Integrated transcriptomics and epigenomics reveal chamber-specific and species-specific characteristics of human and mouse hearts.

DNA methylation, chromatin accessibility, and gene expression represent different levels information in biological process, but a comprehensive multiomics analysis of the mammalian heart is lacking. Here, we applied nucleosome occupancy and methylome sequencing, which detected DNA methylation and chromatin accessibility simultaneously, as well as RNA-seq, for multiomics analysis of the 4 chambers of adult and fetal human hearts, and adult mouse hearts. Our results showed conserved region-specific patterns in the mammalian heart at transcriptome and DNA methylation level. Adult and fetal human hearts showed distinct features in DNA methylome, chromatin accessibility, and transcriptome. Novel long noncoding RNAs were identified in the human heart, and the gene expression profiles of major cardiovascular diseases associated genes were displayed. Furthermore, cross-species comparisons revealed human-specific and mouse-specific differentially expressed genes between the atria and ventricles. We also reported the relationship among multiomics and found there was a bell-shaped relationship between gene-body methylation and expression in the human heart. In general, our study provided comprehensive spatiotemporal and evolutionary insights into the regulation of gene expression in the heart.

Life-Course Cumulative Burden of Body Mass Index and Blood Pressure on Progression of Left Ventricular Mass and Geometry in Midlife: The Bogalusa Heart Study.

RATIONALE: Data are limited regarding the influence of life-course cumulative burden of increased body mass index (BMI) and elevated blood pressure (BP) on the progression of left ventricular (LV) geometric remodeling in midlife. OBJECTIVE: To investigate the dynamic changes in LV mass and LV geometry over 6.4 years during midlife and to examine whether the adverse progression of LV geometric remodeling is influenced by the cumulative burden of BMI and BP from childhood to adulthood. METHODS AND RESULTS: The study consisted of 877 adults (604 whites and 273 blacks; 355 males; mean age=41.4 years at follow-up) who had 5 to 15 examinations of BMI and BP from childhood and 2 examinations of LV dimensions at baseline and follow-up 6.4 years apart during adulthood. The area under the curve (AUC) was calculated as a measure of long-term burden (total AUC) and trends (incremental AUC) of BMI and systolic BP (SBP). After adjusting for age, race, sex, smoking, alcohol drinking, and baseline LV mass index, the annual increase rate of LV mass index was associated with all BMI measures (ß=0.16-0.36, P<0.05 for all), adult SBP (ß=0.07, P=0.04), and total AUC of SBP (ß=0.09, P=0.01) but not with childhood and incremental AUC values of SBP. All BMI and SBP measures (except childhood SBP) were significantly associated with increased risk of incident LV hypertrophy, with odds ratios of BMI (odds ratio=1.85-2.74, P<0.05 for all) being significantly greater than those of SBP (odds ratio=1.09-1.34, P<0.05 for all except childhood SBP). In addition, all BMI measures were significantly and positively associated with incident eccentric and concentric LV hypertrophy. CONCLUSIONS: Life-course cumulative burden of BMI and BP is associated with the development of LV hypertrophy in midlife, with BMI showing stronger associations than BP. Visual Overview: An online visual overview is available for this article.

Tnni3k alleles influence ventricular mononuclear diploid cardiomyocyte frequency.

Recent evidence implicates mononuclear diploid cardiomyocytes as a proliferative and regenerative subpopulation of the postnatal heart. The number of these cardiomyocytes is a complex trait showing substantial natural variation among inbred mouse strains based on the combined influences of multiple polymorphic genes. One gene confirmed to influence this parameter is the cardiomyocyte-specific kinase Tnni3k. Here, we have studied Tnni3k alleles across a number of species. Using a newly-generated kinase-dead allele in mice, we show that Tnni3k function is dependent on its kinase activity. In an in vitro kinase assay, we show that several common human TNNI3K kinase domain variants substantially compromise kinase activity, suggesting that TNNI3K may influence human heart regenerative capacity and potentially also other aspects of human heart disease. We show that two kinase domain frameshift mutations in mice cause loss-of-function consequences by nonsense-mediated decay. We further show that the Tnni3k gene in two species of mole-rat has independently devolved into a pseudogene, presumably associated with the transition of these species to a low metabolism and hypoxic subterranean life. This may be explained by the observation that Tnni3k function in mice converges with oxidative stress to regulate mononuclear diploid cardiomyocyte frequency. Unlike other studied rodents, naked mole-rats have a surprisingly high (30%) mononuclear cardiomyocyte level but most of their mononuclear cardiomyocytes are polyploid; their mononuclear diploid cardiomyocyte level (7%) is within the known range (2-10%) of inbred mouse strains. Naked mole-rats provide further insight on a recent proposal that cardiomyocyte polyploidy is associated with evolutionary acquisition of endothermy.

Filamentous nestin and nonmuscle myosin IIB are associated with a migratory phenotype in neonatal rat cardiomyocytes.

Cardiomyocyte migration represents a requisite event of cardiogenesis and the regenerative response of the injured adult zebrafish and neonatal rodent heart. The present study tested the hypothesis that the appearance of the intermediate filament protein nestin in neonatal rat ventricular cardiomyocytes (NNVMs) was associated in part with the acquisition of a migratory phenotype. The cotreatment of NNVMs with phorbol 12,13-dibutyrate (PDBu) and the p38α/ß mitogen-activated protein kinase inhibitor SB203580 led to the de novo synthesis of nestin. The intermediate filament protein was subsequently reorganized into a filamentous pattern and redistributed to the leading edge of elongated membrane protrusions translating to significant lengthening of NNVMs. PDBu/SB203580 treatment concomitantly promoted the reorganization of nonmuscle myosin IIB (NMIIB) located predominantly at the periphery of the plasma membrane of NNVMs to a filamentous phenotype extending to the leading edge of elongated membrane protrusions. Coimmunoprecipitation assay revealed a physical interaction between NMIIB and nestin after PDBu/SB203580 treatment of NNVMs. In wild-type and heterozygous NMIIB embryonic hearts at E11.5-E14.5 days, nestin immunoreactivity was identified in a subpopulation of cardiomyocytes elongating perpendicular to the compact myocardium, at the leading edge of nascent trabeculae and during thickening of the compact myocardium. In mutant embryonic hearts lacking NMIIB protein expression, trabeculae formation was reduced, the compact myocardium significantly thinner and nestin immunoreactivity undetectable in cardiomyocytes at E14.5 days. These data suggest that NMIIB and nestin may act in a coordinated fashion to facilitate the acquisition of a migratory phenotype in neonatal and embryonic cardiomyocytes.

A role of Hey2 transcription factor for right ventricle development through regulation of Tbx2-Mycn pathway during cardiac morphogenesis.

A basic helix-loop-helix transcription factor Hey2 is expressed in the ventricular myocardium and endocardium of mouse embryos, and Hey2 null mice die perinatally showing ventricular septal defect, dysplastic tricuspid valve and hypoplastic right ventricle. In order to understand region-specific roles of Hey2 during cardiac morphogenesis, we generated Hey2 conditional knockout (cKO) mice using Mef2c-AHF-Cre, which was active in the anterior part of the second heart field and the right ventricle and outflow tract of the heart. Hey2 cKO neonates reproduced three anomalies commonly observed in Hey2 null mice. An earliest morphological defect was the lack of right ventricular extension along the apico-basal axis at midgestational stages. Underdevelopment of the right ventricle was present in all cKO neonates including those without apparent atresia of right-sided atrioventricular connection. RNA sequencing analysis of cKO embryos identified that the gene expression of a non-chamber T-box factor Tbx2 was ectopically induced in the chamber myocardium of the right ventricle. Consistently, mRNA expression of the Mycn transcription factor, which was a cell cycle regulator transcriptionally repressed by Tbx2, was down regulated, and the number of S-phase cells was significantly decreased in the right ventricle of cKO heart. These results suggest that Hey2 plays an important role in right ventricle development during cardiac morphogenesis, at least in part, through mitigating Tbx2-dependent inhibition of Mycn expression.

A 24-segment fractional shortening of the fetal heart using FetalHQ.

OBJECTIVES: To evaluate 24-segment fractional shortening (FS) of the fetal heart using FetalHQ by speckle-tracking regarding reproducibility and the change with advancing gestation. METHODS: Eighty-one pregnant women at 18-21+6 and 28-31+6 weeks of gestation were studied using FetalHQ with the speckle-tracking technique to calculate 24-segment FS of left and right ventricles. Intra- and inter-class correlation coefficients and intra- and inter-observer agreements of measurements for FS were assessed in each segment. RESULTS: With respect to intra-observer reproducibility, all FS values showed correlations between 0.575 and 0.862 for the left ventricle, with good intra-observer agreements except for left ventricular segments 14-24. Right ventricular FS values showed correlations between 0.334 and 0.685, with good intra-observer agreements. With respect to inter-observer reproducibility, all FS values showed correlations between 0.491 and 0.801 for the left ventricle, with good intra-observer agreements except for left ventricular segments 16-22. Right ventricular FS values showed correlations between 0.375 and 0.575, with good inter-observer agreements. There were significant differences in the mean FS values in the basal segment (segments 1-5) of the left ventricle between 18 and 21+6 and 28-31+6 weeks of gestation (p<0.05), whereas there were significant differences in all mean FS values in the right ventricle between both gestational ages (p<0.05). CONCLUSIONS: These results suggest that the reproducibility of the 24-segment FS of the fetal heart using FetalHQ is fair. However, there may be significant differences in FS values with advancing gestational age, especially for the right ventricle.

Conditional inactivation of Foxc1 and Foxc2 in neural crest cells leads to cardiac abnormalities.

Cardiac neural crest cells (cNCCs) are required for normal heart development. cNCCs are a multipotent and migratory cell lineage that differentiates into multiple cell types. cNCCs migrate into the developing heart to contribute to the septation of the cardiac outflow tract (OFT). Foxc1 and Foxc2 are closely related members of the FOX (Forkhead box) transcription factor family and are expressed in cNCC during heart development. However, the precise role of Foxc1 and Foxc2 in cNCCs has yet to be fully described. We found that compound NCC-specific Foxc1;Foxc2 mutant embryos exhibited persistent truncus arteriosus (PTA), ventricular septal defects (VSDs), and thinning of the ventricular myocardium. Loss of Foxc1/c2 expression in cNCCs resulted in abnormal patterns of cNCC migration into the OFT without the formation of the aorticopulmonary septum. Further, loss of Foxc1 expression in cNCCs resulted in normal OFT development but abnormal ventricular septal formation. In contrast, loss of Foxc2 expression in NCCs led to no obvious cardiac abnormalities. Together, we provide evidence that Foxc1 and Foxc2 in cNCCs are cooperatively required for proper cNCC migration, the formation of the OFT septation, and the development of the ventricles. Our data also suggests that Foxc1 expression may play a larger role in ventricular development compared to Foxc2.

Transgenerational effects of maternal obesity and gestational diabetes on offspring body composition and left ventricle mass: the Finnish Gestational Diabetes Prevention Study (RADIEL) 6-year follow-up.

AIM: To investigate the influence of maternal adiposity and gestational diabetes on offspring body composition and left ventricle mass in early childhood. METHODS: The observational follow-up study included 201 mother-child pairs, a sub-cohort from the Finnish Gestational Diabetes Prevention Study, who were recruited 6.1 ± 0.5 (mean ± SD) years postpartum, aiming for an equal number of mothers with and without gestational diabetes. RESULTS: Maternal pre-pregnancy BMI (mean ± SD; 30.5 ± 5.6 kg/m2 ) was associated with child body fat percentage [0.26 (95% CI; 0.08, 0.44)% increase in child body fat per 1 kg/m2 increase in pre-pregnancy BMI of mothers with obesity] and was reflected in child BMI Z-score (mean ± SD; 0.45 ± 0.93). Left ventricle mass, left ventricle mass index and left ventricle mass Z-score were not associated with gestational diabetes, pre-pregnancy BMI or child body fat percentage. After adjusting for child sex, body fat percentage, systolic blood pressure, pre-pregnancy BMI and maternal lean body mass, left ventricle mass increased by 3.08 (95% CI; 2.25, 3.91) g for each 1 kg in child lean body mass. CONCLUSIONS: Left ventricle mass at 6 years of age is determined predominantly by lean body mass. Maternal pre-gestational adiposity is reflected in child, but no direct association between left ventricle mass and child adiposity or evidence of left ventricle mass foetal programming related to gestational diabetes and maternal adiposity was observed in early childhood.

Normal right and left ventricular volumes prospectively obtained from cardiovascular magnetic resonance in awake, healthy, 0- 12 year old children.

INTRODUCTION: Pediatric z scores are necessary to describe size and structure of the heart in growing children, however, development of an accurate z score calculator requires robust normal datasets, which are difficult to obtain with cardiovascular magnetic resonance (CMR) in children. Motion-corrected (MOCO) cines from re-binned, reconstructed real-time cine offer a free-breathing, rapid acquisition resulting in cines with high spatial and temporal resolution. In combination with child-friendly positioning and entertainment, MOCO cine technique allows for rapid cine volumetry in patients of all ages without sedation. Thus, our aim was to prospectively enroll normal infants and children birth-12 years for creation and validation of a z score calculator describing normal right ventricular (RV) and left ventricular (LV) size. METHODS: With IRB approval and consent/assent, 149 normal children successfully underwent a brief noncontrast CMR on a 1.5 T scanner including MOCO cines in the short axis, and RV and LV volumes were measured. 20% of scans were re-measured for interobserver variability analyses. A general linear modeling (GLM) framework was employed to identify and properly represent the relationship between CMR-based assessments and anthropometric data. Scatter plots of model fit and Akaike's information criteria (AIC) results were used to guide the choice among alternative models. RESULTS: A total of 149 subjects aged 22 days-12 years (average 5.1 ± 3.6 years), with body surface area (BSA) range 0.21-1.63 m2 (average 0.8 ± 0.35 m2) were scanned. All ICC values were > 95%, reflecting excellent agreement between raters. The model that provided the best fit of volume measure to the data included BSA with higher order effects and gender as independent variables. Compared with earlier z score models, there is important additional growth inflection in early toddlerhood with similar z score prediction in later childhood. CONCLUSIONS: Free-breathing, MOCO cines allow for accurate, reliable RV and LV volumetry in a wide range of infants and children while awake. Equations predicting fit between LV and RV normal values and BSA are reported herein for purposes of creating z scores. TRIAL REGISTRATION: clinicaltrials.gov NCT02892136, Registered 7/21/2016.

Differences in cardiac geometry in relation to body size among neonates with abnormal prenatal growth and body size at birth.

OBJECTIVES: Both excessive and restricted fetal growth are associated with changes in cardiac geometry and function at birth. There are significant issues when indexing cardiac parameters for body size in the neonatal period. The aims of this study were to determine to what extent cardiac geometry is dependent on body size in term and preterm neonates with restricted or excessive fetal growth and how this is affected by adiposity. METHODS: This was a cross-sectional study of neonates born between 31 and 42 weeks of gestation, divided into three groups: (1) small-for-gestational age (SGA, birth weight > 2 SD below the mean); (2) large-for-gestational age (LGA, birth weight > 2 SD above the mean); and (3) appropriate-for-gestational-age controls (AGA, birth weight ≤ 2 SD from the mean). Cardiac geometry and function were compared between the study groups, adjusting for body size. The potential impact of infant adiposity and maternal disease was assessed. RESULTS: In total, 174 neonates were included, of which 39 were SGA, 45 were LGA and 90 were AGA. Body size was reflected in cardiac dimensions, with differences in cardiac dimensions disappearing between the SGA and AGA groups when indexed for body surface area (BSA) or thoracic circumference. The same was true for the differences in atrial and ventricular areas between the LGA and AGA groups. However, left ventricular inflow and outflow tract dimensions did not follow this trend as, when indexed for BSA, they were associated negatively with adiposity, resulting in diminished dimensions in LGA compared with AGA and SGA neonates. Adiposity was associated positively with left ventricular mass, right ventricular length and area and right atrial area. The SGA group showed increased right ventricular fractional area change, possibly reflecting differences in the systolic function of the right ventricle. We found evidence of altered diastolic function between the groups, with the mitral valve inflow E- to lateral E'-wave peak velocity ratio being increased in the LGA group and decreased in the SGA group. CONCLUSIONS: Cardiac geometry is explained by body size in both term and preterm AGA and SGA infants. However, the nature of the relationship between body size and cardiac dimensions may be influenced by adiposity in LGA infants, leading to underestimation of left ventricular inflow and outflow tract dimensions when adjusted for BSA. Adjustments for thoracic circumference provide similar results to those for BSA. Copyright © 2020 ISUOG. Published by John Wiley & Sons Ltd.

Hand factor ablation causes defective left ventricular chamber development and compromised adult cardiac function.

Coordinated cardiomyocyte growth, differentiation, and morphogenesis are essential for heart formation. We demonstrate that the bHLH transcription factors Hand1 and Hand2 play critical regulatory roles for left ventricle (LV) cardiomyocyte proliferation and morphogenesis. Using an LV-specific Cre allele (Hand1LV-Cre), we ablate Hand1-lineage cardiomyocytes, revealing that DTA-mediated cardiomyocyte death results in a hypoplastic LV by E10.5. Once Hand1-linage cells are removed from the LV, and Hand1 expression is switched off, embryonic hearts recover by E16.5. In contrast, conditional LV loss-of-function of both Hand1 and Hand2 results in aberrant trabeculation and thickened compact zone myocardium resulting from enhanced proliferation and a breakdown of compact zone/trabecular/ventricular septal identity. Surviving Hand1;Hand2 mutants display diminished cardiac function that is rescued by concurrent ablation of Hand-null cardiomyocytes. Collectively, we conclude that, within a mixed cardiomyocyte population, removal of defective myocardium and replacement with healthy endogenous cardiomyocytes may provide an effective strategy for cardiac repair.

CTCF counter-regulates cardiomyocyte development and maturation programs in the embryonic heart.

Cardiac progenitors are specified early in development and progressively differentiate and mature into fully functional cardiomyocytes. This process is controlled by an extensively studied transcriptional program. However, the regulatory events coordinating the progression of such program from development to maturation are largely unknown. Here, we show that the genome organizer CTCF is essential for cardiogenesis and that it mediates genomic interactions to coordinate cardiomyocyte differentiation and maturation in the developing heart. Inactivation of Ctcf in cardiac progenitor cells and their derivatives in vivo during development caused severe cardiac defects and death at embryonic day 12.5. Genome wide expression analysis in Ctcf mutant hearts revealed that genes controlling mitochondrial function and protein production, required for cardiomyocyte maturation, were upregulated. However, mitochondria from mutant cardiomyocytes do not mature properly. In contrast, multiple development regulatory genes near predicted heart enhancers, including genes in the IrxA cluster, were downregulated in Ctcf mutants, suggesting that CTCF promotes cardiomyocyte differentiation by facilitating enhancer-promoter interactions. Accordingly, loss of CTCF disrupts gene expression and chromatin interactions as shown by chromatin conformation capture followed by deep sequencing. Furthermore, CRISPR-mediated deletion of an intergenic CTCF site within the IrxA cluster alters gene expression in the developing heart. Thus, CTCF mediates local regulatory interactions to coordinate transcriptional programs controlling transitions in morphology and function during heart development.

FoxN3 is necessary for the development of the interatrial septum, the ventricular trabeculae and the muscles at the head/trunk interface in the African clawed frog, Xenopus laevis (Lissamphibia: Anura: Pipidae).

BACKGROUND: Fox genes are a large family of transcription factors that play diverse roles in the immune system, metabolism, cancer, cell cycle, and animal development. It has been shown that FoxN3 is indispensable for normal craniofacial development in the mouse and the African clawed frog, Xenopus laevis. Morpholino-mediated knockdown of FoxN3 in X. laevis delays overall development of early tadpole stages and causes eye defects, the absence of some cranial nerve branches, and malformations of the cranial skeleton and some cranial muscles, while the skeleton, nerves and muscles of the trunk are unaffected. RESULTS: We report a delay in heart morphogenesis, the absence of the interatrial septum, and a reduction and compaction of the ventricular trabeculation after knockdown of FoxN3 in X. laevis. Furthermore, we found malformations of the cucullaris and diaphragmatico-branchialis muscles, two head muscles that develop in the head/trunk interface of X. laevis. CONCLUSIONS: FoxN3 is necessary for the development of the interatrial septum and trabeculae in the frog heart, as well as the cranial muscles developing in the head/trunk interface. This gives the first evidence for a dependence on the head myogenic program of the cucullaris muscle in an anuran species.

Multicolor mapping of the cardiomyocyte proliferation dynamics that construct the atrium.

The orchestrated division of cardiomyocytes assembles heart chambers of distinct morphology. To understand the structural divergence of the cardiac chambers, we determined the contributions of individual embryonic cardiomyocytes to the atrium in zebrafish by multicolor fate-mapping and we compare our analysis to the established proliferation dynamics of ventricular cardiomyocytes. We find that most atrial cardiomyocytes become rod-shaped in the second week of life, generating a single-muscle-cell-thick myocardial wall with a striking webbed morphology. Inner pectinate myofibers form mainly by direct branching, unlike delamination events that create ventricular trabeculae. Thus, muscle clones assembling the atrial chamber can extend from wall to lumen. As zebrafish mature, atrial wall cardiomyocytes proliferate laterally to generate cohesive patches of diverse shapes and sizes, frequently with dominant clones that comprise 20-30% of the wall area. A subpopulation of cardiomyocytes that transiently express atrial myosin heavy chain (amhc) contributes substantially to specific regions of the ventricle, suggesting an unappreciated level of plasticity during chamber formation. Our findings reveal proliferation dynamics and fate decisions of cardiomyocytes that produce the distinct architecture of the atrium.

Mechanisms of in utero cortisol effects on the newborn heart revealed by transcriptomic modeling.

We have identified effects of elevated maternal cortisol (induced by maternal infusion 1 mg·kg-1·day-1) on fetal cardiac maturation and function using an ovine model. Whereas short-term exposure (115-130-day gestation) increased myocyte proliferation and Purkinje fiber apoptosis, infusions until birth caused bradycardia with increased incidence of arrhythmias at birth and increased perinatal death, despite normal fetal cortisol concentrations from 130 days to birth. Statistical modeling of the transcriptomic changes in hearts at 130 and 140 days suggested that maternal cortisol excess disrupts cardiac metabolism. In the current study, we modeled pathways in the left ventricle (LV) and interventricular septum (IVS) of newborn lambs after maternal cortisol infusion from 115 days to birth. In both LV and IVS the transcriptomic model indicated over-representation of cell cycle genes and suggested disruption of cell cycle progression. Pathways in the LV involved in cardiac architecture, including SMAD and bone morphogenetic protein ( BMP) were altered, and collagen deposition was increased. Pathways in IVS related to metabolism, calcium signaling, and the actin cytoskeleton were altered. Comparison of the effects of maternal cortisol excess to the effects of normal maturation from day 140 to birth revealed that only 20% of the genes changed in the LV were consistent with normal maturation, indicating that chronic elevation of maternal cortisol alters normal maturation of the fetal myocardium. These effects of maternal cortisol on the cardiac transcriptome, which may be secondary to metabolic effects, are consistent with cardiac remodeling and likely contribute to the adverse impact of maternal stress on perinatal cardiac function.

Right Ventricular Involution: Big Changes in Small Hearts.

BACKGROUND: Before birth, the fetal right ventricle (RV) is the pump for the systemic circulation and is about as thick as the left ventricle (LV). After birth, the RV becomes the pump for the lower pressure pulmonary circulation, and the RV chamber elongates without change in its wall thickness. We hypothesize that the fetal RV may be a model of compensated RV hypertrophy, and understanding this process may aid in discovering therapeutic strategies for RV failure. METHODS: We performed a literature review and identified pertinent articles from 1980 to present. RESULTS: The following topics were identified to be most pertinent in right ventricular involution: morphologic and histologic changes of the RV, cellular proliferation and terminal differentiation, the effect of stress on RV development, excitation contraction coupling and inotropic response change over time, and the amount of apoptosis through RV development. CONCLUSIONS: The RV changes on multiple levels after its transition from systemic to pulmonary circulation. Although published literature has variable results due partly from differences between animal models, the literature shows a clear need for more research in the field.

Fetal cardiac growth is associated with in utero gut colonization.

BACKGROUND AND AIMS: Intra-uterine metabolic environment predicts newborns' cardiac morphology, metabolism and future health. In adults, gut microbiota composition relates to altered cardiac structure and metabolism. We investigated the relationship between gut microbiota colonization and fetal cardiac growth. METHODS AND RESULTS: Bacterial composition in meconium samples of 26 healthy, full-term newborns was assessed by 16S rDNA gene sequencing. Its relationship with birth echocardiographic parameters, and the interaction with cord blood levels of inflammatory markers were investigated. Correlative and cluster analysis, linear discriminant analysis effect size and predictive functional analysis based on Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were applied. Fetal left ventricle growth was related to gut microbiota composition at birth. Specifically, left ventricle posterior wall thickness (LVPW) greater than 4 mm was associated with lower microbiota beta and alpha diversity, depletion (LDA score > 3) of several bacteria at each taxonomic level, including Lactobacillales, and enrichment (LDA score > 5) in Enterobacteriales and Enterobacteriaceae. The latter was significantly related to cord blood gamma-glutamyltransferase levels (r = 0.58, p = 0.0057). Functionally, a thicker LVPW was related to up-regulation of pathways involved in lipopolysaccharide biosynthesis (+50%, p = 0.045 in correlative analysis) and energy metabolism (+12%, p = 0.028), and down-regulation of pathways involved in xenobiotic biodegradation (-21 to -53%, p = 0.0063-0.039), PPAR signaling (-24%, p = 0.021) and cardiac muscle contraction (-100%, p = 0.049). CONCLUSION: Fetal cardiac growth and gut colonization are associated. Greater neonatal LVPW thickness is related to lower diversity of the gut microbiota community, depletion of bacteria having anti-remodeling effects, and enrichment in bacteria functionally linked to inflammation.

Reference Intervals and Percentile Curves of Echocardiographic Left Ventricular Mass, Relative Wall Thickness and Ejection Fraction in Healthy Children and Adolescents.

Despite the clinical utility of echocardiography to measure cardiac target organ injury (TOI) there are scarcities of data about the reference intervals (RIs) and percentiles of left ventricular (LV) mass (LVM) and derived indexes (LVMI and LVMI2.7), relative wall thickness (LVRWT) and ejection fraction (LVEF) from population-based studies in children and adolescents. The aim of this study was to generate reference intervals RIs of LVM and derived indexes (LVMI and LVMI2.7), LVRWT, and LVEF obtained in healthy children, adolescents, and young adults from a South-American population. Echocardiographic studies were obtained in 1096 healthy subjects (5-24 years). Age and sex-specific RIs of LVM, LVMI, LVMI2.7, LVRWT, and LVEF were generated using parametric regression based on fractional polynomials. After covariate analysis (i.e., adjusting by age, body surface area) specific sex-specific RIs were evidenced as necessaries. Age and sex-specific 1st, 2.5th, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97.5th, and 99th percentile and curves were reported and compared with previously reported RIs. RIs showed high concordance and complementarity with what was previously reported for the population of North-American children (0-18 years old). In conclusion, in children and adolescents the interpretation of the LVM, LVMIs, LVRWT, and LVEF RIs requires sex-related RIs. This study provides the largest Argentinean database concerning RIs and percentile curves of LVM, LVMIs, LVRWT, and LVEF as markers of cardiac TOI obtained in healthy children and adolescents. These data are valuable in that they provide RIs values with which data of populations of children, adolescents can be compared.

Early and long-term results of surgery for secondary mitral regurgitation with a damaged heart.

BACKGROUND: Surgery for secondary mitral regurgitation is still controversial, especially when the left ventricle is damaged. The Mitra Clip has been shown to be safe and effective for certain patient groups but does not offer superior control of mitral regurgitation compared with the surgery. If performed safely, the surgery can provide greater benefits over the long-term. The objective of this study was to retrospectively investigate the early and long-term results of mitral valve surgery for secondary mitral valve regurgitation with a damaged, dilated left ventricle. METHODS: Patients with ejection fraction <40% and left ventricular end-diastolic/systolic diameter >50/40 mm who underwent mitral valve surgery for secondary mitral regurgitation were investigated retrospectively. RESULTS: The mean age of the 80 identified cases was 65.7 years, and 63 patients were male. Preoperative echocardiograms showed a mean ejection fraction of 25.2% and mean left ventricular diameters in diastole/systole of 64.5/56.9 mm, respectively. Mitral valve replacement was performed in 39 cases, and mitral valve plasty in 41 cases. The most common concomitant procedures were coronary artery bypass grafting and tricuspid valve surgery (41.3% each). Mitral regurgitation improved significantly from 3.5 to 0.83, and no operative or in-hospital deaths were encountered. Long-term results showed actual 1-, 3- and 5-year survival rates of 93.1%, 80.0%, and 64.7%, respectively (mean follow-up, 1264 days). CONCLUSIONS: Early results of this study were good and long-term results were acceptable. Our results suggest that mitral valve surgery is feasible for secondary mitral valve regurgitation even in dilated, damaged hearts.

Foxc2 is required for proper cardiac neural crest cell migration, outflow tract septation, and ventricle expansion.

BACKGROUND: Proper development of the great vessels of the heart and septation of the cardiac outflow tract requires cardiac neural crest cells. These cells give rise to the parasympathetic cardiac ganglia, the smooth muscle layer of the great vessels, some cardiomyocytes, and the conotruncal cushions and aorticopulmonary septum of the outflow tract. Ablation of cardiac neural crest cells results in defective patterning of each of these structures. Previous studies have shown that targeted deletion of the forkhead transcription factor C2 (Foxc2), results in cardiac phenotypes similar to that derived from cardiac neural crest cell ablation. RESULTS: We report that Foxc2-/- embryos on the 129s6/SvEv inbred genetic background display persistent truncus arteriosus and hypoplastic ventricles before embryonic lethality. Foxc2 loss-of-function resulted in perturbed cardiac neural crest cell migration and their reduced contribution to the outflow tract as evidenced by lineage tracing analyses together with perturbed expression of the neural crest cell markers Sox10 and Crabp1. Foxc2 loss-of-function also resulted in alterations in PlexinD1, Twist1, PECAM1, and Hand1/2 expression in association with vascular and ventricular defects. CONCLUSIONS: Our data indicate Foxc2 is required for proper migration of cardiac neural crest cells, septation of the outflow tract, and development of the ventricles. Developmental Dynamics 247:1286-1296, 2018. © 2018 Wiley Periodicals, Inc.