Risk factors for major adverse events late after Fontan palliation

Cardiac magnetic resonance ventricular parameters correlate with cardiopulmonary fitness in patients with functional single ventricle

Owing to advances in medical and surgical fields, patients with single ventricle (SV) have a greatly improved life expectancy. However, progressive functional deterioration is observed over time, with a decrease in cardiopulmonary fitness. This study aimed to identify, in patients with SV, the association between cardiac magnetic resonance imaging (CMR) parameters and change in cardiopulmonary fitness assessed by cardiopulmonary exercise test (CPET), and if certain thresholds could anticipate a decline in aerobic fitness. Patients with an SV physiology were retrospectively screened from 2011 and 2021 in a single-centre observational study. We evaluated (1) the correlation between baseline CMR and CPET parameters, (2) the association between baseline CMR results and change in peak oxygen uptake (peak VO2), and (3) the cut-off values of end-diastolic and end-systolic volume index in patients with an impaired cardiopulmonary fitness (low peak VO2 and/or high VE/VCO2 slope). 32 patients were included in the study. End-systolic volume index (r = 0.37, p = 0.03), end-diastolic volume index (r = 0.45, p = 0.01), and cardiac index (r = 0.46, p = 0.01) correlated with the VE/VCO2 slope. End-systolic ventricular volume (r = - 0.39, p = 0.01), end-diastolic ventricular volume (r = - 0.38, p = 0.01), and cardiac output (r = - 0.45, p < 0.01) inversely correlated with the peak VO2. In multivariate analysis, the cardiac index obtained from baseline CMR was inversely associated with the change in peak VO2 (p < 0.01). An end-diastolic volume index > 101 ml/m2 and an end-systolic volume index > 47 ml/m2 discriminated patients with impaired cardiopulmonary fitness. CMR parameters correlate with cardiopulmonary fitness in patients with SV and can therefore be useful for follow-up and therapeutic management of these patients.

A Novel Strategy for the Mechanical Subpulmonary Support in Failing Fontan Patients

Background The number of single ventricle patients undergoing Fontan palliation and surviving to adulthood worldwide has steadily increased in recent years. Nevertheless, the Fontan circulation is destined to fail. Ultimately, heart transplantation (HTx) remains the definitive treatment option. Due a shortage of organs, mechanical circulatory support in the form of ventricular assist devices (VADs) is widely used to bridge heart failure patients to HTx, but these devices have been mainly developed to address the needs of normal anatomies. A novel venous cannula has been developed as part of the EXCOR® VAD to provide subpulmonary support in these patients. Its clinical application is investigated in the “Registry to Assess the Safety and Feasibility of the Subpulmonary Support with the Novel Venous Cannula in Patients with Failing/Absence of the Right Heart” (RegiVe study, NCT04782232).

Methods RegiVe is a multicenter, international, observational, prospective, non-randomized registry aiming to collect the routine clinical data of up to 20 patients. The primary endpoints address device performance and safety, while the secondary endpoints target organ status and overall safety (according to the Interagency Registry for Mechanically Assisted Circulatory Support – INTERMACS – definitions). Data analysis will be performed by means of descriptive statistics.

Results RegiVe has received the favorable opinion of an independent ethics committee and enrollment has recently started.

Conclusion RegiVe is the first study evaluating the use of a medical device specifically developed for subpulmonary support of failing Fontan patients. The study will provide important insight and further information on this cohort and help to improve a dedicated VAD strategy.

Adolescents and adults with Fontan circulation: insights from the PREpArE-Fontan registry

The Patient Registry for Adolescents and Adults with Stable Fontan Circulation aims to describe a contemporary cohort of Fontan patients who could be eligible for a clinical trial investigating macitentan, an endothelin receptor antagonist. This international, non-interventional, multicentre, cross-sectional, observational registry enrolled patients with "stable" Fontan circulation ≥10 years following extra-cardiac conduit or lateral tunnel procedure. Main exclusion criteria were NYHA functional class IV, reoperation of Fontan circulation, or signs of disease worsening. Patient characteristics at enrolment are described; available data were collected during a single registration visit. Of the 266 screened patients, 254 were included in this analysis. At enrolment, median (interquartile range) age was 24 (20;30) years, 37%/63% of patients were from the USA/Europe, 54% were male, 54%/47% had undergone extra-cardiac conduit/lateral tunnel procedures, and 95% were in NYHA functional class I or II. History of arrhythmia was more common in older patients and patients with lateral tunnel; overall prevalence was 19%. Most laboratory values were within the normal range but mean creatinine clearance was abnormally low (87.7 ml/min). Angiotensin-converting enzyme inhibitors were used by 48% of patients and their use was associated with creatinine clearance <90 ml/min (p = 0.007), as was Fontan completion at an older age (p = 0.007). 53.4% of patients had clinical characteristics that could potentially meet an endothelin receptor antagonist trial's eligibility criteria. The PREpArE-Fontan registry describes a cohort of patients who could potentially participate in an endothelin receptor antagonist trial and identified early subtle signs of Fontan failure, even in "stable" patients.

Abdominal CT and MRI Findings of Portal Hypertension in Children and Adults with Fontan Circulation

Background Portal hypertension in the Fontan circulation is a function of elevated systemic venous pressure and liver fibrosis. Purpose To quantify the prevalence of radiologic evidence of portal hypertension and elevated VAST score (one point each for varices, ascites, splenomegaly, and thrombocytopenia) of 2 or greater in children and adults with Fontan circulation and to determine the association with hemodynamics and adverse outcomes. Materials and Methods This was a retrospective study of individuals with Fontan circulation who underwent abdominal MRI or CT for focal liver lesion surveillance between January 2012 and December 2019. Portal hypertension was defined as the presence of at least two of the following: varices, ascites, or splenomegaly. Fontan deterioration was defined as a composite of heart failure signs or symptoms requiring diuretic escalation, placement of a ventricular assist device, heart transplant, or death. Relationships between variables and the composite end point were assessed using univariable and multivariable logistic regression. Results A total of 123 patients (age range, 9-55 years; 32 children) were evaluated (median age, 23 years; IQR, 17-30 years; 63 male patients). Median time since diagnosis of Fontan circulation was 16 years (IQR, 12-23 years). Twenty-five of the 123 patients (20%) had radiologic evidence of portal hypertension, and 34 (28%) had a VAST score of 2 or greater. Fontan deterioration occurred in 25 of the 123 patients (20%); median follow-up duration was 0.4 year (IQR, 0.1-3.1 years). Compared with patients who had Fontan circulation without deterioration, patients with Fontan deterioration were more likely to have moderate or severe ventricular systolic dysfunction (P < .01), moderate or severe atrioventricular valve regurgitation (P < .01), higher Fontan pressure (P = .01), radiologic evidence of portal hypertension (P < .01), and VAST score of 2 or greater (P < .01). Conclusion Radiologic evidence of portal hypertension at abdominal imaging in children and adults with Fontan circulation was associated with higher venous pressures and an increased risk for Fontan deterioration. These characteristics may be used to identify patients who warrant comprehensive hemodynamic evaluation. © RSNA, 2022.

A Multimodal Score Accurately Classifies Fontan Failure and Late Mortality in Adult Fontan Patients

Objectives

Despite the outstanding success of the Fontan operation, it is a palliative procedure and a substantial number of patients experience late failure of the Fontan circulation. Clinical presentation and hemodynamic phenotypes of Fontan failure are considerably variable. While various parameters have been identified as risk factors for late Fontan failure, a feasible score to classify Fontan failure and possibly allow timely risk stratification is lacking. Here, we explored the possibility of developing a score based on hemodynamic, clinical and laboratory parameters to classify Fontan failure and mortality.

Methods

We performed a retrospective study in our cohort of adult Fontan patients from two institutions [n = 198, median follow-up after Fontan 20.3 (IQR 15.6–24.3) years], identifying those patients with clinical Fontan failure (n = 52, 26.3%). Various hemodynamic, echocardiographic, laboratory and clinical data were recorded and differences between patients with and without Fontan failure were analyzed. We composed a Fontan Failure Score containing 15 parameters associated with Fontan failure and/or mortality and assessed its accuracy to discriminate between patients with and without late Fontan failure as well as late mortality and survival.

Results

Late failure occurred at a median of 18.2 (IQR 9.1–21.1) years after Fontan completion. Mortality associated with Fontan failure was substantial (25/52, 48.1%) with freedom of death/transplantation/take-down of 64% at 5 years and 36% at 10 years after onset of Fontan failure, respectively. Patients with Fontan failure had a significantly higher median Fontan Failure Score compared to non-failing Fontan patients [8 points (IQR 5–10) vs. 2 points (IQR 1-5), p < 0.001]. The score accurately classifies Fontan failure as well as mortality as assessed with receiver operating characteristic analysis. Area under the curve of the Fontan Failure Score was 0.963 (95% CI 0.921; 0.985, p < 0.001) to discriminate failure and 0.916 (95% CI 0.873; 0.959, p < 0.001) to classify mortality.

Conclusion

We have developed an uncomplex yet remarkably accurate score to classify Fontan failure and late mortality in adult Fontan patients. Prospective validation and most likely refinement and calibration of the score in larger and preferably multi-institutional cohorts is required to assess its potential to predict the risk of Fontan failure and late mortality.

The Epidemiology of Persons Living with Fontan in 2020 and Projections for 2030: Development of an Epidemiology Model Providing Multinational Estimates

Introduction

Fontan surgery is a palliative procedure performed in children with a functionally univentricular heart. Improvements in surgical technique over the past 30 years have increased life expectancy in this rare population. However, the epidemiology of persons living with Fontan is poorly understood. This study aimed to estimate the 2020 and 2030 prevalence of persons living with a Fontan circulation in 11 countries across the US, Europe, Australia and New Zealand, by procedure type: [atriopulmonary connection (AP), lateral tunnel total cavopulmonary connection (LT-TCPC) or extracardiac total cavopulmonary connection (EC-TCPC)]; and age group: [children (< 12 years), adolescents (12–17 years), and adults (≥ 18 years old)] by building an epidemiologic model.

Methods

The annual number of Fontan surgeries by country in 2010–2020 were extracted from hospital or claims databases, via procedure codes. The epidemiology of persons living with Fontan was modelled by applying these surgery frequencies to mid-year populations from 1972 to 2020 and overlaying an uptake curve. A literature search identified: 30-day mortality rates, long-term survival, and median age at surgery. Averages of these estimates were inputted into the model to project prevalence in 2030.

Results

The number of persons living with Fontan in 2020 across the 11 countries was estimated to be 47,881 [66 people per million (ppm)], rising to 59,777 (79 ppm) by 2030. In 2020, this population was 55% adults, 17% adolescents and 28% children shifting to 64%, 13% and 23%, respectively, in 2030. Among all persons living with Fontan, 74%/18%/9% are estimated to have EC-TCPC/LT-TCPC/AP, respectively, in 2020, and 83%/14%/4% in 2030.

Conclusions

According to this epidemiology model, the Fontan population is growing, partly driven by increased survival rates with the more recent LT-TCPC and EC-TCPC procedures (compared with AP). The 2020/2030 prevalence of persons living with Fontan is 66/79 ppm.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-021-02002-3.

Relation of Magnetic Resonance Elastography to Fontan Circulatory Failure in a Cohort of Pediatric and Adult Patients

Elevated magnetic resonance elastography (MRE)-derived liver stiffness may be associated with worse outcomes in people with Fontan circulation. We sought to evaluate the association between liver stiffness and Fontan failure or portal hypertension. Single center cross-sectional retrospective study of people with Fontan circulation who underwent MRE between 2011 and 2020. The cohort was divided into adult (age ≥ 21 years) and pediatric (< 21 years) groups. Fontan circulatory failure (FF) was defined as any of the following: death, transplantation, ventricular assist device, heart failure symptoms requiring escalation of diuretics. Radiologic portal hypertension was defined as the presence of one or more of the following: splenomegaly, ascites, or gastrointestinal varices. 128 patients were included (average age = 22.6 ± 8.7 years) and 58 (45%) were children. Median liver stiffness was 4.3 kPa (interquartile range (IQR) 3.8-5.8) for the entire cohort. Thirty patients (23%) developed FF (16 adults, 14 children). Liver stiffness was higher in adults with FF compared to those without FF (4.9 (IQR 4.0-6.0) vs. 4.2 (IQR 3.8-4.7) kPa, p = 0.04). There was no difference in liver stiffness between pediatric patients with and without FF (4.4 (IQR 4.1-5.4) vs. 4.4 (IQR 3.8-5.0), p = 0.5). Adults with radiologic portal hypertension and adults with moderate or severe atrioventricular valve regurgitation had higher liver stiffness than adults without. MRE-derived liver stiffness is associated with atrioventricular valve regurgitation, portal hypertension, and poor clinical outcomes in adults with Fontan circulation. There was no association between liver stiffness and FF in pediatric patients. This difference may be due to the progressive nature of Fontan-associated liver disease.

Outcomes among adult survivors of total cavopulmonary Fontan palliation for single ventricle

OBJECTIVE

This tertiary centre study aims to identify factors associated with adverse outcomes in adult survivors with total cavopulmonary connection (TCPC) Fontan palliation for single ventricle.

METHODS

This retrospective review of medical records identified adult (≥18 years) survivors of TCPC Fontan palliation who were followed at a single tertiary centre between 1 January 2000 and 1 July 2019. Adverse outcomes were defined as arrhythmia, pacemaker/implantable cardioverter defibrillator placement, liver cirrhosis, protein losing enteropathy, hospitalisation for heart failure, thromboembolic complication and/or death.

RESULTS

160 adult TCPC patients met the inclusion criteria: 117 (73.1%) extracardiac and 43 (26.9%) lateral tunnel. The median (IQR) duration of follow-up since TCPC palliation was 17.5 (11.8-21.3) years. An adverse outcome occurred in 87 (54.4%) patients. Adverse outcome-free survival rates at 10, 20 and 25 years post TCPC were 89% (95% CI 82% to 93%), 60% (95% CI 50% to 69%) and 24% (95% CI 15% to 35%), respectively. On multivariate analysis, extracardiac Fontan (HR 2.21, 95% CI 1.20 to 4.08, p=0.011) was observed to be an independent risk factor for adverse outcomes after adjusting for age, race, morphology of the systemic ventricle and history of fenestration.

CONCLUSIONS

In this single-centre retrospective study of adult survivors of TCPC palliation, extracardiac Fontan was associated with an increased hazard for adverse outcomes. This finding could guide clinicians in developing risk modification strategies and management decisions to improve long-term outcomes in these patients.

Persisting and reoccurring cyanosis after Fontan operation is associated with increased late mortality

OBJECTIVES

The Fontan operation aims at reducing cyanosis and cardiac volume overload in patients with complex univentricular heart malformations. However, persisting or reoccurring cyanosis is frequently observed. We sought to systematically determine the prevalence and clinical consequences of persisting and secondary cyanosis after Fontan operation.

METHODS

A total of 331 Fontan patients, operated between 1984 and 2016 with a median postoperative follow-up of 7.9 (interquartile range 2.6-15.8) years, were studied retrospectively. Cyanosis was defined as transcutaneous oxygen saturation ≤93% at rest measured by pulse oximetry. Prevalence of cyanosis was analysed at 3 different time points (t1 = post-Fontan operation, t2 = post-Fontan cardiac catheterization, t3 = last follow-up) and the association of cyanosis with mortality was examined.

RESULTS

Prevalence of cyanosis was 50% at t1 and 39% at t3. Fenestration was patent in 71% and 33% of all cyanotic patients at t1 and t3, respectively. In patients with clinical indication for catheterization (t2; n = 178/331), prevalence of cyanosis was 72%. At t2, patent fenestration (33%), veno-venous collaterals (24%) or both (32%) were present. Thirty-six (11%) patients died during follow-up. In a time-varying multivariable Cox regression analysis, cyanosis was the strongest predictor for late mortality (P < 0.001, hazard ratio 12.2, 95% confidence interval 3.7-40.5).

CONCLUSIONS

Prevalence of cyanosis was considerable during long-term follow-up after Fontan operation and-as a surrogate parameter for unfavourable Fontan haemodynamics-is associated with increased late mortality. Accordingly, particular attention should be directed towards the persistence or reoccurrence of cyanosis during follow-up since it may indicate haemodynamic attrition and development of Fontan failure.

Longitudinal changes in echocardiographic measures of ventricular function after Fontan operation

BACKGROUND

While numerous indices have been developed in an attempt to quantify ventricular function in patients with single ventricle heart disease after Fontan, there are little data on how these parameters change over time.

METHODS

A retrospective observational study was performed of individuals who underwent Fontan operation at Children's Hospital of Philadelphia (CHOP) in 2006 and 2007. Measurements of fractional area change (FAC), tricuspid annular planar systolic excursion (TAPSE), myocardial performance index (MPI), systolic to diastolic (s/d) ratio, and myocardial strain and strain rate were made offline. A composite outcome of protein-losing enteropathy (PLE), plastic bronchitis, transplant, or death was created, and change in function was compared between those who did and those who did not meet the outcome.

RESULTS

There were 312 echocardiograms from 40 unique patients (75% male, 55% dominant right ventricle). The aggregate mean values for most assessed parameters were worse than what would be expected for a healthy age-matched population. The global longitudinal strain rate increased (worsened) by 0.014 (1/s) per year (P = .02), and the global circumferential strain rate increased (worsened) by 0.011 (1/s) per year (P = .01). There was no difference in the rate of change of ventricular function in the 6 patients who met the composite endpoint vs those who did not.

CONCLUSION

This study demonstrates that global longitudinal strain rate and global circumferential strain rate decrease over 10 years following Fontan operation. These measures of ventricular performance may be early signs of cardiac dysfunction that predate more obvious echocardiographic signs of deterioration.

Modes of late mortality in patients with a Fontan circulation

OBJECTIVES

The mechanisms of attrition of the Fontan population have been poorly characterised and it is unclear whether some of the deaths are potentially preventable. We analysed the circumstances of late death in patients with a Fontan circulation, with a special focus on identifying lesions amenable to intervention that may have contributed to the decline of their circulation.

METHODS

Between 1975 and 2018, a total of 105 patients from a Bi-National Registry died beyond 1 year after Fontan completion, at a median age of 18.6 (IQR 13.8-26.0) years old, 12.7 (IQR 6.0-19.3) years after Fontan completion.

RESULTS

A total of 105 patients died-63 patients (60%) with an atriopulmonary (AP) Fontan, 21 patients (20%) with a lateral tunnel (LT) and 21 patients (20%) with an extracardiac conduit (ECC). 72 patients (69%) were reviewed within 2 years preceding death, with 32% (23/72) deemed to be clinically well. Fontan circulatory failure was the most common cause of death in 42 patients (45%). Other causes of death included sudden death/arrhythmia (19%), perioperative death (12%), neurological complication (7%) and thromboembolism (7%). All patients with an LT or ECC who died from Fontan failure had at least one surgical defect that was amenable to intervention at time of death.

CONCLUSIONS

Conventional clinical surveillance has been insensitive in detecting a significant proportion of patients at risk of late death. Fontan circulatory failure contributes to half of the late deaths. Patients with an LT or ECC Fontan who died with a clinical picture of circulation failure may have potentially correctable lesions.

Transplantation of the failing Fontan

Half a century has passed since the original Fontan palliation. In the interim, surgical and medical advancements have allowed more single ventricle patients to reach Fontan and long-term survival for Fontan patients to improve significantly. However, the risk for Fontan failure and need for heart transplantation remains. In this article we discuss mechanisms of Fontan failure, risk factors and special considerations for Fontan patients in both medical and surgical management around heart transplantation and provide an updated review of survival for Fontan patients after heart transplantation.

Evaluation and Management of the Child and Adult With Fontan Circulation: A Scientific Statement From the American Heart Association

It has been 50 years since Francis Fontan pioneered the operation that today bears his name. Initially designed for patients with tricuspid atresia, this procedure is now offered for a vast array of congenital cardiac lesions when a circulation with 2 ventricles cannot be achieved. As a result of technical advances and improvements in patient selection and perioperative management, survival has steadily increased, and it is estimated that patients operated on today may hope for a 30-year survival of >80%. Up to 70 000 patients may be alive worldwide today with Fontan circulation, and this population is expected to double in the next 20 years. In the absence of a subpulmonary ventricle, Fontan circulation is characterized by chronically elevated systemic venous pressures and decreased cardiac output. The addition of this acquired abnormal circulation to innate abnormalities associated with single-ventricle congenital heart disease exposes these patients to a variety of complications. Circulatory failure, ventricular dysfunction, atrioventricular valve regurgitation, arrhythmia, protein-losing enteropathy, and plastic bronchitis are potential complications of the Fontan circulation. Abnormalities in body composition, bone structure, and growth have been detected. Liver fibrosis and renal dysfunction are common and may progress over time. Cognitive, neuropsychological, and behavioral deficits are highly prevalent. As a testimony to the success of the current strategy of care, the proportion of adults with Fontan circulation is increasing. Healthcare providers are ill-prepared to tackle these challenges, as well as specific needs such as contraception and pregnancy in female patients. The role of therapies such as cardiovascular drugs to prevent and treat complications, heart transplantation, and mechanical circulatory support remains undetermined. There is a clear need for consensus on how best to follow up patients with Fontan circulation and to treat their complications. This American Heart Association statement summarizes the current state of knowledge on the Fontan circulation and its consequences. A proposed surveillance testing toolkit provides recommendations for a range of acceptable approaches to follow-up care for the patient with Fontan circulation. Gaps in knowledge and areas for future focus of investigation are highlighted, with the objective of laying the groundwork for creating a normal quality and duration of life for these unique individuals.

Pediatric Fontan Associated Liver Disease: Non-invasive Evaluation with Serologic Markers and Acoustic Radiation Force Impulse (ARFI) Elastography

Hepatic fibrosis is a significant complication in adult Fontan patients suggesting development as a function of time since the surgery. Children with Fontan circulation are not routinely assessed for development of liver disease. We aimed to evaluate the effectiveness of serologic biomarkers and acoustic radiation force impulse (ARFI) elastography to detect liver disease in pediatric Fontan patients. Patients ≥ 1 year after Fontan operation prospectively had hepatic US with acoustic radiation force impulse and laboratory testing. Clinical cardiac data (echocardiograms, cardiac catheterizations) were reviewed. Statistical analysis was performed using Pearson's correlation coefficient, Wilcoxon rank-sum test and Kruskal-Wallis test. Forty patients were enrolled with median age of 11 years and median time since Fontan of 6.5 years. Platelet count negatively correlated with years since Fontan (p < 0.000). Thrombocytopenia was noted in 15% of patients with the lowest platelet count of 78 K/cu mm, in a patient >10 years from the Fontan (DORV) operation. Alanine transaminase (ALT, p = 0.034) and aspartate aminotransferase (AST, p = 0.009) were higher in patients with Extracardiac Conduit Fontan and not in other Fontan operations. Heterogeneous echotexture on liver ultrasound correlated with years since Fontan (p = 0.022), however all acoustic radiation force impulse values were elevated (> 1.34 m/s) and did not correlate with age, years since Fontan, labs or imaging. FibroSure values did not correlate with years since Fontan. This suggests that ARFI may be elevated due to passive hepatic congestion, limiting its value in this patient population. Additional testing is necessary to identify reliable noninvasive screening modalities for hepatic fibrosis in Fontan patients. Our study is the largest pediatric study to evaluate ARFI in patients after the Fontan operation and showed increased shear wave speed for all patients with no correlation with time since palliation. Decreasing platelet count may indicate the development of liver fibrosis.

Impact of Time Interval Between Glenn and Fontan Procedures on Fontan Operative and Long-Term Follow-up Results

OBJECTIVE

The bidirectional cavopulmonary shunt (BCPS) is an effective palliative procedure which has been widely used to boost outcome of the Fontan procedure. However, there is no standard duration time between these two procedures. Therefore, we investigated whether different time intervals between BCPS and Fontan procedure affects morbidity and mortality of Fontan patients.

METHODS

Between 2004 and 2016, 210 post-BCPS patients underwent Fontan operation at Fuwai Hospital. The median interval between BCPS and Fontan procedure was 3.7 years (range 0.55-11.86 years) and this was used to divide study cohort into Group 1 (< 3.7 years; n = 124) and Group 2 (> 3.7 years; n = 86). We analyzed these patients retrospectively in terms of their preoperative characteristics and post-operative and follow-up results.

RESULTS

Weight z-scores for age at BCPS (- 0.73 ± 1.39 vs - 1.17 ± 1.60, p < 0.05) was significantly higher in Group 2. However, saturation at room air before Fontan (76.42 ± 20.01 vs 82.85 ± 9.69, p < 0.001) was significantly higher in Group 1. The morbidity and mortality were similar between two groups. There were twelve hospital deaths (5.7%): eight (8/124, 6.5%) presented in Group 1 and four (4/86, 4.7%) in Group 2. On multi-variable analysis, risk factors for death were prolonged mechanical ventilation [hazard ratio (HR) 1.02, p = 0.004] and single right ventricle (HR 7.17, p = 0.03). After a mean follow-up of 4.95 years (range 0.74-13.62 years), one patient in Group 1 died of heart failure 13 months after Fontan procedure. The overall Fontan failure in Group 1 was similar to that in Group 2 (2.7% vs 2.6%, p = 0.985). The incidence of arrhythmias and re-intervention were not different between the two groups.

CONCLUSIONS

Fontan procedure could be performed safely in patient who stayed in long duration between Fontan procedure and BCPS without affecting the operative and long-term follow-up results. However, for post-BCPS patients with severe hypoxemia, earlier age at Fontan might be a good choice.

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.

Understanding the Fontan Procedure in Congenital Heart Disease Patients and the Importance of Early Hepatology Referrals: A Case Study

BACKGROUND

Patients with congenital heart disease are surviving into adulthood because of new surgeries developed over the recent decades. One surgery is the Fontan procedure, which is used in patients with only one functioning ventricle. Although it has been saving lives, in the recent years multiple complications have been noted.

OBJECTIVE

To discuss the Fontan procedure and inform nurse practitioners in the primary care setting the importance of early screening and referral because of increasing number of liver complications in these patients. This case study highlights the dilemmas a patient with the Fontan procedure faces as a young adult.

METHODS

Evidence-based articles from the PubMed and Embase databases were used to support the case study.

RESULTS

Patients with the low-pressure Fontan circulation are under chronic passive congestion and have known liver complications such as liver fibrosis, cirrhosis, and protein-losing enteropathy. This can lead to a high-risk dual organ heart-liver transplant.

CONCLUSIONS

Early screening and referral to a hepatologist are critical in these patients.

IMPLICATIONS FOR NURSING

Since patients with congenital heart disease often present to the primary care setting, nurse practitioners in this area should understand the Fontan procedure and its associated complications so they can effectively manage these patients.

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

OBJECTIVE

More patients with Fontan physiology are reaching adulthood. The purpose of this meta-analysis was to evaluate the late outcomes of patients palliated with Fontan procedure and to assess the risk factors for mortality.

METHODS

PubMed, Embase and Web of Science were queried to retrieve observational studies of survival in patients following the Fontan procedure with ≥5 years of follow-up. A random-effects model was used to determine pooled survival estimates at 5, 10 and 15 years. Meta-regression was used to assess potential moderators for death.

RESULTS

Nineteen articles with a total of 5859 patients were included. The weighted mean follow-up time was 8.94±2.64 years with overall 8.3% deaths and 1.5% transplants. Pooled survival estimates at 5, 10 and 15 years were 90.7%, 87.2% and 87.5%, respectively; and 88.4%, 85.7% and 84.1%, respectively, for studies that included all three time intervals (n=4). Earliest surgical year included in the study, proportion of atriopulmonary connections versus extracardiac conduit or lateral tunnel, and older age at Fontan were associated with higher rates of death, but ventricular morphology was not. Protein-losing enteropathy, reoperation and pacemaker insertion were reported in 2.1%, 5.6% and 6.8% patients, respectively.

CONCLUSIONS

Survival following the Fontan procedure has improved with time and is influenced by Fontan type and age at the time of Fontan. At a mean follow-up of 8.9 years, there was no significant association between survival and ventricular morphology, not taking into account the mortality prior to Fontan.

Experimental Investigation of the Effect of Non-Newtonian Behavior of Blood Flow in the Fontan Circulation

The Fontan procedure for univentricular heart defects creates a unique circulation where all pulmonary blood flow is passively supplied directly from systemic veins. Computational simulations, aimed at optimizing the surgery, have assumed blood to be a Newtonian fluid without evaluating the potential error introduced by this assumption. We compared flow behavior between a non-Newtonian blood analog (0.04% xanthan gum) and a control Newtonian fluid (45% glycerol) in a simplified model of the Fontan circulation. Particle image velocimetry was used to examine flow behavior at two different cardiac outputs and two caval blood flow distributions. Pressure and flow rates were measured at each inlet and outlet. Velocity, shear strain, and shear stress maps were derived from velocity data. Power loss was calculated from pressure, flow, and velocity data. Power loss was increased in all test conditions with xanthan gum vs. glycerol (mean 10±2.9% vs. 5.6±1.3%, p=0.032). Pulmonary blood flow distribution differed in all conditions, more so at low cardiac output. Caval blood flow mixing patterns and shear stress were also qualitatively different between the solutions in all conditions. We conclude that assuming blood to be a Newtonian fluid introduces considerable error into simulations of the Fontan circulation, where low-shear flow predominates.

Life After Surviving Fontan Surgery: A Meta-Analysis of the Incidence and Predictors of Late Death

AIM

We now know that 20-40% of patients with a single ventricle will develop heart failure after the second decade post-Fontan surgery. However, we remain unable to risk-stratify the cohort to identify patients at highest risk of late failure and death. We conducted a systematic review of all reported late outcomes for patients with a Fontan circulation to identify predictors of late death.

METHODS

We searched MEDLINE, Embase and PubMed with subject terms ("single ventricle", "Hypoplastic left heart syndrome", "congenital heart defects" or "Fontan procedure") AND ("heart failure", "post-operative complications", "death", "cause of death", "transplantation" or "follow-up studies") for relevant studies between January 1990 and December 2015. Variables identified as significant predictors of late death on multivariate analysis were collated for meta-analysis. Survival data was extrapolated from Kaplan-Meier survival curves to generate a distribution-free summary survival curve.

RESULTS

Thirty-four relevant publications were identified, with a total of 7536 patients included in the analysis. Mean follow-up duration was 114 months (range 24-269 months). There were 688 (11%) late deaths. Predominant causes of death were late Fontan failure (34%), sudden death (19%) and perioperative death (16%). Estimated mean survival at 5, 10 and 20 years post Fontan surgery were 95% (95%CI 93-96), 91% (95%CI 89-93) and 82% (95%CI 77-85). Significant predictors of late death include prolonged pleural effusions post Fontan surgery (HR1.18, 95%CI 1.09-1.29, p<0.001), protein losing enteropathy (HR2.19, 95%CI 1.69-2.84, p<0.001), increased ventricular end diastolic volume (HR1.03 per 10ml/BSA increase, 95%CI 1.02-1.05, p<0.001) and having a permanent pacemaker (HR12.63, 95%CI 6.17-25.86, p<0.001).

CONCLUSIONS

Over 80% of patients who survive Fontan surgery will be alive at 20 years. Developing late sequelae including protein losing enteropathy, ventricular dysfunction or requiring a pacemaker predict a higher risk of late death.

Hemodynamics of Fontan Failure: The Role of Pulmonary Vascular Disease

BACKGROUND

Nonpulsatile pulmonary blood flow in Fontan circulation results in pulmonary vascular disease, but the potential relationships between pulmonary vascular resistance index (PVRI) and Fontan failure have not been studied. The objective was to determine whether the absence of subpulmonary ventricle in the Fontan circulation would make patients more vulnerable to even low-level elevations in PVRI, and when coupled with low cardiac index, this would identify patients at increased risk of Fontan failure.

METHODS AND RESULTS

Two hundred sixty-one adult Fontan patients underwent cardiac catheterization; age 26±3 years, men 146 (56%), atriopulmonary Fontan 144 (55%). Patients were divided into 2 groups: those with high PVRI (>2 WU·m2) and low cardiac index <2.5 L min-1 m-2 (group 1, n=70, 30%), and those with normal PVRI and normal cardiac index (group 2, n=182, 70%). Fontan failure was defined by the composite of all-cause mortality, listing for heart transplantation, or initiation of palliative care. There were 68 (26%) cases of Fontan failure during a mean follow-up of 8.6±2.4 years. When compared with group 2, freedom from Fontan failure was significantly lower in group 1: 66% versus 89% at 5 years. The combination of high PVRI and low cardiac index was an independent risk factor for Fontan failure (hazard ratio, 1.84; 95% confidence interval, 1.09-2.85).

CONCLUSIONS

When coupled with low cardiac index, even mild elevations in PVRI identify patients at high risk of Fontan failure. This suggests that pulmonary vascular disease is a key mechanism underlying Fontan failure and supports further studies to understand the pathophysiology and target treatments to pulmonary vascular tone in this population.

Noninvasive Liver Assessment in Adult Patients With Fontan Circulation Using Acoustic Radiation Force Impulse Elastography and Hepatic Magnetic Resonance Imaging

BACKGROUND

Patients who have undergone the Fontan procedure are at risk of developing hepatic dysfunction. However, broad recommendations regarding liver monitoring are limited. The purpose of this study was to characterize the frequency of liver disease in adult Fontan patients using multimodality imaging (hepatic magnetic resonance imaging [MRI], acoustic radiation force impulse [ARFI] elastography, or hepatic ultrasound).

METHODS

In a prospective cross-sectional analysis of adult patients palliated with a Fontan procedure, hepatic MRI, ARFI, and hepatic ultrasound were used to assess for liver disease. The protocol compared (1) varying prevalence of liver disease based on each imaging technique, (2) agreement between different techniques, and (3) association between noninvasive imaging diagnosis of liver disease and clinical variables, including specific liver disease biomarkers.

RESULTS

Thirty-seven patients were enrolled. The ARFI results showed high wave propagation velocity in 35 patients (94.6%). All patients had some abnormality in the hepatic MRI. Specifically, 8 patients (21.6%) showed signs of chronic liver disease, 10 patients (27%) had significant liver fibrosis, and 27 patients (73%) had congestion. No correlation was found between liver stiffness measured as propagation velocity and hepatic MRI findings. Only 7 patients had an abnormal hepatic ultrasound study.

CONCLUSIONS

There is an inherent liver injury in adult Fontan patients. Signs of liver disease were observed in most patients by both hepatic MRI and ARFI elastography but not by ultrasound imaging. Increased liver stiffness did not identify specific disease patterns from MRI, supporting the need for multimodality imaging to characterize liver disease in Fontan patients.

Current Therapy for Hypoplastic Left Heart Syndrome and Related Single Ventricle Lesions

Universally fatal only 4 decades ago, the progress in the 3-stage palliation of hypoplastic left heart syndrome and related single right ventricular lesions has drastically improved the outlook for these patients. Although the stage II operation (hemi-Fontan or bidirectional Glenn) and stage III Fontan procedure have evolved into relatively low-risk operations, the stage I Norwood procedure remains one of the highest-risk and costliest common operations performed in congenital heart surgery. Yet, despite this fact, experienced centers now report hospital survivals of >90% for the Norwood procedure. This traditional 3-stage surgical palliation has seen several innovations in the past decade aimed at improving outcomes, particularly for the Norwood procedure. One significant change is a renewed interest in the right ventricle-to-pulmonary artery shunt as the source of pulmonary blood flow, rather than the modified Blalock-Taussig shunt for the Norwood. The multi-institutional Single Ventricle Reconstruction trial randomly assigned 555 patients to one or the other shunt, and these subjects continue to be followed closely as they now approach 10 years postrandomization. In addition to modifications to the Norwood procedure, the hybrid procedure, a combined catheter-based and surgical approach, avoids the Norwood procedure in the newborn period entirely. The initial hybrid procedure is then followed by a comprehensive stage II, which combines components of both the Norwood and the traditional stage II, and later completion of the Fontan. Proponents of this approach hope to improve not only short-term survival, but also potentially longer-term outcomes, such as neurodevelopment, as well. Regardless of the approach, traditional surgical staged palliation or the hybrid procedure, survivals have vastly improved, and large numbers of these patients are surviving not only through their Fontan in early childhood, but also into adolescence and young adulthood. As this population grows, it becomes increasingly important to understand the longer-term outcomes of these Fontan patients, not only in terms of survival, but also in terms of the burden of disease, neurodevelopmental outcomes, psychosocial development, and quality of life.

Management of Pregnancy in Patients With Complex Congenital Heart Disease: A Scientific Statement for Healthcare Professionals From the American Heart Association

Today, most female children born with congenital heart disease will reach childbearing age. For many women with complex congenital heart disease, carrying a pregnancy carries a moderate to high risk for both the mother and her fetus. Many such women, however, do not have access to adult congenital heart disease tertiary centers with experienced reproductive programs. Therefore, it is important that all practitioners who will be managing these women have current information not only on preconception counseling and diagnostic evaluation to determine maternal and fetal risk but also on how to manage them once they are pregnant and when to refer them to a regional center with expertise in pregnancy management.

Superior Mesenteric Arterial Flow Pattern is Associated with Major Adverse Events in Adults with Fontan Circulation

Factors contributing to the failure of Fontan circulation in adults are poorly understood. Reduced superior mesenteric arterial (SMA) flow has been identified in pediatric Fontan patients with protein-losing enteropathy. SMA flow has not been profiled in an adult Fontan population and its association with adverse events is unknown. We aimed to examine associations between SMA flow patterns and adverse events in adult Fontan patients. We performed a retrospective review of adult Fontan patients who underwent echocardiograms between 2008 and 2014. SMA Doppler data included peak systolic and end-diastolic velocity and velocity time integral (VTI). Systolic/diastolic (S/D) ratio and resistive index were calculated. The relationship between SMA flow parameters and major adverse events (death or transplantation) was examined using proportional hazard Cox regression analyses. Kaplan-Meyer analysis was conducted to construct survival curve of patients with and without adverse events. 91 post-Fontan adult patients (76 % systemic left ventricle, 20 % atriopulmonary Fontan, mean age 27.9 years) were analyzed. Adverse events occurred in nine patients (death = 4, transplant = 5). When compared with the non-event group, the event group had increased end-diastolic velocity [hazard ratio (HR) 1.5, 95 % confidence interval (CI) 1.1-1.8; p = 0.002], increased systolic VTI (HR 1.5, 95 % CI 1.1-2.2, p = 0.02), increased diastolic VTI (HR 1.7, 95 % CI 1.2-2.4, p = 0.004), decreased S/D velocity ratio (HR 0.32, 95 % CI 0.14-0.71, p = 0.006), decreased S/D VTI ratio (HR 0.76, 95 % CI 0.61-0.97, p = 0.02), and decreased resistive index (HR 0.29, 95 % CI 0.14-0.60, p = 0.0007). Increased end-diastolic velocity and VTI in mesenteric arterial flow, with lower systolic/diastolic ratio and resistive index, were associated with death and need for heart transplant in adult Fontan patients. The mesenteric hyperemic flow was also associated with clinical signs of portal venous outflow obstruction, suggesting the presence of vasodilatory state in end-stage adult Fontan circulation.

Elevated Low-Shear Blood Viscosity is Associated with Decreased Pulmonary Blood Flow in Children with Univentricular Heart Defects

After the Fontan procedure, patients with univentricular hearts can experience long-term complications due to chronic low-shear non-pulsatile pulmonary blood flow. We sought to evaluate hemorheology and its relationship to hemodynamics in children with univentricular hearts. We hypothesized that low-shear blood viscosity and red blood cell (RBC) aggregation would be associated with increased pulmonary vascular resistance (PVR) and decreased pulmonary blood flow (PBF). We performed a cross-sectional analysis of 62 children undergoing cardiac catheterization-20 with isolated atrial septal defect (ASD), 22 status post Glenn procedure (Glenn), and 20 status post Fontan procedure (Fontan). Shear-dependent blood viscosity, RBC aggregation and deformability, complete blood count, coagulation panel, metabolic panel, fibrinogen, and erythrocyte sedimentation rate were measured. PVR and PBF were calculated using the Fick equation. Group differences were analyzed by ANOVA and correlations by linear regression. Blood viscosity at all shear rates was higher in Glenn and Fontan, partially due to normocytic anemia in ASD. RBC aggregation and deformability were similar between all groups. Low-shear viscosity negatively correlated with PBF in Glenn and Fontan only (R (2) = 0.27, p < 0.001); it also negatively correlated with pulmonary artery pressure in Glenn (R (2) = 0.15, p = 0.01), and positively correlated with PVR in Fontan (R (2) = 0.28, p = 0.02). Our data demonstrate that elevated low-shear blood viscosity is associated with negative hemodynamic perturbations in a passive univentricular pulmonary circulation, but not in a pulsatile biventricular pulmonary circulation.

Catheter-measured Hemodynamics of Adult Fontan Circulation: Associations with Adverse Event and End-organ Dysfunctions

BACKGROUND

In heart failure, a high systemic vascular resistance index (SVRI), high central venous pressure (CVP), and low cardiac index (CI) predict poor outcomes. Conversely, late hemodynamic manifestations of failing Fontan circulation and associations with end-organ dysfunction are not well understood.

METHODS

A retrospective review of right-heart catheterization data of adult Fontan patients between 2002 and 2014 was conducted. Relationships between hemodynamic variables and serious adverse events (death or heart transplant) were examined using the Cox proportional hazard analysis. Correlations between the hemodynamic measurements and signs of end-organ dysfunction (MELD-XI, Child-Pugh, VAST score, estimated glomerular filtration rate [eGFR]) were analyzed.

RESULTS

Sixty post-Fontan patients (85% systemic left ventricle, 40% atriopulmonary Fontan, mean age of 28 years, and mean time since Fontan operation of 21.9 years) were included. At baseline, those with an event were statistically younger, had lower transcutaneous oxygen saturations, were more likely to have an atriopulmonary Fontan, and were more likely to have a pacemaker. Eighteen experienced a cardiovascularly significant event. Using univariate analysis to compare the event and nonevent groups, mean CI was 2.8 ± 0.9 vs. 2.4 ± 0.5 L/min/m² (P = .004), and CVP was 18.6 ± 6.5 vs. 16.1 ± 4.3 mmHg (P = .03). However, the statistical significances did not persist in the multivariate model. Higher CVP and pulmonary capillary wedge pressure (PCWP) were associated with higher MELD-XI and Child-Pugh scores, and the VAST score was only associated with PCWP.

CONCLUSIONS

Symptomatic adult Fontan patients who experienced an event manifested with a higher CI and CVP, although the multivariate Cox proportional hazard analysis did not yield any significant associations. The presences of hepatic dysfunction and portal venous outflow obstruction were associated with a higher CVP and PCWP. Renal dysfunction was prevalent but no statistically significant association between the hemodynamic measurements was identified, although trends toward a higher CVP and transpulmonary gradient were identified.

Hospital Resource Utilization for Common Noncardiac Diagnoses in Adult Survivors of Single Cardiac Ventricle

Single ventricle congenital heart disease (SV CHD) has transformed from a nearly universally fatal condition to a chronic illness. As the number of adults living with SV CHD continues to increase, there needs to be an understanding of health care resource utilization (HCRU), particularly for noncardiac conditions, for this patient population. We performed a retrospective database review of the University HealthSystem Consortium Clinical Database/Resource Manager for adult patients with SV CHD hospitalized for noncardiac conditions from January 2011 to November 2014. Patients with SV CHD were identified using International Classification of Disease (ICD)-9 codes associated with SV CHD (hypoplastic left heart, tricuspid atresia, and SV) and stratified into 2 groups by age (18 to 29 years and 30 to 40 years). Direct cost, length of stay (LOS), intensive care unit (ICU) admission rate and mortality data were compared with age-matched patients without CHD. There were 2,083,651 non-CHD and 590 SV CHD admissions in Group 1 and 2,131,046 non-CHD and 297 SV CHD admissions in Group 2. There was no difference in LOS in Group 1, but there were higher costs for several diagnoses. LOS and costs were higher for several diagnoses in Group 2. ICU admission rate and in-hospital mortality were higher for several diagnoses for patients with SV CHD in both groups. In conclusion, adults with SV CHD admitted for noncardiac diagnoses have higher HCRU (longer LOS and higher ICU admission rates) compared with similarly aged patients without CHD. These findings stress the importance of good primary care in this population with complex, chronic cardiac disease to prevent hospitalizations and higher HCRU.

Comparison Between Echocardiography and Cardiac Magnetic Resonance Imaging in Predicting Transplant-Free Survival After the Fontan Operation

Adverse outcomes increase in frequency as patients after Fontan operation approach adulthood. Cardiac magnetic resonance (CMR) imaging-derived parameters have been shown to predict death/transplant; however, limited data are available on the usefulness of echocardiography in risk stratification. We conducted a retrospective, single-center review of records of patients after Fontan operation with an echocardiogram and CMR within 1 year of each other. The primary end point was time to all-cause mortality or listing for transplant. Of the 127 eligible patients, there were 12 end points (9%; 10 deaths and 2 listing for transplant). Median age was 16.8 years (interquartile range 12 to 23.1) with a median follow-up of 3.8 years (interquartile range 2.6 to 5.7). Among clinical parameters, protein-losing enteropathy had the strongest association with the outcome. Among echocardiographic variables, global circumferential strain showed the strongest association (hazard ratio 1.3 per unit change, 95% confidence interval 1.1 to 1.5, p value 0.001, C-index 0.81), whereas among CMR variables indexed ventricular end-diastolic volume showed the strongest association with the outcome (hazard ratio 1.04 per 10 ml/BSA(1.3) increase in volume, 95% confidence interval 1.02 to 1.06, p value 0.001, C-index 0.82). Cox proportional hazards analysis revealed echocardiography and CMR models to each individually have a higher predictive ability than the clinical model; however, in direct comparison, neither technique was superior. In conclusion, both echocardiography-derived circumferential strain and CMR-derived ventricular end-diastolic volume index are associated with transplant-free survival in patients after Fontan operation. Echocardiography and CMR parameters have higher discriminative ability than clinical variables. Although neither imaging technique is superior in this cohort, both introduce important factors for risk stratification.

The Fontan operation: the long-term outlook

PURPOSE OF REVIEW

As perioperative survival following the Fontan procedure has improved and more patients are reaping the benefits of physiologic palliation, the costs of longstanding systemic venous hypertension and the functional limitations of a single ventricle are becoming clearer. Arrhythmias, heart failure, protein-losing enteropathy, hepatic cirrhosis, pulmonary hypertension, and ventricular dysfunction are common in late survivors and result in significant morbidity and mortality. Current research is focused on characterizing late morbidities and developing risk-prediction models for worse outcomes in long-term survivors.

RECENT FINDINGS

Ten-year survival following the Fontan procedure is now 94-98%; however, estimated conditional survival in survivors aged above 18 years is 60% at 40 years of age. Atrial arrhythmias and heart failure are the leading causes of morbidity and mortality. Hypoplastic left heart syndrome, hepatic dysfunction, decreased exercise tolerance, lower quality of life, and markers of neurohormonal activation have been associated with worse outcome. Improvements in exercise tolerance are seen with selective pulmonary vasodilator therapy and exercise training. Heart transplant continues to be an effective therapy for end-stage Fontan failure, and reports of the use of traditional mechanical assist devices and the development of right heart assist devices in the setting of passive venous flow are ongoing.

SUMMARY

Over a generation has passed since the Fontan procedure revolutionized the care of patients with a single ventricle. Data generated from retrospective and prospective observational studies in long-term survivors are identifying patients at risk.