe clinical presentations. The low incidence of adverse events across the studies reinforces the safety of these interventions.

The neo-aortic valve in patients with hypoplastic left heart syndrome is largely preserved: a serial follow-up CMR study

Background

In hypoplastic left heart syndrome (HLHS) patients, neo-aortic valve regurgitation can negatively impact right ventricular (RV) function. We assessed neo-aortic valve function and RV volumetric parameters by analysing serial cardiovascular magnetic resonance (CMR) studies in HLHS patients after completion of total cavopulmonary connection (TCPC).

Methods

Consecutive CMR examinations of 80 patients (female: 22) with two (n = 80) or three (n = 45) examinations each were retrospectively analysed. RV volumetry was performed using short-axis cine images. RV end-diastolic and end-systolic volumes normalised to body surface area (BSA, RVEDVi, RVESVi), ejection fraction (RVEF) and stroke volume (RVSV) were measured. Neo-aortic flow, regurgitant fraction (RF) and peak velocity were quantified from phase-contrast cine images.

Results

Median neo-aortic regurgitation was mild at all three examinations (RF <20%) and there was no significant increase in RF over time (p > 0.05). None of the patients had significant neo-aortic valve stenosis (peak velocity >3 m/s). RF correlated with RVESVi and RVEF at the second examination. At the third examination, RF correlated with RVESVi and RVEDVi even in patients with RF <15% (RVESVi: r = 0.40, p = 0.001; RVEDVi: r = 0.34, p = 0.031).

Conclusion

Assessment of serial CMR studies in HLHS patients after TCPC completion demonstrates a preserved neo-aortic valve function. Nevertheless, thorough follow-up is mandatory as even mild neo-aortic dysfunction might impact RV size and function over a longer term.

Effects of systemic ventricular assist in failing Fontan patients: a theoretical analysis using a computational model

Mechanical circulatory support is a potential treatment for failing Fontan patients. In this study, we performed a theoretical analysis using a computational model to clarify the effects of systemic ventricular assist device (VAD) in failing Fontan patients. Cardiac chambers and vascular systems were described using the time-varying elastance model and modified Windkessel model, respectively. A VAD was simulated as a nonlinear function. In systolic and diastolic ventricular dysfunction and atrioventricular valve regurgitation models, systemic VAD increased the cardiac index and decreased the central venous pressure (CVP). However, in the high pulmonary vascular resistance model, CVP became extremely high above 15 mmHg to maintain the cardiac index when the pulmonary vascular resistance index (PVRI) was above 5 Wood units m2. In Fontan patients with ventricular dysfunction or atrioventricular valve regurgitation, systemic VAD efficiently improves the hemodynamics. In Fontan patients with PVRI of > 5 Wood units m2, systemic VAD seems ineffective.

The impact of blood viscosity modeling on computational fluid dynamic simulations of pediatric patients with Fontan circulation

For univentricular heart patients, the Fontan circulation presents a unique pathophysiology due to chronic non-pulsatile low-shear-rate pulmonary blood flow, where non-Newtonian effects are likely substantial. This study evaluates the influence of non-Newtonian behavior of blood on fluid dynamics and energetic efficiency in pediatric patient-specific models of the Fontan circulation. We used immersed boundary-lattice Boltzmann method simulations to compare Newtonian and non-Newtonian viscosity models. The study included models from twenty patients exhibiting a low cardiac output state (cardiac index of 2 L/min/m2). We quantified metrics of energy loss (indexed power loss and viscous dissipation), non-Newtonian importance factors, and hepatic flow distribution. We observed significant differences in flow structure between Newtonian and non-Newtonian models. Specifically, the non-Newtonian simulations demonstrated significantly higher local and average viscosity, corresponding to a higher non-Newtonian importance factor and larger energy loss. Hepatic flow distribution was also significantly different in a subset of patients. These findings suggest that non-Newtonian behavior contributes to flow structure and energetic inefficiency in the low cardiac output state of the Fontan circulation.

Impact of Atrioventricular Valve Intervention at Each Stage of Single Ventricle Palliation

Background: Significant atrioventricular valve dysfunction can be associated with mortality or need for transplant in functionally univentricular heart patients undergoing staged palliation. The purposes of this study are to characterize the impact of concomitant atrioventricular valve intervention on outcomes at each stage of single ventricle palliation and to identify risk factors associated with poor outcomes in these patients. Methods: The Society of Thoracic Surgeons Congenital Heart Surgery Database was queried for functionally univentricular heart patients undergoing single ventricle palliation from 2013 through 2022. Separate analyses were performed on cohorts corresponding to each stage of palliation (1: initial palliation; 2: superior cavopulmonary anastomosis; 3: Fontan procedure). Bivariate analysis of demographics, diagnoses, comorbidities, preoperative risk factors, operative characteristics, and outcomes with and without concomitant atrioventricular valve intervention was performed. Multiple logistic regression was used to identify predictors associated with operative mortality or major morbidity. Results: Concomitant atrioventricular valve intervention was associated with an increased risk of operative mortality or major morbidity for each cohort (cohort 1: 62% vs 46%, P < .001; cohort 2: 37% vs 19%, P < .001; cohort 3: 22% vs 14%, P < .001). Black race in cohort 1 (odds ratio [OR] 3.151, 95% CI 1.181-9.649, P = .03) and preterm birth in cohort 2 (OR 1.776, 95% CI 1.049-3.005, P = .032) were notable predictors of worse morbidity or mortality. Conclusions: Concomitant atrioventricular valve intervention is a risk factor for operative mortality or major morbidity at each stage of single ventricle palliation. Several risk factors are associated with these outcomes and may be useful in guiding decision-making.

Perioperative Management of Pediatric Combined Heart and Liver Transplantation: A 17 year single center experience

BACKGROUND

An increasing number of centers are undertaking combined heart and liver transplantation in adult and pediatric patients with congenital heart disease.

AIM

The primary aim of this study was to describe the perioperative management of a single center cohort, identifying challenges and potential solutions.

METHODS

We conducted a retrospective review of all patients undergoing combined heart and liver transplantation at Stanford Children's Hospital from 2006 to 2022. Preoperative information included cardiac diagnosis, hemodynamics, and severity of liver disease. Intraoperative data included length of surgery, cardiopulmonary bypass time, and blood products transfused. Postoperative data included blood products transfused in the intensive care unit, time to extubation, length of intensive care unit stay, survival outcomes and 30-day adverse events.

RESULTS

Eighteen patients underwent en bloc combined heart and liver transplantation at Stanford Children's Hospital from 2006 to 2022, and the majority 15 (83%) were transplanted for failing Fontan circulation with Fontan Associated Liver Disease. Median surgical procedure time was 13.4 [11.5, 14.5] h with a cardiopulmonary bypass time of 4.3 [3.9, 5.8] h. Median total blood products transfused in the operating room post cardiopulmonary bypass was 89.4 [63.9, 127.0] mLs/kg. Nine patients (50%) had vasoplegia during cardiopulmonary bypass. Activated prothrombin complex concentrates were used post cardiopulmonary bypass in 15 (83%) patients with a 30-day thromboembolism rate of 22%. Median time to extubation was 4.0 [2.8, 6.5] days, median intensive care unit length of stay 20.0 [7.8, 48.3] days and median hospital length of stay 54.0 [30.5, 68.3] days. Incidence of renal replacement therapy was 11%; however, none required renal replacement therapy by the time of hospital discharge. Neurological events within 30 days were 17% and the 30 day and 1 year survival was 89%.

CONCLUSIONS

Perioperative challenges include major perioperative bleeding, unstable hemodynamics, and end organ injury including acute kidney injury and neurological events. Successful outcomes for en bloc combined heart and liver transplantation are possible with careful multidisciplinary planning, communication, patient selection, and integrated peri-operative management.

Characterization and z-score calculation of cardiovascular magnetic resonance imaging parameters in patients after the Fontan operation: A Fontan Outcome Registry using Cardiovascular Magnetic Resonance Examinations study

BACKGROUND

Cardiac magnetic resonance (CMR) offers valuable hemodynamic insights post-Fontan, but is limited by the absence of normative single ventricle data. The Fontan Outcomes Registry using CMR Examinations (FORCE) is a large international Fontan-specific CMR registry. This study used FORCE registry data to evaluate expected CMR ventricular size/function and create Fontan-specific z-scores adjusting for ventricular morphology (VM) in healthier Fontan patients.

METHODS

"Healthier" Fontan patients were defined as patients free of adverse outcomes, who are New York Heart Association class I, have mild or less valve disease, and <30% aortopulmonary collateral burden. General linear modeling was performed on 70% of the dataset to create z-scores for volumes and function. Models were tested using the remainder (30%) of the data. The z-scores were compared between children and adults. The z-scores were also compared between "healthier" Fontan and patients with adverse outcomes (death, listing for transplantation, or multiorgan disease).

RESULTS

The "healthier" Fontan population included 885 patients (15.0 ± 7.6 years) from 18 institutions with 1156 CMR examinations. Patients with left ventricle morphology had lower volume, mass and higher ejection fraction (EF) compared to right or mixed (two ventricles) morphology (p < 0.001 for all pairwise comparisons). Gender, body surface area, and VM were used in z-scores. Of the "healthier" Fontan patients, 647 were children <18 years and 238 were adults. Adults had lower ascending aorta flow (2.9 ± 0.7 vs 3.3 ± 0.8 L/min/m2, p < 0.001) and ascending aorta flow z-scores (-0.16 ± 1.23 vs 0.05 ± 0.95, 0.02) compared to children. Additionally, there were 1595 patients with adverse outcomes who were older (16.1 ± 9.3 vs 15.0 ± 7.6, p < 0.001) and less likely to have left VM (35 vs 47%, p < 0.001). Patients with adverse outcomes had higher z-scores for ventricular volume and mass and lower z-scores for EF and ascending aorta flow compared to the "healthier" Fontan cohort.

CONCLUSION

This is the first study to generate CMR z-scores post-Fontan. Importantly, the z-scores were generated and tested in "healthier" Fontan patients and both pediatric and adult Fontan patients. These equations may improve CMR-based risk stratification after the Fontan operation.

Physical activity in the Fontan population: provider recommendations and patient actions

BACKGROUND

Emerging evidence suggests that routine physical activity may improve exercise capacity, long-term outcomes, and quality of life in individuals with Fontan circulation. Despite this, it is unclear how active these individuals are and what guidance they receive from medical providers regarding physical activity. The aim of this study was to survey Fontan patients on personal physical activity behaviours and their cardiologist-directed physical activity recommendations to set a baseline for future targeted efforts to improve this.

METHODS

An electronic survey assessing physical activity habits and cardiologist-directed guidance was developed in concert with content experts and patients/parents and shared via a social media campaign with Fontan patients and their families.

RESULTS

A total of 168 individuals completed the survey. The median age of respondents was 10 years, 51% identifying as male. Overall, 21% of respondents spend > 5 hours per week engaged in low-exertion activity and only 7% spend > 5 hours per week engaged in high-exertion activity. In all domains questioned, pre-adolescents reported higher participation rates than adolescents. Nearly half (43%) of respondents reported that they do not discuss activity recommendations with their cardiologist.

CONCLUSIONS

Despite increasing evidence over the last two decades demonstrating the benefit of exercise for individuals living with Fontan circulation, only a minority of patients report engaging in significant amounts of physical activity or discussing activity goals with their cardiologist. Specific, individualized, and actionable education needs to be provided to patients, families, and providers to promote and support regular physical activity in this patient population.

Insulin Resistance after Fontan Palliation

Patients with a single ventricle heart who had Fontan palliation (S/P Fontan) are at increased risk for acquired morbidity. Insulin resistance (IR) is a predictor of cardiac morbidity and mortality. A single-center, cross-sectional study using S/P Fontan and controls was designed to assess IR S/P Fontan. Group comparisons were made in IR via the Quantitative Insulin Index (QUICKI) and the natural log-transformed homeostasis model assessment, ln (HOMA-IR), without/with adjusting for age. A total of 89 patients (59 Fontan and 30 controls) were included. Fontan patients showed a significant decrease in QUICKI (0.34 ± 0.03 vs 0.37 ± 0.02) and an elevation of ln (HOMA-IR) (0.82 ± 0.62 vs 0.24 ± 0.44) compared to controls (both p < 0.0001); this remained significant even adjusting for age. With older age, there was a significant, progressive decrease in QUICKI (p = 0.01) and an increase in ln (HOMA-IR) (p = 0.02) S/P Fontan. Analysis excluding Fontan patients with obesity still showed a significant reduction of QUICKI and an elevation of ln (HOMA-IR) in Fontan patients compared to controls when adjusting for age (both p < 0.05). Using QUICKI, IR was present in 41 (69.5%) Fontan patients vs. 3 (10%) controls (p < 0.0001) and using HOMA-IR, IR was present in 32 (54.2%) vs 5 (16.7%) controls (p = 0.001). Fontan patients had significantly more IR compared to controls and the prevalence of IR increases with age. Since IR is known to correlate with long-term morbidity and mortality and can be ameliorated by therapies, we believe it is critical that IR be identified as early as possible in Fontan patients.

Psychosocial burden and quality of life of parents with children with univentricular hearts compared to ASD parents and parents of heart-healthy children

BACKGROUND

Patients with univentricular hearts can only be palliated by a staged surgical procedure that carries a high morbidity and mortality risk. The aim of this study was to examine the emotional demands, psychosocial burden, and quality of life of parents with children with univentricular hearts compared to parents of children with a simple heart defect, those with no heart defect and children with chronic diseases.

METHODS

An anonymous questionnaire was created to interview parents about their quality of life, stressors, needs, strategies for coping with illness, and partnership satisfaction.

RESULTS

73 families participated in the study. Parents of children with univentricular hearts experience a significantly higher psychosocial burden, limitations in daily life, and distress in family interactions, as well as greater emotional distress compared to the other study groups. When comparing the families of children with other chronic diseases (e.g. cystic fibrosis, chronic arthritis and diabetes), these differences remained significant.

CONCLUSION

The study confirms a higher psychosocial burden, restrictions in daily life and a lower quality of life of parents with children with univentricular hearts, compared to parents of children with simple heart defects and parents of heart-healthy children or those with other chronic diseases. Since this condition persists until adolescence and adulthood, the families are exposed to special challenges and stresses throughout their lives. This has yet to be adequately addressed in the management of these families.

Identifying Frailty and Its Risk Factors in Pediatric Patients with Fontan Physiology

Frailty is a clinical syndrome common in adults with chronic disease with resultant vulnerability to adverse health outcomes. Little is known about frailty in pediatric patients, including those with single-ventricle heart disease. This study aimed to examine the prevalence of frailty and its associated risk factors in patients with Fontan circulation. A single-center, prospective cohort study assessed frailty in patients (10-21 years old) after Fontan palliation. Slowness, weakness, exhaustion, shrinkage, and diminished physical activity were evaluated and scored using a modified Fried frailty assessment comprised of validated pediatric tests. Providers estimated subjects' degree of frailty. Patient-reported quality of life (QOL) was assessed. Of 54 participants (median age 15.3 years, 61% male), 18 (33%) were identified as frail, while 26 (48%) were pre-frail. Patients frequently exhibited frailty in the domains of slowness (93%), weakness (41%), and diminished physical activity (39%). There was poor correlation between frailty scores and provider estimates of frailty (Kappa = 0.11). Frail subjects had lower PedsQL physical functioning scores (mean 62.8 ± SD 18.5 in Frail vs. 75.7 ± 16.0 in No/pre-Frail; p = 0.01). Factors associated with frailty included protein-losing enteropathy (p = 0.03) and at least one hospitalization in the last year (p = 0.047). One-third of pediatric patients after Fontan palliation were frail which was associated with lower physical functioning and higher healthcare utilization. Providers poorly recognized frailty. These findings highlight the need for improved screening and support for an at-risk population where frailty is not easily identified.

Investigation of a chronic single-stage sheep Fontan model

Objectives

Our goal was to conduct a hemodynamic analysis of a novel animal model of Fontan physiology. Poor late-term outcomes in Fontan patients are believed to arise from Fontan-induced hemodynamics, but the mechanisms remain poorly understood. Recent advances in surgical experimentation have resulted in the development of a chronic sheep model of Fontan physiology; however, detailed analysis of this model is lacking.

Methods

We created a single-stage Fontan model in juvenile sheep with normal biventricular circulation. The superior vena cava was anastomosed to the main pulmonary artery, and the inferior vena cava was connected to the main pulmonary artery using an expanded polytetrafluoroethylene conduit. Longitudinal hemodynamics, including catheterization and magnetic resonance imaging were evaluated.

Results

Four out of 12 animals survived, with the longest surviving animal living 3 years after single-stage Fontan. We showed a significant era effect regarding survival (1 out of 8 and subsequently 3 out of 4 animals surviving beyond 2 months) attributed in large part to the procedural learning curve. Key characteristics of Fontan hemodynamics, namely systemic venous hypertension and low normal cardiac output, were observed. However, recapitulation of passive human Fontan hemodynamics is affected by volume loading of the right ventricle given an anatomic difference in sheep azygous venous anatomy draining to the coronary sinus.

Conclusions

A significant learning curve exists to ensure long-term survival and future surgical modifications, including banding of the main pulmonary artery and ligation of the azygous to coronary sinus connection are promising strategies to improve the fidelity of model hemodynamics.

Lymphatic magnetic resonance imaging abnormalities in children with repaired tetralogy of Fallot

INTRODUCTION

Tetralogy of Fallot patients face an elevated risk of developing chylothorax and pleural effusions post-surgery. This patient group exhibits risk factors known to compromise the lymphatic system, such as elevated central venous pressure, pulmonary flow changes, and hypoxia. This study investigates the morphology and function of the lymphatic system in tetralogy of Fallot patients through lymphatic magnetic resonance imaging and near-infrared fluorescence imaging, respectively.

METHODS

Post-repair tetralogy of Fallot patients aged 6-18 years were recruited, along with age and gender-matched controls. Magnetic resonance imaging was used to assess the morphology of the thoracic lymphatic vessels and the thoracic, while near-infrared fluorescence imaging was used to assess lymphatic activity utilising lymph rate, velocity, and pressure.

RESULTS

Nine patients and 10 controls were included. Echocardiography revealed that 2/3 of the patients had moderate-severe pulmonary regurgitation, while none displayed signs of elevated central venous pressure. Magnetic resonance imaging identified three patients with type 3 (out of 4 types) lymphatic abnormalities, while controls had none. The thoracic ducts showed severe (one patient) and moderate (one patient) tortuosity. Mean thoracic duct diameters were 3.3 mm ±1.1 in patients and 3.0 mm ± 0.8 in controls (p-value = 0.53). Near-infrared fluorescence imaging revealed no anomalous patterns.

CONCLUSION

Despite no presence of clinical lymphatic disease, 3/9 of the repaired tetralogy of Fallot patients exhibited lymphatic morphological abnormalities. The significance of these anomalies remains uncertain currently. Further research is needed to determine whether these lymphatic alterations in this patient cohort are a result of congenital malformations, haemodynamic shifts, or prenatal and early-life saturation levels.

Autonomous Fontan pump: Computational feasibility study

Objective

After Fontan palliation, patients with single-ventricle physiology are committed to chronic circulatory inefficiency for the duration of their lives. This is due in large part to the lack of a subpulmonary ventricle. A low-pressure rise cavopulmonary assist device can address the subpulmonary deficit and offset the Fontan paradox. We investigated the feasibility of a Fontan pump that is self-powered by tapping reserve pressure energy in the systemic arterial circulation.

Methods

A double-inlet, double-outlet rotary pump was designed to augment Fontan flow through the total cavopulmonary connection. Pump power is supplied by a systemic arterial shunt and radial turbine, with a closed-loop shunt return to the common atrium (QP:QS 1:1). Computational fluid dynamic analysis and lumped parameter modeling of pump impact on the Fontan circulation was performed.

Results

Findings indicate that a pump that can augment all 4 limbs of total cavopulmonary connection flow (superior vena cava/inferior vena cava inflow; left pulmonary artery/right pulmonary artery outflow) using a systemic arterial shunt powered turbine at a predicted cavopulmonary pressure rise of +2.5 mm Hg. Systemic shunt flow is 1.43 lumped parameter model, 22% cardiac output. Systemic venous pressure is reduced by 1.4 mm Hg with improved ventricular preload and cardiac output.

Conclusions

It may be possible to tap reserve pressure energy in the systemic circulation to improve Fontan circulatory efficiency. Further studies are warranted to optimize, fabricate, and test pump designs for hydraulic performance and hemocompatibility. Potential benefits of an autonomous Fontan pump include durable physiologic shift toward biventricular health, freedom from external power, autoregulating function and exercise responsiveness, and improved quality and duration of life.

High-Performing Fontan Patients: A Fontan Outcome Registry by Cardiac Magnetic Resonance Imaging Study

Background

Fontan patients exhibit decreased exercise capacity. However, there is a subset of high-performing Fontan (HPF) patients with excellent exercise capacity.

Objectives

This study aims to: 1) create a Fontan-specific percent predicted peak VO2 tool using exercise data; 2) examine clinical factors associated with HPF patients; and 3) examine late outcomes in HPF patients.

Methods

Patients in the multi-institutional Fontan Outcomes Registry Using CMR Examination above the age of 8 years who had a maximal exercise test were included. An HPF patient was defined as a patient in the upper Fontan-specific percent predicted peak VO2 quartile. Multivariable logistic regression was employed to investigate factors associated with the HPF and Cox regression was used to examine the association between HPF patients and late outcomes (composite of death or listing for cardiac transplant).

Results

The study included 813 patients (mean age: 20.2 ± 8.7 years). An HPF patient was associated with left ventricular morphology (OR: 1.50, P = 0.04), mixed morphology (OR: 2.23, P < 0.001), and a higher ejection fraction (OR: 1.31 for 10% increase, P = 0.01). Patients with at least moderate atrioventricular valve regurgitation, protein-losing enteropathy, or who were using psychiatric medications, were less likely to be an HPF patient. After a mean follow-up of 3.7 years, 46 (5.7%) patients developed a composite endpoint. HPF had a lower risk of death or listing for cardiac transplant (HR: 0.06 [95% CI: 0.01-0.25]).

Conclusions

Patients with HPF have more favorable outcomes when compared to patients with lower exercise capacity. This large registry data highlights the role of exercise testing in providing personalized care and surveillance post-Fontan.

Echocardiographic Strain to Predict Need for Transplant or Mortality in Fontan Patients with Hypoplastic Left Heart Syndrome

Despite recent advances, hypoplastic left heart syndrome (HLHS) patients subsequent to the Fontan still have significant morbidity and mortality. Some require heart transplant due to systemic ventricular dysfunction. Limited data exist on timing for transplant referral. This study aims to correlate systemic ventricular strain by echocardiography to transplant-free survival. HLHS patients who had Fontan palliation at our institution were included. Patients were divided into: 1) Required transplant or experienced mortality (composite end point); 2) Did not require transplant or survived. For those who experienced the composite endpoint, the last echocardiogram prior to the composite outcome was used, while for those who did not experience the composite endpoint the last echocardiogram obtained was used. Several qualitative and quantitative parameters were analyzed with focus on strain parameters. Ninety-five patients with HLHS Fontan palliation were identified. Sixty-six had adequate images and eight (12%) experienced transplant or mortality. These patients had greater myocardial performance index by flow Doppler (0.72 versus 0.53, p = 0.01), higher systolic/diastolic duration ratio (1.51 versus 1.13, p = 0.02), lower fractional area change (17.65 versus 33.99, p < 0.01), lower global longitudinal strain (GLS) (-8.63 versus - 17.99, p < 0.01), lower global longitudinal strain rate (GLSR) (- 0.51 versus - 0.93, p < 0.01), lower global circumferential strain (GCS) (-6.68 versus -18.25, p < 0.01), and lower (GCSR) global circumferential strain rate (-0.45 versus -1.01, p < 0.01). ROC analysis demonstrated predictive value for GLS - 7.6 (71% sensitive, 97% specific, AUC 81%), GLSR -0.58 (71% sensitive, 88% specific, AUC 82%), GCS - 10.0 (86% sensitive, 91% specific, AUC 82%), and GCSR -0.85 (100% sensitive, 71% specific, AUC 90%). GLS and GCS can help predict transplant-free survival in patients with hypoplastic left heart syndrome having undergone Fontan palliation. Higher strain values (closer to zero) may be a helpful tool in determining when transplant evaluation is warranted in these patients.

Does High-Intensity Exercise Cause Acute Liver Injury in Patients with Fontan Circulation? A Prospective Pilot Study

The Fontan procedure results in chronic hepatic congestion and Fontan-associated liver disease (FALD) characterized by progressive liver fibrosis and cirrhosis. Exercise is recommended in this population, but may accelerate the progression of FALD from abrupt elevations in central venous pressure. The aim of this study was to assess if acute liver injury occurs after high-intensity exercise in patients with Fontan physiology. Ten patients were enrolled. Nine had normal systolic ventricular function and one had an ejection fraction < 40%. During cardiopulmonary exercise testing, patients had near-infrared spectroscopy (NIRS) to measure oxygen saturation of multiple organs, including the liver, and underwent pre- and post-exercise testing with liver elastography, laboratory markers, and cytokines to assess liver injury. The hepatic and renal NIRS showed a statistically significant decrease in oxygenation during exercise, and the hepatic NIRS had the slowest recovery compared to renal, cerebral, and peripheral muscle NIRS. A clinically significant increase in shear wave velocity occurred after exercise testing only in the one patient with systolic dysfunction. There was a statistically significant, albeit trivial, increase in ALT and GGT after exercise. Fibrogenic cytokines traditionally associated with FALD did not increase significantly in our cohort; however, pro-inflammatory cytokines that predispose to fibrogenesis did significantly rise during exercise. Although patients with Fontan circulation demonstrated a significant reduction in hepatic tissue oxygenation based on NIRS saturations during exercise, there was no clinical evidence of acute increase in liver congestion or acute liver injury following high-intensity exercise.

Diastolic dysfunction: assessment and implications on the single ventricle circulation

PURPOSE OF REVIEW

Patients with a functionally single ventricle (SV) are palliated with a series of procedures leading to a Fontan circulation. Over the life span, a substantial proportion of SV patients develop heart failure that can arise from circulatory or ventricular failure. Diastolic dysfunction (DD) is an important determinant of adverse outcomes in SV patients. However, assessment and categorization of DD in the SV remains elusive. We review recent literature and developments in assessment of DD in the SV and its relation to clinical outcomes.

RECENT FINDINGS

DD is prevalent in the SV and associated with worse outcomes. Occult DD can be exposed with provocative testing by exercise or preload challenge during catheterization. Likewise, sensitivity to detect DD may be increased via assessment of atrial function and strain imaging. Recent studies revisiting previous concepts such as incoordinate diastolic wall motion show that these are associated with SV end-diastolic pressures and post-Fontan recovery, yielding accessible DD assessment. Emerging technologies such as ultrafast ultrasound (UFUS) can provide noninvasive assessment of myocardial stiffness, inefficient diastolic flow patterns and intraventricular pressure gradients, thereby yielding new tools and insights into diastolic myocardial and hemodynamic properties.

SUMMARY

Characterizing DD in the SV continues to have substantial limitations, necessitating synthesis of multiple parameters into an overall assessment, accounting for their change over time, and in the context of the patient's clinical status. New and emerging techniques may help advance DD assessment and the ability to track response to treatment of new targets.

Isosorbide DiNitrate Effect on Hemodynamic Profile, Liver Stiffness, and Exercise Tolerance in Fontan Circulation (The NEET Clinical Trial)

After Fontan operation, decreased venous capacitance and venoconstriction are adaptive mechanisms to maintain venous return and cardiac output. The consequent higher venous pressure may adversely impact end-organ function, exercise capacity and result in worse clinical outcomes. This pilot study evaluated the safety and effect of isosorbide dinitrate (ISDN), a venodilator, on exercise capacity, peripheral venous pressure (PVP), and liver stiffness in patients with Fontan circulation. In this prospective single-arm trial, 15 individuals with Fontan circulation were evaluated at baseline and after 4 weeks of therapeutic treatment with ISDN. Primary aims were to assess the safety of ISDN and the effect on maximal exercise. We also aimed to evaluate the effect of ISDN on ultrasound-assessed liver stiffness, markers of submaximal exercise, and PVP at rest and peak exercise. Repeated measures t-tests were used to assess change in variables of interest in response to ISDN. Mean age was 23.5 ± 9.2 years (range 11.2-39.0 years), and 10/15 (67%) were male. There was no statistically significant change in peak VO2 (1401 ± 428 to 1428 ± 436 mL/min, p = 0.128), but VO2 at the anaerobic threshold increased (1087 ± 313 to 1115 ± 302 mL/min, p = 0.03). ISDN was also associated with a lower peak exercise PVP (22.5 ± 4.5 to 20.6 ± 3.0 mmHg, p = 0.015). Liver stiffness was lower with ISDN, though the difference was not statistically significant (2.3 ± 0.4 to 2.1 ± 0.5 m/s, p = 0.079). Of the patients completing the trial, mild headache was common (67%), but there were no major adverse events. Treatment with ISDN for 4 weeks is well-tolerated in patients with a Fontan circulation. ISDN is associated with an increase in VO2 at anaerobic threshold, lower peak PVP, and a trend toward lower liver stiffness. Larger, longer duration studies will be necessary to define the impact of ISDN on clinical outcomes in the Fontan circulation.Clinical Trial Registration: URL: https://clinicaltrials.gov . Unique identifier: NCT04297241.

Alarming rate of liver cirrhosis after the small conduit extracardiac Fontan: A comparative analysis with the lateral tunnel

BACKGROUND

The association between the prevalence of cirrhosis and the types of Fontan operations remains unclear.

METHODS

We conducted a retrospective chart review of 332 patients who underwent the Fontan procedure at our institution. Four patients who underwent the atriopulmonary connection Fontan were excluded from the analysis. Patients who had intracardiac-extracardiac conduit (126) between 1989 and 2021 were pooled with those having extracardiac conduit (ECC) (134). The 260 patients who underwent the ECC and the 68 patients who had the lateral tunnel (LT) Fontan constitute the core of the study.

RESULTS

Median age at the Fontan procedure was 23.7 months (interquartile range [IQR], 20.8-32.6) in the LT group, compared with 28.8 months (IQR, 24.6-39.5) in the ECC group (P < .01). The median follow-up was 14.8 years (IQR, 12.5-16.5) in the LT group and 7 years (IQR, 2.8-10.4) in the extracardiac conduit group. During the follow-up period, 3 patients (4.4%) with LT and 17 patients (6.5%) with ECC (11 patients with 16 mm or less conduit size) were diagnosed with cirrhosis. The prevalence of cirrhosis at 1, 5, 10, and 15 years was 0%, 0%, 0%, and 4.4% in the LT group, respectively, and 0%, 0.9%, 7.7%, and 29.8% in the ECC group (P < .01) Rates of mortality, Fontan revision, Fontan takedown, transplant, and complications were comparable between the 2 groups.

CONCLUSIONS

The extracardiac conduit Fontan seems to be associated with faster development of cirrhosis.

Magnetic resonance lymphangiography abnormalities as extracardiac biomarkers of pulmonary hypertension and functional phenotype in Fontan-Kreutzer univentricular circulation

INTRODUCTION

Lymphatic abnormalities have been documented on magnetic resonance lymphangiography in patients with functionally univentricular circulation.

OBJECTIVE

The aim of this study is to evaluate associations between findings on magnetic resonance lymphangiography, cardiac catheterisation and functional phenotype in patients with Fontan-Kreutzer circulation.

MATERIALS AND METHODS

Between January 2017 and October 2019, seven patients with Fontan-Kreutzer circulation (16.57 ± 7.10 years) were enrolled following ethical committee approval and attainment of informed consent. Clinical data, consecutive magnetic resonance imaging and cardiac catheterisation findings were reviewed. Qualitative lymphatic abnormality types were defined as: 1 - Little or none; 2 - Localised to the supraclavicular region; 3 - Extending into the mediastinum; and 4 - Extending into the lung. Pulmonary hypertension was defined as a transpulmonary gradient > 6 mmHg. Quantitative data were assessed using Mann-Whitney U tests, and p < 0.05 was considered statistically significant.

RESULTS

Patients with lymphatic abnormalities categorised type 1 or 2 and transpulmonary gradient ≤ 6 mmHg had a normal functional phenotype, while those with type 3 or 4 and transpulmonary gradient > 6 mmHg had a failing functional phenotype.

CONCLUSION

Magnetic resonance lymphangiography in patients with Fontan-Kreutzer circulation and pulmonary hypertension revealed lymphatic abnormalities types 3-4, indicative of a failing functional phenotype compared to patients without pulmonary hypertension. If validated in larger studies, these results suggest the potential utility of this extracardiac biomarker for improving risk stratification. Integration of lymphangiography and transpulmonary gradient with functional class, atrioventricular valve function, and ejection fraction allowed for the categorisation of three distinct functional phenotypes, which may be valuable for future analyses.

The Effect of Cardiac Rehabilitation in Paediatric Fontan Circulation Patients: A Prospective Intervention Study

Background and Objectives: The Fontan procedure, a palliative surgery for univentricular heart physiology, often reduces exercise capacity and quality of life. This study aimed to evaluate the impact of cardiac rehabilitation (CR) on improving outcomes in Fontan patients to inform evidence-based care. Materials and Methods: Fontan patients aged 8-30 participated in a structured CR program for at least three months. The program included weekly aerobic and resistance training sessions with educational and nutritional guidance. Baseline and post-CR assessments included cardiac function, fitness, daily activity, and health-related quality of life (HRQOL). Results: The cohort included ten Fontan patients, of whom six had a right systemic ventricle. CR significantly improved cardiorespiratory fitness, as seen in VO2 max (from 27.92 ± 5.15 to 34.69 ± 1.14 mL/kg/min, p = 0.0089) and percent predicted VO2 (from 0.67 ± 0.18 to 0.90 ± 0.02, p = 0.005). VCO2 increased by +8.68 ± 8.59 mL/kg/min but did not reach statistical significance (p = 0.05). Most haemodynamic and ventilatory parameters showed no significant improvement. All the SF-36 questionnaire domains showed significant HRQOL gains (p < 0.001). High adherence (85-93%), no adverse events, and reduced NT-proBNP levels supported the program's safety. Conclusions: This study's findings have important implications for the care of Fontan patients. CR significantly improved exercise capacity and HRQOL in Fontan patients across various anatomies, particularly in the right systemic ventricle. Integrating physical conditioning into standard care could reduce long-term morbidity and mortality; however, further research is needed to refine the protocols and confirm sustained benefits.

Brazilian Guideline for Exercise Testing in Children and Adolescents - 2024

CLASSES OF RECOMMENDATION

LEVELS OF EVIDENCE