Forty years of the Fontan operation: a failed strategy

Application of Principal Component Analysis to Heterogenous Fontan Registry Data Identifies Independent Contributing Factors to Decline

Single ventricle heart disease is a severe and life-threatening illness, and improvements in clinical outcomes of those with Fontan circulation have not yet yielded acceptable survival over the past two decades. Patients are at risk of developing a diverse variety of Fontan-associated comorbidities that ultimately requires heart transplant. Our observational cohort study goal was to determine if principal component analysis (PCA) applied to data collected from a substantial Fontan cohort can predict functional decline (N=140). Heterogeneous data broadly consisting of measures of cardiac and vascular function, exercise (VO2max), lymphatic biomarkers, and blood biomarkers were collected over 11 years at a single site; in that time, 16 events occurred that are considered here in a composite outcome measure. After standardization and PCA, principal components (PCs) representing >5% of total variance were thematically labeled based on their constituents and tested for association with the composite outcome. Our main findings suggest that the 6th PC (PC6), representing 7.1% percent of the total variance in the set, is greatly influenced by blood serum biomarkers and superior vena cava flow, is a superior measure of proportional hazard compared to EF, and displayed the greatest accuracy for classifying Fontan patients as determined by AUC. In bivariate hazard analysis, we found that models combining systolic function (EF or PC5) and lymphatic dysfunction (PC6) were most predictive, with the former having the greatest AIC, and the latter having the highest c-statistic. Our findings support our hypothesis that a multifactorial model must be considered to improve prognosis in the Fontan population.

Effect of patient factors, center, and era on Fontan timing: An observational study using the Pediatric Health Information Systems Database

BACKGROUND

There are no consensus guidelines defining optimal timing for the Fontan operation, the last planned surgery in staged palliation for single-ventricle heart disease.

OBJECTIVES

Identify patient-level characteristics, center-level variation, and secular trends driving Fontan timing.

METHODS

A retrospective observational study of subjects who underwent Fontan from 2007 to 2021 at centers in the Pediatric Health Information Systems database was performed using linear mixed-effects modeling in which age at Fontan was regressed on patient characteristics and date of operation with center as random effect.

RESULTS

We included 10,305 subjects (40.4% female, 44% non-white) at 47 centers. Median age at Fontan was 3.4 years (IQR 2.6-4.4). Hypoplastic left heart syndrome (-4.4 months, 95%CI -5.5 to -3.3) and concomitant conditions (-2.6 months, 95%CI -4.1 to -1.1) were associated with younger age at Fontan. Subjects with technology-dependence (+4.6 months, 95%CI 3.1-6.1) were older at Fontan. Black (+4.1 months, 95%CI 2.5-5.7) and Asian (+8.3 months, 95%CI 5.4-11.2) race were associated with older age at Fontan. There was significant variation in Fontan timing between centers. Center accounted for 10% of variation (ICC 0.10, 95%CI 0.07-0.14). Center surgical volume was not associated with Fontan timing (P = .21). Operation year was associated with age at Fontan, with a 3.1 month increase in age for every 5 years (+0.61 months, 95%CI 0.48-0.75).

CONCLUSIONS

After adjusting for patient-level characteristics there remains significant inter-center variation in Fontan timing. Age at Fontan has increased. Future studies addressing optimal Fontan timing are warranted.

Single-cell multiomics guided mechanistic understanding of Fontan-associated liver disease

The Fontan operation is the current standard of care for single-ventricle congenital heart disease. Individuals with a Fontan circulation (FC) exhibit central venous hypertension and face life-threatening complications of hepatic fibrosis, known as Fontan-associated liver disease (FALD). The fundamental biology and mechanisms of FALD are little understood. Here, we generated a transcriptomic and epigenomic atlas of human FALD at single-cell resolution using multiomic snRNA-ATAC-seq. We found profound cell type-specific transcriptomic and epigenomic changes in FC livers. Central hepatocytes (cHep) exhibited the most substantial changes, featuring profound metabolic reprogramming. These cHep changes preceded substantial activation of hepatic stellate cells and liver fibrosis, suggesting cHep as a potential first "responder" in the pathogenesis of FALD. We also identified a network of ligand-receptor pairs that transmit signals from cHep to hepatic stellate cells, which may promote their activation and liver fibrosis. We further experimentally demonstrated that activins A and B promote fibrotic activation in vitro and identified mechanisms of activin A's transcriptional activation in FALD. Together, our single-cell transcriptomic and epigenomic atlas revealed mechanistic insights into the pathogenesis of FALD and may aid identification of potential therapeutic targets.

Living to Tell the Tale: A First-Person Chronicle of the Development of the Fontan-Kreutzer Procedure

The current surgical approach for patients with a single ventricle is the culmination of decades of dedicated research and groundbreaking innovation. From 1971 to the present day, a series of incremental advancements have significantly extended the life expectancy of these patients. Since the very beginning, Dr Guillermo Kreutzer and his team have pioneered different techniques with the ultimate goal of improving outcomes for these individuals. This is, narrated by him, the story of how it all began.

Central Venous Waveform Patterns in the Fontan Circulation Independently Contribute to the Prediction of Composite Survival

It is well appreciated that the Fontan circulation perturbs central venous hemodynamics, with elevated pressure being the clearest change associated with Fontan comorbidities, such as Fontan-associated liver disease (FALD) and protein-losing enteropathy (PLE). Our group has better quantity of these venous perturbations through single- and multi-location analyses of flow waveforms obtained from magnetic resonance imaging of Fontan patients. Here, we determine if such analyses, which yield principal components (PC) that describe flow features, are associated with Fontan survival. Patients with a Fontan circulation (N = 140) that underwent free-breathing and mechanically ventilated cardiac MRI were included in this study. Standard volumetric and functional hemodynamics, as well as flow analysis principal components, were subjected to univariate and bivariate Cox regression analyses to determine composite clinical outcome, including plastic bronchitis, PLE, and referral and receipt of transplant. Unsurprisingly, ventricular function measures of ejection fraction (EF; HR = 0.88, p < 0.0001), indexed end-systolic volume (ESVi; HR 1.02, p < 0.0001), and indexed end-diastolic volume (EDVi; HR = 1.02, p = 0.0007) were found as specific predictors of clinical events, with specificities uniformly > 0.75. Additionally a feature of IVC flow (PC2) indicating increased flow in systole was found as a highly sensitive predictor (HR = 0.851, p = 0.027, sensitivity 0.93). In bivariate prediction, combinations of ventricular function (EF, ESVi, EDVi) with this IVC flow feature yielded best overall prediction of composite outcome. This suggests that central venous waveform analysis relays additional information about Fontan patient survival and that coupling sensitive and specific measures in bivariate analysis is a useful approach for obtaining superior prediction of survival.

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.

Pediatric Patients Undergoing a Fontan Operation or with a High RACHS-1 Score Require Monitoring for Chronic Kidney Disease in Early Childhood

Although the number of pediatric patients with long-term survival following cardiac surgery is increasing, concerns regarding chronic kidney disease (CKD) after surgery are growing. We examined the frequency of and risk factors for pediatric CKD development in patients with congenital heart disease (CHD) at least 2 years after cardiac surgery. This was a cross-sectional study of 147 patients who underwent open-heart surgery for CHD at Kagoshima University Hospital from April 2010 to March 2017. Data on demographics, acute kidney injury after cardiac surgery, cyanotic heart disease, Fontan circulation, medications in the perioperative period, and Risk Adjustment for Congenital Heart Surgery-1 (RACHS-1) category were recorded. CKD was defined using the current classification system described in the National Kidney Foundation's Kidney Disease Outcomes Quality Initiative and assessed during early childhood within 2-3 years of cardiac surgery. Statistical analyses were performed using SPSS Statistics for Windows version 25.0. We consecutively enrolled 147 patients, of whom 22 (15.0%) had CKD, all with stage-2 severity. Among patients with CKD, a higher proportion underwent Fontan surgery (P < 0.001), a higher proportion had cyanotic heart disease (P = 0.009), and the RACHS-1 category was high (P = 0.003). Patients with CKD appeared more frequently than patients without CKD in RACHS-1 categories 3, 5, and 6. It is essential to evaluate renal function longitudinally and monitor for CKD, given that patients who underwent Fontan surgery or complicated surgery in infancy have a high rate of developing postoperative CKD in early childhood.

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.

Living-Related Donor Kidney Transplant in a Patient With Single Ventricle and Fontan Circulation

The hemodynamic profile of the Fontan circulation presents challenges that raise questions about candidacy for organ transplantation. We report a case of a 24-year-old male with double-inlet right ventricle and aortic atresia, who suffered bilateral renal cortical necrosis due to neonatal cardiovascular shock, received a live-donor kidney transplant from his mother at age 17, and has diminished yet stable renal function seven years posttransplant.

Associated Factors of Liver Disease After Fontan Operation in Relation to Ultrasound Liver Elastography

Although the Fontan operation can improve outcomes, surviving patients still face Fontan-associated liver disease (FALD). The aim of this study was to determine the associated factors of FALD in relation to ultrasound liver elastography. A cross-sectional study was conducted for all patients on whom an ultrasound upper-abdomen and ultrasound liver elastography was performed at more than 1 year after the Fontan operation. The data consisted of the age at operation, type of Fontan operation, and laboratory data such as gamma-glutamyl transferase (GGT), aspartate aminotransferase-to-platelet ratio index (APRI), and fibrosis-4 (FIB-4) score. Cardiovascular evaluations included echocardiography and cardiac catheterization. Eighty patients with a median age of 12 years (range 5-36 years) were eligible for the study. The prevalence of FALD was 41%. For the purpose of univariate logistic regression analysis, the age at the Fontan operation, time elapsed since the Fontan operation, previous Glenn shunt, presence of fenestration, mean pulmonary artery pressure and IVC pressure post-Fontan operation, platelet count, GGT, and FIB-4 score were considered to be factors significantly associated with FALD. Following an adjustment by multivariate logistic regression analysis, age greater than 7 years at the time of Fontan procedure, time elapsed of more than 9 years since the procedure, and GGT level > 130 U/L were found to be significantly associated with FALD. Patients with these factors should be investigated for FALD.

Survival and predictors of mortality in patients after the Fontan operation

BACKGROUND

As a result of the surgical techniques now being employed, the survival rate in patients after undergoing the Fontan operation has improved. The aims of this study were focused on determining the survival rate and predictors of early mortality.

METHODS

In a retrospective cohort study, 117 consecutive patients who underwent the Fontan operation were recruited. Multivariate Cox proportional regression analysis was used to assess the predictors of early mortality, defined as death within 30 days after the Fontan operation.

RESULTS

The median follow-up time was 6.1 years. The median age at the time of the Fontan operation was 5.7 years. Survival rates in the patients at 5, 10, and 15 years postoperatively were 92%, 87% and 84%, respectively. Using univariate Cox regression analysis, the predictors of early mortality were found to be postoperative mean pulmonary artery pressure ≥23 mm Hg (hazard ratio 26.0), renal failure (hazard ratio 9.5), heterotaxy syndrome (hazard ratio 5.3), and uncorrected moderate or severe atrioventricular valve regurgitation (hazard ratio 9.4). After adjusting for confounding factors using multivariate Cox regression analysis, the predictors of early mortality were found to be postoperative mean pulmonary artery pressure ≥23 mm Hg (hazard ratio 23.2) and uncorrected moderate or severe atrioventricular valve regurgitation (hazard ratio 8.2).

CONCLUSIONS

Uncorrected moderate or severe atrioventricular valve regurgitation and postoperative mean pulmonary artery pressure ≥23 mm Hg are independent predictors of early mortality after the Fontan operation. Patients with these factors should undergo aggressive management to minimize morbidity and mortality.

Fontan-Associated Liver Disease: Spectrum of Disease in Children and Adolescents

Background Information is evolving on liver disease in pediatric patients with Fontan physiology. The purpose of this investigation is to evaluate the spectrum of liver disease in a pediatric population of patients with Fontan physiology and evaluate transient elastography (TE) as a noninvasive marker of liver disease. Methods and Results We prospectively enrolled all children with Fontan physiology. All patients underwent comprehensive liver evaluation including liver enzymes (alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transferase, alkaline phosphatase), aspartate transaminase to platelet ratio index, albumin, bilirubin, international normalized ratio, complete blood cell count, abdominal ultrasound, and TE. Transjugular liver biopsies and hemodynamic measurements were performed in a subset of patients. A total of 76 children (median, 11.7; interquartile range, 8.4-14.8 [56% male]) were evaluated, with 17 having a transjugular liver biopsy (median 14.8 years; interquartile range, 14.3-17.4). All biopsies showed pathological changes. The severity of liver pathology did not correlate with TE. There was a positive correlation between TE and time since Fontan (R=0.42, P<0.01), aspartate transaminase to platelet ratio index (R=0.29, P=0.02), aspartate transaminase (R=-0.42, P<0.01), and platelets (R=-0.42, P<0.01). Splenomegaly on abdominal ultrasound was correlated with TE (z=-2.2, P=0.03), low platelet count (z=1.9, P=0.05), low aspartate transaminase (z=1.9, P=0.02), and low alkaline phosphatase (z=2.4, P=0.02). Conclusions Liver disease was ubiquitous in our cohort of pediatric patients with Fontan Physiology. Given the correlation between TE and time from Fontan, TE shows potential as a prospective marker of liver pathology. However, individual measurements with TE do not correlate with the severity of pathology. Given the prevalence of liver disease in this population, protective measures of liver health as well as routine liver health surveillance should be implemented with consideration for hepatology consultation and biopsy in the event of abnormal liver biochemical markers or imaging.

Review on Mechanical Support and Cell-Based Therapies for the Prevention and Recovery of the Failed Fontan-Kreutzer Circulation

Though the current staged surgical strategy for palliation of single ventricle heart disease, culminating in a Fontan circulation, has increased short-term survival, mounting evidence has shown that the single ventricle, especially a morphologic right ventricle (RV), is inadequate for long-term circulatory support. In addition to high rates of ventricular failure, high central venous pressures (CVP) lead to liver fibrosis or cirrhosis, lymphatic dysfunction, kidney failure, and other comorbidities. In this review, we discuss the complications seen with Fontan physiology, including causes of ventricular and multi-organ failure. We then evaluate the clinical use, results, and limitations of long-term mechanical assist devices intended to reduce RV work and high CVP, as well as biological therapies for failed Fontan circulations. Finally, we discuss experimental tissue engineering solutions designed to prevent Fontan circulation failure and evaluate knowledge gaps and needed technology development to realize a more robust single ventricle therapy.

Imaging of complications following Fontan circulation in children - diagnosis and surveillance

The Fontan operation is performed for various cardiac lesions with single-ventricle physiology. The survival rate of Fontan patients is increasing for adolescents and young adults, with an expected 30-year survival of >80%. Medical health care providers including specialists in organ systems and pediatric radiologists need to improve their knowledge about the Fontan circulation and the various organ complications to monitor care. In this review the author explains the basic anatomical and functional features of Fontan palliation and gives an overview of the multiple long-term organ complications that might present in the pediatric population. These include decreased physical capacity, ventricular dysfunction, atrioventricular valve regurgitation and arrhythmia, as well as protein-losing enteropathy, plastic bronchitis, growth/bone composition disturbances, renal dysfunction, and the recently recognized and important liver fibrosis (Fontan-associated liver disease). Neuropsychological and behavioral deficits occur frequently. This review focuses on the key role of radiology in making the diagnosis of these complications, monitoring therapy and predicting outcomes in the pediatric age group. The author discusses how and when radiology is important in Fontan patients, as well as how new techniques enabling quantitative measures in imaging with US, MRI and CT are adapted for pediatric use, and how they contribute to urgently needed surveillance strategies.

Surveillance and screening practices of New England congenital cardiologists for patients after the Fontan operation

INTRODUCTION

Surveillance and management guidelines for Fontan patients are lacking due to the paucity of evidence in the literature of screening efficacy on outcome measures.

METHODS

The Fontan Working Group within the New England Congenital Cardiology Association designed an electronic survey to assess surveillance practices for patients with Fontan procedures among New England congenital cardiologists and to explore variability in screening low-risk vs high-risk Fontan patients across regional programs.

RESULTS

Fifty-six cardiologists representing 12 regional programs responded to the survey, comprising ~40% of the total New England congenital cardiac physicians. The majority of desired testing and consultation was available within 50 miles of the patient's home institution with some limitations of cardiac catheterization and cardiac magnetic resonance imaging availability. Surveillance and screening were less frequent in low-risk Fontan patients compared to high-risk Fontan patients. Counseling practices were similar for both low-risk and high-risk Fontan patients. Aspirin monotherapy was recommended by 82% of providers for low-risk Fontan patients, while anticoagulation regimens were more varied for the high-risk population. Practitioners with ≤15 years of experience were more likely to provide quality of life testing in both low-risk and high-risk Fontan patients. There were no other major differences in testing frequencies by years of practice, quaternary vs nonquaternary care facility, or the number of Fontan patients in a practice.

CONCLUSION

This survey provides insight into regional practices of screening and surveillance of Fontan patients. These data may be used to design future research studies and evidence-based guidelines to streamline the approach to manage these complex patients.

Cavopulmonary assist: Long-term reversal of the Fontan paradox

OBJECTIVE

Fontan circulatory inefficiency can be addressed by replacing the missing subpulmonary power source to reverse the Fontan paradox. An implantable cavopulmonary assist device is described that will simultaneously reduce systemic venous pressure and increase pulmonary arterial pressure, improving preload and cardiac output, in a univentricular Fontan circulation on a long-term basis.

METHODS

A rotary blood pump that was based on the von Karman viscous pump was designed for implantation into the total cavopulmonary connection (TCPC). It will impart modest pressure energy to augment Fontan flow without risk of obstruction. In the event of rotational failure, it is designed to default to a passive flow diverter. Pressure-flow performance was characterized in vitro in a Fontan mock circulatory loop with blood analog.

RESULTS

The pump performed through the fully specified operating range, augmenting flow in all 4 directions of the TCPC. Pressure rise of 6 to 8 mm Hg was readily achieved, ranging to 14 mm Hg at highest speed (5600 rpm). Performance was consistent across a wide range of cardiac outputs. In stalled condition (0 rpm), there was no discernible pressure loss across the TCPC.

CONCLUSIONS

A blood pump technology is described that can reverse the Fontan paradox and may permit a surgical strategy of long-term biventricular maintenance of a univentricular Fontan circulation. The technology is intended for Fontan failure in which right-sided circulatory inefficiencies predominate and ventricular systolic function is preserved. It may also apply before clinical Fontan failure as health maintenance to preempt the progression of Fontan disease.

Increased extracellular volume in the liver of pediatric Fontan patients

BACKGROUND

Patients with single ventricle physiology are at increased risk for developing liver fibrosis. Its extent and prevalence in children with bidirectional cavopulmonary connection (BCPC) and Fontan circulation are unclear. Extracellular volume fraction (ECV), derived from cardiovascular magnetic resonance (CMR) and T1 relaxometry, reflect fibrotic remodeling and/or congestion in the liver. The aim of this study was to investigate whether pediatric patients with single ventricle physiology experience increased native T1 and ECV as markers of liver fibrosis/congestion.

METHODS

Hepatic native T1 times and ECV, using a cardiac short axis modified Look-Locker inversion recovery sequence displaying the liver, were measured retrospectively in children with BCPC- and Fontan circulations and compared to pediatric controls.

RESULTS

Hepatic native T1 time were increased in Fontan patients (n = 62, 11.4 ± 4.4 years, T1 762 ± 64 ms) versus BCPC patients (n = 20, 2.8 ± 0.9 years, T1 645 ± 43 ms, p = 0.04). Both cohorts had higher T1 than controls (n = 44, 13.7 ± 2.9 years, T1 604 ± 54 ms, p < 0.001 for both). ECV was 41.4 ± 4.8% in Fontan and 36.4 ± 4.8% in BCPC patients, respectively (p = 0.02). In Fontan patients, T1 values correlated with exposure to cardiopulmonary bypass time (R = 0.3, p = 0.02), systolic and end diastolic volumes (R = 0.3, p = 0.04 for both) and inversely with oxygen saturations and body surface area (R = -0.3, p = 0.04 for both). There were no demonstrable associations of T1 or ECV with central venous pressure or age after Fontan.

CONCLUSION

Fontan and BCPC patients have elevated CMR markers suggestive of hepatic fibrosis and/or congestion, even at a young age. The tissue changes do not appear to be related to central venous pressures.

TRIAL REGISTRATION

Retrospectively registered data.

Initiating a Fontan multidisciplinary clinic: Decreasing care variability, improving surveillance, and subsequent treatment of Fontan survivors

BACKGROUND

Children with single ventricle (SV) heart disease who undergo Fontan operation are at risk for developing multiorgan dysfunction. Although survival has improved, significant comorbidities involving multiple organ systems may develop, requiring evaluation and management by many subspecialists. Using data from an internal survey, we documented high care variability for our Fontan population. We then developed a multidisciplinary clinic, designed and implemented a clinical care pathway to decrease variability of patient assessment.

METHODS

After creating a multidisciplinary team and a clinical care pathway, we initiated a multidisciplinary clinic (MDC) where patients could see multiple subspecialists during a single encounter. We then monitored our effectiveness by retrospective chart review to determine care pathway adherence (process measure) and incidence of new diagnoses of end-organ injury (outcome measure) as well interventions implemented. Adherence was analyzed using statistical process control (SPC) charts.

RESULTS

Eighty-six patients were seen in the MDC from January 2016 to September 2017. The proportion of patients with appropriate testing increased, related to strong care pathway adherence. A significant amount of novel pathology was diagnosed in all evaluated organ systems, both Fontan-associated comorbidities and general pediatric diagnoses. Subsequent interventions included cardiac catheterization n = 21 (31%) with more than half of these patients undergoing intervention n = 17 (20%), and liver biopsy n = 9 (10%). Additionally, 58 patients (67%) were referred to a neuropsychologist based on perceived clinical need, with n = 34 (40%) undergoing a neuropsychological evaluation.

CONCLUSIONS

Children who have undergone Fontan palliation are at risk for developing cardiac and noncardiac comorbidities. Use and adherence to an institutional care pathway resulted in the diagnosis of significant novel pathology and subsequently provided opportunity for intervention.

Hypoplastic left heart syndrome: from fetus to fontan

The care of children with hypoplastic left heart syndrome is constantly evolving. Prenatal diagnosis of hypoplastic left heart syndrome will aid in counselling of parents, and selected fetuses may be candidates for in utero intervention. Following birth, palliation can be undertaken through staged operations: Norwood (or hybrid) in the 1st week of life, superior cavopulmonary connection at 4-6 months of life, and finally total cavopulmonary connection (Fontan) at 2-4 years of age. Children with hypoplastic left heart syndrome are at risk of circulatory failure their entire life, and selected patients may undergo heart transplantation. In this review article, we summarise recent advances in the critical care management of patients with hypoplastic left heart syndrome as were discussed in a focused session at the 12th International Conference of the Paediatric Cardiac Intensive Care Society held on 9 December, 2016, in Miami Beach, Florida.

A Retrospective Evaluation of Echocardiograms to Establish Normative Inferior Vena Cava and Aortic Measurements for Children Younger Than 6 Years

OBJECTIVES

The ability to plot the inferior vena cava (IVC) size on a normal curve for pediatric patients may prove beneficial. First, in patients with normal cardiac anatomy who present in shock, assessing IVC size may be valuable for evaluating the degree of dehydration. Second, in children with heart disease, understanding how a child's IVC size compares to normal could be particularly beneficial for patients with right heart disease. We sought to create normal curves for the IVC and aorta in children younger than 6 years.

METHODS

Data were gathered from 347 echocardiograms of healthy children younger than 6 years in a retrospective study at a quaternary care children's hospital. From the subcostal long- and short-axis images, maximum diameters in the transverse and longitudinal views were obtained for both the IVC and the aorta.

RESULTS

Both IVC and aortic dimensions increased in a linear fashion and had excellent correlations with the body surface area, body mass, and height (IVC, r = 0.78-0.81; P < .0001; aorta, r = 0.82-0.86; P < .0001).

CONCLUSIONS

In children younger than 6 years, the IVC and aorta increase linearly as the children grow. Such normal curves will be beneficial for assessing a pediatric patient's hydration status or right heart function in patients with congenital heart disease.

Abdominal imaging findings in adult patients with Fontan circulation

Abstract

The Fontan procedures, designed to treat paediatric patients with functional single ventricles, have markedly improved the patient’s survival into adulthood. The physiology of the Fontan circuit inevitably increases systemic venous pressure, which may lead to multi-system organ failure in the long-term follow-up. Fontan-associated liver disease (FALD) can progress to liver cirrhosis with signs of portal hypertension. Focal nodular hyperplasia-like nodules commonly develop in FALD. Imaging surveillance is often performed to monitor the progression of FALD and to detect hepatocellular carcinoma, which infrequently develops in FALD. Other abdominal abnormalities in post-Fontan patients include protein losing enteropathy and pheochromocytoma/paraganglioma. Given that these abdominal abnormalities are critical for patient management, it is important for radiologists to become familiar with the abdominal abnormalities that are common in post-Fontan patients on cross-sectional imaging.

Teaching points

• Fontan procedure for functional single ventricle has improved patient survival into adulthood.

• Radiologists should be familiar with unique imaging findings of Fontan-associated liver disease.

• Focal nodular hyperplasia-like nodules commonly develop in Fontan-associated liver disease.

• Hepatocellular carcinoma, protein-losing enteropathy, pheochromocytoma/paraganglioma may develop.

Electronic supplementary material

The online version of this article (10.1007/s13244-018-0609-2) contains supplementary material, which is available to authorized users.

Transplantation in the single ventricle population

The single ventricle patient population comprises the most complex cohort presenting to the cardiac transplant team, in terms of demographics, anatomic substrate, and unique physiology. It is also the most rapidly growing diagnostic group presenting for heart transplantation. In this manuscript, we aim to describe the changing landscape of transplantation in single ventricle conditions through reflection on our own institution's practice and experience, alongside contemporary literature review. Single ventricle patients are heterogeneous in terms of age, anatomic diagnosis and physiology according to surgical stage of repair. Progress in surgical palliative strategies has impacted upon the present composition of the population, with growing numbers of hypoplastic left heart syndrome patients and those with late physiology failure following Fontan completion. Multiple prior surgeries, immunological sensitivity and multi-organ involvement impart high peri-operative risk but can be mitigated in part by careful pre-operative planning by a dedicated multi-disciplinary team addressing issues such as planning of concurrent reconstructive surgery, minimizing the post-operative effect of collaterals, timely harvesting, oversizing of donor organs to minimize graft failure, and strategies to address anticipated post-operative elevation in pulmonary vascular resistance. Determining optimal timing for transplant in these patients remains unclear, but understanding the risk of alternative surgical options can help guide decision making with regards to listing.

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.

Mechanical Circulatory Support of the Fontan Patient

Because of the inadequacies inherent to a circulation supported by a single ventricle, many Fontan patients will experience failure of their circulation. To date, there is no medical regimen that reliably and consistently restores circulatory function in these patients. Because of the shortage of donor organs and the fact that many of these patients present with features that either preclude or render heart transplantation a high risk, there is an intense need to better understand how mechanical circulatory support (MCS) may benefit these patients. In this report, we share our experience of successful MCS and transplantation of three patients. Our experience and that of others is very encouraging, but also preliminary. In general, a systemic ventricular assist device, with or without a Fontan fenestration, is a reasonable consideration for a patient presenting with predominantly systolic dysfunction. A pulmonary/systemic venous assist device may be sufficient for the patient with preserved systolic function and failure of the systemic venous/lymphatic system; however, this remains speculative. The more comprehensive approach of a total artificial heart or bilateral support is attractive in theory, but beset by the need for a more complex operation. In all scenarios, early referral, before organ failure, is paramount to successful MCS.

Prevalence of non-cardiovascular findings on CT angiography in children with congenital heart disease

BACKGROUND

CT angiography is gaining broader acceptance in the evaluation of children with known or suspected congenital heart disease. These studies include non-cardiovascular structures such as the mediastinum, lung parenchyma and upper abdominal organs. It is important to inspect all these structures for potential abnormalities that might be clinically important and, in some cases, may impact care plans.

OBJECTIVE

To determine the prevalence of non-cardiovascular findings in CT angiography of children with congenital heart disease.

MATERIALS AND METHODS

During 28 months, 300 consecutive children (170 males; mean age: 7.1 years, age range: 6 h-26 years), referred from a tertiary pediatric cardiology center, underwent clinically indicated CT angiography to evaluate known or suspected congenital heart disease. Slightly more than half (n = 169) of the patients were postoperative or post-intervention. Examinations were retrospectively reviewed, and non-cardiovascular findings were recorded and tabulated by organ system, congenital heart disease and operative procedure in conjunction with outcomes from medical charts.

RESULTS

Non-cardiovascular findings were identified in 83% (n = 250 / 300) of the studies for a total of 857 findings. In 221 patients (n = 73.7% of 300) a total of 813 non-cardiovascular findings were clinically significant, while in 9.7% (n = 29 / 300) of patients, 5.1% (n = 44 / 857) of the findings were nonsignificant. In 38.3% (n = 115 / 300) of patients with significant non-cardiovascular pathology, the findings were unexpected and directly impacted patient care plans. Commonly involved organs with non-cardiovascular findings were the lungs with 280 non-cardiovascular findings in 176 / 300 (58.7%) of patients, the airway with 139 non-cardiovascular findings in 103 / 300 (34.3%) of patients and the liver with 108 non-cardiovascular findings in 72 / 300 (24.0%) of patients. Syndromic associations were noted in 22% (n = 66 / 300) of the patients.

CONCLUSION

Non-cardiovascular findings are common in children with congenital heart disease who undergo CT angiography. Based upon our study population, if a child with congenital heart disease has a CT angiography, five out of six will have non-cardiovascular findings, while nearly three out of four (73.7%; 221 / 300) will have significant non-cardiovascular findings. Close attention to the non-cardiovascular structures in children with congenital heart disease presenting for a CT angiography is recommended as in nearly 40% of these children, findings were unexpected and directly altered patient care.

Towards a Tissue-Engineered Contractile Fontan-Conduit: The Fate of Cardiac Myocytes in the Subpulmonary Circulation

The long-term outcome of patients with single ventricles improved over time, but remains poor compared to other congenital heart lesions with biventricular circulation. Main cause for this unfavourable outcome is the unphysiological hemodynamic of the Fontan circulation, such as subnormal systemic cardiac output and increased systemic-venous pressure. To overcome this limitation, we are developing the concept of a contractile extracardiac Fontan-tunnel. In this study, we evaluated the survival and structural development of a tissue-engineered conduit under in vivo conditions. Engineered heart tissue was generated from ventricular heart cells of neonatal Wistar rats, fibrinogen and thrombin. Engineered heart tissues started beating around day 8 in vitro and remained contractile in vivo throughout the experiment. After culture for 14 days constructs were implanted around the right superior vena cava of Wistar rats (n = 12). Animals were euthanized after 7, 14, 28 and 56 days postoperatively. Hematoxylin and eosin staining showed cardiomyocytes arranged in thick bundles within the engineered heart tissue-conduit. Immunostaining of sarcomeric actin, alpha-actin and connexin 43 revealed a well -developed cardiac myocyte structure. Magnetic resonance imaging (d14, n = 3) revealed no constriction or stenosis of the superior vena cava by the constructs. Engineered heart tissues survive and contract for extended periods after implantation around the superior vena cava of rats. Generation of larger constructs is warranted to evaluate functional benefits of a contractile Fontan-conduit.

Effect of Tadalafil on Myocardial and Endothelial Function and Exercise Performance After Modified Fontan Operation

Better postoperative management of patients who have undergone single ventricle (SV) Fontan procedure could potentially reduce long-term complications and improve the quality of life for patients. The present study determined the effect of tadalafil on myocardial and endothelial function and exercise performance after modified Fontan operation. Patients who had undergone SV modified Fontan operation were enrolled in this clinical trial. The demographic characteristics of the patients were recorded. Before administration of tadalafil and after the trial, ventricular function (MPI, EF, FS, E/A, VTI), exercise performance, and endothelial function were evaluated for sonographic and biochemical markers (FMD, IMT, ICAM, VCAM, NO) using echocardiography, exercise testing, vascular ultrasonography, and biochemical measurements, respectively. A single dose of tadalafil of 1 mg/kg was administered daily for 6 weeks, and the functional class of the patients before and after tadalafil was determined. A total of 15 patients completed this clinical trial. Tadalafil was shown to have a significant effect on myocardial function, exercise performance, and improvement in NYHA functional class (p < 0.05) of study population. It had no significant effect on the biochemical variables and endothelial function except for IMT (p > 0.05), which decreased significantly after tadalafil administration (p < 0.05). The findings indicate that tadalafil is a safe, well-tolerated agent for the use after modified Fontan operation to improve myocardial function and exercise performance and possibly reduce long-term morbidity and mortality of patients. More conclusive results could be obtained from further study with a larger sample size and long-term follow-up.

Decision-Making for Surgery in the Management of Patients with Univentricular Heart

A series of technical refinements over the past 30 years, in combination with advances in perioperative management, have resulted in dramatic improvements in the survival of patients with univentricular heart. While the goal of single-ventricle palliation remains unchanged - normalization of the pressure and volume loads on the systemic ventricle, the strategies to achieve that goal have become more diverse. Optimal palliation relies on a thorough understanding of the changing physiology over the first years of life and the risks and consequences of each palliative strategy. This review describes how to optimize surgical decision-making in univentricular patients based on a current understanding of anatomy, physiology, and surgical palliation.

[Update on pediatric cardiology and congenital heart disease: imaging techniques, pulmonary arterial hypertension, hybrid treatment, and surgical treatment]

This article contains a review of the most significant contributions to pediatric cardiology and congenital heart disease reported in publications between September 2009 and August 2010. The review focuses on imaging techniques, new treatment for pulmonary arterial hypertension in pediatric patients, and therapy in general (e.g. hybrid treatment and surgical treatment). With regard to imaging techniques, the review highlights the increasing application of congenital heart disease diagnosis during fetal life, the introduction of new echocardiographic techniques (e.g. tissue Doppler imaging, two-dimensional speckle-tracking imaging and three-dimensional echocardiography) into routine clinical practice, and the growing use of cardiac CT and magnetic resonance imaging in diagnosis and the assessment of cardiac function, respectively. The role played by cardiac interventions continues to increase and cardiac surgery is becoming more advanced and has, in some cases, been combined with hybrid techniques. However, there are still a number of controversial issues in cardiac surgery that have not yet been resolved, such as whether or not fenestration should be used with Fontan surgery, the optimum type of correction for hypoplastic left heart syndrome, and the best conduit for pulmonary artery replacement.

Risk factors for major adverse events late after Fontan palliation

OBJECTIVE

Risk factors for major adverse events late after Fontan palliation are unknown. Prior studies have suggested ventricular function and morphology as important risk factors. The aim of this study is to (1) characterize the late major adverse event profile in adult Fontan patients and (2) identify additional risk factors that may contribute to adverse outcomes.

DESIGN AND SETTING

A retrospective review of all adult patients >15 years post-Fontan seen at a tertiary academic center was conducted. Clinical, laboratory, cardiac data, and abdominal imaging were collected via chart review. Major adverse events (death, cardiac transplantation, or listing) were identified, and timing of events was plotted using Kaplan-Meier methods. Univariate and multivariate logistic regression was used to determine independent predictors of late-term events.

RESULTS

A total of 123 adult Fontan patients were identified (mean time post-Fontan 22.4 years [±4.4]). Major adverse events occurred in 19/123 patients (15%). In this 15-year survivor cohort, transplant-free survival rates were 94.6%, 82.9%, and 59.8% at 20, 25, and 30 years postoperation, respectively. Modes of death were Fontan failure with preserved function (4), congestive heart failure with decreased function (2), sudden death (2), thromboembolic event (1), post-Fontan conversion (2), and posttransplant (2). No differences in adverse outcomes were found based on morphology of the systemic ventricle, Fontan type, or systolic ventricular function. On the other hand, features of portal hypertension (OR 19.0, CI 4.7-77.3, P < .0001), presence of a pacemaker (OR 13.4, CI 2.6-69.8, P = .002), and systemic oxygen desaturation (OR 0.86, CI 0.75-0.98, P = .02) were risk factors for major adverse events in the multivariate analysis.

CONCLUSIONS

In adult Fontan patients surviving >15 years post-Fontan, portal hypertension, oxygen desaturation, and need for pacemaker were predictive of adverse events. Traditional measures may not predict late-term outcomes in adult survivors; further study of the liver's role in late outcomes is warranted.

MR assessment of abdominal circulation in Fontan physiology

The Fontan operation allows for longer survival of those born with functionally single ventricle physiology. Although it effectively eliminates cyanosis, increased systemic venous pressure is an unavoidable consequence and low cardiac output is frequent. The abdomen is particularly vulnerable to these alterations in hemodynamics because the hepatic blood flow consists predominantly of portal venous flow, which relies on a low pressure gradient between the portal and hepatic veins. Therefore, any subtle increase in systemic venous pressure will adversely affect the hemodynamic balance of the liver as well as the intestine. As the clinical manifestations and routine laboratory findings of abdominal complications can lag behind the hemodynamic and pathologic changes in the abdominal organs, regular imaging surveillance is critical. Magnetic resonance (MR) provides excellent visualization of both cardiovascular and abdominal systems. It provides robust anatomic and hemodynamic data which can be used for timely implementation of treatment options. In this review paper, we discuss the pathogenesis and MR findings of abdominal complications following the Fontan operation. Specifically we explore the utility of phase-contrast MR for assessment of the abdominal circulation in children following the Fontan palliation.

Beyond a broken heart: circulatory dysfunction in the failing Fontan

The role of ventricular dysfunction in late morbidity and mortality of univentricular hearts has been described previously. However, a significant proportion of adult Fontan patients who die or require heart transplantation do so with preserved ventricular function. The clinical deterioration in patients who have undergone Fontan palliation requires a broader view of circulatory dysfunction, one that takes into account the complex interaction of regulatory systems affecting hepatic, renal, and pulmonary blood flow, in addition to cardiac function. This review focuses primarily on the pathophysiology of multiple organ involvement in this circulatory dysfunction, with particular focus on the consequences of hepatic dysfunction and portal hypertension. The authors discuss hepatic perfusion, both in health and disease, and review the current understanding of liver histopathology and liver disease in adult Fontan patients and similar clinicopathologic states. They compare and contrast features of postsinusoidal portal hypertension with more typical adult cirrhotic disease. Finally, they delineate the related effects of portal hypertensive physiology on the systemic and pulmonary vasculature, the kidney, and the heart itself and discuss how these changes affect the care of the adult Fontan patient.

Hemodynamic phenotype of the failing Fontan in an adult population

Fontan failure can occur even with normal systolic ventricular function and often in the context of significant liver disease. We hypothesized that Fontan failure is hemodynamically distinct from traditional heart failure and characterized by low systemic vascular resistance (SVR) index and preserved cardiac index. Twenty-seven symptomatic adult Fontan (SAF) patients who underwent catheterization from 2001 to 2011 constituted our study group. Fifty-four predominantly asymptomatic pediatric Fontan (PF) patients who underwent catheterization during the same period were randomly selected to perform a control:case cohort analysis. Clinical comparisons were made between the 2 groups. The adults were more symptomatic than the PF cohort (New York Heart Association classes I and II or III and IV: 48% or 52% [SAF] vs 94% or 6% [PF], respectively, p <0.01). SAF versus PF mean catheterization findings were central venous pressure 18 ± 6 versus 14 ± 3 mm Hg (p <0.01), SVR index 1,680 ± 368 versus 1,960 ± 550 dyn s/cm(5)/m(2) (p = 0.02), and cardiac index 2.7 ± 0.8 versus 2.8 ± 0.7 L/min/m(2) (p = 0.25). By imaging, the SAF cohort demonstrated a greater incidence of abnormal liver texture changes (96% vs 75%, p = 0.04) and nodularity (77% vs 42%, p = 0.02). In conclusion, adult patients with failing Fontan circulation had a lower SVR index and similar cardiac index compared with the pediatric cohort. Liver disease in the adults was more advanced. Our data suggest that Fontan failure is a distinct circulatory derangement with hemodynamic features similar to portal hypertension, albeit with limited ability to augment cardiac output.

End-organ consequences of the Fontan operation: liver fibrosis, protein-losing enteropathy and plastic bronchitis

The Fontan operation, although part of a life-saving surgical strategy, manifests a variety of end-organ complications and unique morbidities that are being recognised with increasing frequency as patients survive into their second and third decades of life and beyond. Liver fibrosis, protein-losing enteropathy and plastic bronchitis are consequences of a complex physiology involving circulatory insufficiency, inflammation and lymphatic derangement. These conditions are manifest in a chronic, indolent state. Management strategies are emerging, which shed some light on the origins of these complications. A better characterisation of the end-organ consequences of the Fontan circulation is necessary, which can then allow for development of specific methods for treatment. Ideally, the goal is to establish systematic strategies that might reduce or eliminate the development of these potentially life-threatening challenges.

Pediatric heart failure and transplantation: where are we in 2013?

PURPOSE OF REVIEW

To review the recent publications on pediatric heart failure and pediatric transplantation.

RECENT FINDINGS

Little progress has been made in the chronic medical management of pediatric heart failure. Basic science studies demonstrating disparate regulation of β2-adrenergic receptors and microRNA between pediatric and adult heart failure may give clues to the lack of improvement in pediatric outcomes. Pediatric ventricular assist devices have significantly improved survival of bridge-to-transplant, but currently have too many limitations for destination therapy for children. Several areas of pediatric heart transplant have had significant developments over the last few years: the role of antibodies in mediating graft dysfunction after transplantation, ABO-incompatible transplant, extending the pediatric limits on acceptable pulmonary vascular resistance, and risk prediction of pediatric transplant outcomes. Failed single-ventricle palliation is a growing indication for heart transplantation with its own unique challenges.

SUMMARY

Pediatric heart transplantation can have excellent outcomes with survival beyond 20 years after transplant common, especially in the infant. However, the growing population of children and young adults being referred for heart transplantation after failed congenital heart surgery, especially after failed single-ventricle palliation, is presenting new obstacles that may start reducing the survival rates for pediatric heart transplantation. This may in part be ameliorated by earlier referral for transplant evaluation.

Options for the failing ventricle in pediatric heart disease

The management of the pediatric patient with the failing ventricle poses its own therapeutic challenges, not least because patient size limits options available. Once medical management has hit its ceiling, attention is turned to surgical options for mechanical support. The approach to these options has to bear in mind that there may be many potential causes for pump failure, and that these occur often in the context of pulmonary hypertension and poor gas exchange. Although extracorporeal life support has been the mainstay of treatment for acute heart failure, in the last decade, attention has been focusing on longer-term options to bridge to recovery or eventual transplant. Added to this are more novel applications of ventricular assist devices, notable in the management of the failing Fontan circulation where there are no perfect solutions. There is growing interest in the use of such devices to power this delicate circulation and extend the functional capacity of patients without resorting to transplantation. In this review article, we explore the role each of these surgical modalities has to play in the management of the child with acute and chronic heart failure, and explore the recent developments in the rapidly growing field of pediatric ventricular assist.

Features of portal hypertension are associated with major adverse events in Fontan patients: the VAST study

BACKGROUND

Chronic congestive hepatopathy is known to cause hepatic fibrosis and portal hypertension in patients post-Fontan operation for single ventricle palliation. The clinical significance of these findings is not clear. We hypothesized that features of portal hypertension would be significantly related to major adverse events.

METHODS

A retrospective review of 73 adult and pediatric post-Fontan patients referred for a liver evaluation from 2001 to 2011 was performed. The relationship between features of portal hypertension (VAST score ≥2, 1 point each for Varices, Ascites, Splenomegaly or Thrombocytopenia) and a major adverse event (death, need for transplant, or hepatocellular carcinoma) was examined using logistic regression.

RESULTS

73 post-Fontan patients (30% female, 73% Caucasian, 66% systemic left ventricle (SLV), mean age 24±11 years, mean interval from Fontan 17±6 years) were included in analysis. Features of portal hypertension (VAST score ≥2) were present in 26 (36%), and there were 19 major adverse events: death (n=12), transplant (n=6), and HCC (n=1). A significant relationship was found between VAST score ≥2 and major adverse events (OR=9.8, 95% CI [2.9-32.7]). After adjusting for time since Fontan, SLV, age, hemoglobin and type of failure, VAST score ≥2 remained significant (OR=9.1, 95% CI [1.4-57.6]).

CONCLUSION

Fontan patients with features of portal hypertension have a 9-fold increased risk for a major adverse event. Therapies targeted to manage clinical manifestations of portal hypertension, and early referral to heart transplant may help delay major adverse events. Future prospective studies are needed to confirm these findings.

Children with protein-losing enteropathy after the Fontan operation are at risk for abnormal bone mineral density

Protein-losing enteropathy (PLE) is a rare but potentially devastating complication of single-ventricle physiology after the Fontan operation. Although abnormal bone mineral density (BMD) is a known complication of chronic disease and congenital heart disease, no reports have described BMD in patients with PLE. This study investigated a cross-sectional sample of children and young adults with a confirmed diagnosis of PLE. Serum levels of 25(OH)D, calcium, total protein, and albumin were recorded from the first outpatient encounter with each subject. Corrected calcium (cCa) was calculated from the serum calcium and albumin levels. Dual-energy X-ray absorptiometry (DXA) was used to measure BMD, and z-scores were generated using appropriate software. DXA results were available for 12 patients (eight males and four females). The age at DXA ranged from 7.2 to 25.2 years. The mean z-score was -1.73 standard deviation (SD) for the entire cohort, with 42 % z-scores below -2 SDs. Serum 25(OH)D levels were abnormal in 58 % of the patients. There was a positive correlation between cCa and DXA z-score and a negative correlation between total protein and DXA z-score. Patients receiving corticosteroid therapy had a significantly lower DXA z-score than those not receiving corticosteroids (-3.15 vs. -0.31; p = 0.02). Children with PLE are at risk for abnormal BMD compared with age- and sex-matched control subjects. In the study cohort, corticosteroid exposure, a marker of disease severity, appeared to be associated with decreased BMD. Routine bone health screening is warranted for children with PLE, particularly those receiving corticosteroid therapy.

Impact of sildenafil on echocardiographic indices of myocardial performance after the Fontan operation

The objective of this study was describe the impact of sildenafil on echocardiographic measures of myocardial performance in children and young adults with a functional single-ventricle physiology late after Fontan surgery. A double-blind, placebo-controlled, crossover trial was conducted in children and young adults after the Fontan operation at a single pediatric center. Subjects were randomized to receive placebo or sildenafil (20 mg tid) for 6 weeks. After a 6-week washout period, subjects were crossed for an additional 6 weeks. Each subject underwent an echocardiogram at the start and finish of each phase. A total of 27 subjects completed study testing at a mean age of 14.9 years and a mean time from Fontan surgery of 11.3 years. After sildenafil, subjects demonstrated improvement in their myocardial performance index (MPI; -0.051; 95% CI -0.095, -0.0077; p 0.02) and in the product of the velocity time integral (VTI) of the dominant outflow tract and the heart rate (HR; 110 cm × bpm; 95% CI 7.5, 220; p = 0.04). Measures of diastolic performance, including inflow velocities, myocardial velocities, and the ratio of blood pool velocity to myocardial velocity during passive inflow, did not change. In this cohort, there were significant improvements in both the MPI and the product of the VTI × HR after 6 weeks of treatment with sildenafil. These findings suggest that sildenafil may be a useful therapy to improve or maintain ventricular performance in select patients after the Fontan operation.