Fontan Patients Research Articles

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.

Active Machine Learning for Pre-procedural Prediction of Time-Varying Boundary Condition After Fontan Procedure Using Generative Adversarial Networks.

The Fontan procedure is the definitive palliation for pediatric patients born with single ventricles. Surgical planning for the Fontan procedure has emerged as a promising vehicle toward optimizing outcomes, where pre-operative measurements are used prospectively as post-operative boundary conditions for simulation. Nevertheless, actual post-operative measurements can be very different from pre-operative states, which raises questions for the accuracy of surgical planning. The goal of this study is to apply machine leaning techniques to describing pre-operative and post-operative vena caval flow conditions in Fontan patients in order to develop predictions of post-operative boundary conditions to be used in surgical planning. Based on a virtual cohort synthesized by lumped-parameter models, we proposed a novel diversity-aware generative adversarial active learning framework to successfully train predictive deep neural networks on very limited amount of cases that are generally faced by cardiovascular studies. Results of 14 groups of experiments uniquely combining different data query strategies, metrics, and data augmentation options with generative adversarial networks demonstrated that the highest overall prediction accuracy and coefficient of determination were exhibited by the proposed method. This framework serves as a first step toward deep learning for cardiovascular flow prediction/regression with reduced labeling requirements and augmented learning space.

Predictive Role of Atrial Strain, Aortic Stiffness, and Muscle-Related Factors for Maximal and Submaximal Exercise Capacity in Fontan Patients.

Fontan patients' exercise capacity and associated risks of morbidity and mortality necessitate a comprehensive study. We aim to explore maximal and submaximal exercise capacity, assessing the impact of cardiovascular and peripheral factors, including atrial strain, aortic stiffness, and muscle-related factors. Fontan patients and matched controls were examined. Clinical details were recorded, and atrial strain and aortic stiffness were measured using echocardiography. Hand grip and knee extensor strength were assessed, and muscle oxygenation was recorded. Cardiopulmonary exercise test determined exercise capacity, with peak oxygen uptake/kg (VO2/kg) and oxygen uptake efficiency slope/kg (OUES/kg) as markers for maximal and submaximal capacity, respectively. Thirty-one Fontan patients (median age = 18, range = 7-31years) and 30 controls (median age = 18, range = 7-32years) were studied. No significant differences in body composition and muscle strength were observed between Fontan patients and controls (p > 0.05). Fontan patients exhibited lower peak VO2/kg and OUES/kg (p < 0.001 for both), along with decreased atrial strain and increased aortic stiffness compared to controls (p < 0.001). Aortic pulse wave velocity (PWV), left atrial strain contractile phase (LASct), and knee extensor strength independently predicted peak VO2/kg (R2 = 0.514) and OUES/kg (R2 = 0.486) in Fontan patients; age was a predictor for peak VO2/kg. Atrial contractile strain, aortic stiffness, and knee extensor muscle strength are predictors of submaximal exercise capacity; furthermore, age, along with these variables, serves as predictors of maximal exercise capacity in Fontan patients. Evaluating hemodynamic, vascular, and muscular parameters, in conjunction with assessing both maximal and submaximal exercise capacities, is crucial for optimizing disease management in Fontan patients. Clinicaltrials.gov registration: NCT05011565.

Effect of Fontan circulation on body composition and correlation with exercise capacity

Abstract Background There is growing attention to body composition in Fontan patients (FP) and preliminary results suggest that FP have an increased fat mass and a decreased muscle mass compared to the healthy population. FP also have reduced exercise capacity compared to health peers. However, data are still limited. Purpose The aim of our study was to compare the body composition (BC) of adult patients with Fontan circulation and healthy controls and to assess the correlation with functional capacity. Material and Methods Case control study on adult patients with Fontan circulation (FP) and age and gender matched healthy controls (HC). The following characteristics were recorded: age, gender, morphology of the systemic ventricle, type of Fontan circulation, level of physical activity (PAR, 0-7 points, 0 = sedentary - 7 = running &amp;gt; 3hours/week). S-score muscle, T-score bone, fat mass (FM%), intra-muscular adipose tissue (IMAT), abdominal adipose tissue (AAT), intracellular water (ICW), extracellular water (ECW), total body water (TBW), were measured through multi-frequency bioelectrical impedance technology in the FP and in the HC. Correlation was made for FP between body composition and oxygen consumption at peak exercise (VO2 peak), VE/VCO2 slope and NYHA class as indicator of functional capacity. Results Thirty Fontan patients (FP, mean age 24±6 yrs, 70% males) and 30 matched healthy controls (HC) were recruited in the study. The systemic ventricle was dominant left in 14 patients (47%), dominant right in 16 (53%). Four patients had atrio-pulmonary connection, the remaining were palliated with a lateral tunnel (n=26, 87%). The analysed parameters are summarised in Table 1. PAR was reduced in FP compared to HC (median 4.0 points in FP versus 7.0 points in HC, p 0.024). There was no difference in the BMI, fat mass, and body water between FP and HC. However, FP showed significantly lower S and T scores compared to the HC (S-score: -0,75 in FP versus 0,0 in HC, p 0.003. T-score: -0.9 in FP versus -0.25 in HC, p 0.001). In FP, NYHA Class was I in 28 patients (93%), II in 1 (3,5%) and III in 1 (3.5%) patient. The mean VO2 was 23.4±5.4mlO2/kg/min and mean VE/VCO2 slope 32±7. There was a direct correlation between VO2 peak and the PAR (rho 0.443, p 0.044). No correlation was found between the VO2 peak, the VE/VCO2 slope or the NYHA Class and the analysed parameters of body composition. Conclusion FP have reduced muscle mass, and bone density compared to HC. In addition to the known reduced efficiency of the cardiac pump during exercise in FP, the lower level of conditioning contributes to the reduced exercise capacity in this population. Programs aiming to encourage physical activity are key and should be part of patients’ care.

Outcomes and management of Haemoptysis in the Fontan population

Abstract Background Patients with a Fontan circulation for palliation of a univentricular congenital heart defect commonly possess pulmonary vascular abnormalities including arteriovenous malformations (AVM), aortopulmonary and venous-venous collaterals (1). These vessels are prone to haemorrhage which may result in life-threatening haemoptysis (2). This risk is increased with oral anticoagulant medication, given to reduce the risk of thromboembolism in Fontan patients (3). Management of these patients is difficult, and strategies vary across institutions. Purpose We aim to describe our experience with managing adult Fontan patients presenting with haemoptysis in a tertiary centre with a large Fontan cohort. Methods We retrospectively reviewed the records of 410 adult Fontan patients. Individuals admitted to our institution with an episode of haemoptysis were included. Details relating to anticoagulation regimens, interventions and mortality of patients were captured. Results From a cohort of 410 Fontan patients, 35 haemorrhagic events were observed in 11 patients (2.68%). The median age at initial haemoptysis was 24.5 years (range 19 to 43 years). 6 of the 11 patients were female (54.5%). Haemoptysis recurred in 8 of the 11 patients (72.7%). 2 out of 11 had a prior history of haemoptysis in childhood. All patients were administered with oral vitamin K antagonists at presentation. 24 of the 35 events were managed conservatively with IV fluids, anticoagulation reversal and tranexamic acid (66.7%). 11 events required catheter-based interventions, with coil and/or plug embolization of bleeding vessels. Prior to intervention, CT successfully identified potential bleeding sites in 10 of the 11 events (90.9%) but could not visualise all vessels that were subsequently embolized. The most common culprits for haemoptysis were aortopulmonary collaterals, followed by AVMs and venous-venous collaterals. In severe cases, more extensive management was required including transfusions, bronchoscopy, intubation, surgical exploration (1 patient) and pneumonectomy (1 patient). 3 patients died following recurrent severe haemoptysis (27.3%), and 2 patients died of subsequent Fontan failure and sudden cardiac death respectively. Total mortality of the cohort is 5 out of 11 (45.5%) with a median follow up of 10.75 years (range 3 days to 27 years). Conclusions Haemoptysis is a rare but potentially fatal complication in patients who have undergone a Fontan procedure. The variability in presentation of this condition mandates an individualised approach to management with involvement of a multidisciplinary team. There is a high rate of recurrence following haemoptysis and a comprehensive assessment of all potential bleeding sites is necessary. CT is a useful tool to help facilitate this and guide further management. Our policy is to close all potential sources of bleeding as CT and invasive angiography rarely identifies an active point of bleeding.

In vivo study of pulmonary artery remodeling and pulsatility in long Fontan patient

Abstract Background Pulmonary vasculopathy associated with Fontan circulation is a relatively unexplored entity that could have clinical and therapeutic implications. Purpose Our aim was to evaluate the physiology of the pulmonary artery in patients with Fontan circulation using conventional right heart catheterization (RHC) and intravascular ultrasound (IVUS). Methods From December 2022 to January 2024, data from all consecutive Fontan patients undergoing RHC were prospectively collected at a tertiary referral center for adult congenital heart disease. Pressures and pulmonary artery wall high-definition IVUS recordings (OptiCrossTM, 60 MHz, Boston Scientific) were recorded at rest and during apnea. Pathological Fontan pressure was defined when as exceeding 15 mmHg. IVUS pulsatility index was defined as [(systolic lumen area - diastolic lumen area)/(diastolic lumen area) ×100], Peterson's elastic modulus as (pulmonary pulse pressure/IVUS pulsatility index), and area of wall thickness as [(wall area - lumen area)/(lumen area) x100)]. In the literature, the mean ± standard deviation (SD) normal values of elastic modulus and wall thickness area have been reported as 21 ± 1.7 mmHg and 1.4 ± 1.3%, respectively, in healthy patients without pulmonary hypertension (1: doi: 10.1186/s12931-017-0568-z). We define an alteration in intrinsic pulmonary arterial wall viscoelastic properties as an elastic modulus &amp;gt; 70 mmHg, and we define structural pulmonary wall remodeling as an increase in wall thickness area greater than 5%. Results 13 patients were studied. Median age was 28.1 years interquartile range (IQR) (25.6- 41.4), 7 (53.9%) were female, and 4 (30,8%) were in functional New York Heart Associtation (NYHA) class I. RHC and pulmonary arterial wall IVUS values are presented in Figure 1. 6 (46.2%) had Fontan abnormal pressures at rest. All patients showed minimal pulse pressure in the pulmonary arteries synchronized with heart rate, median pulmonary pulse pressure (IQR) 3 (2-4) mmHg. This pulsatility was detected in the IVUS study in all patients, pulsatility index (median (IQR) 4.8 (3.3-10.1)) and elastic modulus (median (IQR) 51.5 (20.5-101.6) mmHg). All of them had some degree of structural pulmonary wall remodeling (&amp;gt;5% wall thickness area), and 10 (76.9%) of them had marked remodeling (&amp;gt; 10%). The median (IQR) of wall thickness area was 13.6 (10.5-18.3) % (Figure 2). We think that the pseudo-normality of the elastic modulus is due to a low pulmonary pulse pressure, however, structural remodeling could be secondary to the endothelial dysfunction present and described in arteries with very low pulsatility. Conclusions The IVUS evaluation of the pulmonary artery in Fontan patients may be useful for revealing significant information regarding pulmonary physiology. Pulmonary wall thickening has been observed, providing insight into altered structural remodeling of the pulmonary arteries in this population.

Optimising liver screening in patients with a Fontan circulation: a cost-effective approach to detection of Fontan associated liver disease which enhances patient care

Abstract Introduction Patients with Fontan circulation, require screening for liver cirrhosis and malignancy, to which they are susceptible with time. Surveillance biopsies reveal nearly all adult Fontan patients develop asymptomatic fibrosis, and a majority have abnormal liver function tests (LFTs). This presents significant financial healthcare burden and psychological stress with testing for patients. Objective We aim to present "real-world" liver screening data, from a leading Adult Congenital Heart Disease (ACHD) centre, to propose a cost-reducing testing regimen, which delivers effective screening, while taking account of the challenges of current guidance, patient compliance, and clinical practice. Methods We analysed liver screening data for Fontan patients at a leading ACHD centre, focusing on biochemical tests (bilirubin, ALT, GGT) and imaging. We evaluated the 10-year financial impact of current practices, versus a hypothetical model based on age and risk factors, alongside biannual and annual screening strategies. Tariffs for biochemical test were provided by the local pathology service and we used NHS HRG tariffs for imaging and phlebotomy. Results We included data from 114 patients with a Fontan circulation (median age 32 range 19-56, 42% females). Eighteen patients developed liver cirrhosis diagnosed on imaging (median age 32, range 22-48). None developed hepatocellular carcinoma. A lack of clear and agreed local screening guidelines (over years) resulted in vastly different investigations for FALD, with inconsistent time intervals for testing. Bilirubin was elevated in 59% (55% in age 18-29), ALT was elevated in 41% (31% in age 18-29), GGT was elevated in 83% (80% in age 18-29). We found 3 cases of cirrhosis in the age group 18-29, all with hypoplastic left heart; 4 cases of cirrhosis in age group 30-34 - all had significant comorbidities; 33% had normal bilirubin, LFT and GGT, potentially not requiring further screening until the age of 35. Eleven patients (22%) age 35+ had confirmed cirrhosis (Figure 1). Performing full FALD screening with biochemistry and liver ultrasound every 12-24 months would increase the cost of screening three- to six-fold. We propose rationalising liver screening by age and underlying risk (Figure 2) to minimise the economic burden and equally the psychological impact of frequent testing on patients. Conclusions Our analysis underscores the necessity for an optimised liver screening protocol in Fontan patients, balancing diagnostic accuracy with cost-efficiency. By integrating this data, we have identified a pathway to streamline screening, tailoring it to individual risk profiles and age groups, thereby reducing unnecessary tests, lowering costs and reducing the impact of testing on patients. This approach not only fosters better patient care, but also provides a framework for developing clearer, cost-effective screening guidelines, to monitor liver health, in these complex CHD patients.

Late outcomes of Fontan operation from the EUROFONTAN experience

Abstract Background Fifty years after the first Fontan operation, the persisting challenges and evolving landscape of post-Fontan complications are explored in the EUROFONTAN experience. Aim of the study is the evaluation of long term outcomes of a large cohort of Fontan patients, focusing on age at Fontan and onset of Fontan-associated liver disease (FALD). Methods A retrospective clinical study across 21 european congenital cardiac centers across Europe. Clinical and operative data of patients who underwent Fontan operation between January 1990 and December 2022 were gathered through a RedCap online database. Results 2606 patients were included in this analysis (M/F: 59%/41%, median age and median weight at Fontan of 4.3 y.o (IQR 3.3-6.4), and 16kg (IQR 14-20), respectively. Most frequent cardiac anomaly were tricuspid atresia and pulmonary atresia with intact ventricular septum (781, 30%). Ventricular morphology was left in 1379 patients (53%), and right in 1029 patients (40%). Extra cardiac conduit (ECC) was performed in the majority of patients (2335, 90%), with a median conduit size of 20mm (IQR 18-20). Early post-operative complications were present in 52% (1340), with an early reintervention in 349 patients (249 surgical , 99 catheter driven) At a median follow-up median of 10 years (IQR 4-15), there were 79 late deaths (3%). Adverse events occurred in 49% (1288 , non-surgical in 962 , surgical in 249). The clinical status was stage A in 60% (1288 patients), while only a minority (1.3%) was in status D. Systemic Ventricular function was normal in 1898 patients (73%), while absent or mild Atrioventricular Valve regurgitation was presnet in 86% (1816). Of note, FALD was detected in 388 (15 %) , and sinus rhythm was present in 99%. Statistical analysis shows that late death and adverse events are significantly associated right ventricular morphology of the systemic ventricle (p-value 0.019). Of note, when compared to lateral tunnel, TCPC extracardiac conduit demonstrated lower late mortality (2.3% vs 8.2%, p-value &amp;lt;0.001) and complication rates (60% vs 48%, p-value 0.001). Analyzing age at Fontan, a linear relationship exists between age and late mortality, whereby mortality increases with advancing age (graph 1). However, concerning the development of late adverse events, the risk decreases with age at Fontan up to 7 years; beyond 7 years, the risk increases with advancing age (graph 2). The analysis demonstrated growing FALD-prevalence with increasing time from Fontan completion (significant especially after 10 years). Conclusion current long term outcomes of Fontan operation are highly satisfactory. However, the longer survival is associated to an increasing incidence of late term extracardiac complications (namely FALD) which are more evident if Fontan is performed at older age.Data of Fontan PatientsCorrelation between age at Fontan and AE

Comparative Analysis of Respiratory and Functional Outcomes in Children Post-Fontan Procedure Versus Healthy Peers.

Studies have shown that respiratory muscle training enhances functional capacity and pulmonary function in Fontan patients. However, diaphragm muscle characteristics in Fontan children have not been fully elucidated. The aim of this study was to compare respiratory function, maximal and submaximal functional capacities, and quality of life, as well as to assess diaphragm mobility and thickness, between Fontan patients aged 8 to 12years and healthy individuals. This cross-sectional study included 45 children-27 Fontan patients, Fontan Group (FG) and 18 healthy control Group (CG) subjects. Different examinations were performed: spirometry was used to analyze pulmonary volume and capacity; manovacuometry was used to determine respiratory muscle strength; chest ultrasound was used to determine diaphragm muscle characteristics; cardiopulmonary exercise and the six-minute walk test (6MWT) wereused to determine functional capacity; the AUQEI questionnaire was used to determine quality of life. Descriptive analysis and intergroup comparisons were performed for all the data. Compared with the CG, the FG exhibited impaired pulmonary function and reduced functional capacity. Significant differences in median values were noted for forced expiratory volume in one second (FEV1): 2.39L/min, p = 0.002; forced vital capacity (FVC): 1.73 vs. 3.06L/min, p = 0.002; maximal inspiratory pressure: - 73 vs. - 117cmH2O, p = 0.007; absolute peak VO2: 1.09 vs. 1.51L/min, p < 0.001; relative peak VO2: 31.9 vs. 42.5mL/kg/min, p = 0.003; and 6MWT distance: 420 vs. 586m, p < 0.001. Diaphragmatic thickness, mobility and quality of life were similar between the groups. Despite the reduced functional capacity, impaired pulmonary volume and capacity, and respiratory muscle weakness of the FG compared to those of the CG, the diaphragm characteristics and quality of life were similar between the groups.

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

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 abaseline for future targeted efforts to improve this. 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. 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. 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.

Comparison of Echocardiographically-Calculated Fontan Fenestration Gradient and Catheter-Based Measurement.

Patients born with single ventricle anatomy typically undergo surgical palliation in three stages, culminating in the Fontan procedure. Assessment of flow across a Fontan fenestration by Doppler ultrasound theoretically allows for non-invasive estimation of the transpulmonary gradient (TPG). Our objective was to determine the relationship between Doppler-derived mean fenestration gradient (mFG) and direct catheter-based measurements of TPG in patients with fenestrated Fontans. We performed a single-center retrospective cohort study of 59 patients with fenestrated Fontans completed between 2000 and 2022. The primary outcome was catheter-based measurement of TPG and the primary predictor was mFG from echo performed within 6 months of the catheterization. Linear regression and R2 were used to determine the relationship between predictors and outcomes. Catheter-based measurements of TPG and mFG were weakly correlated (R2 = 0.382, p < 0.001); the regression coefficient was 0.550, with a standard error of 0.09 for every increase in mFG (Cath TPG = 0.55 [mFG] + 1.92). mFG had a slightly better predictive relationship with cath-derived TPG in patients with systemic left ventricles with R2 of 0.47, p < 0.004. mFG accounts for approximately 38% of the variance in catheter-derived TPG. Although mFG is non-invasive and intuitive, mFG in Fontan patients should be interpreted with caution and direct measurement by cardiac catheterization should be considered.

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.

Characterization and Z-score Calculation of Cardiac MRI parameters in patients after the Fontan operation. A Fontan Outcome Registry using CMR Examinations (FORCE) study

BackgroundCardiac 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). ResultsThe “healthier” Fontan population included 885 patients (15.0 ± 7.6 years) from 18 institutions with 1,156 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, BSA 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 ± 0.8L/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 LV morphology (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. ConclusionThis 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.

Cardiac MRI Predictors of ArrhythmicSudden Cardiac Events in Patients With Fontan Circulation.

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. The goal of this study was to determine the prevalence of SCE and risk factors for SCE in the Fontan population. 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. 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 >104mL/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%. 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.

Segmental MRI Pituitary and Hypothalamus Volumes post Fontan: An analysis of the Australian and New Zealand Fontan Registry.

ObjectiveShort stature, central hypothyroidism and infertility are common in those with a Fontan circulation. Given that the Fontan circulation often results in hepatic portal venous congestion, we hypothesize that the hypothalamic-pituitary portal circulation is also affected, contributing to subsequent hypothalamic-pituitary axis dysfunction. MethodsMRI data from the Australian and New Zealand Fontan Registry (86 cases) was compared to 86 age- and sex- matched normal published controls. Total pituitary volumes (both anterior and posterior glands) were measured using a manual tracing segmentation method, and hypothalamic (and subunit) volumes using an automated segmentation tool. Measured gland volume was normalized to total brain volumes. A generalized linear model was used for statistical analysis. ResultsNormalized total pituitary volumes (nTPV) were increased in Fontan patients compared to controls (p <0.0001), due to an increase in anterior pituitary volumes (nAPV) (p <0.0001), with no difference in normalized posterior pituitary volumes (p = 0.7). Furthermore, normalized anterior and tubular hypothalamic subunit groups) were increased in Fontan patients compared to the controls (p <0.01 and p <0.0001, respectively).The time between Fontan and MRI was positively related to nTPV, nAPV and bilateral hypothalamic volumes. nTPV increased with age, and the increase in nAPV was greater in Fontan patients. ConclusionsSegmental MRI Pituitary and Hypothalamus volumes post Fontan are increased and are related to the time since Fontan procedure. These findings are consistent with venous congestion of the anterior hypothalamic-pituitary portal venous system and may explain the high frequency of endocrine dysfunction in this patient group.

Effect of maneuvers, diuresis, and fluid administration on ultrasound-measured liver stiffness after Fontan.

To determine the effect of stress maneuvers/interventions on ultrasound liver stiffness measurements (LSMs) in patients with Fontan circulation and healthy controls. In this prospective, IRB-approved study of 10 patients after Fontan palliation and 10 healthy controls, ultrasound 2D shear-wave elastography LSMs were acquired at baseline and after maximum inspiration, expiration, standing, handgrip, aerobic exercise, i.v. fluid (500mL normal saline) administration, and i.v. furosemide (20mg) administration. Absolute and percent change in LSM were compared between baseline and each maneuver, and then from fluid infusion to after diuresis. Median ages were 25.5 and 26 years in the post-Fontan and control groups (p = 0.796). LSMs after Fontan were higher at baseline (2.6 vs. 1.3m/s) and with all maneuvers compared to controls (all p < 0.001). Changes in LSM with maneuvers, exercise, fluid, or diuresis were not significant when compared to baseline in post-Fontan patients. LSM in controls increased with inspiration (+0.02m/s, 1.6%, p = 0.03), standing (+0.07m/s, 5.5%, p = 0.03), and fluid administration (+0.10m/s, 7.8%, p = 0.002), and decreased 60 minutes after diuretic administration (-0.05m/s, -3.9%, p = 0.01) compared to baseline. LSM after diuretic administration significantly decreased when compared to after i.v. fluid administration at 30 minutes (-0.79m/s, -26.5%, p = 0.004) and 60 minutes (-0.78m/s, -26.2%, p = 0.017) for patients after Fontan and controls at 15 minutes (-0.12m/s, -8.70%, p = 0.002), 30 minutes (-0.15m/s, -10.9%, p = 0.003), and 60 minutes (-0.1m/s, -10.9%, p = 0.005). LSM after Fontan is higher with more variability compared to controls. Diuresis is associated with significantly decreased liver stiffness in both patients after Fontan and controls, with the suggestion of a greater effect in Fontan patients.

Fontan circulation and systemic disease – a retrospective cohort analysis over 35 years of follow-up: Fontan systemic disease at 35 years

BackgroundThe Fontan operation provides lifesaving palliation for individuals with single ventricle (SV) physiology. Given recent concerns of systemic disease (SD) for patients with a Fontan circulation, we sought to 1) quantify the increase in SD incidence associated with the Fontan circulation; 2) identify the risk factor of SD; 3) assess the association between SD and mortality in patients with a Fontan circulation. MethodsA matched retrospective cohort study design was adopted. From the Quebec Congenital Heart Disease (CHD) Database with up to 35 years of follow-up, patients who survived at least 30 days after the Fontan operation were identified. For each Fontan patient, patients with isolated ventricular septal defect (VSD) with the same sex and age were identified and 20 of them were randomly selected to form the control group. The presence of SD was defined as at least one hospitalization due to extra-cardiac complications including liver, respiratory, gastrointestinal or renal disease. Time-to-event analysis including Kaplan-Meier curve analysis and Cox proportional hazard models were conducted to assess the cumulative risk of SD, risk factors of SD, and the association between SD and 10-year mortality. ResultsA total of 533 patients with Fontan circulation were identified and matched with 10,280 VSD patients. The cumulative probabilities of SD at 10- and 35-years follow-up were 59.02% and 89.66% in patients with a Fontan circulation, 4-7 times of the probabilities in VSD patients (8.68% and 23.34%, respectively; LogRank tests p<0.0001). In Fontan patients, cardiovascular complications were associated with a 4.1-fold (95% CI: 3.52-4.88) higher risk of developing SD. Multisystem disease (>1 extra-cardiac organ affected) disease was associated with a 3.38-fold (95%CI: 1.73-6.60) increase in 10-year mortality risk when comparing to the absence of SD. ConclusionsThis population-based study demonstrated that patients with a Fontan circulation had increased risk of SD, which in turn led to higher risk of mortality. These findings underscore the need for more systematic surveillance of cardiac and systemic disease for patients after Fontan operation.

Long-term outcome of direct total cavopulmonary connection versus extracardiac conduit in Fontan circulation

ObjectiveThe long-term outcome of direct total cavopulmonary connection (dTCPC) in Fontan circulation has not been reported yet. This study aimed to compare the long-term outcome of the dTCPC procedure with the extracardiac conduit (ECC) procedure in Fontan patients. MethodsFrom October 2004 to August 2021, 297 patients undergoing Fontan operation by ECC (n=268) or dTCPC (n=29) procedure at our institution were retrospectively reviewed. The propensity score matching method was utilized to match the ECC and dTCPC groups in a 1:2 ratio, yielding 23 dTCPC patients and 40 ECC patients. ResultsThe in-hospital morbidity and mortality were similar between the two groups in both pre-matched and matched cohorts (p > 0.05). The estimated transplantation-free survival rate at 10 years in the matched dTCPC group was 89.7%±7.0%, in contrast to 92.8%±5.0% in the matched ECC group (p = 0.55). The estimated 10-year estimated freedom from Fontan failure in the matched dTCPC group was 85.2%±8.0%, also similar to the 85.9%±6.7% in the matched ECC group (p = 0.72). The dTCPC pathways at the follow-up were significantly larger than those before Fontan surgery (p < 0.05). ConclusionsThe dTCPC procedure is a feasible and effective strategy for highly selected Fontan candidates who have well-developed pulmonary arteries of adequate length and size. This approach not only allows for the potential growth of dTCPC pathways but also demonstrates non-inferior short-term and long-term outcomes in contrast to the ECC strategy.

Clinical characteristics and outcomes in middle-aged Fontan patients

BackgroundMiddle-aged Fontan patients are underrepresented in contemporary studies. The purpose of this study was to describe the clinical characteristics and outcomes in middle-aged patients with Fontan palliation. MethodsAll adults with Fontan palliation were divided into ‘middle-aged’ group (>40 years of age at baseline encounter), and ‘young adult’ group. Clinical characteristics were assessed across multiple domains (atrial arrhythmias, heart failure, and hepatorenal function). Clinical outcomes were assessed as composite outcome of death/heart transplant. ResultsOf 455 adults (median age 26 years), 63 (14 %) were middle-aged adults while 392 (86 %) were young adults. Compared to the young adult group, the middle-aged group had a higher prevalence of atrial arrhythmias, greater neurohormonal activation, and worse hepatorenal function. Of 63 patients in the middle-aged group, 26 (41 %) patients died, and 4 (6 %) patients underwent heart transplant. The middle-aged group had a higher 5-year cumulative incidence of death/transplant (45 % versus 21 %, p < 0.001), and 10-year cumulative incidence of death/transplant (64 % versus 29 %, p < 0.001) compared to the young adult group. Higher pulmonary artery wedge pressure (hazard ratio 1.18 [1.09–1.27]), and higher model for end-stage liver disease excluding international normalized ratio score (hazard ratio 1.07, [1.03–1.14]), were associated with death/transplant. ConclusionsAbout 14 % of adults with Fontan palliation were middle-aged, and these patients had higher prevalence of cardiovascular comorbidities, hepatorenal dysfunction, and mortality. These data underscore the need for better risk stratification strategies to identify patients at risk for adverse outcomes and allow for early referral for transplant evaluation in this emerging subpopulation. Clinical summaryThe purpose of this study was to describe the clinical characteristics (comorbidities and end-organ dysfunction) and outcomes (death/transplant) in middle-aged patients with Fontan palliation. Of 455 patients (median age 26 years), 63 (14 %) were middle-aged adults while 392 (86 %) were young adults. Compared to the young adult group, the middle-aged group had a higher prevalence of atrial arrhythmias, greater neurohormonal activation, worse hepatorenal function, and higher risk of death/transplant. The correlates of death/transplant were higher pulmonary artery wedge pressure and hepatorenal dysfunction. These data underscore the need for better risk stratification in this emerging population.

Transcatheter occlusion of venovenous collaterals in the total cavopulmonary Fontan circulation.

Venovenous collaterals are abnormal connections between the systemic and pulmonary venous systems. They are commonly seen in the Fontan circulation and may lead to significant hypoxaemia. Transcatheter closure of venovenous collaterals is a potential but controversial treatment as the long-term benefits and outcomes are not well understood. This retrospective cohort study utilised data from the Australian and New Zealand Fontan Registry. Patients who underwent transcatheter venovenous collateral occlusion for hypoxemia from the year 2000 onwards were included. Atriopulmonary and Kawashima-type Fontan circulations were excluded to reflect a more contemporary Fontan cohort. Nineteen patients (age 19.3 ± 7.8 years, 53% female) underwent transcatheter venovenous collateral occlusion. Compared to baseline, mean oxygen saturation was improved at latest follow-up (90.5% vs 87.0%; p = 0.003). Nine patients achieved a clinically significant response (defined as an increase of at least 5% to 90% or greater), and this was associated with lower baseline Fontan pressures (12.9 v 15.6 mmHg; p = 0.02). No heart failure hospitalisations, arrhythmia, transplant referrals, or mortality were observed during the median follow-up period of 4 years. Two patients experienced thromboembolic events and five patients underwent re-intervention. Transcatheter occlusion of venovenous collaterals in Fontan patients with chronic hypoxaemia resulted in a modest increase in oxygenation over a median follow-up of 4 years and longer-term prognosis did not appear to be adversely affected. Lower Fontan pressures at baseline were associated with a greater improvement in oxygenation.