Late outcomes after the Fontan procedure in patients with single ventricle: a meta-analysis

Association of patient-level characteristics with long-term outcomes after Fontan palliation: Rationale, design, and baseline characteristics of the Pediatric Cardiac Care Consortium Fontan cohort study

BACKGROUND

The Fontan operation is used to palliate single ventricle congenital heart defects (CHD) but poses significant morbidity and mortality risks. We present the design, planned analyses, and rationale for a long-term Fontan cohort study aiming to examine the association of patient characteristics at the time of Fontan with post-Fontan morbidity and mortality.

METHODS AND RESULTS

We used the Pediatric Cardiac Care Consortium (PCCC), a US-based, multicenter registry of pediatric cardiac surgeries to identify patients who underwent the Fontan procedure for single ventricle CHD between 1 and 21 years of age. The primary outcomes are in-hospital Fontan failure (death or takedown) and post-discharge mortality through 2022. A total of 1461 (males 62.1%) patients met eligibility criteria and were included in the analytical cohort. The median age at Fontan evaluation was 3.1 years (IQR: 2.4-4.3). While 95 patients experienced in-hospital Fontan failure (78 deaths and 17 Fontan takedown), 1366 (93.5%) survived to discharge with Fontan physiology and formed the long-term analysis cohort. Over a median follow-up of 21.2 years (IQR: 18.4-24.5) 184 post-discharge deaths occurred. Thirty-year post Fontan survival was 75.0% (95% CI: 72.3%-77.8%) for all Fontan types with higher rates for current techniques such as lateral tunnel and extracardiac conduit 77.1% (95% CI: 73.5-80.8).

CONCLUSION

The PCCC Fontan study aims to identify predictors for post-Fontan morbidity and mortality, enabling risk- stratification and informing surveillance practices. Additionally, the study may guide therapeutic interventions aiming to optimize hemodynamics and enhance Fontan longevity for individual patients.

Pacemaker-Related Factors and Outcomes of Fontan Patients - Impact of Paced QRS Duration

BACKGROUND

Permanent pacemaker (PPM) implantation has been identified as a risk factor for morbidity and mortality after Fontan operation. This study investigated the factors associated with outcomes in patients with Fontan physiology who underwent PPM implantation.Methods and Results: We retrospectively reviewed 508 patients who underwent Fontan surgery at Asan Medical Center between September 1992 and August 2022. Of these patients, 37 (7.3%) received PPM implantation. Five patients were excluded, leaving 32 patients, of whom 11 were categorized into the poor outcome group. Poor outcomes comprised death, heart transplantation, and "Fontan failure". Clinical, Fontan procedure-related, and PPM-related factors were compared between the poor and good outcome groups. Ventricular morphology, Fontan procedure-associated factors, pacing mode, high ventricular pacing rate, and time from first arrhythmia to PPM implantation did not differ significantly between the 2 groups. However, the poor outcome group exhibited a significantly longer mean paced QRS duration (P=0.044). Receiver operating characteristic curve analysis revealed a paced QRS duration cut-off value of 153 ms with an area under the curve of 0.73 (P=0.035).

CONCLUSIONS

A longer paced QRS duration was associated with poor outcomes, indicating its potential to predict adverse outcomes among Fontan patients.

Morbidity and mortality in adults with a Fontan circulation beyond the fourth decade of life

AIMS

To evaluate the late outcomes of adults (above 35 years) with a Fontan-type circulation, for whom current data on morbidity and mortality are lacking.

METHODS AND RESULTS

Data were collected retrospectively on consecutive patients with Fontan circulation above the age of 35 years followed in three European specialist centres. Overall, 115 Fontan patients were included [median age 35 (range 35-48) years, 47.8% female]. The most common underlying congenital heart disease diagnosis was tricuspid atresia (n = 58, 50.4%), and the age at first Fontan completion was 9.1 (interquartile range 5.0-15.8) years. Almost two-thirds (61.7%) of patients had undergone an atriopulmonary Fontan, and 23.5% had received a total cavopulmonary connection. One-third required repeat surgery or intervention. Most patients (55.9%) were in New York Heart Association functional class II or class I (30.6%), 76 (66.1%) patients had experienced at least one arrhythmia, and eight (7.0%) protein-losing enteropathy. At a median follow-up of 5.0 (2.4-10.3) years, 15 (13.0%) patients were referred for transplantation assessment and 19 (16.5%) patients died, mainly from heart failure (84.2%). Univariable predictors of death or transplantation included lower serum albumin level [hazard ratio (HR) 1.09 per g/L decrease, 95% confidence interval (CI): 1.04-1.15, P = 0.0009], prior heart failure admission (HR 4.28, 95% CI:1.75-10.44, P = 0.001), prior atrial tachycardia or flutter (HR 3.02, 95% CI: 1.23-7.38, P = 0.02), and baseline pulmonary vasodilator therapy (HR 8.59, 95% CI:1.05-70.13, P = 0.04). Lower serum albumin and prior atrial tachycardia or flutter remained significant on bivariable analysis.

CONCLUSION

Our study highlights the significant morbidity and mortality in older adults with a Fontan-type circulation, emphasizing the need for lifelong specialist surveillance with frequent risk stratification, close monitoring, and early consideration for transplantation assessment.

Fetal single ventricle journey to first postnatal procedure: a multicentre UK cohort study

OBJECTIVES

UK single ventricle (SV) palliation outcomes after first postnatal procedure (FPP) are well documented. However, survival determinants from fetal diagnosis to FPP are lacking. To better inform parental-fetal counselling, we examined factors favouring survival at two large UK centres.

DESIGN

Retrospective multicentre cohort study.

SETTING

Two UK congenital cardiac centres: Leeds and Birmingham.

PATIENTS

SV fetal diagnoses from 2015 to 2021.

MAIN OUTCOME MEASURES

Survival from fetal diagnosis with intention to treat (ITT) to birth and then FPP. Maternal, fetal and neonatal risk factors were assessed.

RESULTS

There were 666 fetal SV diagnoses with 414 (62%) ITT. Of ITT, 381 (92%) were live births and 337 (81%) underwent FPP. Survival (ITT) to FPP was notably reduced for severe Ebstein's 14/22 (63.6%), unbalanced atrioventricular septal defect 32/45 (71%), indeterminate SV 3/4 (75%), mitral atresia 8/10 (80%) and hypoplastic left heart syndrome 127/156 (81.4%). Biventricular pathway was undertaken in five (1%). After multivariable adjustment, prenatal risk factors for mortality were increasing maternal age (OR 1.05, 95% CI 1.0 to 1.1), non-white ethnicity (OR 2.6, 95% CI 1.4 to 4.8), extracardiac anomaly (OR 6.34, 95% CI 1.8 to 22.7) and hydrops (OR 7.39, 95% CI 1.2 to 45.1). Postnatally, prematurity was significantly associated with mortality (OR 6.3, 95% CI 2.3 to 16.8).

CONCLUSIONS

Around 20% of ITT fetuses diagnosed with SV will not reach FPP. Risk varies according to the cardiac lesion and is significantly influenced by the presence of an extracardiac anomaly, fetal hydrops, ethnicity, increasing maternal age and gestation at birth. These data highlight the need for fetal preprocedure data to be used in conjunction with procedural outcomes for fetal counselling.

Severe Fontan-Associated Liver Disease and Its Association With Mortality

Background Data are rare about the incidence of severe Fontan-associated liver disease (FALD) and its association with mortality. We sought to: (1) estimate the probability of developing severe FALD in patients who undergo the Fontan procedure (Fontan patients), compared with severe liver complications in patients with a ventricular septal defect; (2) assess the severe FALD-mortality association; and (3) identify risk factors for developing severe FALD. Methods and Results Using the Quebec Congenital Heart Disease database, a total of 512 Fontan patients and 10 232 patients with a ventricular septal defect were identified. Kaplan-Meier curves demonstrated significantly higher cumulative risk of severe FALD in Fontan patients (11.95% and 52.24% at 10 and 35 years, respectively), than the risk of severe liver complications in patients with a ventricular septal defect (0.50% and 2.75%, respectively). At 5 years, the cumulative risk of death was 12.60% in patients with severe FALD versus 3.70% in Fontan patients without FALD (log-rank P=0.0171). Cox proportional hazard models identified significant associations between the development of severe FALD and congestive heart failure and supraventricular tachycardia, with hazard ratios (HRs) of 2.36 (95% CI, 1.38-4.02) and 2.45 (95% CI, 1.37-4.39), respectively. More recent Fontan completion was related to reduced risks of severe FALD, with an HR of 0.95 (95% CI, 0.93-0.97) for each more recent year. Conclusions This large-scale population-based study documents that severe FALD in Fontan patients was associated with a >3-fold increase in mortality. The risk of FALD is time-dependent and can reach >50% by 35 years after the Fontan operation. Conditions promoting poor Fontan hemodynamics were associated with severe FALD development.

Exercise capacity in the Danish Fontan population remains stable after ten years of follow-up - is physical activity the key to success?

BACKGROUND

Most Fontan patients have impaired exercise capacity, and a further decline in exercise capacity over time seems inevitable. However, few longitudinal studies exist, and there is a lack of data from newer eras. We aimed to describe the natural evolution of exercise capacity over a 10-year period in a contemporary, population-based cohort of Danish Fontan patients.

METHODS

The study was a nationwide, prospective study. A cardiopulmonary exercise test (CPET) was used to assess the exercise capacity. All Danish Fontan patients who participated in a national study in 2011 (CPET1), were invited to a follow-up visit in 2021 (CPET2). All patients who completed CPET1 and CPET2 with a respiratory exchange ratio over 1.0 were included. The main outcome was percent predicted VO2peak (%pred VO2peak). At the time of CPET2, patients filled out a questionnaire including questions regarding physical activity.

RESULTS

Seventy-seven patients completed both CPET1 and CPET2, and seventy patients completed the questionnaire. The time interval between the two CPETs was 10.4 ± 0.9 years. The median age was 15 years at CPET1 and 26 years at CPET2. The exercise capacity remained stable with a mean %pred VO2peak of 53.8 ± 11.3 at CPET1 and 55.6 ± 10.9 in CPET2 (p = 0.314). Higher levels of vigorous physical activity were associated with higher %pred VO2peak in CPET2 in a multivariate regression model.

CONCLUSION

The %pred VO2peak remained stable over a ten-year period in this population-based Fontan cohort. Higher levels of self-reported vigorous physical activity were associated with higher %pred VO2peak in the most recent CPET.

20 years of experience with the Fontan procedure: characteristics and clinical outcomes of children in a tertiary referral hospital

INTRODUCTION

Without participating in a contractile chamber, the Fontan procedure seeks to create a separation of oxygenated and deoxygenated blood in patients with univentricular heart, reducing the risks of long-term hypoxemia and improving their survival. This study describes the clinical outcomes of children undergoing the Fontan procedure between 2000 and 2020 in a tertiary referral hospital care centre in southwestern Colombia.

MATERIALS AND METHODS

A retrospective observational descriptive study. The 81 patients who underwent the Fontan procedure were included. Categorical variables were presented with percentages and continuous variables with measures of central tendency according to the distribution of the data evaluated through the Shapiro-Wilk test. Sociodemographic, clinical, surgical variables, complications, and mortality were described.

RESULTS

Between 2000 and 2020, 81 patients underwent the Fontan procedure: 43 (53.1%) males and a median age of 5.3 years (interquartile range 4.3-6.6). The most common diagnosis was tricuspid atresia (49.4%). The median mean pulmonary arterial pressure was 12 mmHg (interquartile range 10-15), the Nakata index 272 mm2/m2 (interquartile range 204-327), and the McGoon index (interquartile range 1.86-2.3). Seventy-two (88.9%) patients underwent extracardiac Fontan and 44 (54.3%) patients underwent fenestration. The median hospitalisation days were 19 days. The main complication was coagulopathy (19.8%), mortality in the first month between 2000 and 2010 was 8.6%, and after 2010 was 1.2%.

CONCLUSION

The Fontan procedure is a palliative surgery for children with complex heart disease. According to anatomical and physiological variables, the proper choice of patients determines the short- and long-term results.

Pre-Fontan Assessment Utilizing Combined Cardiac Catheterization and Cardiac MRI: Comparison to the Pre-Fontan Catheterization

Single ventricle patients eligible for Fontan completion undergo pre-Fontan catheterization for hemodynamic and anatomic assessment prior to surgery. Cardiac magnetic resonance imaging may be used to evaluate pre-Fontan anatomy, physiology, and collateral burden. We describe our center's outcomes in patients undergoing pre-Fontan catheterization combined with cardiac magnetic resonance imaging. A retrospective review of patients undergoing pre-Fontan catheterization from 10/2018 to 04/2022 at Texas Children's Hospital was performed. Patients were divided into 2 groups: combined cardiac magnetic resonance imaging and catheterization (combined group) and those who underwent catheterization only (catheterization only group). There were 37 patients in the combined group and 40 in the catheterization only group. Both groups were similar in age and weight. Patients undergoing combined procedures received less contrast, and experienced less in-lab time, fluoroscopy time and catheterization procedure time. Median radiation exposure was lower in the combined procedure group but was not statistically significant. Intubation and total anesthesia times were higher in the combined procedure group. Patients undergoing a combined procedure were less likely to have collateral occlusion performed than in the catheterization only group. Bypass time, intensive care unit length of stay, and chest tube duration were similar in both groups at the time of Fontan completion. Combined pre-Fontan assessment decreases catheterization procedure and fluoroscopy time associated with cardiac catheterization at the expense of longer anesthetic times, and results in similar Fontan outcomes compared to when cardiac catheterization alone is utilized.

Survival After Intervention for Single-Ventricle Heart Disease Over 15 Years at a Single Institution

BACKGROUND

Children with single-ventricle (SV) heart disease possess a spectrum of heart malformations, yet progress through similar hemodynamic states, suggesting differences in outcomes are related to fundamental morphologic differences, patient characteristics, or procedural pathways. We sought to provide a holistic overview of survival after intervention for SV heart disease at our institution.

METHODS

SV heart disease was defined as patients born with a hypoplastic or dysfunctional ventricle with uncertain or unacceptable candidacy for a 2-ventricle circulation. Patients were stratified into 8 diagnostic groups and 11 procedural categories based on the initial interventional procedure.

RESULTS

Between 2005 and 2020, 381 patients born with SV heart disease underwent intervention at our institution. Ten-year survival was highest for patients with double inlet left ventricle (89% ± 7%) and lowest for patients with hypoplastic left heart syndrome (55% ± 5%). Initial palliation with less invasive procedures, such as ductal stent (4-year: 100%) or pulmonary artery banding (10-year: 95% ± 5%), demonstrated superior survival compared with more invasive procedures such as the Norwood procedure (10-year: 59% ± 4%). Survival of patients who achieved a biventricular circulation was superior to patients who remained with SV physiology (10-year: 87% ± 5% vs 63% ± 3%, P = .04). In a multivariable analysis, chromosomal/syndromic abnormality, lower weight, hybrid Norwood procedure, nonleft ventricular dominance, and earlier year of operation were risk factors for death.

CONCLUSIONS

Survival differences in patients with SV heart disease were related primarily to underlying cardiac anatomy, patient characteristics, and procedural complexity. Left ventricular dominance, more recent intervention, and attainment of a 2-ventricle circulation were associated with improved survival.

Role of Cardiovascular Imaging in the Follow-Up of Patients with Fontan Circulation

Since its first description in 1971, the Fontan procedure and its modifications have led to a substantial improvement in the survival rates of patients with a variety of types of complex Congenital Heart Disease (CHD) characterised by the presence of a single, dominant ventricle. However, despite the significant improvement of the prognosis over the years, Fontan patients are still exposed to several cardiovascular and systemic complications. It is, therefore, important to fully understand the pitfalls hidden behind a Fontan anatomy and the potential predictors of ventricular failure. Cardiovascular imaging plays a key role in this context, allowing for the early identification of complications with important prognostic implications. Echocardiography remains the first-line imaging modality for serial evaluation of Fontan patients. However, there is a growing role of cardiovascular magnetic resonance and cardiac computed tomography from pre-operative assessment to longitudinal follow-up. The aim of this paper will be to provide a comprehensive overview of the role, strengths, and weaknesses of each imaging modality in the assessment of congenital cardiac conditions palliated with the Fontan procedure.

Opportunities and short-comings of the axolotl salamander heart as a model system of human single ventricle and excessive trabeculation

Few experimental model systems are available for the rare congenital heart diseases of double inlet left ventricle (DILV), a subgroup of univentricular hearts, and excessive trabeculation (ET), or noncompaction. Here, we explore the heart of the axolotl salamander (Ambystoma mexicanum, Shaw 1789) as model system of these diseases. Using micro-echocardiography, we assessed the form and function of the heart of the axolotl, an amphibian, and compared this to human DILV (n = 3). The main finding was that both in the axolotl and DILV, blood flows of disparate oxygen saturation can stay separated in a single ventricle. In the axolotl there is a solitary ventricular inlet and outlet, whereas in DILV there are two separate inlets and outlets. Axolotls had a lower resting heart rate compared to DILV (22 vs. 72 beats per minute), lower ejection fraction (47 vs. 58%), and their oxygen consumption at rest was higher than peak oxygen consumption in DILV (30 vs. 17 ml min^-1 kg^-1). Concerning the ventricular myocardial organization, histology showed trabeculations in ET (n = 5) are much closer to the normal human setting than to the axolotl setting. We conclude that the axolotl heart resembles some aspects of DILV and ET albeit substantial species differences exist.

Impact of older age at Fontan completion on mid-term survival

BACKGROUND

The optimum age of Fontan completion remains unknown. Currently, the majority of centers worldwide are performing Fontan completion at 2-4 years of age. In Indonesia, lack of awareness and limited resources probably explain why patients seek treatment at advanced stage. This study aimed to evaluate the impact of older age at Fontan completion on mid-term survival.

RESULTS

A single-center retrospective cohort study was performed on 261 patients who underwent Fontan completion between 2008 and 2019 and survived to discharge. The patients were followed up until April 2020, with a median follow-up period of 3 years (range 0-12 years). The median age was 5 years (range 2-24 years). The survival rates of patients with the age at operation ≤ 6 years and > 6 years were 92.1% and 82.8%, respectively. A subgroup analysis showed that the survival rates for age < 4 years, 4-6 years (reference age), 6-8 years, 8-10 years, 10-18 years, and > 18 years were 85.7%, 94.8%, 85.4%, 78.8%, 85.7%, and 66.7%, respectively. Age at Fontan completion of > 6 years (HR 3.84; p = 0.020) was associated with a lower 12-year survival rate. The age at operation of 8-10 years (HR 6.79; p = 0.022) and > 18 years (HR 15.30; p = 0.006) had the worst survival rates.

CONCLUSIONS

An older age at Fontan completion (> 6 years) significantly reduced mid-term survival rate. The age at Fontan of 8-10 years and > 18 years had higher risk of mid-term death than age of 4-6 years.

State-of-the-art imaging for lymphatic evaluation in children

The lymphatic system has been poorly understood and its importance neglected for decades. Growing understanding of lymphatic flow pathophysiology through peripheral and central lymphatic flow imaging has improved diagnosis and treatment options in children with lymphatic diseases. Flow dynamics can now be visualized by different means including dynamic contrast-enhanced magnetic resonance lymphangiography (DCMRL), the current standard technique to depict central lymphatics. Novel imaging modalities including intranodal, intrahepatic and intramesenteric DCMRL are quickly evolving and have shown important advances in the understanding and guidance of interventional procedures in children with intestinal lymphatic leaks. Lymphatic imaging is gaining importance in the radiologic and clinical fields and new techniques are emerging to overcome its limitations.

Older age at Fontan completion is associated with reduced lung volumes and increased lung reactance

BACKGROUND

Fontan patients have abnormal lung function, in particular restrictive lung disease and low diffusing capacity of carbon monoxide (DLCO). We sought to further characterise these abnormalities with detailed pulmonary function testing and examine associations with clinical parameters.

METHODS

132 Fontan patients across Australia and New Zealand underwent spirometry, with 126 subjects included in final analyses. Measurement of diffusion capacity (DLCO) including its components (alveolar volume (VA) and rate of uptake of CO (KCO)) and oscillometry (reactance (X5) and resistance (R5)) were assessed in a subset of Fontan patients (n = 44) and healthy controls (n = 12). Double diffusion (to assess diffusing capacity of nitric oxide (DLNO), capillary blood volume (Vc), alveolar capillary membrane function (DmCO)) was performed in Fontan patients (n = 18) and healthy controls (n = 12).

RESULTS

FEV₁ and FVC z-scores were low in Fontan subjects (mean - 1.67 ± 1.24 and - 1.61 ± 1.29, respectively) and correlated with exercise capacity. Compared to controls, z-scores for X5, DLCO, KCO, VA and DLNO were significantly lower in Fontan patients. R5, Vc and DmCO z-scores were preserved. X5 was associated with VA (r = 0.41,p = 0.009) and DmCO (r = 0.61,p = 0.008). Older age at Fontan completion was associated with lower z-scores for FEV₁ (r = -0.46,p = 0.002), FVC (r = -0.47,p = 0.002), X5 (r = -0.32,p = 0.033) and VA (r = -0.36,p = 0.022).

CONCLUSION

Fontan patients have a reduced DLCO which is largely driven by low VA. Lung stiffness (X5) is increased which is associated with VA and DmCO. These parameters negatively correlate with older age of Fontan completion suggesting that earlier Fontan completion may have a beneficial effect on lung function.

Vitamin D, liver-related biomarkers, and distribution of fat and lean mass in young patients with Fontan circulation

INTRODUCTION/AIM

Young patients with Fontan circulation may have low serum 25-hydroxyvitamin D levels, an affected liver, and unhealthy body compositions. This study aimed to explore the association between vitamin D intake/levels, liver biomarkers, and body composition in young Fontan patients.

METHOD

We collected prospective data in 2017 to 2018, obtained with food-frequency questionnaires, biochemical analyses of liver biomarkers, and dual-energy X-ray absorptiometry scans in 44 children with Fontan circulation. Body compositions were compared to matched controls (n = 38). Linear regression analyses were used to investigate associations of biomarkers, leg pain, and lean mass on serum levels of 25-hydroxyvitamin D. Biomarkers were converted to z scores and differences were evaluated within the Fontan patients.

RESULTS

Our Fontan patients had a daily mean vitamin D intake of 9.9 µg and a mean serum 25-hydroxyvitamin D of 56 nmol/L. These factors were not associated with fat or lean mass, leg pain, or biomarkers of liver status. The Fontan patients had significantly less lean mass, but higher fat mass than controls. Male adolescents with Fontan circulation had a greater mean abdominal fat mass than male controls and higher cholesterol levels than females with Fontan circulation.

CONCLUSION

Vitamin D intake and serum levels were not associated with body composition or liver biomarkers in the Fontan group, but the Fontan group had lower lean mass and higher fat mass than controls. The more pronounced abdominal fat mass in male adolescents with Fontan circulation might increase metabolic risks later in life.

Cardiac Implantable Electronic Devices in the Fontan Patient

As a result of remarkable progress in operative techniques and cardiology care during childhood, Fontan patients continue to age and require team-based multidisciplinary expertise to manage complications encountered in adulthood. They face particular challenges in terms of altered hemodynamic stressors, cardiac and hepatic failure, and arrhythmias. Arrhythmias in Fontan patients are highly prevalent and associated with underlying anatomy, surgical technique, and postoperative sequelae. Diagnostic tools, treatments, and device strategies for arrhythmias in Fontan patients should be adapted to the specific anatomy, type of surgical repair, and clinical status. Great strides in our understanding of arrhythmia mechanisms, options and techniques to obtain access to relevant cardiac structures, and application of both old and new technologies have contributed to improving cardiac implantable electronic device (CIED) therapies for this unique population. In this state-of-the-art review, we discuss the various arrhythmias encountered in Fontan patients, their diagnosis, and options for treatment and prevention, with a focus on CIEDs. Throughout, access challenges particular to the Fontan circulation are considered. Recently developed technologies, such as the sub-cutaneous implantable cardioverter defibrillator carry the potential to be transformative but require awareness of Fontan-specific issues. Moreover, new leadless pacing technology represents a promising strategy that may soon become applicable to Fontan patients with sinus node dysfunction. CIEDs are essential tools in managing Fontan patients but the complex clinical scenarios that arise in this patient population are among the most challenging for the congenital electrophysiologist.

Medical Therapies for Heart Failure in Hypoplastic Left Heart Syndrome

Significant surgical and medical advances over the past several decades have resulted in a growing number of infants and children surviving with hypoplastic left heart syndrome (HLHS) and other congenital heart defects associated with a single systemic right ventricle (RV). However, cardiac dysfunction and ultimately heart failure (HF) remain the most common cause of death and indication for transplantation in this population. Moreover, while early recognition and treatment of single ventricle-related complications are essential to improving outcomes, there are no proven therapeutic strategies for single systemic RV HF in the pediatric population. Importantly, prototypical adult HF therapies have been relatively ineffective in mitigating the need for cardiac transplantation in HLHS, likely due to several unique attributes of the failing HLHS myocardium. Here, we discuss the most commonly used medical therapies for the treatment of HF symptoms in HLHS and other single systemic RV patients. Additionally, we provide an overview of potential novel therapies for systemic ventricular failure in the HLHS and related populations based on fundamental science, pre-clinical, clinical, and observational studies in the current literature.

Cardiopulmonary Exercise Test Outcomes in Fontan Patients With Right Versus Left Single Ventricle Morphology

Background: Congenital heart defects (CHDs) palliated with Fontan surgery often result in a functional single ventricle that is either a morphologically right or left ventricle, and much less commonly undefined. Given this departure from normal physiology, especially for systemic right ventricle Fontan patients, our study sought to compare cardiopulmonary exercise test (CPET) results of adult patients with single right ventricle (SRV) and single left ventricle (SLV) morphology. Methods: Of 237 Fontan patients from the Ahmanson/UCLA Adult Congenital Heart Disease Center database, 135 patients met the inclusion criteria and were split into 2 groups: SRV (n = 44) and SLV (n = 91). Data were collected on baseline demographics, cardiac history, and CPET results. The 2 groups were compared using unpaired t-test, Mann-Whitney, or Chi-square test. Results: Regarding baseline demographics, SRV patients underwent CPET at a slightly younger age than the SLV group (26.5 ± 6.2 vs 29.6 ± 8.5 years, P = .03). There were no significant differences in CPET parameters (including peak heart rate, oxygen saturation, and maximum VO₂/kg) between the SRV and SLV groups. When evaluated subsequent CPET at 3 to 4 years, there was no difference in CPET peak heart rate, peak oxygen saturation, and maximum VO₂/kg between the 2 groups. Conclusions: This single-center retrospective analysis suggests that dominant single ventricle morphology may not be associated with an appreciable difference in exercise performance in adult survivors with a Fontan palliation.

Home-Based Long-Term Physical Endurance and Inspiratory Muscle Training for Children and Adults With Fontan Circulation—Initial Results From a Prospective Study

Background

Patients with congenital heart disease (CHD)—including those after Fontan operation—are encouraged to be physically active.

Aim

To prospectively determine the effects of an individually adapted, home-based cycle ergometer endurance training in combination with inspiratory muscle training (IMT) in pediatric and adult Fontan patients. We, herein, report the results of the initial 10-months follow-up (phase 1).

Methods

18 patients (median age 16.5 years; range 10-43 years) completed baseline check-ups, and 4 and 10 months follow-up visits, which each included cardiopulmonary exercise testing (CPET), bodyplethysmography (including measurement of respiratory muscle strength), and a quality of life questionnaire (PedsQL™). The training program consisted of a home-based cycle ergometer endurance training on a “Magbike® AM-5i/3i” (DKN Technology®, Clermont-Ferrand, France) and IMT with a handheld “POWERbreathe® Medic plus” device. Patients performed 90 min of endurance training per week in addition to IMT (30 breaths per day, 6-7 times per week). After the first 4 months, patients underwent additional interval training.

Results

After 10 months of training, we observed significant increases in maximum relative workload (W/kg, p = 0.003) and in maximum inspiratory (MIP, p = 0.002) and expiratory (MEP, p = 0.008) pressures. Peak VO2 values did not increase significantly as compared to baseline (p = 0.12) in the entire cohort (n = 18), but reached statistical significance in a subgroup analysis of teenage/adult patients (n = 14; p = 0.03). Patients' subjective quality of life did not show any significant changes after 10 months of training.

Discussion

In Fontan patients, an individually adapted home-based training is safe and associated with improvements in some CPET variables. However, these improvements did not translate into an improved QoL after 10 months. With an unclear, but most likely negative, impact of the COVID-19 pandemic, improvements in QoL may become evident during further follow-up (phase 2 of the study).

Fontan circulation has improved life expectancy for infants born with complex heart disease over the last 50 years but has also resulted in significant morbidity

The prognosis for infants born with complex heart disease improved dramatically with the introduction of the Fontan circulation 50 years ago. With today's carefully designed and staged operations to a Fontan circulation, life expectancy has increased and most children will survive into adult life. The Fontan circulation entails an unphysiological circulation with high risk for multiple organ system dysfunction. Neurodevelopmental disabilities with adverse psychosocial effects are prevalent. The Fontan circulation may eventually fail and necessitate heart transplantation. CONCLUSION: Fifty years development of the Fontan circulation to today's staged surgical procedures has improved survival but also revealed the burden of a high morbidity for a growing number of patients.

Acute Liver Failure due to Altered Fontan Circulation in a Patient With Tricuspid Atresia: A Case Report

Tricuspid atresia is a congenital malformation of the tricuspid valve resulting in a lack of blood flow between the right atrium and the right ventricle. Management generally involves staged surgical intervention enabling affected individuals to survive into adulthood. Although surgical intervention greatly improves morbidity and mortality in this patient population, there are many long-term complications associated with the creation of a surgical shunt. We report a case of a 33-year-old male with tricuspid atresia who underwent Fontan surgery as a child and presented to our hospital with acute liver failure.

Predictors of Poor Functional Status in Adult Fontan Patients Living at Moderate Altitude

Patients who have undergone Fontan palliation have reduced exercise tolerance measured by maximal oxygen consumption (VO₂ max). Declining exercise capacity is associated with increased morbidity and mortality. The impact of hemodynamics and other variables on this population's functional status is not well understood. This study sought to identify variables that predict low VO₂ max in Fontan patients living at moderate altitude (5,000-8,000 feet). We performed a retrospective cohort study of 44 adult Fontan patients living at moderate altitude who had undergone cardiopulmonary exercise testing (CPET) and cardiac catheterization. We evaluated hemodynamic parameters measured during catheterization, imaging results, and laboratory studies for correlation with VO₂ max measured during CPET. Our study cohort (median age 30 years, 52% female) had exercise impairment with mean VO₂ max of 21.6 mL/kg/min. Higher trans-pulmonary gradient (TPG) (p < 0.001) and mean pulmonary artery (PA) pressure (p = 0.013) were predictors of lower maximal and submaximal VO₂. Higher BNP values correlated with lower VO₂ max (p = 0.01). Platelet count, GGT, albumin, and pulmonary vasodilator therapy did not correlate with VO₂ max. None of the studied variables were associated with higher minute ventilation to peak carbon dioxide production (VE/VCO₂ slope) or change in VO₂ max over time. In conclusion, higher TPG and mean PA pressure predicted lower exercise tolerance amongst our cohort of adult Fontan patients living at moderate altitude. Future studies are needed to determine if these clinical variables represent viable therapeutic targets that could result in improved exercise tolerance and outcomes in patients with Fontan circulation.

The Identification and Impact of Abnormal Spirometry Patterns on Exercise Capacity in Pediatric Patients with Fontan Palliation

Reduced exercise capacity and restrictive lung physiology are common in patients after Fontan palliation (FP). However, there is paucity of data regarding the association between specific spirometry patterns and key exercise parameters in this population. This is a single-center, cross-sectional, study correlating pulmonary function and exercise parameters in children with FP. Patients who were ≤ 18 years of age and underwent a comprehensive cardiopulmonary treadmill exercise stress test (CPT) and spirometry at the same time, were included. Patients were categorized as (i) normal or (ii) abnormal based on the results of spirometry. The abnormal group was subdivided into (a) restrictive, (b) obstructive, and (c) mixed patterns. Demographic and key exercise parameters were compared between groups. Our study included 82 patients who underwent CPT at 13.6 (IQR, 11.3-15.4) years of age. A reduced exercise capacity (%VO₂ ≤ 85%) was noted in the majority (n = 50, 61%). Spirometry was abnormal in 47 (57%) patients [restrictive (n = 25, 30%), obstructive (n = 12, 15%), and mixed (n = 10, 12%)]. The abnormal spirometry group had significant lower %VO₂ (77% vs. 92%, p = 0.01) and METS (8.4 vs. 9.6, p = 0.02). Subgroup analysis revealed that obstructive (p = 0.04) and mixed (p = 0.02) patterns were associated with a significant decrease in % VO₂. Majority of the children demonstrated an abnormal spirometry pattern post-FP. Abnormal pulmonary function was associated with the reduced exercise capacity. Identification and treatment of the abnormal lung function may improve the exercise capacity in these patients and improve the morbidity.

Myocardial deformation in patients with a single left ventricle using 2D cardiovascular magnetic resonance feature tracking: a case-control study

Ventricular dysfunction is a well-known complication in single ventricle patients in Fontan circulation. As studies exclusively examining patients with a single left ventricle (SLV) are sparse, we assessed left ventricular (LV) function in SLV patients by using 2D-cardiovascular magnetic resonance (CMR) feature tracking (2D-CMR-FT) and 2D-speckle tracking echocardiography (2D-STE). 54 SLV patients (11.4, 3.1–38.1 years) and 35 age-matched controls (12.3, 6.3–25.8 years) were included. LV global longitudinal, circumferential and radial strain (GLS, GCS, GRS) and strain rate (GLSR, GCSR, GRSR) were measured using 2D-CMR-FT. LV volumes, ejection fraction (LVEF) and mass were determined from short axis images. 2D-STE was applied in patients to measure peak systolic GLS and GLSR. In a subgroup analysis, we compared double inlet left ventricle (DILV) with tricuspid atresia (TA) patients. The population consisted of 19 DILV patients, 24 TA patients and 11 patients with diverse diagnoses. 52 patients were in NYHA class I and 2 patients were in class II. Most SLV patients had a normal systolic function but median LVEF in patients was lower compared to controls (55.6% vs. 61.2%, p = 0.0001). 2D-CMR-FT demonstrated reduced GLS, GCS and GCSR values in patients compared to controls. LVEF correlated with GS values in patients (p < 0.05). There was no significant difference between GLS values from 2D-CMR-FT and 2D-STE in the patient group. LVEF, LV volumes, GS and GSR (from 2D-CMR-FT) were not significantly different between DILV and TA patients. Although most SLV patients had a preserved EF derived by CMR, our results suggest that, LV deformation and function may behave differently in SLV patients compared to healthy subjects.

Super Glenn for staged biventricular repair: impact on left ventricular growth?

 

OBJECTIVES

The Super Glenn procedure involves targeted increased in blood flow to left sided heart structures with fenestrated atrial septation. The objective of this study was to examine the outcomes of patients who had this procedure as a part of biventricular staging and specifically evaluate the effect on dimensions of left heart structures.

METHODS

Data for patients who had this procedure between 2005 and 2019 were retrospectively identified.

RESULTS

Thirty-seven patients were identified. Most common diagnosis was hypoplastic left heart syndrome in 40% (n = 15). On echocardiography, the median mitral valve z score was -2.26. On cardiac magnetic resonance imaging, median indexed left ventricular end-diastolic volume was 31.5 ml/m2 and mitral/tricuspid inflow ratio was 0.35. The median age at Super Glenn was 2.3 years (interquartile range 1.5-3.6) while median weight was 12 kg (interquartile range 9.8-14). There were no early/hospital deaths. The median intensive care unit length of stay was 4 days, and median hospital length of stay was 10 days. Median follow-up for the entire cohort was 3 years (range 15 days to 13.2 years). There was a statistically significant increase in indexed left ventricular dimensions. There were 5 deaths (14%). Three patients (8%) underwent heart transplant. Freedom from death/transplant was 79% at 5 years. Seven patients (19%) needed a reoperation. Twenty-three patients (62%) underwent biventricular conversion after a median of 11.3 months after Super Glenn.

CONCLUSIONS

The Super Glenn procedure achieves consistent increase in left ventricular dimensions. This may be a useful strategy to help achieve a successful biventricular circulation in patients with borderline left ventricle. The superiority/non-inferiority of this approach over the conventional Fontan pathway is unclear.

Prevalence of Sleep-Disordered Breathing in a Cohort of Adult Fontan Patients

Sleep-disordered breathing (SDB) is described in patients with acquired heart failure but its prevalence in adults with congenital heart disease is not well documented. It is likely that single-ventricle patients who have undergone Fontan palliation poorly tolerate the additional stress of SDB on their fragile cardiac physiology. This study sought to determine the prevalence of SDB in a population of adult Fontan patients. We performed a retrospective chart review of adult Fontan patients followed in our program (n = 55). All charts were evaluated for documentation of polysomnography (PSG). SDB was characterized as nocturnal hypoxemia without apnea or obstructive sleep apnea (OSA). Baseline demographics and clinical characteristics were documented, as were PSG findings including Apnea Hypopnea Index (AHI, events/hour) and desaturation events of > 5% from baseline saturation. Twenty-two of our 55 patients (40%) had undergone PSG (45% male, mean age 29 years). Of these patients, 17 had a PSG positive for SDB (77%). Nine patients (41%) had nocturnal hypoxemia without apnea, while 8 patients (36%) had a PSG positive for OSA. Lower baseline oxygen saturations, but not BMI or age, were statistically significantly correlated with higher AHI. SDB was present in the majority of our Fontan cohort who had undergone PSG, occurring at a higher prevalence than what is described in the general population, suggesting that screening should be considered for all Fontan patients. However, further study is needed to confirm this prevalence in a larger population, and if therapy has an impact on clinical outcomes.

Tricuspid atresia: Where are we now?

Tricuspid atresia (TA) is a complex congenital heart disease that presents with cyanosis in the neonatal period. It is invariably fatal if left untreated and requires multiple stages of palliation. Early recognition and timely surgical intervention are therefore pivotal in the management of these infants. This literature review considers the pathophysiology, presentation, investigations, and classification of TA. Moreover, it discusses the evidence upon which the latest medical and surgical treatments are based, as well as numerous recent case reports. Further work is needed to elucidate the etiology of TA, clarify the role of pharmacotherapy, and optimize the surgical management that these patients receive.

Effect of Ventricular Pacing on Morbidity in Adults After Fontan Repair

Implantation of a permanent pacemaker is a negative prognostic marker in patients with Fontan palliation; however, data delineating outcomes in adult patients with pacemaker requirements are lacking. We hypothesize that high ventricular pacing burden is associated with adverse outcomes in adult Fontan patients. We performed a retrospective review comprising adult patients with history of Fontan repair. A high burden of ventricular pacing was defined as ≥40% pacing. Major adverse clinical events (MACE) were defined as all-cause mortality or need for advanced cardiac therapies (ventricular assist device or heart transplant). A total of 145 adult patients with Fontan were studied for a median of 3.1 years. Twenty (14%) patients had implanted pacemakers with ≥40% ventricular pacing. Twelve events occurred in those with ≥40% ventricular pacing (incidence 60.0%) versus 11 in those without (incidence 8.8%). In multivariable analysis, ≥40% ventricular-pacing (odds ratio 12.51, confidence interval [CI] 3.56 to 43.83, p <0.001) was associated with MACE independent of initial Fontan type, New York Heart Association functional class at baseline, or history of atrial tachyarrythmia. In survival analysis, patients with ≥40% ventricular pacing had nearly 8 times the risk of MACE compared with those with a lower ventricular pacing burden (hazard ratio 7.79, 95% CI 2.56 to 23.66, p <0.001), whereas patients with atrial-only or <40% ventricular pacing burden had a trend toward higher hazard of MACE compared with those without permanent pacemaker (hazard ratio 3.38, 95% CI 0.92 to 12.47, p = 0.07) that did not meet statistical significance. These findings suggest that high ventricular pacing burden contributes to poor outcomes in the adult Fontan patients and bear consideration when determining optimal treatment of tachyarrhythmias in this population.

Where are we after 50 years of the Fontan operation?

First introduced in 1971, the Fontan procedure is the final common destination for all patients with a functional single ventricle. The procedure itself has evolved tremendously over the last five decades. This review traces this journey and presents the importance, outcomes and future outlook of the procedure in the current era.

Surgical outcomes in complex adult congenital heart disease: a brief review

Life expectancy of patients with congenital heart disease (CHD) continues to increase dramatically over the last few decades, primarily due to significant medical and surgical advancements in the field. Adult congenital heart disease (ACHD) patients are now living longer but continue to face morbidity and reduced long-term survival when compared to the general population. We briefly describe the growth of ACHD with a focus on surgical procedures and outcomes in the more complex lesions including Tetralogy of Fallot, Ebsteins Anomaly of the tricuspid valve, Coarctation of the Aorta, Transposition of the Great Arteries and single ventricle lesions. The advancing role of mechanical circulatory support and cardiac transplantation in ACHD patients is also highlighted. Cardiac surgery in these patients continues to improve with low surgical mortality rate and outstanding long-term outcomes and efficacy.

Management of the adult Fontan patient

Adults with congenital heart disease who underwent the Fontan operation to palliate single ventricle heart defects—by direct connection of caval venous return to the pulmonary circulation—have improved survival due to advancements in surgical and interventional techniques. However, cardiac and non-cardiac comorbidities often coexist, complicating management, and contributing to premature morbidity and mortality. Cardiac issues include heart failure symptoms related to systolic and diastolic dysfunction, atrial and ventricular arrhythmias and systemic atrioventricular valve regurgitation. Structural issues may be related to obstruction of the Fontan pathway, or to branch pulmonary artery stenosis, both of which exacerbate symptoms. Non-cardiac complications in adults involve hepatic congestion, fibrosis and cirrhosis, hepatocellular carcinoma, chronic kidney disease, stroke, venous stasis, lymphatic issues and involvement of other organ systems. ‘Fontan failure’ refers to circulatory dysfunction, either cardiac, non-cardiac, or both, diagnosed after exclusion or treatment of reversible contributors such as structural issues and arrhythmias. Counselling about reproductive health, mental health, perioperative management and overall wellness are paramount for patients’ well-being. Fontan patients are typically managed in highly specialised adult congenital heart centres, but may present to cardiologists or other practitioners with cardiac and non-cardiac emergencies or urgencies, sometimes after being out of care. In this review, we discuss the management of the adult Fontan patient, including surveillance, cardiac and non-cardiac complications, reproductive health, and advanced therapies.

Hypoplastic left heart syndrome: From bedside to bench and back

Hypoplastic Left Heart Syndrome (HLHS) is a complex Congenital Heart Disease (CHD) that was almost universally fatal until the advent of the Norwood operation in 1981. Children with HLHS who largely succumbed to the disease within the first year of life, are now surviving to adulthood. However, this survival is associated with multiple comorbidities and HLHS infants have a higher mortality rate as compared to other non-HLHS single ventricle patients. In this review we (a) discuss current clinical challenges associated in the care of HLHS patients, (b) explore the use of systems biology in understanding the molecular framework of this disease, (c) evaluate induced pluripotent stem cells as a translational model to understand molecular mechanisms and manipulate them to improve outcomes, and (d) investigate cell therapy, gene therapy, and tissue engineering as a potential tool to regenerate hypoplastic cardiac structures and improve outcomes.

Postoperative and long-term outcomes in children with Trisomy 21 and single ventricle palliation

OBJECTIVE

Patients with Trisomy 21 (T21) and single ventricle (SV) physiology present unique challenges compared to euploidic counterparts. This study reports postoperative and long-term outcomes in patients with T21 and SV palliation.

DESIGN

This retrospective cohort study from the Pediatric Cardiac Care Consortium (PCCC) included patients with T21 (<21 years old) that underwent surgical palliation for SV between 1982 and 2008 and control patients without known genetic anomaly following Fontan palliation for similar diagnoses. Kaplan-Meier survival plots were created based on death events obtained from the PCCC and by linkage with the National Death Index (NDI) and the Organ Procurement and Transplantation Network (OPTN) through 2014 for patients with adequate identifiers.

RESULTS

We identified 118 children with T21 who underwent initial surgical SV palliation. Among 90 (75.6%) patients surviving their first surgery, 66 (73.3%) underwent Glenn anastomosis and 25 (27.8%) completed Fontan palliation with in-hospital survival of 80.3% and 76.0%, respectively. Fifty-three patients had sufficient identifiers for PCCC-NDI-OPTN linkage. Ten-year survival, conditioned on discharge alive after the Fontan procedure, was 66.7% compared to 92.2% for 51 controls without genetic anomaly (P = .001). Median age at death for T21 patients following initial surgical SV palliation was 2.69 years (IQR 1.34-7.12) with most deaths (89.2%) attributed to the underlying congenital heart disease (CHD).

CONCLUSIONS

Children with T21 and SV are at high risk for procedural and long-term mortality related to their genetic condition and underlying CHD. Nevertheless, a select group of patients can successfully complete Glenn or Fontan palliation, reaching satisfactory long-term survival.

Single Ventricle Palliation in a Developing Sub-Saharan African Country: What Should be Improved?

Introduction:

Single ventricle physiology management is challenging, especially in low-income countries.

Objective:

To report the palliation outcomes of single ventricle patients in a developing African country.

Methods:

We retrospectively studied 83 consecutive patients subjected to single ventricle palliation in a single center between March 2011 and December 2017. Preoperative data, surgical factors, postoperative results, and survival outcomes were analyzed. The patients were divided by palliation stage: I (pulmonary artery banding [PAB] or Blalock–Taussig shunt [BTS]), II (Glenn procedure), or III (Fontan procedure).

Results:

Of the 83 patients who underwent palliation (stages I-III), 38 deaths were observed (31 after stage I, six after stage II, and one after stage III) for an overall mortality of 45.7%. The main causes of operative mortality were multiple organ dysfunction due to sepsis, shunt occlusion, and cardiogenic shock. Twenty-eight survivors were lost to follow-up (22 after stage I, six after stage II). Thirteen stage II survivors are still waiting for stage III. The mean follow-up was 366 ± 369 days. Five-year survival was 28.4 % for PAB and 30.1% for BTS, while that for stage II and III was 49.8% and 57.1%, respectively. Age (hazard ratio, 0.61; 95% confidence interval: 0.47-0.7; P = .000) and weight at surgery (hazard ratio, 0.45; 95% confidence interval: 0.31-0.64; P = .002) impacted survival.

Conclusion:

A high-mortality rate was observed in this initial experience, mainly in stage I patients. A large number of patients were lost to follow-up. A task force to improve outcomes is urgently required.

Pathophysiology, adaptation, and imaging of the right ventricle in Fontan circulation

The Fontan procedure, which creates a total cavopulmonary anastomosis and represents the final stage of palliation for hypoplastic left heart syndrome, generates a unique circulation relying on a functionally single right ventricle (RV). The RV pumps blood in series around the systemic and pulmonary circulation, which requires adaptations to the abnormal volume and pressure loads. Here, we provide a complete review of RV adaptations as the RV assumes the role of the systemic ventricle, the progression of RV dysfunction to a distinct pattern of heart failure unique to this disease process, and the assessment and management strategies used to protect and rehabilitate the failing RV of Fontan circulation.

Long Term Consequences of the Fontan Procedure and How to Manage Them

In 1971, Fontan and Baudet described a surgical technique for successful palliation of patients with tricuspid atresia. Subsequently, this technique has been applied to treat most forms of functional single ventricles and has become the current standard of care for long-term palliation of all patients with single ventricle congenital heart disease. Since 1971, the Fontan procedure has undergone several variations. These patients require lifelong management including a thorough knowledge of their anatomic substrate, hemodynamic status, management of rhythm and ventricular function along with multi organ evaluation. As these patients enter middle age, there is increasing awareness regarding the long-term complications and mortality. This review highlights the long-term outcomes of the Fontan procedure and management of late sequelae.

State of the art of the Fontan strategy for treatment of univentricular heart disease

In patients with a functionally univentricular heart, the Fontan strategy achieves separation of the systemic and pulmonary circulation and reduction of ventricular volume overload. Contemporary modifications of surgical techniques have significantly improved survival. However, the resulting Fontan physiology is associated with high morbidity. In this review, we discuss the state of the art of the Fontan strategy by assessing survival and risk factors for mortality. Complications of the Fontan circulation, such as cardiac arrhythmia, thromboembolism, and protein-losing enteropathy, are discussed. Common surgical and catheter-based interventions following Fontan completion are outlined. We describe functional status measurements such as quality of life and developmental outcomes in the contemporary Fontan patient. The current role of drug therapy in the Fontan patient is explored. Furthermore, we assess the current use and outcomes of mechanical circulatory support in the Fontan circulation and novel surgical innovations. Despite large improvements in outcomes for contemporary Fontan patients, a large burden of disease exists in this patient population. Continued efforts to improve outcomes are warranted. Several remaining challenges in the Fontan field are outlined.