Hypoplastic Left Heart Syndrome Patients Research Articles

Abstract 4114497: Shape Variations in Right Ventricular 3D Geometry are associated with adverse outcomes in Hypoplastic Left Heart Syndrome Patients: A Fontan Outcomes Registry using CMR Examination (FORCE) Study

Introduction: Right ventricular (RV) function is critical to the long-term health of patients with hypoplastic left heart syndrome (HLHS). However, conventional measurements do not consider the range of RV morphology that may impact RV function and lead to adverse outcomes. In this study, we determined associations between RV shape and clinical outcomes of HLHS using statistical shape modeling (SSM) and a large cardiac magnetic resonance (CMR) multicenter registry. Methods: Three hundred and twenty-eight studies from unique HLHS patients in the F ontan O utcomes R egistry using C MR E xaminations (FORCE) were post-processed by a core lab at one institution, including volumetry and strain analysis. 3D end-diastolic models of RV were reconstructed using Mimics (Materialise). SSM was performed via Shapeworks Studio (NIH/NIGMS CIBC) to derive mean template and quantified shape variations (shape mode) representing deviation from the mean. RV shape relationship with mortality/heart transplant was assessed using bivariable/multivariable analyses with stepwise model selection. Results: The mean template from all 328 patients resembled a circumferentially dilated RV with loss of concavity in septal wall (Fig A). Several generalized variants were identified (Fig B), particularly p1 – a sigmoidal / “apical bulge” variant where the RV apex dilates and "wraps” around the hypoplastic left ventricle (Fig C). Twenty-eight patients (8.5%) experienced mortality/heart transplant at 2.5±2.4 years after CMR. On bivariable analysis, p1 was associated with mortality/heart transplant, along with larger indexed RV end-diastolic volume/mass and reduced global circumferential strain. On multivariable analysis, p1 and indexed RV mass were associated with mortality/heart transplant (Table). Conclusions: Statistical Shape Modeling can define the “usual” RV shape of HLHS. A sigmoidal shape variant is associated with adverse outcomes. SSM may provide patient-specific metrics to define RV dysfunction in HLHS.

Abstract 4138483: Outcomes of Hypoplastic Left Heart Syndrome by Subtype and Presence of Ventriculocoronary Connections: A Fetal Heart Society Multi-Center Retrospective study

Background: Hypoplastic left heart syndrome (HLHS) is classified by subtype: mitral atresia and aortic atresia (MA-AA), mitral stenosis and aortic atresia (MS-AA), and mitral stenosis and aortic stenosis (MS-AS). It is controversial whether specific HLHS subtypes and presence of ventriculocoronary connections (VCC) are associated with transplant-free survival. We aimed to determine whether there is an increased risk of mortality associated with specific HLHS subtypes, whether this risk is stratified by the presence of VCC, and if a specific type of stage I palliation in patients with VCC improves survival. We also aimed to determine practice variation in the evaluation of HLHS patients with VCC. Methods: We performed a multicenter retrospective cohort study of fetuses and infants < 2 months of age with HLHS admitted between 1/2012-12/2016 to participating Fetal Heart Society institutions. Patients with HLHS variants were excluded. We collected patient specific data and surveyed participating centers for practice variation. Kaplan-Meier curves with log-rank test were used to assess transplant-free survival and cox proportional hazard analysis was performed with adjustment for center as a random intercept. Results: 341 patients from nine centers were included. MA-AA was the most common subtype (177, 52%), followed by MS-AA (102, 30%), and MS-AS (62, 18%). VCC were diagnosed or suspected in 65 patients (19%). A total of 287 patients were live born with intention to treat. HLHS subtype was not associated with transplant-free survival (Figure 1A). Presence of VCC was associated with a lower transplant-free survival (p=0.026, Figure 1B). In the subset of patients diagnosed with VCC, there was not a significant difference in survival based on type of stage I palliation (Figure 1C). Cox proportional hazard modeling adjusted for center demonstrates that presence of VCC has a hazard ratio of 1.74 (CI 1.02-2.98), p =0.04. Survey data regarding practice variation for patients with VCC (Figure 2) demonstrates 33% of centers modify the type of stage I palliation based on presence of VCC. Conclusions: In a multicenter cohort of HLHS patients, patients with VCC had lower transplant-free survival compared to those without VCC, while subtype and type of stage I palliation did not have a statistical difference. There is considerable practice variation in the management of HLHS patients with VCC that may warrant further investigation.

MYH6 Variants Are Associated with Atrial Dysfunction in Neonates with Hypoplastic Left Heart Syndrome

Background: MYH6 variants are the most well-known genetic risk factor (10%) for hypoplastic left heart syndrome (HLHS) and are associated with decreased cardiac transplant-free survival. MYH6 encodes for α-myosin heavy chain (α-MHC), a contractile protein expressed in the neonatal atria. We therefore assessed atrial function in HLHS patients with MYH6 variants. Methods: We performed a retrospective, blinded assessment of pre-stage I atrial function using 2D speckle-tracking echocardiography (2D-STE). Variant carriers were control-matched based on AV valve anatomy, sex, and birth year. Studies were obtained postnatally from awake patients prior to surgical intervention. Right atrial (RA) and right ventricular (RV) strain and strain rate (SR) were measured from the apical four-chamber view. Results: A total of 19 HLHS patients with MYH6 variants had echocardiograms available; 18 were matched to two controls each, and one had a single control. RA active strain (ASct) was decreased in variant carriers (−1.41%, IQR −2.13, −0.25) vs. controls (−3.53%, IQR −5.53, −1.28; p = 0.008). No significant differences were identified in RV strain between the groups. RA reservoir strain (ASr) and conduit strain (AScd) positively correlated with heart rate (HR) in MYH6 variant carriers only (ASr R = 0.499, p = 0.029; AScd R = 0.469, p = 0.043). RV global longitudinal strain (GLS) as well as RV systolic strain (VSs) and strain rate (VSRs) correlated with HR in controls only (GLS R = 0.325, p = 0.050; VSs R = 0.419, p = 0.010; VSRs R = 0.410, p = 0.012). Conclusions: We identified functional consequences associated with MYH6 variants, a known risk factor for poor outcomes in HLHS. MYH6 variant carriers exhibit impaired RA contractility despite there being no differences in RV function between variant carriers and controls. MYH6 variants are also associated with an ineffective RA reservoir and conduit function at high heart rates, despite preserved RV diastolic function. RA dysfunction and reduced atrial “kick” may therefore be a significant contributor to RV failure and worse clinical outcomes in HLHS patients with MYH6 variants.

The neo-aortic valve in patients with hypoplastic left heart syndrome is largely preserved: a serial follow-up CMR study

BackgroundIn hypoplastic left heart syndrome (HLHS) patients, neo-aortic valve regurgitation can negatively impact right ventricular (RV) function. We assessed neo-aortic valve function and RV volumetric parameters by analysing serial cardiovascular magnetic resonance (CMR) studies in HLHS patients after completion of total cavopulmonary connection (TCPC).MethodsConsecutive CMR examinations of 80 patients (female: 22) with two (n = 80) or three (n = 45) examinations each were retrospectively analysed. RV volumetry was performed using short-axis cine images. RV end-diastolic and end-systolic volumes normalised to body surface area (BSA, RVEDVi, RVESVi), ejection fraction (RVEF) and stroke volume (RVSV) were measured. Neo-aortic flow, regurgitant fraction (RF) and peak velocity were quantified from phase-contrast cine images.ResultsMedian neo-aortic regurgitation was mild at all three examinations (RF <20%) and there was no significant increase in RF over time (p > 0.05). None of the patients had significant neo-aortic valve stenosis (peak velocity >3 m/s). RF correlated with RVESVi and RVEF at the second examination. At the third examination, RF correlated with RVESVi and RVEDVi even in patients with RF <15% (RVESVi: r = 0.40, p = 0.001; RVEDVi: r = 0.34, p = 0.031).ConclusionAssessment of serial CMR studies in HLHS patients after TCPC completion demonstrates a preserved neo-aortic valve function. Nevertheless, thorough follow-up is mandatory as even mild neo-aortic dysfunction might impact RV size and function over a longer term.

Assessment of B-Natriuretic Peptide Levels After Stage 1 Palliation in Hypoplastic Left Heart Syndrome Patients.

We describe the perioperative BNP trends in patients with HLHS from S1P until interstage discharge to home, death, or S2P. This prospective cohort study includes all newborns with hypoplastic left heart syndrome (HLHS) who underwent Norwood procedures (S1P) at Texas Children's Hospital from April 2018 through April 2019. Our study included 19 newborns with HLHS. There was no interstage mortality; 47% were discharged home prior to the S2P procedure. Nine patients (50%) had higher BNP levels immediately after arrival to the cardiac intensive care unit (ICU) after S1P compared to preoperative levels. BNP levels were higher in those with a shorter duration of mechanical intubation (P = 0.02) and those with moderately depressed right ventricular systolic function in the immediate postoperative period (P = 0.02). RVPAs patients had higher BNP levels (median 3357pg/mL) than mBTTs (median 2862pg/mL), that was not statistically significant (P = 0.4). Despite higher BNP levels in RVPAs in the early postoperative period, these subjects had shorter mechanical ventilation, ICU, and hospital length of stay duration. BNP trends for HLHS patients vary in the postoperative period after S1P. RVPAs had higher BNP levels than mBTTs in the early postoperative period after S1P; however, this was not associated with worse outcomes.

Update of How Pediatric Cardiologists Noninvasively Evaluate Patients with Hypoplastic Left Heart Syndrome: 2013 vs. 2023.

Noninvasive functional assessment of systemic right ventricles (RV) in hypoplastic left heart syndrome (HLHS) is challenging. This study aimed to compare pediatric cardiologists' current noninvasive imaging practices to those reported in 2013. A web-based survey was distributed to pediatric cardiologists via various listservs which queried timing of echocardiograms during HLHS palliative stages and measurements of RV function. Demographics of 156 participants who completed the 2023 survey were similar to survey participants in 2013 (n = 222). Respondents were mostly male (62%), echocardiographers (48%), in university-based practice (67%) in North America (95%). Echocardiograms were predominantly obtained monthly during interstage I (41%), every 6months during interstage II (56%), and every year post-Fontan (68%), which is consistent from 2013. Routine cardiac magnetic resonance imaging (cMRI) significantly increased in interstage II (8.2%, 17%) and post-Fontan (24%, 56%) populations, respectively. Qualitative assessment (41%), ejection fraction (EF) by 3D (20%), fractional area change (16%), and RV strain/strain rate (13%) were preferred methods for systolic assessment, whereas a plurality of respondents (41%) did not believe RV diastolic measurements were valid. The largest gap between currently obtained and desired measurements existed for EF by 3D (46.5% points) and RV strain/strain rate (44.5% points). No differences existed between imagers compared to non-imagers. Variability in evaluating HLHS patients continues among pediatric cardiologists compared to 10years ago. Qualitative assessment remains the primary RV systolic functional evaluation. Providers do not rely on quantitative RV diastolic function assessments in HLHS patients. Use of cMRI is increasing for RV functional analysis.

Abstract Mo088: RBFOX2 haploinsufficiency impairs cardiomyocyte adhesion and contractility through faulty RNA metabolism

Background: Hypoplastic left heart syndrome (HLHS) is a severe form of congenital heart disease that is uniformly lethal if left untreated. Protein damaging mutations in one allele of RBFOX2, a highly conserved RNA binding protein, are enriched in HLHS patients, suggesting they are causal. However, it remains unclear how RBFOX2 haploinsufficiency contributes to disease pathogenesis as heterozygous animal models appear healthy. Methods: We generated and characterized RBFOX2 heterozygous and null human induced pluripotent stem cells (hiPSCs) and assessed their phenotypes in differentiated cardiomyocytes (iPSC-CMs) in 2D culture. To learn if altered function might be revealed in a more native microenvironment, we also generated 3D engineered heart tissues (EHTs) from RBFOX2 heterozygous hiPSC-CMs. To delineate the underlying molecular mechanisms, we performed bulk RNA-seq to reveal differential gene expression (DGE) and alternative splicing events (ASEs) between the different genetic cohorts and eCLIP-seq to detect RNAs directly bound by RBFOX2 in the CM lineage. Results: We observed dose-dependent reductions in cell adhesion, size, maturation, respiration, calcium handling, and action potential duration with no significant effect on proliferation in 2D culture. Although myofibril alignment and contractility were completely abolished in null hiPSC-CMs, these features were surprisingly preserved in heterozygous cells. However, in EHTs, we found that RBFOX2 is haploinsufficient for tissue maturation and contractility, suggesting that myocardial-intrinsic defects contribute to RBFOX2 -mediated HLHS. Integration of DGE, ASEs and eCLIP-seq datasets uncovered significant enrichment of DGE and/or ASEs of RBFOX2-bound and unbound transcripts involved in cell adhesion between the extracellular matrix (ECM) and the actin cytoskeleton/sarcomere network. Included in the direct targets with altered expression and alternative splicing was the ECM ligand FIBRONECTIN 1 ( FN1 ), which when downregulated was previously associated with HLHS. Conclusions: Our data suggest that RBFOX2 sits atop an expression and splicing hierarchy that promotes optimal CM cell growth, adhesion, and contractility that protects the heart from HLHS pathogenesis.

Abstract Mo090: Altered Cardiac Cell Populations in Hypoplastic Left Heart Syndrome

Background: Congenital heart disease (CHD) affects ~1% of infants. Hypoplastic left heart syndrome (HLHS), a severe form of CHD in which the left ventricle is underdeveloped, is associated by a 15% incidence of heart failure by 6 years of age. Only 6% of HLHS patients have a genetic cause identified on exome sequencing, limiting the ability of patients to receive a diagnosis and potentially benefit from targeted treatments. Hypothesis: Novel HLHS genes are differentially expressed in HLHS cardiac tissues, or in cells with differential abundance in HLHS hearts. Goals: To use single nucleus RNA sequencing of HLHS patient cardiac tissues to identify candidate HLHS genes. Methods: Single nucleus RNA sequencing (nucSeq) was performed on paired left and right ventricular tissues (LV, RV) from 9 participants with HLHS. Left ventricular cardiac tissues from children (4) and adults (12) without CHD were used for comparison. Filtering with CellBender and Solo were used to remove low-quality nuclei. Analysis was performed in R using the Seurat package. Results: HLHS LV tissues had a higher proportion of cardiomyocytes than pediatric or adult control tissues, (78.7% vs 64.1%, p=0.005; 78.7 % vs 47.0%, p=1.8E-08, respectively), and a lower proportion of mural cells (3.1% vs 9.3%, p=3.9E-05; 3.1 % vs 23.5%, p=7.3E-15, respectively). By contrast, there were similar proportions of endothelial cells in the HLHS, pediatric and adult tissues (7.1%, 8.8% and 7.9%, respectively; p=0.56). Within HLHS tissues, the LV had a higher proportion of cardiomyocytes than the RV (78.7% vs 51.2%, p=4.8E-04) while the proportion of endothelial cells were similar in the LV and RV (7.3% and 9.1%, respectively; p=0.33). LV tissues from HLHS participants 2-18 years of age had fewer capillary endothelial cells than pediatric controls (31.2% vs 57.8%, p=0.001), and gene markers of HLHS endothelial cells included PBX1 , which is required for Hox D-3 mediated angiogenesis, as well as ARHGAP26 and RORA, inhibitors of VEGF signaling. Conclusion: HLHS cardiac tissues have a higher proportion of cardiomyocytes in the LV despite a smaller chamber size. Differences in gene expression that accompany the differences in cell proportion could identify novel HLHS genes as well as potential therapeutic targets.

Common atrial reservoir strain during the interstage period is a predictor of poor outcomes prior to Fontan completion in hypoplastic left heart syndrome.

The atrium augments ventricular function, but the significance of atrial function in hypoplastic left heart syndrome (HLHS) has not been well evaluated. We investigated the association of atrial reservoir strain (common atrial strain [CAS]) to death or need for transplantation in patients with HLHS. In this retrospective single-center study, echocardiograms from three timepoints (pre-stage 1 palliation [S1P], 4-8weeks post-S1P, and pre-Glenn) were analyzed in infants with classic HLHS. Patients were separated based on transplant-free survival to Fontan (survivors) versus death or heart transplant prior to Fontan (composite outcome). Echocardiographic parameters evaluated included CAS, right ventricle (RV) global longitudinal strain (RVGLS), RV fractional area change (FAC), and tricuspid annular plane systolic excursion (TAPSE). An equal variance t-test, regression, and receiver operating characteristic (ROC) analyses were performed. A total of 45 HLHS patients (25 survivors, 20 patients meeting endpoint) were included in this study. There were no significant differences in any of the functional parameters during the pre-stage 1 or post-stage 1 timepoints. Pre-Glenn CAS and RVGLS were significantly worse in those meeting composite endpoint compared to survivors. CAS was significantly correlated to RVGLS during the pre-S1P and pre-Glenn timepoints. A pre-Glenn CAS<19.5 had an area under the curve of .78 and a 75% sensitivity and 83% specificity for death or need for transplantation. Pre-Glenn CAS is significantly lower in patients with mortality or need for the transplantation prior to Fontan completion and may carry prognostic significance in patients with HLHS.

Comparison of Morbidity and Mortality Outcomes between Hybrid Palliation and Norwood Palliation Procedures for Hypoplastic Left Heart Syndrome: Meta-Analysis and Systematic Review.

Background/Objectives: Hybrid palliation (HP) procedures for hypoplastic left heart syndrome (HLHS) are increasing. Our objective was to compare mortality and morbidity following HP and NP (Norwood palliation) procedures. Methods: Systematic review and meta-analysis of HLHS patients of peer-reviewed literature between 2000 and 2023. Mortality and/or heart transplantation in HP versus NP in the neonatal period, interstage period, and at 1, 3 and 5 years of age, and morbidity including completion of Stage II and Stage III palliation, unexpected interventions, pulmonary artery pressures, right ventricle function, neurodevelopmental outcomes and length of hospital stay were evaluated. Results: Twenty-one (meta-analysis: 16; qualitative synthesis: 5) studies evaluating 1182 HLHS patients included. HP patients had higher interstage mortality (RR = 1.61; 95% CI: 1.10-2.33; p = 0.01) and 1-year mortality (RR = 1.22; 95% CI: 1.03-1.43; p = 0.02) compared to NP patients without differences in 3- and 5-years mortality. HP procedure in high-risk HLHS patients had lower mortality (RR = 0.48; 95% CI: 0.27-0.87; p = 0.01) only in the neonatal period. HP patients underwent fewer Stage II (RR = 0.90; 95% CI: 0.81-1.00; p = 0.05) and Stage III palliation (RR = 0.78; 95% CI: 0.69-0.90; p < 0.01), had more unplanned interventions (RR = 3.38; 95% CI: 2.04-5.59; p < 0.01), and longer hospital stay after Stage I palliation (weighted mean difference = 12.88; 95% CI: 1.15-24.62; p = 0.03) compared to NP patients. Conclusions: Our study reveals that HP, compared to NP for HLHS, is associated with increased morbidity risk without an improved survival rate.

Atrial septal interventions during and after hybrid stage I palliation of hypoplastic left heart syndrome.

Hybrid stage I palliation (HS1P) is an alternative approach for initial palliation in hypoplastic left heart syndrome (HLHS) patients. Unlike surgical stage I palliation where atrial septectomy is routinely performed, atrial septal intervention (ASI) during HS1P is variable. In this study, we described our experience with ASI in single ventricle (SV) patients who underwent HS1P and identified factors associated with need for ASI after HS1P. Data were retrospectively collected for all HLHS patients who underwent HS1P at our center over the past 12 years. We evaluated ASIs performed during the HS1P (intra-HS1P ASI) and ASIs performed during the period from HS1P to the subsequent surgical stage, either interval Norwood stage I or comprehensive stage II (post-HS1P ASI). Patient factors and procedural data were compared to identify factors associated with undergoing post-HS1P ASI and the impact of ASI on patient outcomes was evaluated. Of 50 SV patients included, 23 (46%) underwent intra-HS1P ASI and 26 (52%) underwent post-HS1P ASI. Need for post-HS1P ASI was lower among patients who had an intra-HS1P ASI as compared to those who did not (30% vs. 70%; p = 0.005). There were no significant differences in short or Midterm outcomes between patients who underwent intra-HS1P ASI or post-HS1P ASI and their counterparts. ASI is common both during and after HS1P but is generally well tolerated and type of ASI does not significantly impact overall patient outcomes. Our findings suggest that the current approach of individualizing management of ASI in the HS1P population is effective and safe.

Survival and reverse progression outcome of fetal aortic valvuloplasty and extra-cardiac conduit or lateral tunnel Fontan procedure in evolving and evolved hypoplastic left heart syndrome: a systematic review and meta-analysis

Background: Hypoplastic left heart syndrome (HLHS) is a severe congenital heart defect characterized by the underdevelopment of the left-sided heart structures, necessitating staged univentricular palliation to repurpose the right ventricle as the systemic pumping chamber. While the Fontan procedure offers a well-established method to manage single-ventricle physiology and improve survival, the potential of fetal aortic valvuloplasty (FAV) to prevent the progression of critical aortic stenosis to HLHS and achieve biventricular circulation postnatally remains significant. However, the long-term outcomes of both interventions are still uncertain. Therefore this study aims to evaluate the survival and reverse progression outcome of fetal aortic valvuloplasty and extra-cardiac conduit or lateral tunnel Fontan procedure in evolving and evolved hypoplastic left heart syndrome Methods: The literature search was conducted using PubMed, ScienceDirect, and Google Scholar databases up to May 2024. The analyses in this study were performed using R statistical software v.3.3. Results: This analysis reviewed 25 prospective and retrospective cohort studies discussing the outcomes of the FAV procedure in evolving HLHS fetuses and the Fontan procedure in pediatric HLHS patients. Among evolving HLHS fetuses, the FAV procedure had a mortality rate of 0.18 (95% CI 0.07-0.29) and a procedural success rate of 0.81 (95% CI 0.78-0.85). In pediatric patients with evolved HLHS undergoing the Fontan procedure, the mortality rate was 0.13 (95% CI 0.00-0.25), and the procedural success rate was 0.93 (95% CI 0.85-1.00). Conclusion: The Fontan procedure has shown better results than FAV, likely due to interstage procedural interventions and more established techniques for reducing morbidity and mortality in HLHS patients.

Critical Organ Dysfunction and Preoperative Mortality in Newborns with Hypoplastic Left Heart Syndrome.

Hypoplastic left heart syndrome (HLHS) is fatal without surgical intervention. An important subset of HLHS patients die prior to surgical intervention, but this population is underevaluated. The neonatal sequential organ failure assessment score (nSOFA) is an operational definition of organ dysfunction that can identify those with a high risk of mortality among neonatal intensive care unit (NICU) patients. The utility of the nSOFA to predict preoperative mortality in the unique HLHS population is unknown and could inform care, particularly care provided by neonatology staff. We performed a multicenter retrospective cohort study of HLHS cases across three level IV NICUs from January 1, 2009 to December 3, 2023. Patients were classified as either survived or died prior to surgical intervention. Demographic variables were curated from medical records including the maximum nSOFA (nSOFAmax) before surgical intervention or death. We identified 265 patients with HLHS over the study period. The nSOFAmax was greater in patients who died preoperatively (14/265; 5%) compared with survivors to surgical intervention (median 8 [interquartile range, 6, 12] vs. 2 [0, 4]; p < 0.001). The area under receiver operating characteristics curve for the nSOFAmax to discriminate for mortality was 0.93 (95% confidence interval, 0.88-0.98; p < 0.001). Compared with an nSOFAmax of 0, the likelihood ratio for preoperative death doubled at 2, tripled at 4, and was 10-fold at 9. This is the first demonstration of nSOFA utility in specific to congenital heart disease and HLHS. The nSOFAmax represents a novel, electronic health record-compatible, and generalizable method to identify patient-level organ dysfunction and risk for preoperative mortality in HLHS patients. KEY POINTS: · An important subset of HLHS patients die preoperatively.. · nSOFA can be used to measure preoperative HLHS severity.. · nSOFA predicts preoperative mortality risk in HLHS patients..

Fetal Echocardiographic Evaluation of Tricuspid Valve and Right Ventricular Function Including Global Longitudinal Strain in Hypoplastic Left Heart Syndrome and Association with Postnatal Outcomes.

Despite significant advancements in the care of patients with hypoplastic left heart syndrome (HLHS) morbidity and mortality remain high. Postnatal right ventricular dysfunction and tricuspid regurgitation (TR) are associated with worse outcomes in HLHS. We aim to determine if right ventricle functional parameters and TR on fetal echocardiogram are associated with postnatal outcomes in HLHS patients. Retrospective review was performed on all fetuses with HLHS from 2014 to 2022 at our institution. Initial and follow up fetal echocardiogram measurements of right ventricular myocardial performance index (MPI), fractional area change (FAC) and global longitudinal strain (GLS) were retrospectively measured. The presence and severity of TR was recorded from the fetal echocardiogram reports. Postnatal outcomes including transplant-free survival, hospital length of stay > 30days after initial palliation and need for bidirectional Glenn at < 4months were reviewed. Forty-three subjects met inclusion criteria. Mean gestational age at presentation was 26.1 ± 5.9weeks. Nine subjects died and 3 required heart transplantation. Initial fetal echocardiogram MPI was significantly lower (better) (0.36 ± 0.06 vs 0.44 ± 0.11; p = < 0.001) and FAC was significantly higher (better) (45 ± 6% vs 40 ± 8%; p = 0.035) in transplant-free survivors. Fetal right ventricular GLS and presence of mild TR were not associated with postnatal outcome. In fetuses with HLHS, abnormal MPI and right ventricular FAC are associated with decreased transplant-free survival. There was no observed association between GLS and postnatal outcomes. To our knowledge this is the first study examining fetal right ventricular function and GLS in HLHS patients and its link to postnatal outcomes.

Prognostic Value of RV Function Analysis During the Interstage Period in Patients with Hypoplastic Left Heart Syndrome.

Cardiac dysfunction is associated with mortality in children with hypoplastic left heart syndrome (HLHS). We evaluated the ability of qualitative and quantitative RV functional parameters to predict outcomes in HLHS patients. In this retrospective, single-center study, echocardiograms from 3 timepoints (pre-stage 1 palliation, 4-8weeks post-stage 1 palliation, and pre-Glenn) were analyzed in infants with HLHS. Patients were stratified into two groups based on outcome of transplant-free survival post-Glenn (survivors) versus mortality or transplantation prior to Fontan (non-survivors). Images were retrospectively reviewed to obtain RV global longitudinal strain (RVGLS), RV-free wall strain (RVFWS), fractional area change (FAC), tricuspid annular systolic plane excursion (TAPSE), tissue motion annular displacement of the tricuspid valve (TMAD-TV) and qualitative systolic function assessment during the predetermined timepoints. An equal variance t-test and chi-square were used to determine significant differences and ROC curve analysis was performed to derive optimal cutoff values to predict mortality/transplant. A total of 47 patients met inclusion criteria, of which, 21 patients met composite endpoint. There were no significant differences in any RV functional parameter during the pre- or post-stage 1 palliation timepoints. The absolute values of RVFWS, RVGLS, and TMAD-TV were significantly greater in survivors than non-survivors during the pre-Glenn timepoint. A pre-Glenn RVGLS > -15.6 (AUC 0.79), RVFWS > -18.6 (AUC 0.75), and TMAD-TV < 12.6% (AUC 0.82) were sensitive and specific for predicting death or need for transplantation prior to Fontan completion. RVGLS, RVFWS, and TMAD-TV may help identify higher-risk HLHS patients during the interstage period.

Regenerating the ailing heart: Stem cell therapies for hypoplastic left heart syndrome.

Hypoplastic left heart syndrome (HLHS) is a complex congenital heart defect (CHD) characterized by a spectrum of underdeveloped left-sided cardiac structures. It is a serious defect and warrants either 3-staged surgical palliation or a heart transplant. Despite numerous surgical advancements, long-term outcomes remain challenging and still have significant morbidity and mortality. There have been notable advancements in stem cell therapy for HLHS, including developments in diverse stem cell origins and methods of administration. Clinical trials have shown safety and potential benefits, including improved ventricular function, reduced heart failure, and fewer adverse events. Younger myocardium seems particularly receptive to stem cell signals, suggesting the importance of early intervention. This review explores the potential of emerging stem cell-based therapies as an adjunctive approach to improve the outcomes for HLHS patients.

Mortality and Heart Transplantation After Hybrid Palliation of Hypoplastic Left Heart Syndrome: A Systematic Review and Meta-Analysis.

Newborns with hypoplastic left heart syndrome (HLHS) who are considered at increased risk for death following Norwood/Sano surgery often undergo hybrid palliation (HP) as initial surgery. We aimed to compile the HP experience in HLHS and its variants and assess the rates of, and risk factors for, death and heart transplantation. CINAHL, CINAHL PLUS, PubMed/MEDLINE, and SCOPUS were systematically searched for HP outcome studies of death or heart transplantation in HLHS between 1998 and 2022. Pooled incidence was estimated, and potential risk factors were identified using random-effects meta-analysis and reconstructed time-to-event data from Kaplan-Meier curves. Thirty-three publications were included in our review. Overall, of 1,162 patients 417 died and 57 underwent heart transplantation, resulting in a combined outcome of 40.7%, (474/1,162). There was a trend toward decreasing mortality risk across the stages of palliation. Pooled mortality between HP and comprehensive stage 2 palliation was 25%, after stage 2 up to Fontan palliation was 16%, and 6% post-Fontan. The incidence of death or heart transplantation was higher in high-risk patients-43% died and 10% received heart transplantation. Our systematic review and meta-analysis found high rates of death or heart transplantation in HP of HLHS patients between HP and Fontan surgeries. All patients should be closely followed during the initial interstage period, which is associated with the highest hazard. Prospective studies on appropriate patient selection, indications, and / or alternatives, as well as refining HP strategies for managing newborns with HLHS are needed to improve outcomes.

Cardiovascular magnetic resonance reference values of right ventricular volumetric variables in patients with hypoplastic left heart syndrome

Cardiovascular magnetic resonance (CMR) has established itself as the gold standard for serial assessment of systemic right ventricular (RV) performance but due to the lack of standardized RV reference values for hypoplastic left heart syndrome (HLHS) patients, the interpretation of RV volumetric data in HLHS remains difficult. Therefore, this study aimed to close this gap by providing CMR reference values for the systemic RV in HLHS patients. CMR scans of 160 children, adolescents, and young adults (age range 2.2-25.2years, 106 males) with HLHS were retrospectively evaluated. All patients were studied following total cavopulmonary connection. Short-axis stacks were used to measure RV end-diastolic and end-systolic volumes (RVEDV, RVESV), RV stroke volume (RVSV), RV ejection fraction (RVEF), and RV end-diastolic myocardial mass (RVEDMM). Univariable and multiple linear regression analyses were performed to assess associations between RV parameters and demographic and anthropometric characteristics. Following the results of the regression analysis, reference graphs and tables were created with the Lambda-Mu-Sigma method. Multiple linear regression analysis showed strong associations between body height and RVEDV, RVESV as well as RVSV. Age was highly associated with RVEDMM. Therefore, percentile curves and tables were created with respect to body height (RVEDV, RVESV, RVSV) and age (RVEDMM). The influence of demographic and anthropometric parameters on RVEF was mild, thus no percentile curves and tables for RVEF are provided. We were able to define CMR reference values for RV volumetric variables for HLHS patients. These data might be useful for the assessment and interpretation of CMR scans in these patients and for research in this field.

Molecular Pathways and Animal Models of Hypoplastic Left Heart Syndrome.

Hypoplastic left heart syndrome (HLHS) is a severe congenital heart disease (CHD) with underdevelopment of left-sided heart structures. While previously uniformly fatal, surgical advances now provide highly effective palliation that allows most HLHS patients to survive their critical CHD. Nevertheless, there remains high morbidity and mortality with high risk of heart failure. As hemodynamic compromise from restricted aortic blood flow has been suggested to underlie the poor LV growth, this suggests the possibility of prenatal fetal intervention to recover LV growth. As such interventions have yielded ambiguous results, the optimization of therapy will require more mechanistic insights into the developmental etiology for HLHS. Clinical studies have shown high heritability for HLHS, with an oligogenic etiology indicated in conjunction with genetic heterogeneity. This is corroborated with the recent recovery of mutant mice with HLHS. With availability-induced pluripotent stem cell (iPSC)-derived cardiomyocytes from HLHS mice and patients, new insights have emerged into the cellular and molecular etiology for the LV hypoplasia in HLHS. Cell proliferation defects were observed in conjunction with metaphase arrest and the disturbance of Hippo-YAP signaling. The left-sided restriction of the ventricular hypoplasia may result from epigenetic perturbation of pathways regulating left-right patterning. These findings suggest new avenues for fetal interventions with therapies using existing drugs that target the Hippo-YAP pathway and/or modulate epigenetic regulation.

Outcomes of Children With Hypoplastic Left Heart Syndrome and Heart Failure on Medical Therapy

BackgroundSystemic right ventricle (RV) dysfunction is associated with lower transplant-free survival (TFS) in hypoplastic left heart syndrome (HLHS), but the likelihood of functional improvement and utility of heart failure (HF) medications is not understood. ObjectivesThe authors aimed to describe TFS, HF medication use, and surgical interventions in HLHS patients with RV dysfunction with and without subsequent improvement in function. MethodsThe SickKids HF Database is a retrospective cohort that includes all pediatric HLHS patients with RV dysfunction lasting >30 days. We compared TFS, HF medications, and surgical interventions in HLHS patients with and without functional normalization. ResultsOf 99 patients with HLHS and RV dysfunction, 52% had normalized function for ≥30 days. TFS at 2 years after dysfunction onset was lower in those without normalization (14% vs 78%, P < 0.001). Patients without normalization were less likely to reach target dosing (TD) of HF medications (27% vs 47% on 1 medication at TD, P < 0.001) and undergo Fontan completion (7% vs 53%, P < 0.001). Clinical factors associated with improved TFS were normalization of function for ≥30 days, onset of dysfunction after bidirectional Glenn, and exposure to ACE inhibition. ConclusionsOur cohort of HLHS patients with systemic RV dysfunction demonstrated a novel finding of improved TFS in those with functional normalization for ≥30 days. Achieving TD of HF medications was associated with improved outcomes. This may reflect patient stability and tolerance for HF medication more than its therapeutic effect, but it can help inform decisions to proceed with surgical palliation or list for transplant.