Fontan Circulation Associated Organ Abnormalities Beyond the Heart, Lungs, Liver, and Gut: A Systematic Review

Introduction

Patients with a Fontan circulation are at risk for sequelae of Fontan physiology during follow-up. Fontan physiology affects all organ systems and an overview of end-organ damage is needed.

Methods

We performed a systematic review of abnormalities in multiple organ systems for patients with a longstanding Fontan circulation. We searched online databases for articles describing abnormalities in multiple organ systems. Cardio-pulmonary abnormalities, protein losing enteropathy, and Fontan associated liver disease have already extensively been described and were excluded from this systematic review.

Results

Our search returned 5,704 unique articles. After screening, we found 111 articles relating to multiple organ systems. We found abnormalities in, among others, the nervous system, pituitary, kidneys, and musculoskeletal system. Pituitary edema—relating to the unique pituitary vasculature- may affect the thyroid axis. Renal dysfunction is common. Creatinine based renal function estimates may be inappropriate due to myopenia. Both lean muscle mass and bone mineral density are decreased. These abnormalities in multiple organ systems may be related to Fontan physiology, cyanosis, iatrogenic factors, or lifestyle.

Conclusions

Health care providers should be vigilant for hypothyroidism, visual or hearing deficits, and sleep disordered breathing in Fontan patients. We recommend including cystatin C for assessment of renal function. This review may aid health care providers and guide future research.

Systematic Review Registration:https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021232461, PROSPERO, identifier: CRD42021232461.

Biomarkers for heart failure and prognostic prediction in patients with Fontan circulation

A wide variety of pathologies are involved in heart failure in patients with congenital heart disease (CHD). Specific causes of heart failure after the Fontan procedure include not only single-ventricle circulation, but also the function of the right ventricle as the systemic ventricle, atrioventricular or semilunar valve stenosis or regurgitation, pulmonary hypertension, and left ventricular dysfunction secondary to right ventricular enlargement or dysfunction. As heart failure can occur post-Fontan, for a variety of reasons, clarification of the pathophysiology is the first step in management and treatment. At the same time, it is important to understand each patient's current condition and treatment plan to make an accurate prognosis. Because of the wide variety of pathophysiologies in post-Fontan CHD patients, however, no single biomarker is useful in all situations. Relevant biomarkers must be selected according to each patient's disease state, and combinations of multiple biomarkers should also be considered. In this review, the author describes the clinical importance of various biomarkers for patients who have undergone a Fontan procedure.

Identification of metabolomic profile related to adult Fontan pathophysiology

Background

Metabolic disorders are important pathophysiologies that can cause multiple organ dysfunction and worsen prognosis in Fontan patients. This study aimed to comprehensively evaluate the metabolomic profile of adult Fontan patients and characterize its pathophysiology in relation to 2 control groups.

Methods and Results

We performed metabolomic analysis of 31 plasma samples using capillary electrophoresis time-of-flight mass spectrometry. This observational cross-sectional study compared plasma metabolites of 14 heterogeneous adult Fontan patients with those of control groups, including 9 patients with congenital heart disease after biventricular repair and 8 normal healthy controls. Fontan patients exhibited significant differences in intermediate metabolite concentrations related to glycolysis, the tricarboxylic acid (TCA) cycle, and the urea cycle. The plasma concentrations of lactic acid, 2-oxoglutarate, isocitric acid, malic acid, cis-aconitic acid, arginine, citrulline, and the ratio of ornithine/citrulline showed significantly differences among the groups. Multiple logistic regression analysis with a stepwise selection-elimination method identified 2-oxoglutaric acid (odds ratio [OR] 1.98, 95% confidence interval [CI] 1.05–3.76) and cis-aconitic acid (OR 2.69, 95% CI 1.04–6.99) as independently associated with Fontan patients. After adjustment for the covariates of age and gender, 2-oxoglutaric acid (OR 1.97, 95% CI 0.98–3.93) and cis-aconitic acid (OR 3.88, 95% CI 0.99–15.2) showed remarkable relationships with Fontan patients.

Conclusions

The present findings suggest that abnormalities in the TCA cycle and amino acid metabolism are distinguishing features in the pathophysiology of Fontan patients. Future metabolomic studies will assist in developing biomarkers for the early prediction of “silent” Fontan pathophysiologies.

Patients with Single-Ventricle Physiology over the Age of 40 Years

Background: Single-ventricle physiology (SVP) is associated with significant morbidity and mortality at a young age. However, survival prospects have improved and risk factors for a negative outcome are well described in younger cohorts. Data regarding older adults is scarce. Methods: In this study, SVP patients under active follow-up at our center who were ≥40 years of age at any point between January 2005 and December 2018 were included. Demographic data, as well as medical/surgical history were retrieved from hospital records. The primary end-point was all-cause mortality. Results: Altogether, 49 patients (19 female (38.8%), mean age 49.2 ± 6.4 years) were included. Median follow-up time was 4.9 years (interquartile range (IQR): 1.8–8.5). Of these patients, 40 (81.6%) had undergone at least one cardiac surgery. The most common extracardiac comorbidities were thyroid dysfunction (n = 27, 55.1%) and renal disease (n = 15, 30.6%). During follow-up, 10 patients (20.4%) died. On univariate analysis, renal disease and liver cirrhosis were predictors of all-cause mortality. On multivariate analysis, only renal disease (hazard ratio (HR): 12.5, 95% confidence interval (CI): 1.5–106.3, p = 0.021) remained as an independent predictor. Conclusions: SVP patients ≥40 years of age are burdened with significant morbidity and mortality. Renal disease is an independent predictor of all-cause mortality.

Novel mechanisms for cerebral blood flow regulation in patients with congenital heart disease

BACKGROUND

The mechanisms that regulate cerebral flow in patients after surgery for congenital heart diseases (CHDs) remain poorly understood. We tested our hypothesis that postoperative patients with CHD have disease- or hemodynamic-specific compensatory mechanisms for maintaining cerebral perfusion.

METHODS

A total of 89 children with specific hemodynamics including Glenn (n = 14), Fontan (n = 19), repaired tetralogy of Fallot (n = 24), and control patients (n = 32) were enrolled. The resistance and blood flow distribution between the brain (Rc and CIc) and lower body (Rs and CIs) were calculated by measuring the hemodynamic changes resulting from inferior vena cava occlusion during cardiac catheterization.

RESULTS

Despite considerable differences in cardiac index and superior vena cava pressure (SVCp), cerebral blood flow was preserved in all noncontrol groups, with a ratio between the vascular resistances in the cerebral and lower body circulation (Rc/Rs) that was significantly lower than that in controls. Interestingly, the reduced Rc/Rs of Glenn patients was mediated by the reduced Rc, whereas augmented Rs was conducive to the reduced Rc/Rs in the Fontan and tetralogy of Fallot groups. Multivariate analysis revealed that high SVCp was significantly associated with low Rc. Although low cardiac index was significantly associated with increased Rc and Rs, its impact was much greater on Rs than on Rc.

CONCLUSIONS

Compensatory mechanisms for cerebral flow regulation occur according to hemodynamic abnormality type in postoperative patients with CHD. Because such a regulation mechanism implies cerebral circulation fragility, further investigations are needed to address the impacts of cerebral circulation properties on neurodevelopmental outcomes.

Galectin-3 Is Elevated and Associated With Adverse Outcomes in Patients With Single-Ventricle Fontan Circulation

BACKGROUND

Galectin-3 may play a role in cardiac and noncardiac fibrosis, and elevated circulating levels of this protein predict adverse outcomes in patients with heart failure who do not have congenital heart disease. We investigated galectin-3 in adults with single-ventricle Fontan circulation, patients who are prone to premature clinical deterioration in the context of extensive multiorgan fibrosis.

METHODS AND RESULTS

We measured plasma galectin-3 concentrations in 70 ambulatory adult Fontan patients and 21 age- and sex-matched control participants. Galectin-3 level was significantly higher in the Fontan group (11.85 ng/mL, interquartile range 9.9 to 15.0 ng/mL) versus the control group (9.4 ng/mL, interquartile range 8.2 to 10.8 ng/mL; P<0.001). Among Fontan patients, galectin-3 was positively correlated with age, uric acid, and high-sensitivity C-reactive protein and negatively correlated with estimated glomerular filtration rate. There was no significant relationship between galectin-3 and oxygen saturation, Fontan type, or ventricular morphology. Over a median follow-up of 461 days, 15 events occurred among the Fontan patients: 12 nonelective hospitalizations (with 2 subsequent deaths) and 3 deaths without prior hospitalization. Patients with elevated galectin-3 (n=19, defined as >2 SD above the control group mean value) had a higher risk of nonelective hospitalization or death (hazard ratio 6.0, 95% CI 2.1 to 16.8, P<0.001). This relationship persisted after individual adjustment for covariates including age, New York Heart Association functional class, C-reactive protein, and estimated glomerular filtration rate and after multivariable adjustment for independently predictive covariates (hazard ratio 9.2, 95% CI 2.4 to 35.2, P=0.001).

CONCLUSIONS

Galectin-3 concentrations are elevated among adults with a Fontan circulation, and elevated galectin-3 is associated with an increased risk of nonelective cardiovascular hospitalization or death.

Stem cell therapies in patients with single ventricle physiology

Single ventricle physiology, especially hypoplastic left heart syndrome, is one of the most high-risk lesions in children with congenital heart disease, and the ensuing heart failure remains as a major problem related to adverse outcomes in these patients. The field of stem cell therapy for heart failure has shown striking advances during the past 10 years, and many clinical trials using stem cell technologies have been conducted in adults, which suggest that stem cell therapy is associated with long-term improvement in cardiac function. Cardiac progenitor cells have recently been discovered, and their strong regenerative ability has been demonstrated in several studies. Although no large clinical trials have been performed in the field of congenital heart disease, recent investigations indicate that stem cell therapy may hold great potential to treat children with cardiac defects.

Risk factors and serological markers of liver cirrhosis after Fontan procedure

Liver cirrhosis (LC), which may result in hepatic failure or cancer, has been reported in patients after Fontan procedure. The purpose of this study was to clarify the frequency and histological characteristics of LC, and to evaluate the risk factors and serological markers of LC with Fontan circulation. Retrospective review of contrast-enhanced CT scans (CT) of the liver was carried out in 57 patients after Fontan procedure. Patients were divided into two groups: LC group (n = 31) and no LC group (n = 26). Age at Fontan procedure, duration after Fontan procedure, catheterization data, and history of failing Fontan circulation were compared between groups. Serological data including γ-GTP and hyaluronic acid were compared. Histology of autopsy specimens was assessed when available. Duration after Fontan procedure was significantly longer in LC group than no LC group. History of failing Fontan circulation was more frequent in LC group than in no LC group. There was no correlation between type of procedure (APC/Bjork/lateral tunnel/TCPC) and LC in this series. Serum hyaluronic acid, γ-GTP, and Forns index were significantly higher in LC group. Significant risk factors for LC were duration after Fontan procedure (>20 years). In autopsy specimens, histopathological changes of LC were observed predominantly in the central venous area. LC diagnosed with CT is frequent in patients long after Fontan procedure, especially after 20 years. Hyaluronic acid and γ-GTP could be useful markers to monitor the progression of liver fibrosis in Fontan patients.

BNP in children with congenital cardiac disease: is there now sufficient evidence for its routine use?

Interest in brain natriuretic peptide (BNP) and N-terminal pro-brain natriuretic peptide (NT-proBNP) in the management of children with CHD has increased. There are, however, no current guidelines for their routine use. The aim of this review article is to provide an update on the data regarding the use of BNP/NT-proBNP in the evaluation and surgical treatment of children with CHD. BNP/NT-proBNP levels in children with CHD vary substantially according to age, laboratory assay methods, and the specific haemodynamics associated with the individual congenital heart lesion. The accuracy of BNP/NT-proBNP as supplemental markers in the integrated screening, diagnosis, management, and follow-up of CHD has been established. In particular, the use of BNP/NT-proBNP as a prognostic indicator in paediatric cardiac surgery has been widely demonstrated, as well as its role in the subsequent follow-up of surgical patients. Most of the data, however, are derived from single-centre retrospective studies using multivariable analysis; prospective, randomised clinical trials designed to evaluate the clinical utility and cost-effectiveness of routine BNP/NT-proBNP use in CHD are lacking. The results of well-designed, prospective clinical trials should assist in formulating guidelines and expert consensus recommendations for its use in patients with CHD. Finally, the use of new point-of-care testing methods that use less invasive sampling techniques - capillary blood specimens - may contribute to a more widespread use of the BNP assay, especially in neonates and infants, as well as contribute to the development of screening programmes for CHD using this biomarker.

Recanalisation of the left superior caval vein after Fontan procedure: not so rare complication: possibilities of percutaneous closure using various devices

AIM

Evaluation of possibilities of percutaneous closure of recanalised left superior caval vein after total cavopulmonary connection.

METHODS AND RESULTS

We analysed 19 patients after total cavopulmonary connection catheterised because of a sudden increase of desaturation. In four of them, the recanalisation of the left superior caval vein was identified. For this reason, the balloon occlusion tests of the veins were made temporarily. In all cases, the haemodynamic status of patients did not change, and arterial oxygen saturation increased significantly. Thus, using different types of implants, these veins were closed effectively in all patients. During the short-term follow-up, the effectiveness of treatments and constantly maintaining a high level of saturation were confirmed.

CONCLUSIONS

Meticulous investigation of unclear causes of desaturation in cyanotic patients after Fontan completion is necessary. Almost all causes of desaturation, including recanalised additional left superior caval vein, can be effectively treated percutaneously.

Association between N-terminal pro-brain natriuretic peptide and quality of life in adult patients with congenital heart disease

AIMS

Advances in medical treatment have resulted in increased life expectancy in congenital heart disease. Consequently, the focus of management has shifted from reducing mortality to reducing long-term morbidity with the goal of improving quality of life. A predictor of quality of life might be N-terminal pro-brain natriuretic peptide, a well-established marker for heart failure. We aimed to determine the association between N-terminal pro-brain natriuretic peptide and quality of life in patients with congenital heart disease.

METHODS

We collected blood samples from consecutive patients who were initially operated between 1968 and 1980 (47.8% women; mean age 40.2±5.4 years). The 36-item Short-Form Health Survey was completed to assess subjective health status as a measure of quality of life. Analysis was performed for the entire group and for subgroups defined as simple versus complex congenital heart diseases. Median N-terminal pro-brain natriuretic peptide level was 15.2 pmol/L (overall range 1.3-299.3 pmol/L). N-terminal pro-brain natriuretic peptide levels were associated with the subdomain physical functioning (β=-0.074, p=0.031). This association remained significant after adjustment for age and sex (β=-0.071, p=0.038) and after adjustment for age, sex, body mass index, left ventricular function, and renal function (β=-0.069, p=0.048). In complex congenital heart disease, the association between N-terminal pro-brain natriuretic peptide and physical functioning remained significant in multivariable analysis (β=-0.076, p=0.046). No associations were found in the simple congenital heart disease group or on the other health status subdomains.

CONCLUSION

In adults operated for congenital heart disease, N-terminal pro-brain natriuretic peptide is associated with the subdomain physical, primarily in the complex subgroup.

Comparison of prognostic variables in children and adults with Fontan circulation

BACKGROUND

Non-cardiac complications, such as hepato-renal and metabolic problems, are emerging late after the Fontan operation due to its unique hemodynamics. Consequently, associations between clinical variables and postoperative outcome may change during the prolonged postoperative course.

METHODS AND RESULTS

To determine if child and adult Fontan patients differ in the impact of cardiac and non-cardiac variables on clinical outcome, we prospectively evaluated associations between hemodynamics, neurohumoral factors, exercise variables, hepato-renal function and metabolic variables and unscheduled hospitalization, including death in 167 consecutive child and 116 adult Fontan patients. When compared with child patients, the adult patients showed higher rates of medications, lower cardiac index, higher values of natriuretic peptides, greater renal dysfunction, more cholestatic livers, and more impaired responses to exercise (p<0.05-0.0001). During the follow-up of 3.7 ± 2.1 years, 64 clinical events (37 in adults), including 13 deaths, occurred. A high CVP and low arterial oxygen satutration strongly predicted the child events (p<0.001), whereas these prognostic parameters were marginal in the adults. Instead, renal dysfunction and metabolic abnormality predicted adult events (p<0.05). Neurohumoral activation, low albumin, hyponatremia, and impaired exercise variables equally predicted clinical events in child and adult Fontan patients.

CONCLUSIONS

Distinctive differences in predictive value of clinical variables exist between child and adult Fontan patients. In addition to cardiac issues, we should consider non-cardiac determinents of clinical outcome to maximize our efforts to improve prognosis for adult Fontan survivors.

Long-term serial aerobic exercise capacity and hemodynamic properties in clinically and hemodynamically good, "excellent", Fontan survivors

BACKGROUND

The serial hemodynamics and predictors of long-term, good Fontan survivors remain unknown.

METHODS AND RESULTS

Two hundred one patients who had undergone a Fontan operation before September 1998 were reviewed to compare their long-term clinical status with serial hemodynamics. During a mean follow-up of 18.7 years, 47 (30.1%) of the 156 survivors had no clinical events that required an unscheduled hospitalization. Of those, 18 survivors exhibited good serial hemodynamics and the respective mean values of central venous pressure (CVP, mmHg), cardiac index (CI, L·min(-1)·m(2)), and ventricular ejection fraction (EF, %) before and 1, 5, 10, and 15 years after the operation were as follows: 3.8, 9.0, 11.3, 10.6, and 10.1 (CVP); 3.6, 3.1, 2.8, 2.6, and 2.6, and 69 (CI); 57, 56, 58, 54, and 53 (EF). Serial values of CVP, ventricular end-diastolic pressure (EDP) and the grade of atrioventricular valve regurgitation (AVVR) were lower and the peak oxygen uptake was greater in the good patients (P<0.05 for all). A 1-year postoperative lower CVP and no history of AVVR repair during the Fontan operation independently predicted the good patients (P<0.05).

CONCLUSIONS

A lower CVP and EDP, better atrioventricular valvular function, and greater exercise capacity characterize good Fontan survivors and an early postoperative low CVP without an AVVR repair predicts good survivors.

Clinical profile of the adolescent/adult Fontan survivor

OBJECTIVES

The study aims to describe the clinical profile of the adult Fontan survivor and identify the worries, symptoms, and the impact of cardiac surveillance most commonly experienced.

DESIGN

A descriptive, cross-sectional design was used.

SETTING

The study was performed in outpatient adult and pediatric cardiology clinics in university-affiliated and private practice offices.

PATIENTS

Fifty-four adolescent and adult patients with single ventricle congenital heart disease who have undergone the Fontan procedure participated in the study. The mean age was 26 ± 9 years with 52% female and 63% Caucasian.

OUTCOME MEASURES

Demographic and clinical data were obtained by a standard intake form and retrospective chart reviews. The Congenital Heart Disease TNO/AZL Adult Quality Of Life questionnaire was completed to assess worries, symptoms, and the impact of cardiac surveillance.

RESULTS

The majority were single (73%), employed or full-time students (93%), with health insurance (94%), had a single left ventricle (78%), the diagnosis of tricuspid atresia or double inlet left ventricle (59%), lateral tunnel Fontan type (44%), history of arrhythmias (76%), left ventricle ejection fraction percentage >50 (66%), oxygen saturations >90% (70%), frequent headaches (50%), scoliosis (22%), varicose veins, ascites, and liver cirrhosis (46%), normal body mass index (59%), and New York Heart Association class I (48%) and II-III (52%). Primary worries related to current health (83%), job/employment (69%), ability to work, (61%) and living independently (54%). The most bothersome symptoms were shortness of breath with ambulation (69%), dizziness (61%), and palpitations (61%).

CONCLUSIONS

Fontan survivors experience residua and sequelae from multiple surgical procedures and the natural disease course. Our results support the need for ongoing assessment of both physical symptoms and psychosocial concerns, and suggest the need for multiple risk factor intervention strategies that improve physical and emotional health in Fontan survivors.