Single Ventricle Congenital Heart Defects Research Articles

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

BackgroundThe Fontan operation is used to palliate single ventricle congenital heart defects (CHD) but poses significant morbidity and mortality risks. We present the design, planned analyses, and rationale for a long-term Fontan cohort study aiming to examine the association of patient characteristics at the time of Fontan with post-Fontan morbidity and mortality. Methods and ResultsWe used the Pediatric Cardiac Care Consortium (PCCC), a US-based, multicenter registry of pediatric cardiac surgeries to identify patients who underwent the Fontan procedure for single ventricle CHD between 1 and 21 years of age. The primary outcomes are in-hospital Fontan failure (death or takedown) and post-discharge mortality through 2022. A total of 1461 (males 62.1%) patients met eligibility criteria and were included in the analytical cohort. The median age at Fontan evaluation was 3.1 years (IQR: 2.4–4.3). While 95 patients experienced in-hospital Fontan failure (78 deaths and 17 Fontan takedown), 1366 (93.5%) survived to discharge with Fontan physiology and formed the long-term analysis cohort. Over a median follow-up of 21.2 years (IQR: 18.4-24.5) 184 post-discharge deaths occurred. Thirty-year post Fontan survival was 75.0% (95% CI: 72.3%-77.8%) for all Fontan types with higher rates for current techniques such as lateral tunnel and extracardiac conduit 77.1% (95% CI: 73.5-80.8). ConclusionThe PCCC Fontan study aims to identify predictors for post-Fontan morbidity and mortality, enabling risk- stratification and informing surveillance practices. Additionally, the study may guide therapeutic interventions aiming to optimize hemodynamics and enhance Fontan longevity for individual patients.

Impact of an Impaired Maternal-Fetal Environment on Death in Children With Congenital Heart Defects Undergoing Surgery in Denmark From 1994 to 2018.

Studies show that an impaired maternal-fetal environment (iMFE) increases the mortality risk in children with single-ventricle congenital heart defects (CHDs). We investigated the impact of an iMFE on death in children with various surgically corrected CHDs. In this nationwide register-based study, we examined the association between an iMFE (including preeclampsia, gestational hypertension, gestational diabetes, maternal smoking during pregnancy) and death in a large cohort of children with surgically corrected CHDs in Denmark (1994-2018). Survival analysis was done using Cox regression, adjusted for confounding and mediating covariates. The cohort included 3304 children: 1662 (50.3%) with minor CHD and 1642 (49.7%) with major CHD. Among them, 792 (24%) children were exposed to an iMFE. During the study, there were 290 deaths: 71 (9.3%) in children exposed to an iMFE and 219 (8.7%) in those unexposed. There were no differences in mortality risk between children with CHD exposed to an iMFE and those unexposed (hazard ratio [HR], 1.12 [95% CI, 0.86-1.47]; P=0.4). This was consistent across subgroups, including minor CHD (HR, 0.76 [95% CI, 0.39-1.47]; P=0.4), major CHD (HR, 1.23 [95% CI, 0.92-1.64]; P=0.2), and hypoplastic left heart syndrome/univentricular heart (HR, 1.08 [95% CI, 0.64-1.85]; P=0.8). Impairment of the maternal-fetal environment did not impact the mortality rate in children with CHD undergoing operation in Denmark from 1994 to 2018. We believe the cause of these discrepant findings to previous studies may be due to differences in the composition of CHD and prenatal maternal health care and health status of the population.

Cochlear Implantation with Fontan Circulation: A Rare Case of Non-Cardiac Pediatric Surgery

Background: Fontan circulation is a cardiac circulation following the Fontan procedure in patients with a single ventricle congenital heart defect. This circulation depends on the difference in pressure between pulmonary capillaries and central venous pressure to achieve optimal cardiac output. This case report aims to discuss intraoperative anesthesia management in a patient with Fontan circulation undergoing a non-cardiac surgical operation.
 Case presentation: The patient is a 7-year-old male with a history of congenital heart disease who has undergone the Fontan circulation procedure and is now undergoing Cochlear implantation surgery. The patient was managed with general anesthesia - endotracheal intubation and controlled ventilation during the operation, following the principle of minimizing intrathoracic positive pressure, low PEEP, and low tidal volume with a target peripheral saturation > 95%. Cardiac output monitoring during the intraoperative period is done using intra-arterial blood pressure. After 5 hours of surgery, the patient was extubated with stable hemodynamics. 
 Conclusion: The primary goal of intraoperative anesthesia management in patients with Fontan circulation is to maintain an optimal transpulmonary gradient by ensuring optimal transpulmonary blood flow, thus preserving cardiac output.

Lymphatic Abnormalities on Magnetic Resonance Imaging in Single-Ventricle Congenital Heart Defects Before Glenn Operation.

Background In the palliative pathway of single-ventricle physiology, lymphatic abnormalities on T2-weighted magnetic resonance imaging have been shown after the Glenn operation. It is believed that postsurgical hemodynamic changes contribute to the lymphatic changes.However, little is known about how early these abnormalities occur. Our purpose was to determine if lymphatic abnormalities occur as early as before the Glenn operation. Methods and Results We retrospectively reviewed patients with single-ventricle physiology and a T2-weighted magnetic resonance imaging scan before their Glenn operation (superior cavopulmonary connection) at The Children's Hospital of Philadelphia from 2012 to 2022. Lymphatic perfusion patterns on T2-magnetic resonance imaging were categorized from type 1 (no supraclavicular T2-signal) to type 4 (supraclavicular, mediastinal, lung parenchymal T2-signal). Types 1 and 2 were considered normal variants. Distribution of lymphatic abnormalities were tabulated, as well as secondary outcomes including chylothorax and mortality. Comparison was done using analysis of variance, Kruskal-Wallis test, and Fisher's exact test. Seventy-one children were included: 30 with hypoplastic left heart syndrome and 41 with nonhypoplastic left heart syndrome. Lymphatic abnormalities were present before Glenn operation in 21% (type 3) and 20% (type 4), and normal lymphatic perfusion patterns (type1-2) were seen in 59% of patients. Chylothorax was present in 17% (only types 3 and 4). Pre-Glenn mortality and mortality at any time was significantly increased when having a type 4 lymphatic abnormality compared with types 1 and 2 (P=0.04). Conclusions Lymphatic abnormalities can be found on T2-weighted magnetic resonance imaging in children with single-ventricle physiology before their Glenn operation. Mortality and chylothorax were more prevalent with advancing grade of lymphatic abnormality.

Abstract 14039: The Cardioprotective and Anti-Inflammatory Effect of Inhaled Nitric Oxide During Fontan Surgery: A Prospective Randomized Study

Introduction: Open heart surgery that requires cardiopulmonary by-pass (CPB) evokes tremendous stress and inflammatory responses, affecting postoperative organ function, morbidity, and mortality. Although part of this reaction triggers protective and anti-inflammatory phenomena, it is harmful, particularly in patients with single ventricle congenital heart defects during Fontan surgery. Unfortunately, there is no perfect anti-inflammatory and stress defence strategy despite decades of research. Hypothesis: This study aimed to investigate the influence of nitric oxide (NO) inhaled directly into the oxygenator during CPB on a proteome profile of inflammatory cytokines, metabolic response markers, heart and lung protection indicators, and the early clinical outcomes. Methods: The study involved 115 patients randomized to the Fontan-NO group, receiving NO inhalation (n=48) and the Fontan group, not receiving NO (n=49). Eighteen patients were excluded from the study. The clinical data were prospectively analyzed. Proteome profiler essays were used for repeated measurements of investigated analytes. Results: Fontan-NO patients had significantly lower levels of lactate (p=0.04) and glucose (p=0.02), lower pulmonary artery pressure (p=0.03) and catecholamine index (p=0.042), shorter ventilatory support time (p=0.03) and ICU stay (p=0.04). Plasma factors analysis has shown a significantly higher concentration of interleukin-10, tissue inhibitor of metalloproteinase, prolactin, and angiopoietin and a lower concentration of interleukin-6, interleukin-8, interleukin-1β, granulocyte-macrophage colony-stimulating factor, pentraxin, matrix metalloproteinase-8, troponin-I, CK-MB, and insulin in Fontan-NO group. Multiple regression analysis revealed the influence of Il-6 and Il-8 on respiratory support time and ICU stay and the relationship between catecholamine index, duration of effusions, and indicators of myocardial damage. Conclusions: NO inhaled into the oxygenator during CPB can alleviate the inflammatory response, improve myocardial and lung protection, and reduce metabolic stress in patients with a single ventricle undergoing Fontan surgery. The observed effects can influence short-term clinical outcomes.

Anticoagulation therapy and thromboembolic complications in pediatric patients undergoing the Fontan procedure

Objectives: We assessed the children with complex heart anomalies who undergone operative intervention of any form of Fontan intervention and analyzed them for thromboembolic complications after Fontan procedure performed at the Pediatric Clinic of Pristina.Background: Thromboembolic complications are a major cause of early and late mortality in children with single-ventricle congenital heart defects who have undergone a Fontan procedure.Thrombosis is an important and unpredictable complication, not only after Fontan operation but also associated with each stage of single-ventricle palliation. It is an important cause of morbidity, particularly when it leads to pulmonary embolism or stroke, and contributes to mortality.Methodology: The research was conducted at the Pediatric Clinic in the Cardiology and Intensive Care Service, during 2018-2021. The study includes patients who have undergone tertiary level intervention - one of the forms of the Fontan procedure, the research included 40 patients aged 0 -19 years. The children were divided into two groups: the group 29 patients using Aspirin therapy and the group of 11 patients without Aspirin therapy. In children after admission, laboratory tests were performed: hemogram, bleeding time, coagulation time, INR, PTT, and PT.Results: The mean age of children with antithrombotic therapy was 6.03 years (DS ± 5.84 years), those without therapy 3.27 years (DS ± 5.44 years). Aspirin as antithrombotic therapy was applied to 29 patients at a dose of 15 to 115 mg / 24 hours. In 6 patients the dose was less than 3-5 mg / kg body weight.Thepatients with congenital heart malformations after Fontan procedure receiving antithrombotic therapy are 1.4 times more likely to have reduced prothrombin time.Conclusions: Fontan procedure in children has been gratifying, with most survivors now leading lives of good quality into adulthood.

The cardioprotective and anti-inflammatory effect of inhaled nitric oxide during Fontan surgery in patients with single ventricle congenital heart defects: a prospective randomized study

BackgroundFontan surgery with cardiopulmonary bypass (CPB) causes tremendous systemic stress and inflammatory responses, affecting postoperative organ function, morbidity, and mortality. Although this reaction triggers partially protective anti-inflammatory responses, it is harmful in patients with single ventricle congenital heart defects. Despite decades of research, an effective anti-inflammatory and stress defense strategy is lacking. This study investigated the influence of inhaled nitric oxide (NO) during CPB on early clinical results, including the duration of postoperative respiratory support as a primary outcome and a panel of laboratory analytes.MethodsIn this study, 115 patients were randomized to the Fontan-NO group (n = 48) and the Fontan group (n = 49). Eighteen patients were excluded from the study. The Fontan-NO group received NO inhaled directly into the oxygenator during CPB. Clinical data were collected, and blood samples were drawn for analysis at repeated intervals. Multiplex assays were used to analyze a proteome profile of molecules involved in stress response, inflammation, metabolic reactions, as well as heart and lung protection.ResultsFontan-NO patients had significantly shorter respiratory support time with a median of 9.3 h (7.0; 13,2) vs 13.9 h (3.7; 18.5) by the absolute difference of 4.6 h [95% confidence interval, − 30.9 to 12.3; (p = 0.03)]. In addition, they have a shorter time in intensive care (p = 0.04) and lower pulmonary artery pressure after CPB discontinuation (p = 0.04), 4 h (p = 0.03) and 8 h (p = 0.03) after surgery. Fontan-NO patients also had a lower concentration of lactates (p = 0.04) and glucose after separation from CPB (p = 0.02) and lower catecholamine index (p = 0.042). Plasma factors analysis has shown a significantly higher concentration of interleukin-10, and a lower concentration of interleukin-6, interleukin-8, interleukin-1β, pentraxin, matrix metalloproteinase-8, troponin-I, creatine kinase myocardial band (CK-MB), and insulin in Fontan-NO group.ConclusionsNO inhaled into the oxygenator during CPB can improve short-term clinical outcomes. It shortens intubation time and intensive care time. It reduces inflammatory response, improves myocardial and lung protection, and diminishes metabolic stress in patients with a single ventricle undergoing Fontan surgery.Trial registration number: The trial was preregistered, supervised, and supported by The Polish National Science Center (NCN/01/B/NZ5/04246).

Abstract P162: Comorbid Asthma And Allergies Are Common In Children With Congenital Heart Disease And Related To Decreased Physical Functioning

Background: Congenital heart defects (CHD) are the most common birth defect and asthma and allergies are common conditions in childhood. The co-occurrence of these is not well understood but may be increased due to similar risk factors or immune dysregulation related to early life inflammation. This study aimed to compare the prevalence of asthma and allergies between children with CHD and their unaffected siblings and assess their impact on physical functioning in children with CHD. Methods: Parent-reported data was collected on allergy medications and asthma diagnosis, physical functioning (PedsQL physical health), and characteristics in children (age 12-17) with surgically treated CHD and an unaffected sibling (age 11-18). The McNemar test compared the comorbidities between siblings. Among children with CHD, logistic and linear regression were used to estimate the association of each comorbidity with child characteristics and physical functioning respectively. Models included CHD severity, SES, age, BMI, and sex. Results: Among 218 sibling pairs, the children with CHD had a higher, but not statistically significant, prevalence of asthma and allergies (Figure 1). In all 497 children with CHD, single ventricle CHD had a 2.5 times greater odds of allergies compared with non-critical (95%CI=1.0,6.0) with no difference in asthma. Asthma was associated with decreased physical functioning (8.7 point decrease vs no asthma, 95%CI=-14.5,-2.9). Conclusions: Children with CHD and their siblings had similar levels of allergies and asthma. However, as symptoms of these conditions may overlap, studies should further investigate a possible link with CHD, especially given the lower physical health in patients with CHD and asthma.

Children with single ventricle congenital heart defects: An interpretative phenomenological analysis of the lived parent experience

ObjectivesCongenital heart defects (CHD) can be detected during routine antenatal scans or go undiagnosed until birth. Parents of children with Single Ventricle CHD (SVCHD) have a complex experience. This study aimed to explore the lived experiences of parents of children with SVCHD from diagnosis through to adolescence. DesignInterviews were conducted with 12 parents whose children had completed the Fontan procedure. Interpretative Phenomenological Analysis (IPA) identified themes across parents' accounts. ResultsData were analysed into three superordinate themes of super parents, striving for normality and accepting SVCHD and their role. Through accepting SVCHD, becoming experts, and taking responsibility for the management of their child's physical healthcare, parents developed their own sense of normality. Following distress at the point of diagnosis, parents found their own way of accepting and integrating SVCHD into family life and regained a sense of control and normality within the family. ConclusionsTransition points such as starting nursery, final surgery, puberty, and reaching adulthood are key time points when parents may struggle with their changing roles and the gradual shift of responsibility and independence onto their children. There are implications for supporting parents to educate their children in terms of the management and long-term prognosis of their condition, especially when the child with SVCHD enters puberty or moves into adult services where they gain agency of their condition and its management. The role of healthcare professionals promoting emotional wellbeing and providing support to families during significant periods is discussed.

An in-vitro evaluation of the flow haemodynamic performance of Gore-Tex extracardiac conduits for univentricular circulation

Objective(s)The Fontan procedure is a common palliative intervention for sufferers of single ventricle congenital heart defects that results in an anastomosis of the venous return to the pulmonary arteries called the total cavopulmonary connection (TCPC). In patients with palliated single ventricular heart defects, the Fontan circulation passively directs systemic venous return to the pulmonary circulation in the absence of a functional sub-pulmonary ventricle. Therefore, the Fontan circulation is highly dependent on favourable flow and energetics, and minimal energy loss is of great importance. The majority of in vitro studies, to date, employ a rigid TCPC model. Recently, few studies have incorporated flexible TCPC models, without the inclusion of commercially available conduits used in these surgical scenarios.MethodThe methodology set out in this study successfully utilizes patient-specific phantoms along with the corresponding flowrate waveforms to characterise the flow haemodynamic performance of extracardiac Gore-Tex conduits. This was achieved by comparing a rigid and flexible TCPC models against a flexible model with an integrated Gore-Tex conduit.ResultsThe flexible model with the integrated Gore-Tex graft exhibited greater levels of energy losses when compared to the rigid walled model. With this, the flow fields showed greater levels of turbulence in the complaint and Gore-Tex models compared to the rigid model under ultrasound analysis.ConclusionThis study shows that vessel compliance along with the incorporation of Gore-Tex extracardiac conduits have significant impact on the flow haemodynamics in a patient-specific surgical scenario.

Early Integration of Palliative Care in Single Ventricle Families: A Quality Improvement Project for Enhanced Family Support

Background: Children with single ventricle congenital heart defects (SVCHD) experience a significant risk of mortality throughout their lifespan, particularly in their first year of life. The early involvement of pediatric palliative care (PPC) for children with SV physiology allows PPC providers to establish a relationship with the family and provide continuity throughout their journey. The intense care needed for these children and families predicates the need for PPC consults to be routine; however, medical staff are reluctant to broach the concept of PPC to families because of the association with …

Deep Learning for Improved Risk Prediction in Surgical Outcomes

The Norwood surgical procedure restores functional systemic circulation in neonatal patients with single ventricle congenital heart defects, but this complex procedure carries a high mortality rate. In this study we address the need to provide an accurate patient specific risk prediction for one-year postoperative mortality or cardiac transplantation and prolonged length of hospital stay with the purpose of assisting clinicians and patients’ families in the preoperative decision making process. Currently available risk prediction models either do not provide patient specific risk factors or only predict in-hospital mortality rates. We apply machine learning models to predict and calculate individual patient risk for mortality and prolonged length of stay using the Pediatric Heart Network Single Ventricle Reconstruction trial dataset. We applied a Markov Chain Monte-Carlo simulation method to impute missing data and then fed the selected variables to multiple machine learning models. The individual risk of mortality or cardiac transplantation calculation produced by our deep neural network model demonstrated 89 ± 4% accuracy and 0.95 ± 0.02 area under the receiver operating characteristic curve (AUROC). The C-statistics results for prediction of prolonged length of stay were 85 ± 3% accuracy and AUROC 0.94 ± 0.04. These predictive models and calculator may help to inform clinical and organizational decision making.

Comparison of Fontan Surgical Options for Patients with Apicocaval Juxtaposition.

Apicocaval juxtaposition (ACJ) is a rare form of viscerocardiac malpositions in association with single-ventricle congenital heart defects. The Fontan surgery is the common palliation, and possible surgical options include ipsilateral, contralateral, and intra-atrial conduits. Concerns include lower hemodynamic performances or risks of conduit compression by the cardiac mass. This study investigates the hemodynamics and clinical outcomes of ACJ patients and potential surgical improvements. Ten consecutive ACJ patients were included, along with a reference cohort of ten non-ACJ patients. Magnetic resonance images were acquired at 6 ± 0.6year follow-up for anatomical analysis and hemodynamic assessments using computational fluid dynamics. Metrics of interest are deformation index (DI), indexed power loss (iPL), and hepatic flow distribution (HFDoff). A "virtual" surgery was performed to explore potential hemodynamic improvements using a straightened conduit. DI for ACJ patients fell within the DI range of non-ACJ patients. Contralateral conduits had insignificantly higher iPL (0.070 [0.032,0.137]) than ipsilateral conduits (0.041 [0.013,0.095]) and non-ACJ conduits (0.034 [0.011,0.061]). HFDoff was similar for the ipsilateral (21 [12,35]), contralateral (26 [7,41]), and non-ACJ Fontan conduits (17 [0,48]). Virtual surgery demonstrated that a straightened conduit reduced HFDoff and iPL for the contralateral and ipsilateral conduits, potentially leading to improved clinical outcomes. In this limited sample, the hemodynamic performance of ACJ patients was not significantly different from their non-ACJ counterparts. The use of a straightened conduit option could potentially improve patient outcomes. Additionally, the fear of significant compression of conduits for ACJ patients was unsupported.

Inferior Vena Cava Diameter Predicts Nephropathy in Patients Late After Fontan Palliation

Single ventricle congenital heart defect patients have improved survival with Fontan palliation. However, they remain at risk for nephropathy, as indicated by pathologic microalbuminuria. We sought to investigate whether echocardiographic measures of the inferior vena cava diameter (a surrogate for elevated CVP) indexed to the body surface area (iIVC) or cardiac index (CI) can predict the presence of nephropathy in Fontan patients. We performed a single-center case-control study, including 39 asymptomatic Fontan (age 14.8 ± 7.9years) and 29 healthy controls (age 12.7 ± 2.7years). The primary outcome was abnormal microalbumin-creatinine ratio (MCR) from the first-morning void urine in Fontan patients. Measurements of iIVC and CI were derived using transthoracic echocardiography by two investigators with a high intra-class correlation coefficient (ICC = 0.97). Group comparison between Fontan and controls as well as between Fontan with normal and abnormal MCR was performed using Fisher's exact and t tests. Pearson and Spearman's correlations and multivariate regressions were performed to analyze the relations between the MCR, iIVC, and CI. Abnormal MCR was noted in 13/39(33%) of Fontan patients. The mean iIVC was larger in the Fontan compared to controls (p < 0.0001) and in Fontan with abnormal MCR compared to those with normal MCR (p = 0.0006). A positive correlation (r = 0.62; p < 0.001) was noted between MCR and iIVC. All patients with abnormal MCR had the iIVC > 1cm/m2. There were no significant relations between the CI and MCR. Significant prevalence of nephropathy late after Fontan palliation warrents screening. Echocardiographic measurement of iIVC could serve as one of the screening measures. The finding of the iIVC diameter > 1cm/m2 should prompt further renal evaluation.

Early Integration of Palliative Care in Families of Children with Single Ventricle Congenital Heart Defects: A Quality Improvement Project to Enhance Family Support.

Children with single ventricle congenital heart defects (SVCHD) experience a significant risk of early mortality throughout their lifespan, particularly during their first year of life. Due to the intense care needed for these children and families, pediatric palliative care (PPC) team consults should be routine; however, medical staff are often reluctant to broach the idea of PPC to families. The involvement of PPC for many carries with it an association to end-of-life (EOL) care. Setting the standard of PPC involvement from the time of admission for the first palliative surgery led to increased family support, decreased days to consult, improved acceptance and communication. The purpose of this article is to describe a quality improvement project of early integration of PPC with families of children with SVCHD. Lessons learned will be presented, including the resources needed and the barriers encountered in assimilating PPC into the standard of care for all patients with SVCHD. The single ventricle (SV) and PPC teams collaborated to enhance the support given to SV families. Education was initiated with cardiology and PPC providers to understand the goal of consistent PPC consults beginning after birth for patients with SVCHD. Parents were educated during fetal consultation regarding the involvement of the PPC team. The SV team ensured compliance with the PPC initiative by identifying eligible patients and requesting consult orders from the primary providers. PPC consultation increased significantly over the 40month study period to nearly 100% compliance for children with SVCHD who are undergoing pre-Fontan surgery. In addition, mean days to consult decreased dramatically during the study to a current average of 3days into the patient's hospitalization; the data likely suggest that more PPC consults were routinely ordered versus urgently placed for unexpected complications. Data indicate that patients are being followed by the PPC team at an earlier age and stage in their SV journey which allows for more opportunity to provide meaningful support to these patients and families. The early involvement of the PPC team for children with SV physiology was operationally feasible and was accepted by families, thus allowing PPC providers to establish a therapeutic relationship early in the disease trajectory with the family. It allowed more continuity throughout the SV journey in a proactive fashion rather than a reactive manner.

3212 Development of a Contractile Fontan Circuit to Decrease Central Venous Pressures in Single Ventricle Patients

OBJECTIVES/SPECIFIC AIMS: Children born with a single ventricle congenital heart defect requires three invasive open-heart surgeries in the first three years of life. The third operation, the Fontan procedure, includes connection of the vena cava (VC) to the pulmonary artery (PA) using a bio-inert conduit to reduce work required by the right ventricle (RV). While this operation greatly extends the lives of HLHS patients, the Fontan circuit eventually fails, and the only solution is a scarcely available donor heart. This failed circuit is explained by the “Fontan paradox” where central venous pressures build up over time, causing increased systemic resistance and congestion. The absence of the sub-pulmonary ventricle leads to abnormal hemodynamics associated with life-threatening complications. We believe that decreasing central venous pressures through the use of a tissue engineered contractile, patient specific conduit will decrease the amount and severity of complications caused by the “Fontan paradox.” We will use amniotic fluid derived induced pluripotent stem cells (AF-iPSCs) differentiated into cardiomyocytes (CMs) to generate flow within a biodegradable conduit. Additionally, AF-iPSC will be differentiated into structural support cells (SSCs), including cardiac fibroblasts and epicardium. Several studies suggest advanced contraction and structure of CMs in specific ratios with SSCs, particularly mouse and human fetal fibroblasts. In combination, these cells have shown advanced tissue organization and function through mechanically and electrically aligned junctions. This allows them to have a magnitude higher contractile force than CMs alone, making them ideal for increasing pressure within a tissue engineered construct. This poster focuses on the differentiation and selection of SSCs. METHODS/STUDY POPULATION: AF-iPSCs differentiation began at roughly 80% confluency. Mesoderm formation occurred via WNT pathway modulation by supplementing RPMI+insulin media with 0.5 ng/mL BMP4 at day 0, followed by 3 ng/mL BMP4, 2 ng/mL Activin A, and 5 ng/mL BFGF for four days. Then, RPMI+insulin media was supplemented with 10 ng/mL of BMP4 until day fifteen for epicardial formation. Cells were lifted to induce epithelial-to-mesenchymal transition (EMT) and RPMI-insulin media was supplemented with 10 ng/mL BFGF for cardiac fibroblasts. They were then harvested and characterized using immunofluorescence. Planned experiments include RT-qPCR for further characterization of cardiac fibroblasts. Additionally, a fibroblast isolation plating technique will be utilized to obtain cardiac fibroblast from AF-iPSC CMs and AF-iPSC epicardium. Commercially obtained human cardiac fibroblasts will be utilized as a control for all studies. RESULTS/ANTICIPATED RESULTS: Immunofluorescence (IF) revealed positive expression of vimentin and α-SMA indicating a fibroblast and vascular smooth muscle phenotype after supplementation with 10 ng/mL of BMP4 after EMT induction. It is expected that IF of epicardial formation at day 15 will show positive expression of WT1, a well-known epicardial marker. We also suspect RT-qPCR will reveal high expression of cardiac fibroblast specific markers COL1A1, PDGFA, TCF21, and THSB1. We expect to yield a higher number of cardiac fibroblast from the small molecule AF-iPSC differentiation compared to a timed plating technique of AF-iPSC CMs and AF-iPSC epicardium (separately plated). Results will be quantified and compared using the aforementioned techniques. DISCUSSION/SIGNIFICANCE OF IMPACT: Discussion/significance of impact: Although fibroblasts make up a large portion of cells in the heart and greatly enhance CM function, they are poorly characterized in the literature and not easily obtained. This study will provide an efficiency comparison on the best method for acquiring cardiac fibroblast for cardiac tissue engineering applications as we move forward with translational cardiac pediatric research.

The HAND1 frameshift A126FS mutation does not cause hypoplastic left heart syndrome in mice.

To test if a human Hand1 frame shift mutation identified in human samples is causative of hypoplastic left heart syndrome (HLHS). HLHS is a poorly understood single ventricle congenital heart defect that affects two to three infants in every 10 000 live births. The aetiologies of HLHS are largely unknown. The basic helix-loop-helix transcription factor HAND1 is required for normal heart development. Interrogation of HAND1 sequence from fixed HLHS tissues identified a somatic frame-shift mutation at Alanine 126 (NP_004812.1 p.Ala126Profs13X defined as Hand1A126fs). Hand1A126fs creates a truncated HAND1 protein that predictively functions as dominant negative. To determine if this mutation is causative of HLHS, we engineered a conditional Hand1A126fs mouse allele. Activation of this allele with Nkx2.5Cre results in E14.5 lethality accompanied by cardiac outflow tract and intraventricular septum abnormalities. Using αMHC-Cre or Mef2CAHF-Cre to activate Hand1A126fs results in reduced phenotype and limited viability. Left ventricles of Hand1A126FS mutant mice are not hypoplastic. Somatically acquired Hand1A126FS mutation is not causative of HLHS. Hand1A126FS mutation does exhibit embryonic lethal cardiac defects that reflect a dominant negative function supporting the critical role of Hand1 in cardiogenesis.

Increased Energy Loss Due to Twist and Offset Buckling of the Total Cavopulmonary Connection

The hemodynamic energy loss through the surgically implanted conduits determines the postoperative cardiac output and exercise capacity following the palliative repair of single-ventricle congenital heart defects. In this study, the hemodynamics of severely deformed surgical pathways due to torsional deformation and anastomosis offset are investigated. We designed a mock-up total cavopulmonary connection (TCPC) circuit to replicate the mechanically failed inferior vena cava (IVC) anastomosis morphologies under physiological venous pressure (9, 12, 15 mmHg), in vitro, employing the commonly used conduit materials: Polytetrafluoroethylene (PTFE), Dacron, and porcine pericardium. The sensitivity of hemodynamic performance to torsional deformation for three different twist angles (0 deg, 30 deg, and 60 deg) and three different caval offsets (0 diameter (D), 0.5D, and 1D) are digitized in three dimensions and employed in computational fluid dynamic (CFD) simulations to determine the corresponding hydrodynamic efficiency levels. A total of 81 deformed conduit configurations are analyzed; the pressure drop values increased from 80 to 1070% with respect to the ideal uniform diameter IVC conduit flow. The investigated surgical materials resulted in significant variations in terms of flow separation and energy loss. For example, the porcine pericardium resulted in a pressure drop that was eight times greater than the Dacron conduit. Likewise, PTFE conduit resulted in a pressure drop that was three times greater than the Dacron conduit under the same venous pressure loading. If anastomosis twist and/or caval offset cannot be avoided intraoperatively due to the anatomy of the patient, alternative conduit materials with high structural stiffness and less influence on hemodynamics can be considered.

A Method for In Vitro TCPC Compliance Verification.

The Fontan procedure is a common palliative intervention for sufferers of single ventricle congenital heart defects that results in an anastomosis of the venous return to the pulmonary arteries called the total cavopulmonary connection (TCPC). Local TCPC and global Fontan circulation hemodynamics are studied with in vitro circulatory models because of hemodynamic ties to Fontan patient long-term complications. The majority of in vitro studies, to date, employ a rigid TCPC model. Recently, a few studies have incorporated flexible TCPC models, but provide no justification for the model material properties. The method set forth in this study successfully utilizes patient-specific flow and pressure data from phase contrast magnetic resonance images (PCMRI) (n = 1) and retrospective pulse-pressure data from an age-matched patient cohort (n = 10) to verify the compliance of an in vitro TCPC model. These data were analyzed, and the target compliance was determined as 1.36 ± 0.78 mL/mm Hg. A method of in vitro compliance testing and computational simulations was employed to determine the in vitro flexible TCPC model material properties and then use those material properties to estimate the wall thickness necessary to match the patient-specific target compliance. The resulting in vitro TCPC model compliance was 1.37 ± 0.1 mL/mm Hg-a value within 1% of the patient-specific compliance. The presented method is useful to verify in vitro model accuracy of patient-specific TCPC compliance and thus improve patient-specific hemodynamic modeling.

Validation of association of the apolipoprotein E ε2 allele with neurodevelopmental dysfunction after cardiac surgery in neonates and infants

Apolipoprotein E (APOE) genotype is a determinant of neurologic recovery after brain ischemia and traumatic brain injury. The APOE ε2 allele has been associated with worse neurodevelopmental (ND) outcome after repair of congenital heart defects (CHD) in infancy. Replication of this finding in an independent cohort is essential to validate the observed genotype-phenotype association. The association of APOE genotype with ND outcomes was assessed in a combined cohort of patients with single-ventricle CHD enrolled in the Single Ventricle Reconstruction and Infant Single Ventricle trials. ND outcome was assessed at 14 months using the Psychomotor Development Index (PDI) and Mental Development Index (MDI) of the Bayley Scales of Infant Development-II. Stepwise multivariable regression was performed to develop predictive models for PDI and MDI scores. Complete data were available for 298 of 435 patients. After adjustment for preoperative and postoperative covariates, the APOE ε2 allele was associated with a lower PDI score (P = .038). Patients with the ε2 allele had a PDI score approximately 6 points lower than those without the risk allele, explaining 1.04% of overall PDI variance, because the ε2 allele was present in only 11% of the patients. There was a marginal effect of the ε2 allele on MDI scores (P = .058). These data validate the association of the APOE ε2 allele with adverse early ND outcomes after cardiac surgery in infants, independent of patient and operative factors. Genetic variants that decrease neuroresilience and impair neuronal repair after brain injury are important risk factors for ND dysfunction after surgery for CHD.