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Background Overall one-year non-mortality outcomes for surgically palliated hypoplastic left heart syndrome (HLHS) patients remain understudied. Using the metric Days Alive and Outside of Hospital (DAOH), the present study sought to characterize expectations for surgically palliated patients’ first year of life. Methods The Pediatric Health Information System database was used to identify by ICD-10 code all HLHS patients who underwent surgical palliation (Norwood/hybrid and/or heart transplantation [HTx]) during their index neonatal admission and were successfully discharged alive (n = 2227) and for whom one-year DAOH could be calculated. DAOH quartiles were used to group patients for analysis. Results Median one-year DAOH was 304 (interquartile range [IQR] 250-327), including a median index admission length of stay of 43 days (IQR 28-77). Patients required a median 2 (IQR 1-3) readmissions, each spanning 9 days (IQR 4-20). One-year readmission mortality or hospice discharge occurred in 6% of patients. Patients with lower-quartile DAOH had a median DAOH of 187 (IQR 124-226), whereas upper-quartile DAOH patients had a median DAOH of 335 (IQR 331-340) ( P 7 days at surgery (1.50 [1.14-1.99]), and non-white race/ethnicity (1.33 [1.01-1.75]). Conclusions In the current era, surgically palliated HLHS infants spend approximately 10 months alive and outside of the hospital, although outcomes are highly variable. Knowledge of the factors associated with lower DAOH can inform expectations and guide management decisions.

This study describes the evolving in-hospital management strategies for neonates who are diagnosed with tetralogy of Fallot (ToF).The Pediatric Health Information System (PHIS) database was used to identify admitted patients aged 0 to 1 month old with ToF from 2010 through 2019; era 1, 2010 through 2014; and era 2, 2015 through 2019. International Classification of Diseases codes were used to identify related interventions that occurred during this admission but not necessarily as a neonate: full repair, systemic-to-pulmonary shunt, and percutaneous stent in the right ventricular outflow tract and/or patent ductus arteriosus.Among 6021 neonates diagnosed with ToF, 2030 (34%) underwent an intervention: 60% had total repair, 31% systemic-to-pulmonary shunt, and 9% percutaneous stent. In the no-intervention cohort, in-hospital mortality was 9%. In-hospital mortality between repair (6%), shunt (6%), and stent (3%) patients (P = .446) did not differ. Regarding regional practices, no intervention was most frequently used in the Midwest (69% vs 65% average for all other regions [avg], P = .075) while interventions overall were performed most frequently in the West (36% vs 33.5% avg, P = .075). Among the interventions, full repair was most frequent in the Northeast (76% vs 57% avg, P.001), shunt was most frequent in the Midwest (39% vs 28% avg, P.001), and stent was most frequent in the South (11% vs 7% avg, P = .083). Between eras 1 and 2, the type of intervention changed: full repair (52% vs 69%, P.001) and stent (1% vs 16%, P.001) increased, while shunt decreased (47% vs 15%, P.001).Although most neonates admitted with ToF are discharged with no intervention, more than one-third undergo some intervention with a 3% to 6% mortality. The proportion of these patients who undergo an intervention is unchanged during the past decade, but the types of intervention have changed, and significant regional differences exist.

Genetic and genomic testing in pediatric CHD is becoming increasingly routine, and can have important psychosocial, clinical and reproductive implications. In this paper we highlight important challenges and considerations when providing genetics consults and testing in pediatric CHD and illustrate the role of a dedicated CHD genetics clinic. Key lessons include that a) a genetic diagnosis can have clinical utility that justifies testing early in life, b) adequate genetic counselling is crucial to ensure families are supported, understand the range of possible results, and are prepared for new or unexpected health information, and c) further integration of the clinical genetics and cardiology workflows will be required to effectively manage the burgeoning information arising from genetic testing. Our experience demonstrates that a dedicated CHD genetics clinic is a valuable addition to a multidisciplinary team providing care to children with CHD.

BackgroundValve remodeling is a complex process involving extracellular matrix organization, development of trilaminar structures, and physical elongation of valve leaflets. However, the cellular and molecular mechanisms regulating valve remodeling and their roles in congenital valve disorders remain poorly understood.MethodsSemilunar valves and atrioventricular valves from healthy and age-matched human fetal hearts with pulmonary stenosis (PS) were collected. Single-Cell RNA-sequencing (scRNA-seq) was performed to determine the transcriptomic landscape of multiple valvular cell subtypes in valve remodeling and disease. Spatial localization of newly-identified cell subtypes was determined via immunofluorescence and RNAin situhybridization. The molecular mechanisms mediating valve development was investigated utilizing primary human fetal heart valve interstitial cells (VICs) and endothelial cells (VECs).ResultsscRNA-seq analysis of healthy human fetal valves identified a novel APOE+elastin-producing VIC subtype (Elastin-VICs) spatially located underneath VECs sensing the unidirectional flow. Knockdown ofAPOEin fetal VICs resulted in significant elastogenesis defects. In pulmonary valve with PS, we observed decreased expression ofAPOEand other genes regulating elastogenesis such asEMILIN1andLOXL1, as well as elastin fragmentation. These findings suggested the crucial role of APOE in regulating elastogenesis during valve remodeling. Furthermore, cell-cell interaction analysis revealed that JAG1 from unidirectional VECs activates NOTCH signaling in Elastin-VICs through NOTCH3.In vitroJag1 treatment in VICs increased elastogenesis, while similar observations were found in VICs co-cultured with VECs in the presence of unidirectional flow. Notably, we found that the JAG1-NOTCH3 signaling pair was drastically reduced in the PS valves. Lastly, we demonstrated that APOE is indispensable for JAG1-induced NOTCH activation in VICs, reinforcing the presence of a synergistic intrinsic and external regulatory network involving APOE and NOTCH signaling that is responsible for regulating elastogenesis during human valve remodeling.ConclusionscRNA-seq analysis of human fetal valves identified a novel Elastin-VIC subpopulation, and revealed mechanism of intrinsic APOE and external NOTCH signaling in regulating elastogenesis during cardiac valve remodeling. These mechanisms may contribute to deciphering the pathogenesis of elastin malformation in congenital valve diseases.Clinical PerspectiveWhat Is New?High-resolution single-cell transcriptome atlas generated from healthy human fetal heart valves and valves affected by pulmonary stenosis during the early phase of valve remodeling prior to birth.A unique subset of valve interstitial cells (VICs) that produce elastin (Elastin-VICs) was identified.Elastin-VICs specifically located underneath the valve endothelial cells (VECs) sensing unidirectional flow, and played a crucial role in elastin maturation via the expression of APOE.Elastin-VICs communicated with adjacent VECs via the JAG1-NOTCH signaling, facilitating elastin formation and valve remodeling.What Are the Clinical Implications?Elastin-VICs from patient valvular tissues with Pulmonary Stenosis exhibit decreased APOE-NOTCH signaling and elastin fragmentation.Direct targeting of APOE and NOTCH signaling could be a novel approach to promote elastin fiber formation and valve remodeling in patients with valvular defects.

Objective To study the outcomes of a novel modified pulmonary artery banding (mPAB) technique used for staged repair of a subset of patients with complex transposition physiology. Methods A total of 13 patients who underwent mPAB during their staged repair (biventricular repair [BVR], n = 6) or palliation (1-1/2 repair, n = 1; univentricular repair [UVR], n = 6) from 2004 to 2020 were studied retrospectively. A restrictive interposition graft was used to reconstruct the main PA between the pulmonary root and the distal pulmonary confluence, functioning as a mPAB. Twelve of the 13 patients (92.3%) underwent a concurrent arterial switch operation (ASO), of which 6 were palliative ASOs for 1-1/2 repair (n = 1) or UVR (n = 5). Patient weight and cardiac anatomy determined the size of interposition graft. Results The disease spectrum included dextro transposition of the great arteries (d-TGA) with multiple ventricular septal defects (VSDs) (n = 4), Taussig–Bing anomaly (n = 3), d-TGA with VSD and hypoplastic right ventricle (RV) (n = 3), double-inlet left ventricle with l-TGA (n = 2), and congenitally corrected TGA with double-outlet RV (n = 1). The Lecompte procedure was performed in 10 patients. Predischarge echocardiography revealed a band gradient of 61 mm Hg (interquartile range [IQR], 40-90 mm Hg) for BVR/1-1/2 ventricular repair (n = 7) and 49 mm Hg (IQR, 37-61 mm Hg) for UVR (n = 6). Survival was 100% at a median follow-up of 3.7 years (IQR, 2.6-4.0 years). Conclusions The mPAB technique is effective and reproducible for staged BVR or UVR for patients with TGA. It effectively regulates pulmonary blood flow, may reduce neopulmonary root distortion, and eliminates complications associated with band migration in standard PAB., Graphical abstract

Mechanical ventilation prior to pediatric heart transplantation predicts inferior post-transplant survival, but the impact of ventilation duration on survival is unclear.Data from the United Network for Organ Sharing and Pediatric Health Information System were used to identify pediatric (18 years) heart transplant recipients from 2003 to 2020. Patients ventilated pretransplant were first compared to no ventilation, then ventilation durations were compared across quartiles of ventilation (≤1 week, 8 days-5 weeks,5 weeks).At transplant, 11% (511/4506) of patients required ventilation. Ventilated patients were younger, had more congenital heart disease, more urgent listing-status, and greater rates of nephropathy, TPN-dependence, and inotrope and ECMO requirements (p .001 for all). Post-transplant, previously ventilated patients experienced longer ventilation durations, ICU and hospital stays, and inferior survival (all p .001). Hospital outcomes and survival worsened with longer pretransplant ventilation. One-year and overall survival were similar between the no-ventilation and ≤1 week groups (p = .703p = .433, respectively) but were significantly worse for ventilation durations1 week (p .001). On multivariable analysis, ventilation ≤1 week did not predict mortality (HR 0.98 [95% CI 0.85-1.43]), whereas ventilation1 week did (HR: 1.18 [1.01-1.39]).Longer pretransplant ventilation portends worse outcomes, although only ventilation1 week predicts mortality. These findings can inform pretransplant prognostication.

Background: Infants experience the worst one-year post-heart transplant (HTx) survival of any other pediatric group. Although mechanical ventilatory (MV) requirement at the time of transplant is an established predictor of post-transplant mortality, the impacts of commonly co-utilized support modalities such as total parenteral nutrition (TPN)-dependence and paralytics are understudied. Methods: All infant HTx recipients from 2003 to 2020 in both the United Network for Organ Sharing and Pediatric Health Information System databases were identified (n = 1344) and categorized depending upon support requirement at the time of transplant—none (59%), MV-only (10%), MV + Paralytics (2%), TPN-dependence-only (15%), MV + TPN (10%), and MV + Paralytics + TPN (4%). The primary study aim was to characterize the impact of TPN-dependence and paralytics on one-year post-transplant survival (PTS). Results: Compared to no-support, supported infants were generally at higher risk and more ill at transplant, with greater rates of congenital heart disease, renal and hepatic dysfunctions, and inotrope requirements. Post-transplant hospital outcomes were inferior among supported patients; all support groups experienced longer post-transplant MV, intensive care unit, and hospital lengths of stay (all P

Congenital heart disease (CHD) has a multifactorial aetiology, raising the possibility of an underlying genetic burden, predisposing to disease but also variable expression, including variation in disease severity, and incomplete penetrance. Using whole genome sequencing (WGS), the findings of this study, indicate that complex, critical CHD is distinct from other types of disease due to increased genetic burden in common variation, specifically among established CHD genes. Additionally, these findings highlight associations with regulatory genes and environmental "stressors" in the final presentation of disease.

OBJECTIVES Previous studies investigating risk factors associated with reoperation or mortality after repair of complete atrioventricular septal defect (CAVSD) often have not included sizeable cohorts undergoing modified single-patch repair. Both double patch and modified single-patch techniques have been widely used in Australia since the 1990s. Using a large multi-institutional cohort, we aimed to identify risk factors associated with reoperation or mortality following CAVSD repair. METHODS Between January 1990 and December 2015, a total of 829 patients underwent biventricular surgical repair of CAVSD in Australia at 4 centres. Patients with associated tetralogy of Fallot and other conotruncal abnormalities were excluded. Demographic details, postoperative outcomes including reoperation and survival, and associated risk factors were analysed. RESULTS Fifty-six patients (6.8%) required early reoperation (≤30 days) for significant left atrioventricular valve regurgitation or residual septal defects. Freedom from reoperation at 10, 15 and 20 years was 82.7%, 81.1% and 77%, respectively. Patients without Down syndrome and moderate left atrioventricular valve regurgitation on postoperative echocardiogram were found to be independent risk factors for reoperation. Operative mortality was 3.3%. Overall survival at 10, 15 and 20 years was 91.7%, 90.7% and 88.7%, respectively. Prior pulmonary artery banding was a predictor for mortality, while later surgical era (2010–2015) was associated with a reduction in mortality risk. CONCLUSIONS Improved survival in the contemporary era is in keeping with improvements in surgical management and higher rates of primary CAVSD repair over time. The presence of residual moderate left atrioventricular valve regurgitation on postoperative echocardiography is an important factor associated with reoperation and close surveillance is essential to allow timely reintervention. Primary CAVSD repair at age

Background: We sought to evaluate the outcomes following right ventricle to pulmonary artery (RV-PA) conduit placement in pediatric patients, excluding those with a RV-PA conduit for the Ross procedure which is associated with improved conduit durability, partly related to its orthotopic position. Methods: Outcomes for 119 patients who underwent RV-PA conduit placement at a single institution from January 2004 to December 2016 were reviewed. Primary outcome measures were reintervention-free survival (RFS) and overall survival. Survival analyses were performed using the Kaplan-Meier method, and risk factors associated with reintervention were evaluated. Results: The median age at the time of conduit placement was 6 months (interquartile range, IQR: 1-14), and the median length of follow-up was 63 months (range: 0-156). During follow-up, 39 patients required conduit-related reintervention, while 6 patients died perioperatively with an overall survival of 90% at 10 years. Among the remaining 113 patients, the RFS at one, five, and ten years was 91% (84%-95%), 72% (60%-80%), and 33% (16%-50%), respectively. The median time to conduit replacement in the series was 43.5 months (IQR: 19.3-76.2). The use of a pulmonary homograft was associated with improved RFS ( P = .03), and this was particularly pronounced in comparison with aortic homografts in neonates. Infection was the indication for replacement in only one patient. Conclusions: The majority of the conduits placed during the neonatal period required conduit replacement before the age of five years. Endocarditis was not a common indication for replacement. In neonates and infants, we prefer pulmonary homografts for most indications.

Fontan takedown remains an option for the management of Fontan failure. We sought to evaluate early and late outcomes after Fontan takedown.The Australia and New Zealand Fontan Registry was interrogated to identify all patients who had a Fontan takedown.Over a 43-year study period (1975-2018), 36 of 1540 (2.3%) had a Fontan takedown. The median age at takedown was 5.1 years (interquartile range [IQR], 3.7, 7.0). Nine (25%) patients had a takedown within 48 hours, 6 (16%) between 2 days and 3 weeks, 14 (39%) between 3 weeks and 6 months, whereas 7 (19%) had a late takedown (6 months). Median interval to takedown was 26 days (IQR, 1.5, 127.5). Sixteen (44%) patients died at a median of 57.5 days (IQR, 21.8, 76.8). The greatest mortality occurred between 3 weeks and 6 months (2 days: 1/9, 11%; 2 days to 3 weeks: 2/6, 33%; 3 weeks to 6 months: 11/14, 79%;6 months: 2/7, 28%; P = .007). At median follow-up of 9.4 years (IQR, 4.5, 15.3), 11 (31%) patients were alive with an intermediate circulation (10 in New York Heart Association class I/II). Five (14%) patients underwent a successful second Fontan. Freedom from death/transplant after Fontan takedown was 59%, 56%, and 52% at 1, 5, and 10 years, respectively.The incidence of Fontan takedown is low, but mortality is high. The majority of takedowns occurred within 6 months. Mortality was lowest when takedown occurred2 days and highest between 3 weeks and 6 months. A second Fontan is possible in a small proportion of survivors.

A child with repaired double outlet right ventricle presented with Staphylococcus aureus bacteremia. Despite unsuspecting echocardiography on admission and clinical improvement on antibiotics, repeat routine echocardiography detected an aortic pseudoaneurysm, requiring a Ross-Konno operation. In repaired congenital heart defects with bacteremia, close echocardiographic surveillance is required to detect aortic pseudoaneurysm. (Level of Difficulty: Intermediate.), Central Illustration

We studied the effect of various coronary transfer techniques (CTT) on neo-aortic root size after an arterial switch operation (ASO) in simple transposition by excluding the impact of recognized predisposing factors. One hundred and seventy-eight patients with simple transposition were reviewed retrospectively (January 2004-December 2018) and grouped as Punch Hole (n = 83/178), Nonpunch Hole (n = 65/178; Trapdoor or Standard) and Mixed (n = 30/178). Factors predicting the neo-aortic root z-scores- annulus, mid-sinus, and sinotubular junction (STJ) were analyzed by uni/multivariable linear regression. Follow-up was 6 years, Interquartile range (IQR) 3.4,10.6. Preoperative aortic (7.4 mm, IQR 6.9,8) and pulmonary annulus (7.5 mm, IQR 6.8,8.1) sizes were identical (P = 0.831). The changes in preoperative, postoperative, and latest median z-scores for neo-aortic annulus (-0.2, IQR -1.2,0.9; 0.0, IQR -0.9,0.9; 0.9, IQR -0.4,2.6; P0.001), mid-sinus (1.1, IQR-0.1,2; 2.6, IQR 1.6,3.7; 2.9, IQR 1.8,4.3; P0.001) and STJ (-0.1, IQR -0.8,1.1; 2.1, IQR 0.7,3; 2.4, IQR 1,3.5; P0.001) were significant. On multivariate analysis, preoperative pulmonary annulus z-score predicted the latest neo-aortic annulus z-score [Beta estimate (BE) = 0.32, 95% confidence interval (CI) = 0.03,0.62; P = 0.03] and STJ z-score (BE= 0.45, 95% CI= 0.20,0.70; P0.0001). CTT did not predict any of the latest neo-aortic z-scores (all P0.05). Mild plus neo-aortic regurgitation (neoAR) was not significantly different across CTT groups [punch hole 20% (n = 15/74), mixed 37% (n = 11/30), nonpunch hole 21% (n = 13/62); Fisher-exact P = 0.186], one patient required valve replacement for severe neoAR. The neo-aortic root enlarges significantly over time at all 3 levels following an ASO in simple transposition, however, this is not significantly influenced by the CTT utilized.

Objective Identify early pregnancy associations of congenital heart disease (CHD) in a multiethnic cohort. Methods This retrospective observational cohort study compared the general obstetric population to women who gave birth at a referral centre in Australia between 2012 and 2017, after 20 weeks' of gestation, with a pregnancy affected by CHD. We defined mood disorder and anxiety as a history of self-reported or medically diagnosed anxiety, depression, postpartum depression or bipolar disorder. Results We compared epidemiological factors between 30 842 general obstetric patients and 470 obstetric patients with a fetus affected by CHD. Multivariate analysis showed independent associations between CHD and use of selective serotonin reuptake inhibitors (SSRIs) or serotonin-norepinephrine reuptake inhibitors (SNRIs) in the first trimester (relative risk [RR] 4.14, 95% CI 2.58-6.65), history of anxiety or mood disorder with no SSRI/SNRI first trimester (RR 2.26, 95% CI 1.82-2.82), folate and/or pregnancy multivitamin use in the first trimester (RR 0.68, 95% CI 0.54-0.86) and increased risk with maternal age >40 years (RR 2.30, 95% CI 1.57-3.38). Conclusions Our data show maternal mood disorders with and without SSRI or SNRI use, maternal age >40 years and lack of multivitamin/folate use to be independently associated with CHD in pregnancy. This article is protected by copyright. All rights reserved.

Background Surgery is the cornerstone of treatment for single-ventricle patients, but life just begins for most when the staged procedures are completed. A package of care, including primary care, out-of-hospital specialist visits, and medication, is required for patients living with Fontan. This study quantified the current state of out-of-hospital health care use across childhood for Fontan patients using evidence from Australia. Methods Patients recruited from the Fontan Registry were linked with the administrative Medicare (universal health insurance) data. Frequency of medical and pharmaceutical care and costs were estimated. Results Data for 115 patients with 12,726 medical and 8,336 pharmaceutical claims were obtained. From age 0 to 20 years, patients on average visited a general practitioner an estimated 6.4 times per year (95% confidence interval [CI], 5.9-7.0 times per year), and specialists, including cardiologists, 2.8 times per year (95% CI, 2.5-3.0 times per year). Average use of allied health professional care peaked at age 6 to 9 years (1.0 visits per year; 95% CI, 0.7-1.4 visits per year) with psychologic services being most prominent. For pharmaceuticals, an average of 13.3 prescriptions filled per patient per year throughout childhood was observed (95% CI, 12.4-14.2 prescriptions per year). Overall, out-of-hospital doctor visits of all types averaged 11 visits per year from birth to 20 years. A decline in care was observed when patients reached 18 years across services. Conclusions Patterns of out-of-hospital health care use were observed; however, current guidelines are silent about whether this is optimal. Further research is needed to better understand the comprehensive needs of this population.

Right ventricle to pulmonary artery (RV-PA) conduits are required for the surgical management of pulmonary atresia with ventricular septal defect and truncus arteriosus. Bioengineered RV-PA connections may address some of the shortcomings of homografts and xenografts, such as lack of growth potential and structural deterioration and may be manufactured to accommodate patient-specific anatomy. The aim of this study was to develop a methodology for in silico patient-specific design and analysis of RV-PA conduits.Cross-sectional imaging was obtained from patients with truncus arteriosus (n = 5) and pulmonary atresia with ventricular septal defect (n = 5) who underwent complete repair with a RV-PA conduit. Three-dimensional models of the heart were constructed by segmentation of the right ventricle, existing conduit, branch pulmonary arteries, and surrounding structures. A customized conduit design for each patient was proposed. Computational fluid dynamics analysis was performed and outputs, including wall shear stress and energy loss, were used to compare the performance of the existing conduits and the customized geometries.In this study, a methodology for patient-specific analysis of RV-PA conduit in silico was developed. The results of simulations for 10 patients showed between 23% and 56% decrease in the average wall shear stress and between 24% and 87% reduction in average power requirements in customized designs compared with the stenosed conduits, translating into better hemodynamic performance.Creation of an optimal conduit for an individual patient can be achieved using surgeon-guided design and computational fluid dynamics analysis. Manufacture of personalized RV-PA conduits may obviate the need for surgical customization to accommodate existing materials and provide superior long-term outcomes.

Biventricular repair of complete atrioventricular septal defect (CAVSD) is largely achieved using the double-patch (DP) or modified single-patch (MSP) techniques in the current era; however, long-term results following MSP repair are not well defined. We aimed to compare long-term outcomes including reoperation and mortality after CAVSD repair using DP and MSP techniques, and identify the risk factors associated with adverse outcomes. A retrospective cohort study was performed including all patients who underwent CAVSD repair using DP and MSP techniques at our institution between 17 May 1990 and 14 December 2015. Demographic details, early (≤30 days) and late (>30 days) outcomes (reoperation, mortality) were studied. Competing risks analysis with cumulative incidence function was used for survival analyses. Overall, 273 consecutive patients underwent CAVSD repair (120 DP and 153 MSP) and 41 patients required reoperation during follow-up. Competing risks analysis showed no association between repair technique and reoperation (P = 1.0) or mortality (P = 0.9). Considering competing risks due to mortality, the cumulative incidence of reoperation at 5, 10, and 15 years was 14%, 17%, and 17% for DP and 12%, 13%, and 16% for MSP, respectively. Non-Down syndrome and moderate or greater left atrioventricular valve regurgitation were predictors for reoperation. Pulmonary artery banding was predictive of mortality, though strongly associated with earlier surgical era. Median follow-up duration was 8.0 years (interquartile range 3.9–20.8) for DP and 11.6 years (interquartile range 5.4–16.1) for MSP (P = 0.4). Event-free survival is similar after DP and MSP repair of CAVSD indicating either repair technique can be safely utilized.

Congenital heart disease (CHD) is the most common birth defect and brings with it significant mortality and morbidity. The application of exome and genome sequencing has greatly improved the rate of genetic diagnosis for CHD but the cause in the majority of cases remains uncertain. It is clear that genetics, as well as environmental influences, play roles in the aetiology of CHD. Here we address both these aspects of causation with respect to the Notch signalling pathway. In our CHD cohort, variants in core Notch pathway genes account for 20% of those that cause disease, a rate that did not increase with the inclusion of genes of the broader Notch pathway and its regulators. This is reinforced by case-control burden analysis where variants in Notch pathway genes are enriched in CHD patients. This enrichment is due to variation in NOTCH1. Functional analysis of some novel missense NOTCH1 and DLL4 variants in cultured cells demonstrate reduced signalling activity, allowing variant reclassification. Although loss-of-function variants in DLL4 are known to cause Adams-Oliver syndrome, this is the first report of a hypomorphic DLL4 allele as a cause of isolated CHD. Finally, we demonstrate a gene-environment interaction in mouse embryos between Notch1 heterozygosity and low oxygen- or anti-arrhythmic drug-induced gestational hypoxia, resulting in an increased incidence of heart defects. This implies that exposure to environmental insults such as hypoxia could explain variable expressivity and penetrance of observed CHD in families carrying Notch pathway variants.

OBJECTIVES Atrioventricular valve regurgitation is known to adversely impact outcomes of single-ventricle palliation, and valve repair rarely provides long-lasting results. Closure of a atrioventricular valve can sometimes be performed, but the long-term outcomes of this manoeuvre are unknown. METHODS This retrospective study was conducted using patient data extracted from an existing bi-national, population-based registry of survivors of the Fontan procedure. RESULTS Between January 1975 and June 2018, 1574 patients survived to hospital discharge with an intact Fontan circulation. Of these patients, 128 with a common atrioventricular valve were excluded. Thirty-eight patients underwent closure of an atrioventricular valve, and complete follow-up data were available for 36 patients. Twenty-nine patients underwent closure of the tricuspid valve and 7 patients underwent closure of the mitral valve. Seventeen patients underwent valve closure prior to Fontan, 13 patients underwent valve closure concomitant with Fontan and 6 patients underwent valve closure post-Fontan. Valve closure was performed using a patch technique in 29 cases and with direct suture in 7 cases. At the most recent echocardiography, 33 patients had no regurgitation, 2 patients had recurrent mild regurgitation and 1 patient had no echocardiographic follow-up. Six patients required reintervention post-valve closure and 7 patients required permanent pacemaker insertion post-valve closure. Freedom from reintervention at 1, 5 and 18 years post-valve closure was 86% [95% confidence interval (CI) 76–98%], 83% (95% CI 72–96%) and 83% (95% CI 72–96%), respectively. CONCLUSION Atrioventricular valve closure is an effective surgical technique in selected patients with a single ventricle providing long-lasting competency in the majority of cases.

Next-generation sequencing (NGS) technologies generate thousands to millions of genetic variants per sample. Identification of potential disease-causal variants is labor intensive as it relies on filtering using various annotation metrics and consideration of multiple pathogenicity prediction scores. We have developed VPOT (variant prioritization ordering tool), a python-based command line tool that allows researchers to create a single fully customizable pathogenicity ranking score from any number of annotation values, each with a user-defined weighting. The use of VPOT can be informative when analyzing entire cohorts, as variants in a cohort can be prioritized. VPOT also provides additional functions to allow variant filtering based on a candidate gene list or by affected status in a family pedigree. VPOT outperforms similar tools in terms of efficacy, flexibility, scalability, and computational performance. VPOT is freely available for public use at GitHub (https://github.com/VCCRI/VPOT/). Documentation for installation along with a user tutorial, a default parameter file, and test data are provided. Keywords: Next-generation sequencing, Pathogenicity predictions, Variant prioritization, Customizable ranking, Genomic annotation

Tricuspid valve regurgitation (TR) increases adverse outcomes in children with hypoplastic left heart syndrome (HLHS). Changes in tricuspid valve (TV) annulus and leaflet geometry have been described but the underlying causes for TR in HLHS remain uncertain. We aimed to examine the association between left ventricular (LV) size and TR in infants with HLHS as right ventricular (RV)–LV interactions may be important in TR development. Echocardiograms of 50 infants with HLHS were reviewed. LV size, RV function, TR grade, TV annulus z-score, and aortic arch obstruction were examined at birth and 1 year of age (or the latest study post-bidirectional Glenn anastomosis if the patient was