It is established that neurodevelopmental disability (NDD) is common in neonates undergoing complex surgery for congenital heart disease (CHD); however, the trajectory of disability over the lifetime of individuals with CHD is unknown. Several ‘big issues’ remain undetermined and further research is needed in order to optimise patient care and service delivery, to assess the efficacy of intervention strategies and to promote best outcomes in individuals of all ages with CHD. This review article discusses ‘gaps’ in our knowledge of NDD in CHD and proposes future directions.

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 VO 2 (β=70.6 mL /min, P =0.001). A ppendicular 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.

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Background: Neurocognitive outcomes beyond childhood in people with a Fontan circulation are not well-defined. This study aimed to investigate neurocognitive functioning in adolescents and adults with a Fontan circulation and associations with structural brain injury, brain volumetry and post-natal clinical factors. Methods: In a bi-national study, participants with a Fontan circulation without a pre-existing major neurological disability were prospectively recruited from the Australia and New Zealand Fontan Registry. Neurocognitive function was assessed using Cogstate software in 107 Fontan-participants and compared with control groups with transposition of the great arteries (TGA; n=50) and a normal circulation (n=41). Brain MRI with volumetric analysis was performed in the Fontan-participants and compared with healthy control data from the ABIDE I and II and PING data repositories. Clinical data were retrospectively collected. Results: Of the Fontan-participants with neurocognitive assessment, 55% were male and the mean age was 22.6 years (SD 7.8). Fontan-participants performed worse in several areas of neurocognitive function compared with those with TGA and healthy controls (p<0.05). Clinical factors associated with worse neurocognitive outcomes included more inpatient days during childhood, younger age at Fontan and longer time since Fontan procedure (p<0.05). Fontan-adults had more marked neurocognitive dysfunction than Fontan-adolescents in two domains (psychomotor function, p=0.01 and working memory, p=0.02). Structural brain injury was present in the entire Fontan cohort; presence of white matter injury was associated with worse paired associate learning (p<0.001), but neither the presence or severity of infarct, subcortical grey matter injury and microhemorrhage was associated with neurocognitive outcomes. Compared with healthy controls, people with a Fontan circulation had smaller global brain volumes (p<0.001 in all regions) and smaller regional brain volumes in the majority of cerebral cortical regions (p<0.05). Smaller global brain volumes were associated with worse neurocognitive functioning in several domains (p<0.05). A significant positive association was also identified between global brain volumes and resting oxygen saturations (p≤0.04). Conclusions: Neurocognitive impairment is common in adolescents and adults with a Fontan circulation and is associated with smaller grey and white matter brain volume. Understanding modifiable factors that contribute to brain injury to optimize neurocognitive function is paramount.

In the second decade after Fontan hepatic and renal structure and function are abnormal in a significant number of patients: close to 60% have ultrasonographic evidence of structural hepatic abnormalities, 46% have elevated serum hepatic fibrosis scores, and 57% have either reduced glomerular filtration rate or microalbuminuria. Hepatic and renal function should be monitored for potential impacts on outcomes after Fontan completion.

This study was conducted to see whether children living in socially deprived areas were more likely than other children to be admitted to hospital for asthma, and, if so, whether their excess risk was attributable to a higher prevalence of asthma or poorer treatment. Hospital admission rates for asthma were obtained for Cardiff electoral wards and compared with the Townsend indices of deprivation. A survey of respiratory symptoms was conducted in schoolchildren; prevalence of symptoms was compared with Townsend index and asthma admission rate for the schools' catchment areas. Asthma admissions were strongly correlated with Townsend indices at all ages. The prevalence of reported asthma and various degrees of wheeze in the schools was not significantly correlated with Townsend index or hospital admission rate in the corresponding areas. The presence of a smoker in the house was strongly associated with Townsend index and admission rate; children whose houses contained a smoker were more likely than others to have wheezed in the past year and to have disturbed nights due to wheezing. There was a non-significant negative association between Townsend index and regular use of inhaled steroids. The relationship between hospital admission for asthma and social deprivation is not explained by variations in prevalence, but it may be attributable to the aggravation of symptoms by active or passive smoking, and perhaps also to differences in management.

Stroke, established by neuroimaging in contemporary clinical practice, was detected in 12% of neonates having CPB, and those undergoing the Norwood procedure have a 3-fold risk of injury. Stroke was associated with NDD at 12 months of age.

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 (&lt;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.