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Over time, long-term survival has dramatically increased for patients with complex congenital heart disease who undergo the Fontan operation. With this increased survival, it has become apparent that such a circulation has important consequences for other organ systems, particularly the liver and kidney. The adverse milieu created by chronic venous hypertension, low cardiac output, and an inflammatory state contribute to the pathologic changes observed in the liver and kidneys over the long term in Fontan patients. The clinical importance of these hepatic and renal comorbidities have only recently begun to be recognized in the context of increasing life expectancy in this population. The objectives of this review are to provide an overview of the pathophysiology of the Fontan circulation and how liver and kidney disease evolve in this setting; to summarize the current evidence base as it relates to the diagnostic approach to liver and kidney disease in Fontan patients; and to discuss the therapeutic approaches to Fontan- associated liver and kidney disease. Given that this is a very active area of research in congenital heart disease, we have identified knowledge gaps and priority research areas to improve the care of Fontan patients. These include establishing the optimal diagnostic tests to detect and track liver and kidney disease change over time, determining which treatable risk factors contribute to the development of liver and kidney disease, and evaluating therapies to prevent or slow progression of liver and kidney disease., (Copyright © 2022 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.)

Interventions in adults with congenital heart disease (ACHD) focus on surgical and percutaneous interventions in light of rapidly evolving ACHD clinical practice. To bring rigour to our process and amplify the cumulative nature of evidence ACHD care we used the ADAPTE process; we systematically adjudicated, updated, and adapted existing guidelines by Canadian, American, and European cardiac societies from 2010 to 2020. We applied this to interventions related to right and left ventricular outflow obstruction, tetralogy of Fallot, coarctation, aortopathy associated with bicuspid aortic valve, atrioventricular canal defects, Ebstein anomaly, complete and congenitally corrected transposition, and patients with the Fontan operation. In addition to tables indexed to evidence, clinical flow diagrams are included for each lesion to facilitate a practical approach to clinical decision-making. Excluded are recommendations for pacemakers, defibrillators, and arrhythmia-directed interventions covered in separate designated documents. Similarly, where overlap occurs with other guidelines for valvular interventions, reference is made to parallel publications. There is a paucity of high-level quality of evidence in the form of randomized clinical trials to support guidelines in ACHD. We accounted for this in the wording of the strength of recommendations put forth by our national and international experts. As data grow on long-term follow-up, we expect that the evidence driving clinical practice will become increasingly granular. These recommendations are meant to be used to guide dialogue between clinicians, interventional cardiologists, surgeons, and patients making complex decisions relative to ACHD interventions., (Copyright © 2021 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.)

Background/objectives: Pregnancy may potentiate the inherent hypercoagulability of the Fontan circulation, thereby amplifying adverse events. This study sought to evaluate thrombosis and bleeding risk in pregnant women with a Fontan., Methods: We performed a retrospective observational cohort study across 13 international centres and recorded data on thrombotic and bleeding events, antithrombotic therapies and pre-pregnancy thrombotic risk factors., Results: We analysed 84 women with Fontan physiology undergoing 108 pregnancies, average gestation 33±5 weeks. The most common antithrombotic therapy in pregnancy was aspirin (ASA, 47 pregnancies (43.5%)). Heparin (unfractionated (UFH) or low molecular weight (LMWH)) was prescribed in 32 pregnancies (30%) and vitamin K antagonist (VKA) in 10 pregnancies (9%). Three pregnancies were complicated by thrombotic events (2.8%). Thirty-eight pregnancies (35%) were complicated by bleeding, of which 5 (13%) were severe. Most bleeds were obstetric, occurring antepartum (45%) and postpartum (42%). The use of therapeutic heparin (OR 15.6, 95% CI 1.88 to 129, p=0.006), VKA (OR 11.7, 95% CI 1.06 to 130, p=0.032) or any combination of anticoagulation medication (OR 13.0, 95% CI 1.13 to 150, p=0.032) were significantly associated with bleeding events, while ASA (OR 5.41, 95% CI 0.73 to 40.4, p=0.067) and prophylactic heparin were not (OR 4.68, 95% CI 0.488 to 44.9, p=0.096)., Conclusions: Current antithrombotic strategies appear effective at attenuating thrombotic risk in pregnant women with a Fontan. However, this comes with high (>30%) bleeding risk, of which 13% are life threatening. Achieving haemostatic balance is challenging in pregnant women with a Fontan, necessitating individualised risk-adjusted counselling and therapeutic approaches that are monitored during the course of pregnancy., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. No commercial re-use. See rights and permissions. Published by BMJ.)

Objective: Patients with Fontan surgery experience late complications in adulthood. We studied the factors associated with the development and maintenance of atrial arrhythmias and thromboembolic complications in an adult population with univentricuar physiology post Fontan surgery., Methods: Single centre retrospective cohort study of patients ≥18 years of age with Fontan circulation followed at our quaternary care centre for more than 1 year were included. Univariate and multivariate regression models were used where applicable to ascertain clinically significant associations between risk factors and complications., Results: 93 patients were included (age 30.2±8.8 years, 58% men). 28 (30%) had atriopulmonary Fontan connection, 35 (37.6%) had lateral tunnel Fontan and 29 (31.1%) had extracardiac Fontan pathway. After a mean of 7.27±5.1 years, atrial arrhythmia was noted in 37 patients (39.8%), of which 13 developed had atrial fibrillation (14%). The presence of atrial arrhythmia was associated with the number of prior cardiac surgeries/procedures, increasing age and prior atriopulmonary Fontan operation. Thromboembolic events were present in 31 patients (33%); among them 14 had stroke (45%), 3 had transient ischaemic attack (9.7%), 7 had pulmonary embolism (22.6%) and 5 had atrial thrombus with imaging (16.1%). The presence of thromboembolic events was only associated with age and the presence of cirrhosis in multivariate analysis., Conclusions: Atrial arrhythmias are common in adults with Fontan circulation at an early age, and are associated with prior surgical history and increasing age. Traditional risk factors may not be associated with atrial arrhythmia or thromboembolism in this cohort., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: The impact of Fontan circuit thrombus is poorly understood. The objectives of this study were to determine (1) the incidence of Fontan circuit thrombus and proportion of silent thrombus; (2) any association between Fontan circuit thrombus and markers of Fontan circulatory dysfunction; and (3) the association of Fontan circuit thrombus with adverse cardiac outcomes., Methods: We conducted a retrospective review of adult patients who underwent the Fontan procedure (aged > 18 years) followed at St. Paul's Hospital who underwent cardiac computed tomography or magnetic resonance imaging assessment (n = 67). Fontan circulatory dysfunction markers included clinical heart failure, N-terminal pro-brain natriuretic peptide, ventricular dysfunction, atrioventricular valvular regurgitation, refractory arrhythmias, declining exercise capacity, and hepatic/renal dysfunction. Adverse cardiac outcomes were death, heart transplantation, or surgery for Fontan revision or atrioventricular valve replacement., Results: Fontan circuit thrombus was present in 15 of 67 patients (22%): 41% (7/17) classic/modified Fontan and 16% (8/50) total cavopulmonary connection. Incidence was 36% among those suspected to have Fontan circuit thrombus; 14% in those with no clinical/echocardiographic suspicion; and clinically silent in 40% diagnosed with Fontan thrombus. The time from Fontan surgery to Fontan circuit thrombus diagnosis was 22 ± 6 years in the classic/modified group vs 14 ± 8 years in the total cavopulmonary connection group (P = 0.03. Fontan circuit thrombus was associated with adverse cardiac outcomes (27% [4/15] vs 8% [4/52], P = 0.02), but there was no difference in Fontan circulatory dysfunction markers., Conclusion: Given the incidence of Fontan circuit thrombus and association with adverse cardiac outcomes, routine surveillance of the Fontan circuit should strongly be considered. The identification of thrombus should lead to anticoagulation implementation/optimization, along with screening/intervention for reversible Fontan circulatory issues in an attempt to prevent adverse cardiac outcomes., (Copyright © 2019 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.)

Many adults with single-ventricle congenital heart disease who have undergone a Fontan procedure have abnormal pulmonary function resembling restrictive lung disease. Whether this contributes to ventilatory limitations and increased dyspnea has not been comprehensively studied. We recruited 17 Fontan participants and 17 healthy age- and sex-matched sedentary controls. All participants underwent complete pulmonary function testing followed by a symptom-limited incremental cardiopulmonary cycle exercise test with detailed assessments of dyspnea and operating lung volumes. Fontan participants and controls were well matched for age, sex, body mass index, height, and self-reported physical activity levels (all P > 0.05), although Fontan participants had markedly reduced cardiorespiratory fitness and peak work rates ( P < 0.001). Fontan participants had lower values for most pulmonary function measurements relative to controls with 65% of Fontan participants showing evidence of a restrictive ventilatory defect. Relative to controls, Fontan participants had significantly higher breathing frequency, end-inspiratory lung volume (% total lung capacity), ventilatory inefficiency (high ventilatory equivalent for CO 2 ), and dyspnea intensity ratings at standardized absolute submaximal work rates. There were no between-group differences in qualitative descriptors of dyspnea. The restrictive ventilatory defect in Fontan participants likely contributes to their increased breathing frequency and end-inspiratory lung volume during exercise. This abnormal ventilatory response coupled with greater ventilatory inefficiency may explain the increased dyspnea intensity ratings in those with a Fontan circulation. Interventions that enhance the ventilatory response to exercise in Fontan patients may help optimize exercise rehabilitation interventions, resulting in improved exercise tolerance and exertional symptoms. NEW & NOTEWORTHY This is the first study to comprehensively characterize both ventilatory and sensory responses to exercise in adults that have undergone the Fontan procedure. The majority of Fontan participants had a restrictive ventilatory defect. Compared with well-matched controls, Fontan participants had increased breathing frequency, end-inspiratory lung volume, and ventilatory inefficiency. These abnormal ventilatory responses likely form the mechanistic basis for the increased dyspnea intensity ratings observed in our Fontan participants during exercise.

Objectives: 1) To determine the accuracy of estimated GFR (eGFR) as compared to directly measured GFR (mGFR) in the adult Fontan population; 2) to determine the true prevalence of chronic kidney damage (CKD) as determined by uACR AND eGFR., Methods: Prospective study of 81 patients Fontan patients (≥18years) followed at St. Paul's Hospital, University of British Columbia. CKD-EPI and MDRD equations used to calculate eGFR, mGFR determined by 99m Tc-DTPA renal dynamic imaging and urine albumin to creatinine ratios were calculated., Results: The mGFR was 93±27ml/min/1.73m 2 : 28 (53%) had an mGFR<90ml/min/1.73m 2 and 1 (2%) had an mGFR <60ml/min/1.73m 2 . There was a modest correlation between mGFR and eGFR (EPI/MDRD) (r=0.50, p<0.0001 and r=0.54, p<0.0001 respectively). Both eGFR (EPI) (bias 27.0; 95% CI 18.0-27.7ml/min/m 2 , p<0.0001) and eGFR (MDRD) (bias 15.5; 95% CI 7.6-17.4ml/min/m 2 , p<0.0001) overestimated GFR as compared to mGFR. Among patients with an eGFR (EPI)/(MDRD) >90ml/min/1.73m 2 , 50% and 46% respectively had an mGFR <90ml/min/1.73m 2 . Significant albuminuria (>3mg/mmol) was present in 33% and upwards of 32% of patients with a normal eGFR (MDRD/EPI) had evidence of CKD with uACR >3mg/mmol. Using combined criteria of eGFR <90ml/min/1.73m 2 and/or uACR >3mg/mmol, 46% of patients had evidence of CKD., Conclusions: This study draws attention to the need for stringent CKD screening as an important proportion of CKD is currently not being detected. Mild undetected CKD, an early marker of end organ damage, may also be an early sign of Fontan failure that requires warrants further research., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The Fontan procedure is increasingly being used to palliate univentricular physiology. It is a complex anatomic and physiologic repair that can fail at any age, often leaving heart transplantation as the only remaining solution. A meta-analysis was performed to achieve the aim of systematically evaluating the existing evidence for survival after heart transplantation in patients who have undergone a Fontan palliation. MEDLINE, Embase, PubMed, and Web of Science were searched for original research studies. The primary outcome was mortality at 1 and 5 years after transplantation. Five hundred eighty-two records were screened, after the removal of duplicates, 12 retrospective observational studies were selected for inclusion in our meta-analysis. This encompassed a total of 351 Fontan patients undergoing heart transplantation. Mean age was 14 years (range 7 to 24 years) and 65% were men. One- and 5-year survival rates after heart transplantation were found to be 80.3% (95% CI 75.9% to 84.2%) and 71.2% (95% CI 66.3% to 75.7%), respectively. No significant association was found between age, gender, and pulmonary pressures and 1-year mortality. In conclusion, in the largest analysis to date, we found that heart transplantation in younger patients after Fontan procedure has an acceptable early and mid-term mortality. It is comparable to published mortality data of heart transplantation for other forms of congenital heart disease. Heart transplantation in the younger failing Fontan population appears to be a reasonable option when all other avenues have been exhausted and appropriate screening has taken place., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: Thromboembolic complications have been noted after the Fontan operation. However, the prevalence of silent events among an adult contemporary population is not known. Noninvasive screening by any method including computed tomography (CT) has been technically limited to date., Objectives: The objective of this study was to evaluate a novel dual-energy CT (DECT) protocol in determining the prevalence of "silent" intracardiac thrombus and thrombus in the Fontan and pulmonary circulations among adults after the Fontan operation., Methods: All post-Fontan patients attending the Pacific Adult Congenital Heart Clinic were approached for study participation. Those agreeable underwent a full clinical assessment, cardiopulmonary stress testing, transthoracic echocardiogram, and DECT low kilovoltage imaging protocol., Results: Twenty-three patients were included in the study (30 ± 10 years, 26% women). Three (13%) patients had evidence of silent thrombi detected on DECT. All three of these patients had an extracardiac conduit and mural thrombus was found within the conduit. Older age at the time of the Fontan operation was associated with the presence of thrombus (21 ± 14 vs. 11 ± 6 years, P =.05)., Conclusions: Thirteen percent of adult patients post-Fontan procedure have clinically silent thrombi. These were all found among patients with an extracardiac conduit traditionally thought to be at low risk for thromboembolism. Given the significant risk of thromboembolic complications, large randomized prospective studies looking at anticoagulation therapy in all Fontan patients are urgently needed. In the meanwhile, given the important rate of silent thrombi, a systematic robust screening protocol that includes noninvasive low radiation methods such as DECT methods should be considered., (© 2012 Wiley Periodicals, Inc.)