Positive pediatric exercise capacity trajectory predicts better adult Fontan physiology rationale for early establishment of exercise habits

Stress imaging in patients with a Fontan circulation: A systematic review

INTRODUCTION

The aims of this study were to provide an overview of the cardiac stress response in Fontan patients and of the use, safety and clinical value of stress imaging in Fontan patients.

METHODS

Studies evaluating cardiac function using stress imaging in Fontan patients published up until 12 December 2021 were included in this review.

RESULTS

From 1603 potential studies, 32 studies met the inclusion criteria. In total, stress imaging tests of 728 Fontan patients were included. Cardiac function was most often measured using physical stress (61%), all other studies used dobutamine-induced stress. Stroke volume (SV) increased in most studies (71%), mean SV at rest ranged from 27 mL/m2 to 60 mL/m2 versus 27 mL/m2 to 101 mL/m2 during stress, and increased with an average of 4%. Ejection fraction increased in almost all studies, whereas both end-systolic volume and end-diastolic volume decreased during stress. Higher heart rates were obtained with physical stress (82-180) compared to dobutamine induced stress (73-128). Compared to controls, increases in heartrate and SV were lower and end-diastolic volume decreased abnormally in 75% of reporting studies. No major adverse events were reported. Poorer cardiac stress response was related to decreased exercise capacity and higher risk for long-term (adverse) outcomes in Fontan patients.

DISCUSSION

Cardiac stress response in Fontan patients differs from healthy subjects, reflected by lower increases in heart rate, diminished preload and decreased cardiac output, especially during higher levels of exercise. Stress imaging is safe, however the added clinical value needs to be investigated in more detail.

Exploring the Promise of Telemedicine Exercise Interventions in Children and Adolescents With Congenital Heart Disease

Youth with congenital heart disease (CHD) have reduced exercise capacity via various physical and psychosocial mechanisms. In addition to limited physiologic exercise capacity, these patients experience lower levels of physical activity, physical activity self-efficacy, health-related quality of life, and endothelial function. The study of exercise interventions and cardiac rehabilitation programs in pediatric CHD populations remains limited, particularly home-based interventions that incorporate real-time physiologic monitoring. Home-based interventions provide improved access and convenience to patients. This is principally important for patients from geographically disperse regions who receive their care at centralized subspecialty centres, as is the case for Canadian pediatric cardiac care. These programs, however, have traditionally not permitted the supervision of safety, technique, and adherence that are afforded by hospital/facility-based programs. As such, telemedicine is an important evolving area that combines the benefits of traditional home and facility-based cardiac rehabilitation. An additional key area lacking study surrounds the types of exercise interventions in youth with CHD. To date, interventions have often centred around moderate-intensity continuous exercise. High-intensity interval training might offer superior cardiorespiratory advantages but remains understudied in the CHD population. In this review, we highlight the existing evidence basis for exercise interventions in youth with CHD, explore the promise of incorporating telemedicine home-based solutions, and highlight key knowledge gaps. To address identified knowledge gaps, we are undertaking a 12-week randomized crossover trial of a home-based telemedicine high-intensity interval training intervention in youth with repaired moderate-severe CHD using a video game-linked cycle ergometer (known as the MedBIKE; https://spaces.facsci.ualberta.ca/ahci/projects/medical-projects/remote-rehab-bike-projects).

Pilot Project: Heart Chargers-A Successful Model for a Home-Based Physical Activity Program Utilizing Telemedicine for Fontan Patients

Fontan patients have decreased exercise capacity which further declines throughout adolescence. A positive exercise capacity trajectory in children predicts better adult Fontan outcomes. Hospital-based physical activity programs improve exercise capacity and attenuate the age-expected decline in Fontan patients. The purpose of this project was to investigate the feasibility and safety of a partially reimbursable 12-month, home-based, individualized physical activity program (Heart Chargers) for Fontan patients utilizing telemedicine. The Heart Chargers team included a cardiologist, nurse coordinator, and exercise physiologists. Eligible participants with a Fontan completed a baseline cardiopulmonary exercise test (CPET) and consented to participate in Heart Chargers, a 12-month home-based exercise prescription. The individualized exercise prescription focused on skeletal and respiratory muscle strength training and aerobic activities. Participants received a Garmin© device to monitor adherence. Telephone check-ins ranged from weekly to monthly as participants gained independence. Pre- and post-program CPET and informal surveys of physical activity self-efficacy were completed. Nine participants have completed the Heart Chargers program. There was no pre-post difference in maximal or submaximal oxygen consumption (VO2), peak heart rate, or oxygen saturation. There was a significant pre-post increase in systolic blood pressure (p-value 0.004) and minute ventilation (p-value 0.012) at peak exercise. Per subjective report, exercise-related self-efficacy increased after program completion. There were no adverse events. At present, 7 participants remain actively enrolled in the program. Heart Chargers, a novel, home-based, partially reimbursable, 12-month individualized exercise program using telemedicine was successfully implemented in Fontan patients with no adverse events. The lack of decline in exercise capacity for participants is encouraging.

Body composition in patients with Fontan physiology: a systematic review

Fontan circulation is a highly abnormal circulatory state that may affect various organ systems. The effect on body composition is an important factor to assess the condition of the patient. This systematic review assesses body composition and possibly related adverse outcomes in patients with a Fontan circulation, to provide an overview of current insights. Studies evaluating body composition by compartment (either fat mass or lean/muscle mass) in Fontan patients published up to April 2023 were included in this systematic review. Of 1392 potential studies, 18 studies met the inclusion criteria. In total, body composition measurements of 774 Fontan patients were included. Body composition was measured using dual-energy X-ray absorptiometry (DXA) (n = 12), bioelectrical impedance analysis (BIA) (n = 5), computer tomography (CT) (n = 1), or magnetic resonance imaging (MRI) (n = 1). All studies reported a normal body mass index (BMI) in Fontan patients, compared to controls. Five out of nine studies reported significantly higher body fat values, and twelve out of fifteen studies reported significantly lower muscle or lean mass values in the Fontan population compared to the healthy population. Unfavorable body composition in Fontan patients was associated with decreased exercise capacity, worse cardiac function, and adverse outcomes including hospital admissions and death.   Conclusions: Despite having a normal BMI, Fontan patients have an increased fat mass and decreased muscle mass or lean mass compared to the healthy population. This unfavorable body composition was associated with various adverse outcomes, including a decreased exercise capacity and worse cardiac function. What is Known: • Patients with a Fontan circulation have a decreased exercise capacity compared to healthy peers, an unfavorable body composition might be a contributor to their impaired exercise capacity. What is New: • Fontan patients are predisposed to an unfavorable body composition, characterized by increased fat mass and decreased muscle mass accompanied by a normal BMI compared to the healthy population. • Among others, unfavorable body composition was associated with decreased exercise capacity, cardiac function, and increased morbidity in patients with a Fontan circulation.

Clinical and invasively-measured predictors of high exercise capacity in Fontan patients

INTRODUCTION

Fontan patients have variable exercise capacity. Contemporary understanding as to which factors predict high tolerance is limited.

METHODS

Records from the Ahmanson/University of California, Los Angeles Adult Congenital Heart Disease Center were reviewed for adult Fontan patients who underwent CPET. Patients were considered "high performers" if their maximum oxygen uptake (VO2 max/kg)-predicted was greater than 80%. Cross-sectional clinical, hemodynamic, and liver biopsy data was gathered. High-performers were compared to control patients across these parameters via associations and regression.

RESULTS

A total of 195 adult patients were included; 27 patients were considered "high performers". They had lower body mass indices (BMI, p < 0.001), mean Fontan pressures (p = 0.026), and cardiac outputs (p = 0.013). High performers also had higher activity levels (p < 0.001), serum albumin levels (p = 0.003), non-invasive and invasive systemic arterial oxygen saturations (p < 0.001 and p = 0.004), lower New York Heart Association (NYHA) heart failure class (p = 0.002), and were younger at Fontan completion (p = 0.011). High performers had less severe liver fibrosis (p = 0.015). Simple regression found Fontan pressure, non-invasive O2 saturation, albumin level, activity level, age at Fontan surgery, NYHA class, and BMI to predict significant changes in VO2 max/kg %-predicted. These associations persisted in multiple regression for non-invasive O2 saturation, NYHA class II, activity level, and BMI.

CONCLUSIONS

Thin Fontan patients who exercise more had better exercise capacity, Fontan hemodynamic profiles, and less liver fibrosis.

Prevalence and clinical correlates and characteristics of "Super Fontan"

BACKGROUND

Super-Fontan (SF) is an excellent phenotype of patients with Fontan circulation and normal exercise capacity. This study aimed to clarify the prevalence and clinical correlates and characteristics of SF.

METHODS

We reviewed 404 Fontan patients who had undergone cardiopulmonary exercise testing, and the results were compared with clinical profiles.

RESULTS

Seventy-seven (19%) patients had SF, and the postoperative prevalence at 5, 10, 15, 20, and ≥ 25 years was 16 (35%), 30 (39%), 18 (19%), 13 (14%), and 0 (0%), respectively. Compared with non-SF, SF patients were younger (P < .001) and were mostly men (P < .05). SF was characterized by a current high arterial blood pressure and oxygen saturation (SaO2), low systemic ventricle (SV) end-diastolic pressure, favorable body composition, superior pulmonary function, preserved hepatorenal and hemostatic functions, and better glucose tolerance (P < .05-.001). Pre-Fontan better SV function, low pulmonary artery resistance, and high SaO2 were associated with current SF (P < .05-.01). Furthermore, positive trajectory of exercise capacity and high daily activity during childhood were associated with current adult SF (P < .05). During the follow-up, 25 patients died, and 74 patients were unexpectedly hospitalized. There was no death in the SF group, and the rate of hospitalization was 67% lower than that of the non-SF group (P < .01-.001).

CONCLUSIONS

The prevalence of SF gradually decreased over time. SF was characterized by preserved multi-end-organ function and an excellent prognosis. Pre-Fontan hemodynamics and post-Fontan childhood daily activity were associated with being adult SF.

Surrogates of Muscle Mass on Cardiac MRI Correlate with Exercise Capacity in Patients with Fontan Circulation

BACKGROUND

Sarcopenia is an increasingly recognized marker of frailty in cardiac patients. Patients with a history of congenital heart disease and Fontan procedure have a higher risk of developing progressive muscle wasting. Our objective was to determine if we could use routine cardiac MRI (CMR) for the surveillance of muscle wasting.

METHODS

A retrospective study of all Fontan patients (n = 75) was conducted at our institution, with CMR performed from 2010 to 2022 and exercise stress testing performed within 12 months (4.3 ± 4.2 months). The skeletal muscle area (SMA) for the posterior paraspinal and anterior thoracic muscles were traced and indexed for body surface area (BSA). Patients were stratified by percentile into the upper and lower quartiles, and the two groups were compared. Multivariable regression was performed to control for sex and age.

RESULTS

There was a significant positive association of both anterior (r = 0.34, p = 0.039) and paraspinal (r = 0.43, p = 0.007) SMA to peak VO2. Similarly, paraspinal but not anterior SMA was negatively associated with the VE/VCO2 (r = -0.45, p = 0.006). The upper quartile group had significantly more males (18/19 vs. 8/20; p = 0.0003) and demonstrated a significantly higher peak VO2 (32.2 ± 8.5 vs. 23.8 ± 4.7, p = 0.009), a higher peak RER (1.2 ± 0.1 vs. 1.1 ± 0.04, p = 0.007), and a significantly lower VE/VCO2 (32.9 ± 3.6 vs. 40.2 ± 6.2, p = 0.006) compared to the lowest quartile. The association of SMA to VO2 peak and VE/VCO2 was redemonstrated after controlling for sex and age.

CONCLUSION

Thoracic skeletal muscle area may be an effective surrogate of muscle mass and is correlated to several measures of cardiorespiratory fitness post-Fontan. CMR would be an effective tool for the surveillance of sarcopenia in post-Fontan patients given its accessibility and routine use in these patients.

Exercise capacity in a cohort of children with congenital heart disease

In patients with congenital heart disease (CHD), reduced exercise capacity can be a predictor for late complications and may be used to guide interventions. Yet, the interpretation of exercise capacity is challenged by changes in body composition during growth. Our aim was to create an overview of disease-specific exercise capacity in children with CHD. We performed a multicentre retrospective study of exercise capacity of CHD patients, aged 6-18 years, tested between January 2001 and October 2018. Sex-specific distribution graphs were made using the LMS method and height to relate to body size. We included all CHD with N > 50, including severe defects (e.g., univentricular heart, tetralogy of Fallot) and "simple" lesions as ventricular septum defect and atrial septum defect. We included 1383 tests of 1208 individual patients for analysis. The peak oxygen uptake (VO₂peak, 37.3 ml/min/kg (25th-75th percentile 31.3-43.8)) varied between specific defects; patients with univentricular hearts had lower VO_2peak compared with other CHD. All groups had lower VO_2peak compared to healthy Dutch children. Males had higher VO_2peak, W_peak and O₂pulse_peak than females. Sex- and disease-specific distribution graphs for VO_2peak, W_peak and O2pulse_peak showed increase in variation with increase in height.   Conclusion: Disease-specific distribution graphs for exercise capacity in children with CHD from a large multicentre cohort demonstrated varying degrees of reduced VO_2peak and W_peak. The distribution graphs can be used in the structured follow-up of patients with CHD to predict outcome and identify patients at risk. What is Known: • Children with congenital heart disease (COnHD) are at risk to develop heart failure, arrhytmia's and other complications. Exercise capacity may be an important predictor for outcome in children with ConHD. In children, the interpretation of exercise capacity poses an additional challenge related to physical changes during growth. What is New: • In this report of a multi-center cohort >1300 childrewn with ConHD, we related the changes in exercise capacity to length. We demonstrated that exercise capacity was reduced as compared with healthy children and we observed variation between disease groups. Patients with a univentricular circulation (Fontan) had worse exercise capacity. We constructed disease specific charts of development of exercise capacity throughout childhood, accessible via a web-site. These graphs may help practitioner to guide children with ConHD.

Fitter Fontans for future—Impact of physical exercise on cardiopulmonary function in Fontan patients

Background

In Fontans, exercise tolerance is poorer compared to their healthy peers. Higher V˙O2peak represents a strong predictor for mortality and morbidity in these patients. Cardiac rehabilitation programs have been shown to improve cardiopulmonary function in Fontans. More habitual physical activity should therefore lead to a better exercise tolerance.

Methods

We performed cardiopulmonary exercise testing in 24 Fontan patients who had engaged in physical activity for a minimum of 3 h per week over their lifetime. As a control we performed cardiopulmonary exercise testing in 20 Fontan patients who had undertaken no physical activity or &lt;3 h per week in the past.

Results

A total of 44 Fontan patients was included (mean age 18.1 years). The mean parameters measured at peak exercise differed significantly between the active and inactive group (peak oxygen uptake [V˙O2peak] of 34.0 vs. 25.0 ml/min/kg, peak heart rate (HR) of 169.8/min vs. 139.8/min). Even though the O2pulse and the EF did not differ significantly between both groups, N-Terminal-Pro-B-Type Natriuretic Peptide (NT-pro BNP) was significantly higher in the inactive group. The two groups did not differ with respect to their cardiac function determined by magnetic resonance imaging (MRI). V˙O2peak was positively correlated with hours of sports performed by Fontans.

Conclusions

V˙O2peak and maximum HR were significantly higher in Fontans who had been physically active compared to those who had been inactive. The values reported in this study were higher than in other studies and reached normal values for V˙O2peak for most Fontans in the physically active group. The positive correlation between V˙O2peak and physical activity is an indicator of the importance of incorporating physical exercise programs into the treatment of Fontan patients.

Body mass index and age are associated with ventricular end-diastolic pressure in adults with a Fontan circulation

INTRODUCTION

Systemic ventricular end-diastolic pressure is an important haemodynamic variable in adult patients with Fontan circulation. Risk factors associated with elevated end-diastolic pressure have not been clearly identified in this population.

METHODS

All patients > 18 years with Fontan circulation who underwent cardiac catheterisation at our centre between 1/08 and 3/19 were included. Relevant patient variables were extracted. Univariate and multivariate general linear models were analysed to identify variables associated with end-diastolic pressure.

RESULTS

Forty-two patients were included. Median age was 24.0 years (20.9-29.0) with a body mass index of 23.7 kg/m² (21.5-29.7). 10 (23.8%) patients had a systemic right ventricle. The median (Interquartile range) and mean pulmonary artery pressure were 11.0 mmHg (9.0-12.0) and 16.0 mmHg (13.0-18.0), respectively. On univariate analysis, end-diastolic pressure was positively associated with body mass index (p < 0.01), age > 25 years (p = 0.04), symptoms of heart failure (p < 0.01), systemic ventricular systolic pressure (p = 0.03), pulmonary artery mean pressure (p < 0.01), and taking diuretics (p < 0.01) or sildenafil (p < 0.01). End-diastolic pressure was negatively associated with aortic saturation (p < 0.01). On multivariate analysis, end-diastolic pressure was positively associated with age ≥ 25 years (p < 0.01), and body mass index (p = 0.04).

CONCLUSIONS

In a cohort of adult patients with Fontan circulation undergoing catheterisation, end-diastolic pressure was positively associated with age ≥ 25 years and body mass index on multivariate analysis. Maintaining a healthy body mass index may offer haemodynamic benefit in adults with Fontan physiology.

Exercise Capacity and Training Programs in Paediatric Fontan Patients: A Systematic Review

Background

Exercise training programs can effectively enhance exercise capacity in adults with congenital heart disease, including Fontan patients. However, few studies have explored the impact of exercise training exclusively on paediatric Fontan cohorts. This study systematically reviews exercise capacity in paediatric Fontan patients and the impact of training programs on their cardiovascular health.

Methods

Medline and Embase were searched for articles published between January 1990 and November 2021. Studies were included in which data could be analyzed discretely for patients who had undergone the Fontan procedure and were ≤20 years old at the time of study. Cardiopulmonary exercise parameters were extracted from all studies, and training protocols were collected from training programs.

Results

The studies demonstrated that Fontan patients exhibit significantly diminished peak exercise capacity relative to healthy peers. We identified 9 training programs that exclusively studied Fontan patients ≤20 years. The programs ranged from 6 weeks to 12 months in duration, with 8 programs incorporating aerobic activity and 1 focused only on inspiratory muscle training. At least 1 measure of maximal or submaximal exercise capacity improved significantly within each program in which statistical analysis was performed, with no reported adverse events. There were 2 additional training programs in which the patients were predominantly (>65%), but not exclusively, Fontan patients.

Conclusions

Overall, the results indicate that exercise training programs can safely and effectively improve at least 1 measure of exercise capacity in paediatric Fontan patients.

Associations between blood biomarkers, cardiac function and adverse outcome in a young tetralogy of Fallot cohort

BACKGROUND

To determine the potential prognostic value and clinical correlations of blood biomarkers in a cohort of patients with Tetralogy of Fallot (TOF).

METHODS

In the setting of multicenter prospective research studies TOF patients underwent blood sampling, cardiopulmonary exercise testing and low-dose dobutamine stress cardiac magnetic resonance (CMR) imaging. In the blood sample NT-proBNP, GDF-15, Galectin-3, ST-2, DLK-1, FABP4, IGFBP-1, IGFBP-7, MMP-2, and vWF were assessed. During subsequent follow-up, patients were evaluated for reaching the study endpoint (cardiac death, arrhythmia-related hospitalization or cardioversion/ablation, VO₂ max ≤65% of predicted). Regression analysis was used to explore the correlation between blood biomarkers (corrected for age and gender) and other clinical parameters. The potential predictive value of blood biomarkers and events were assessed with Kaplan-Meier analysis and Cox proportional hazard analysis.

RESULTS

We included 137 Fallot patients, median age 19.2 (interquartile range: 14.6-25.7) years, median age at TOF-repair 0.9 (0.5-1.9) years. After a median follow-up of 8.7 (6.3-10.7) years, 20 (14.6%) patients reached the composite endpoint. In a multivariable cox-regression analysis corrected for age at study baseline, elevated IGFBP-7 and MMP-2 levels were associated with the composite endpoint. We also noted a correlation between DLK-1 and relative change in right ventricular end systolic volume during dobutamine stress CMR (β = -0.27, p = 0.010), a correlation between FABP4 and Max VO₂ (β = -0.41, p ≤0.001 and between MMP-2 and tricuspid valve E/A ratio (β = -0.15, p = 0.037).

CONCLUSIONS

IGFBP-7, MMP-2 and DLK-1 levels are related to cardiac function and long-term outcome in TOF patients.

Being Born with a Single Cardiac Ventricle: What Do We Tell Prospective Parents

Being born with a single ventricle remains one of the most extreme congenital cardiac conditions. It encompasses a wide variety of lesions characterized by the existence of one small ventricular cavity. To allow survival, these patients must undergo a series of operations in the first years of life. It was long considered that the success of these interventions would be short-lived and that only a few of these patients would live beyond adulthood. The last decade has seen publication of multiple large outcomes researches on this population, and we now realize that its survival is longer than expected, but with a considerable burden of disease. As a consequence, the size of this single ventricle population is growing rapidly. As primary conveyer of the information on the future of these babies, obstetricians need to be aware of these changes in perspective. This article is protected by copyright. All rights reserved.

Exercise Training for People Living with a Fontan Circulation: An Underutilized Intervention

Surgical repair for children born with single ventricle congenital heart disease, culminating in the Fontan operation, has resulted in dramatic improvements in survival; children born with these lesions are now typically expected to survive well into adulthood. Most, but not all, individuals with a Fontan circulation have reduced exercise capacity compared with the general population that in turn is associated with increased cardiovascular morbidity and mortality. The cause of reduced exercise capacity is multifactorial. A significant contributor is the absence of a subpulmonary ventricular pump, which limits preload and appropriate cardiac output augmentation to meet the increased metabolic demands that occur with exercise. While in its infancy relative to adults with acquired heart disease, the evidence to date suggests that exercise interventions to improve exercise capacity and Fontan physiology in children and adults with Fontan circulation are safe, effective and well tolerated. However, many knowledge gaps remain, including a detailed understanding of the unique physiological adaptations that occur, the optimal approach to exercise in this population and the effectiveness of home-based interventions utilizing telemedicine and remote physiologic monitoring technologies. Furthermore, the long-term impact of such interventions on the Fontan-cardiovascular system, physical activity levels, health-related quality of life, and late cardiovascular morbidity and mortality are not well characterized. In this review, we outline the factors associated with reduced exercise capacity in individuals with Fontan circulation, review the experience to date of dedicated interventions to improve exercise capacity, and highlight the current knowledge gaps in the field and priorities for further study.

Circulatory Response to Rapid Volume Expansion and Cardiorespiratory Fitness in Fontan Circulation

The role of dysfunction of the single ventricle in Fontan failure is incompletely understood. We aimed to evaluate hemodynamic responses to preload increase in Fontan circulation, to determine whether circulatory limitations in different locations identified by experimental preload increase are associated with cardiorespiratory fitness (CRF), and to assess the impact of left versus right ventricular morphology. In 38 consecutive patients (median age = 16.6 years, 16 females), heart catheterization was supplemented with a rapid 5-mL/kg body weight volume expansion. Central venous pressure (CVP), ventricular end-diastolic pressure (VEDP), and peak systolic pressure were averaged for 15‒30 s, 45‒120 s, and 4‒6 min (steady state), respectively. CRF was assessed by peak oxygen consumption (VO_2peak) and ventilatory threshold (VT). Median CVP increased from 13 mmHg at baseline to 14.5 mmHg (p < 0.001) at steady state. CVP increased by more than 20% in eight patients. Median VEDP increased from 10 mmHg at baseline to 11.5 mmHg (p < 0.001). Ten patients had elevated VEDP at steady state, and in 21, VEDP increased more than 20%. The transpulmonary pressure difference (CVP‒VEDP) and CVP were consistently higher in patients with right ventricular morphology across repeated measurements. CVP at any stage was associated with VO_2peak and VT. VEDP after volume expansion was associated with VT. Preload challenge demonstrates the limitations beyond baseline measurements. Elevation of both CVP and VEDP are associated with impaired CRF. Transpulmonary flow limitation was more pronounced in right ventricular morphology. Ventricular dysfunction may contribute to functional impairment after Fontan operation in young adulthood.ClinicalTrials.gov identifier NCT02378857.

The "Super-Fontan" Phenotype: Characterizing Factors Associated With High Physical Performance

Background: People with a Fontan circulation usually have moderately impaired exercise performance, although a subset have high physical performance ("Super-Fontan"), which may represent a low-risk phenotype. Methods: People with a "Super-Fontan" phenotype were defined as achieving normal exercise performance [≥80% predicted peak oxygen uptake (VO₂) and work rate] during cardiopulmonary exercise testing (CPET) and were identified from the Australian and New Zealand Fontan Registry. A Fontan control group that included people with impaired exercise performance (<80% predicted VO₂ or work rate) was also identified based on a 1:3 allocation ratio. A subset of participants were prospectively recruited and completed a series of physical activity, exercise self-efficacy, and health-related quality of life questionnaires. Results: Sixty CPETs ("Super-Fontan", n = 15; control, n = 45) were included. A subset ("Super-Fontan", n = 10; control, n = 13) completed a series of questionnaires. Average age was 29 ± 8 years; 48% were males. Exercise capacity reflected by percent predicted VO₂ was 67 ± 17% in the entire cohort. Compared to the "Super-Fontan" phenotype, age at Fontan completion was higher in controls (4.0 ± 2.9 vs. 7.2 ± 5.3 years, p = 0.002). Only one (7%) person in the "Super-Fontan" group had a dominant right ventricle compared to 15 (33%) controls (p = 0.043). None of those in the "Super-Fontan" group were obese, while almost a quarter (22%) of controls were obese based on body mass index (p = 0.046). Lung function abnormalities were less prevalent in the "Super-Fontan" group (20 vs. 70%, p = 0.006). Exercise self-efficacy was greater in the "Super-Fontan" group (34.2 ± 3.6 vs. 27.9 ± 7.2, p = 0.02). Self-reported sports participation and physical activity levels during childhood and early adulthood were higher in the "Super-Fontan" group (p < 0.05). The total average time spent participating in structured sports and physical activity was 4.3 ± 2.6 h/wk in the "Super-Fontan" group compared to 2.0 ± 3.0 h/wk in controls, p = 0.003. There were no differences in self-reported current total physical activity score or health-related quality of life between groups (p ≥ 0.05). Conclusions: The "Super-Fontan" phenotype is associated with a healthy weight, lower age at Fontan completion, better exercise self-efficacy, and higher overall levels of sport and physical activity participation during physical development.

Correlation of exercise-induced peripheral venous hypertension with exercise intolerance in patients with Fontan circulation

Owing to the absence of a sub-pulmonary ventricle, the central venous pressure rises in patients with Fontan circulation. During exercise, central venous pressure may rise further to increase the systemic ventricular preload and cardiac output. We performed a single-centre prospective trial of cardiopulmonary exercise test while monitoring peripheral venous pressure which strongly correlates with central venous pressure. The objective of this study was to test the hypothesis that peripheral venous pressure at peak exercise inversely correlates with exercise capacity in patients with Fontan circulation. Seventeen patients following Fontan operation performed cardiopulmonary exercise test while monitoring peripheral venous pressure. Peak oxygen uptake, heart rate reserve, peak oxygen pulse (divided by body surface area), and peripheral venous pressure at peak exercise were measured. Correlations of peripheral venous pressure at peak exercise with the peak oxygen uptake, heart rate reserve, and peak oxygen pulse were evaluated. The peripheral venous pressure at peak exercise inversely correlated with the peak oxygen uptake (R = -0.66, p < 0.01), heart rate reserve (R = -0.6, p < 0.05), and peak oxygen pulse (R = -0.48, p < 0.05). Exercise-induced peripheral venous hypertension correlates with exercise intolerance in patients with Fontan circulation. Peak oxygen uptake is a useful index for evaluating the status of congestion in the daily life of patients with Fontan circulation.

The role of cardiopulmonary exercise testing in predicting mortality and morbidity in people with congenital heart disease: a systematic review and meta-analysis

AIMS

The role of cardiopulmonary exercise testing (CPET) in predicting major adverse cardiovascular events (MACE) in people with congenital heart disease (ConHD) is unknown. A systematic review with meta-analysis was conducted to report the associations between CPET parameters and MACE in people with ConHD.

METHODS AND RESULTS

Electronic databases were systematically searched on 30 April 2020 for eligible publications. Two authors independently screened publications for inclusion, extracted study data, and performed risk of bias assessment. Primary meta-analysis pooled univariate hazard ratios across studies. A total of 34 studies (18 335 participants; 26.2 ± 10.1 years; 54% ± 16% male) were pooled into a meta-analysis. More than 20 different CPET prognostic factors were reported across 6 ConHD types. Of the 34 studies included in the meta-analysis, 10 (29%), 23 (68%), and 1 (3%) were judged as a low, medium, and high risk of bias, respectively. Primary univariate meta-analysis showed consistent evidence that improved peak and submaximal CPET measures are associated with a reduce risk of MACE. This association was supported by a secondary meta-analysis of multivariate estimates and individual studies that could not be numerically pooled.

CONCLUSION

Various maximal and submaximal CPET measures are prognostic of MACE across a variety of ConHD diagnoses. Further well-conducted prospective multicentre cohort studies are needed to confirm these findings.

Decline Is Not Inevitable: Exercise Capacity Trajectory in an Australian and New Zealand Fontan Cohort

BACKGROUND

In people with a Fontan circulation, serial cardiopulmonary exercise testing (CPET) to evaluate change in peak exercise capacity has been increasingly recognised as a useful prognostic tool; a decline is associated with adverse clinical outcomes. The aim of this study is to describe the "natural" history of exercise capacity in the Australian and New Zealand (ANZ) Fontan cohort and to identify factors associated with a decline.

METHODS

The ANZ Fontan registry was retrospectively reviewed for adolescent and adult patients (≥16 years) with serial CPET results performed on a cycle ergometer ≥6 months apart. Patients were excluded if they underwent a surgical procedure or fenestration closure in-between tests or if the tests were considered as submaximal effort. Exercise capacity trajectory was defined as the change in percentage of predicted peak oxygen uptake (% pred VO_2peak) points per year.

RESULTS

Thirty-seven (37) patients (59.5% male, mean age 24±7 years) were eligible. Average duration between CPET was 5.3±3.9 years. At baseline, % pred VO_2peak was 61.3±14.5%. Thirteen (13) (35%) had a systemic right ventricle, and 14 (38%) had an atriopulmonary type Fontan circulation. Average change in % pred VO_2peak overall was +1.3±6.4 percentage points per year. Sixteen (16) had a negative exercise capacity trajectory, and the average decline in that group was -2.7±3.4 percentage points per year. There was no association between exercise capacity trajectory and clinical characteristics. Of the 18 patients with physical activity levels recorded, 12 (67%) were physically active and % pred VO_2peak in that group increased by 2.7±4.0 percentage points per year compared with the physically inactive group who fell by 0.5±0.8 percentage points per year.

CONCLUSIONS

In this ANZ series of Fontan patients, over half of our cohort had stable, or an increase, in peak exercise capacity. Regular participation in physical activity was common in patients with a positive exercise capacity trajectory. Clinical characteristics were not associated with exercise capacity trajectory.

Exercise Intolerance, Benefits, and Prescription for People Living With a Fontan Circulation: The Fontan Fitness Intervention Trial (F-FIT)-Rationale and Design

Background: Despite developments in surgical techniques and medical care, people with a Fontan circulation still experience long-term complications; non-invasive therapies to optimize the circulation have not been established. Exercise intolerance affects the majority of the population and is associated with worse prognosis. Historically, people living with a Fontan circulation were advised to avoid physical activity, but a small number of heterogenous, predominantly uncontrolled studies have shown that exercise training is safe-and for unique reasons, may even be of heightened importance in the setting of Fontan physiology. The mechanisms underlying improvements in aerobic exercise capacity and the effects of exercise training on circulatory and end-organ function remain incompletely understood. Furthermore, the optimal methods of exercise prescription are poorly characterized. This highlights the need for large, well-designed, multi-center, randomized, controlled trials. Aims and Methods: The Fontan Fitness Intervention Trial (F-FIT)-a phase III clinical trial-aims to optimize exercise prescription and delivery in people with a Fontan circulation. In this multi-center, randomized, controlled study, eligible Fontan participants will be randomized to either a 4-month supervised aerobic and resistance exercise training program of moderate-to-vigorous intensity followed by an 8-month maintenance phase; or usual care (control group). Adolescent and adult (≥16 years) Fontan participants will be randomized to either traditional face-to-face exercise training, telehealth exercise training, or usual care in a three-arm trial with an allocation of 2:2:1 (traditional:telehealth:control). Children (<16 years) will be randomized to either a physical activity and exercise program of moderate-to-vigorous intensity or usual care in a two-arm trial with a 1:1 allocation. The primary outcome is a change in aerobic exercise capacity (peak oxygen uptake) at 4-months. Secondary outcomes include safety, and changes in cardiopulmonary exercise testing measures, peripheral venous pressure, respiratory muscle and lung function, body composition, liver stiffness, neuropsychological and neurocognitive function, physical activity levels, dietary and nutritional status, vascular function, neurohormonal activation, metabolites, cardiac function, quality of life, musculoskeletal fitness, and health care utilization. Outcome measures will be assessed at baseline, 4-months, and 12-months. This manuscript will describe the pathophysiology of exercise intolerance in the Fontan circulation and the rationale and protocol for the F-FIT.

Body Composition and Exercise Performance in Youth With a Fontan Circulation: A Bio-Impedance Based Study

Background Adults with a Fontan circulation tend to have myopenia and elevated adiposity when measured by dual energy x-ray absorptiometry. Bioelectrical impedance analysis is an alternative validated approach to assess body composition. We used bioelectrical impedance analysis to compare body composition between pediatric patients with a Fontan circulation and control individuals without heart disease. Methods and Results A retrospective chart review identified all patients aged <22 years with a Fontan circulation who presented for cardiopulmonary exercise testing and bioelectrical impedance analysis from April 2019 to January 2020. Data were compared with control subjects tested during the same period. We studied 47 patients with a Fontan circulation (53% boys; 15±3.1 years) and 165 controls (48% boys; 14.4±2.5 years). Fontan status was associated with shorter height, but similar age, sex, and overall body mass. Patients with Fontan had lower lean body mass (-12.0±22%, Z-score -0.5±1, P=0.005), skeletal muscle mass (-13.6±1.4%; Z-score, -0.5±1; P=0.004), skeletal muscle indexed to height (-10.3±13.3%; Z-score, -0.5±1; P=0.005), and higher percent body fat (+13.8±18.6%; Z-score, 0.4±1.2; P=0.03). Greater skeletal muscle mass was associated with higher peak oxygen consumption (r2=0.52, P<0.0001) and oxygen pulse (r2=0.68, P<0.0001). Patients who had suffered a late complication (ie, heart transplant referral or evidence of extracardiac organ dysfunction) of the Fontan operation (13 of 47, 27.7%) had lower skeletal muscle mass (P=0.048) and higher body fat percentage (P=0.003). Conclusions The Fontan circulation is associated with marked myopenia and increased adiposity. Higher muscle mass was associated with better exercise capacity. Fontan complications are associated with lower muscle mass and increased adiposity.

Secondary sarcopenia assessed by computed tomography can predict hospitalization for heart failure in adults with Fontan circulation

BACKGROUND

Sarcopenia is one of the important predictors of heart failure (HF) in patients with cardiac problems. Skeletal muscle pump is important to maintain Fontan circulation. We aimed to quantify the volume of the psoas major muscle (PMM) and investigate whether it is relevant to HF hospitalization in adults with Fontan circulation.

METHODS

A total of 154 adults with Fontan circulation, and 30 age-matched adults were studied retrospectively. We identified secondary sarcopenia by measuring the PMM volume, using non-contrast abdominal computed tomography.

RESULTS

PMM indexed volume in Fontan patients was lower than controls (206.4+/-18.0 cc/m² vs 288.0+/-61.1 cc/m², p < 0.0001). In Fontan men, PMM indexed volume correlated with New York Heart Association functional class (NYHA FC). PMM indexed volume in Fontan women correlated with age, NYHA FC, and serum creatinine. Using a multivariate Cox hazards analysis, NYHA FC ≧3 was an important predictor of hospitalization due to HF in Fontan men. In Fontan women, NYHA FC ≧3, brain natriuretic peptide, PMM indexed volume, and protein losing enteropathy were important predictions of hospitalization due to HF. Among all Fontan patients, those with low PMM volumes had a poorer prognosis in HF [log rank p = 0.012 (men) and 0.0009 (women)].

CONCLUSIONS

PMM volume reduction has an adjunctive prediction of HF hospitalization in adults with Fontan circulation, particularly in Fontan females. Secondary sarcopenia may have a negative impact on the prognosis of HF in this population. The assessment of skeletal muscle mass also may be a comprehensive screening tool for multi-organ dysfunction in Fontan circulation.

Physical exercise training in patients with a Fontan circulation: A systematic review

BACKGROUND

Patients with a Fontan circulation have a reduced exercise capacity, which is an important prognostic predictor of morbidity and mortality. A way to increase exercise capacity in Fontan patients might be exercise training. This systematic review assesses the effects of exercise training investigated in Fontan patients in order to provide an overview of current insights.

DESIGN AND METHODS

Studies evaluating an exercise training intervention in Fontan patients published up to February 2020 were included in this systematic review.

RESULTS

From 3000 potential studies, 16 studies reported in 22 publications met the inclusion criteria. In total, 264 Fontan patients with mean age range 8.7-31 years, were included. Different training types including inspiratory muscle training, resistance training and aerobic training were investigated. Main outcome measures reported were peak oxygen uptake, cardiac function, lung function, physical activity levels and quality of life. Peak oxygen uptake increased significantly in 56% of the studies after training with an overall mean increase of +1.72 ml/kg/min (+6.3%). None of the studies reported negative outcome measures related to the exercise programme. In four studies an adverse event was reported, most likely unrelated to the training intervention.

CONCLUSIONS

Exercise training in Fontan patients is most likely safe and has positive effects on exercise capacity, cardiac function and quality of life. Therefore exercise training in Fontan patients should be encouraged. Further studies are required to assess the optimal training type, intensity, duration and long-term effects.

Targeted metabolomic analysis of serum amino acids in the adult Fontan patient with a dominant left ventricle

Growing interest lies in the assessment of the metabolic status of patients with a univentricular circulation after Fontan operation, especially in changes of amino acid metabolism. Using targeted metabolomic examinations, we investigated amino acid metabolism in a homogeneous adult Fontan-patient group with a dominant left ventricle, seeking biomarker patterns that might permit better understanding of Fontan pathophysiology and early detection of subtle ventricular or circulatory dysfunction. We compared serum amino acid levels (42 analytes; AbsoluteIDQ p180 kit, Biocrates Life Sciences, Innsbruck, Austria) in 20 adult Fontan patients with a dominant left ventricle and those in age- and sex-matched biventricular controls. Serum concentrations of asymmetric dimethylarginine, methionine sulfoxide, glutamic acid, and trans-4-hydroxyproline and the methionine sulfoxide/methionine ratio (Met-SO/Met) were significantly higher and serum concentrations of asparagine, histidine, taurine, and threonine were significantly lower in patients than in controls. Met-SO/Met values exhibited a significant negative correlation with oxygen uptake during exercise. The alterations in amino acid metabolome that we found in Fontan patients suggest links between Fontan pathophysiology, altered cell energy metabolism, oxidative stress, and endothelial dysfunction like those found in biventricular patients with congestive heart failure. Studies of extended amino acid metabolism may allow better understanding of Fontan pathophysiology that will permit early detection of subtle ventricular or circulatory dysfunction in Fontan patients.

Targeted metabolomic analysis of serum phospholipid and acylcarnitine in the adult Fontan patient with a dominant left ventricle

BACKGROUND

Patients with a Fontan circulation have altered cholesterol and lipoprotein values. We analysed small organic molecules in extended phopsholipid and acylcarnitine metabolic pathways ('metabolomes') in adult Fontan patients with a dominant left ventricle, seeking differences between profiles in baseline and Fontan circulations.

METHODS

In an observational matched cross-sectional study, we compared phosphatidylcholine (PC), sphingomyelin (SM), and acylcarnitine metabolomes (105 analytes; AbsoluteIDQ® p180 kit (Biocrates Life Sciences AG, Innsbruck, Austria) in 20 adult Fontan patients having a dominant left ventricle with those in 20 age- and sex-matched healthy controls.

RESULTS

Serum levels of total PC (q-value 0.01), total SM (q-value 0.0002) were significantly lower, and total acylcarnitines (q-value 0.02) were significantly higher in patients than in controls. After normalisation of data, serum levels of 12 PC and 1 SM Fontan patients were significantly lower (q-values <0.05), and concentrations of 3 acylcarnitines were significantly higher than those in controls (q-values <0.05).

CONCLUSION

Metabolomic profiling can use small specimens to identify biomarker patterns that track derangement in multiple metabolic pathways. The striking alterations in the phospholipid and acylcarnitine metabolome that we found in Fontan patients may reflect altered cell signalling and metabolism as found in heart failure in biventricular patients, chronic low-level inflammation, and alteration of functional or structural properties of lymphatic or blood vessels.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Identifier NCT03886935.

Body Composition in Young Adults Living With a Fontan Circulation: The Myopenic Profile

Background

We sought to characterize body composition abnormalities in young patients living with a Fontan circulation and explore potential pathophysiologic associations.

Methods and Results

Twenty‐eight patients with a Fontan circulation were prospectively recruited in this cross‐sectional study. Participants underwent cardiopulmonary exercise testing, dual‐energy X‐ray absorptiometry, echocardiography, and biochemical assessment. Mean age was 26±7 years. Skeletal muscle mass, estimated by appendicular lean mass index Z score, was reduced compared with reference data (−1.49±1.10, P<0.001). Percentage body fat Z score overall was within normal range (0.23±1.26, P=0.35), although 46% had elevated adiposity. Those with reduced skeletal muscle mass (appendicular lean mass index Z score of −1 or lower) had lower percent predicted oxygen pulse (55±15 versus 76±16%, P=0.002). Overall agreement between body mass index and dual‐energy X‐ray absorptiometry to assess adiposity was fair only (weighted [linear] κ coefficient: 0.53; 95% CI, 0.34–0.73) and slight in the setting of muscle mass deficiency (weighted κ coefficient: 0.32; 95% CI, 0.13–0.50). Appendicular lean mass was independently associated with absolute peak VO₂ (β=70.6 mL/min, P=0.001). Appendicular lean mass index Z score was inversely associated with hemoglobin (r=−0.4, P=0.04), and the degree of muscle deficit was associated with ventricular systolic impairment.

Conclusions

Young patients with a Fontan circulation have a body composition characterized by reduced skeletal muscle mass, which is associated with peak exercise capacity. Increased adiposity is common despite a normal body mass index. Low skeletal muscle mass is associated with systolic dysfunction and compensatory erythrocytosis.

The "Journal of Functional Morphology and Kinesiology" Journal Club Series: Highlights of Recent Papers in Pediatric Exercise

We are glad to introduce the ninth Journal Club. This edition is focused on several relevant studies published in the last years in the field of Pediatric Exercise, chosen by our Editorial Board members and their colleagues. We hope to stimulate your curiosity in this field and to share with you the passion for the sport as seen also from the scientific point of view. The Editorial Board members wish you an inspiring lecture.