Effect of Preterm Birth on Cardiac and Cardiomyocyte Growth and the Consequences of Antenatal and Postnatal Glucocorticoid Treatment

Neonatal hyperoxia exposure leads to developmental programming of cardiovascular and renal disease in adult rats

Premature infants are often exposed to hyperoxia. However, there is limited data regarding the mechanistic underpinnings linking neonatal hyperoxia exposure and its contribution to cardio-renal dysfunction in adults born preterm. Our objective was to determine whether neonatal hyperoxia induces systemic vascular stiffness and cardio-renal dysfunction in adulthood. Newborn rats were randomly assigned to room air (RA) or hyperoxia (85% O2) from postnatal day 1 to 14, then recovered in RA until 1 year of life. Arterial stiffness, cardio-renal histomorphometry, and fibrosis in the aorta, heart, and kidney were assessed. RNA-sequencing (RNA-seq) of the aorta and kidney was also done. Adult rats exposed to neonatal hyperoxia had increased aortic and mesenteric artery stiffness as demonstrated by wire and pressure myography. They also had cardiomyocyte hypertrophy, glomerulomegaly, and tubular injury. Hyperoxia exposure altered the transcriptome profile associated with fibrosis and matrix remodeling in the aorta and kidney. There was also increased TGF-β1 levels and fibrosis in the aorta, left ventricle, and kidney. In conclusion, neonatal hyperoxia exposure was associated with systemic vascular and cardio-renal alterations in 1-year-old rats. Further studies to determine how targeted therapies could reprogram cardio-renal injury after neonatal hyperoxia exposure are indicated.

Cardiac Development and Related Clinical Considerations

The anatomy, physiology, and hemodynamics of the premature heart vary along the range of gestational ages cared for in neonatal intensive care units, from 22 weeks to term gestation. Clinical management of the preterm neonate should account for this heterogenous development. This requires an understanding of the impact of ex utero stressors on immature and disorganized cardiac tissue, the different state of hemodynamics across intracardiac shunts impacting the natural transition from fetal to neonatal life, and the effects of intensive pharmacologic and non-pharmacologic interventions that have systemic consequences influencing cardiac function. This article provides a review of the increasing but still limited body of literature on the anatomy, hemodynamics, and electrophysiology of the preterm heart with relevant clinical considerations.

Short-term effects of antenatal betamethasone on fetal cardiovascular and circulation status: A quasi-experimental observational (before-after) study

Background

The administration of antenatal corticosteroid is a standard treatment to reduce the rate of perinatal mortality and morbidity; however, there is limited evidence regarding the potential effects of betamethasone on the constriction of the ductus arteriosus (DA).

Objective

This study aimed to investigate the short-term effects of antenatal betamethasone on fetal cardiovascular and circulation status.

Materials and Methods

This quasi-experimental observational (before-after) study was conducted on 32 singleton fetuses. The participants were healthy pregnant women with a diagnosis of placenta accreta spectrum who were eligible for 2 doses of betamethasone and referred to prenatal care clinic, Vali-E-Asr hospital, Tehran, Iran from January 2021-May 2022. The results of fetal echocardiography and Doppler sonography were compared before and after the administration of antenatal corticosteroid therapy.

Results

Following betamethasone injection, significant increases were observed in peak systolic and diastolic velocity of the DA without constriction of the DA (p < 0.001, p = 0.002 respectively). However, no significant changes were observed in right ventricular function, tricuspid valve function, Doppler of ductus venous, and peak systolic velocity of the aortic isthmus (p > 0.05). Doppler examination of the uterine, umbilical, and middle cerebral arteries also showed no significant changes (p > 0.05).

Conclusion

Considering the benefits of antenatal corticosteroid therapy, its administration seems reasonable in preterm births. The transient changes in ductal blood flow are not prohibitive.

HDL Function across the Lifespan: From Childhood, to Pregnancy, to Old Age

The function of high-density lipoprotein (HDL) particles has emerged as a promising therapeutic target and the measurement of HDL function is a promising diagnostic across several disease states. The vast majority of research on HDL functional biology has focused on adult participants with underlying chronic diseases, whereas limited research has investigated the role of HDL in childhood, pregnancy, and old age. Yet, it is apparent that functional HDL is essential at all life stages for maintaining health. In this review, we discuss current data regarding the role of HDL during childhood, pregnancy and in the elderly, how disturbances in HDL may lead to adverse health outcomes, and knowledge gaps in the role of HDL across these life stages.

Case report: A case of spinal muscular atrophy in a preterm infant: risks and benefits of treatment

Spinal muscular atrophy (SMA) is a neuromuscular genetic disorder caused by the loss of lower motor neurons leading to progressive muscle weakness and atrophy. With the rise of novel therapies and early diagnosis on newborn screening (NBS), the natural history of SMA has been evolving. Earlier therapeutic interventions can modify disease outcomes and improve survival. The role of treatment in infants born preterm is an important question given the importance of early intervention. In this study, we discuss the case of an infant born at 32 weeks who was diagnosed with SMA on NBS and was treated with Spinraza® (Nusinersen) and Zolgensma® (Onasemnogene abeparvovec-xioi) within the first 2 months of life. With the scarce evidence that currently exists, clinicians should be aware of the efficacy and safety impact of early therapy particularly in the preterm infant.

Association of Gestational Age at Birth With Left Cardiac Dimensions at Near-Term Corrected Age Among Extremely Preterm Infants

BACKGROUND

Remodeling and altered ventricular geometry have been described in adults born preterm. Although they seem to have an adverse cardiac phenotype, the impact of various degrees of prematurity on cardiac development has been scarcely reported. In this study, we evaluated the impact of gestational age (GA) at birth on cardiac dimensions and function at near-term age among extremely preterm infants.

METHODS

This is a retrospective single-center cohort study of infants born at <29 weeks of GA between 2015 and 2019. Infants with available clinically acquired echocardiography between 34 and 43 weeks were included. Two groups were investigated: those born <26 weeks and those born ≥26 weeks. All measurements were done by an expert masked to clinical data using the raw images. The primary outcome was measurements of cardiac dimensions and function based on GA group. Secondary outcomes were the association between cardiac dimensions and postnatal steroid exposure and with increments of GA at birth.

RESULTS

A total of 205 infants were included (<26 weeks, n = 102; ≥26 weeks, n = 103). At time of echocardiography, weight (2.4 ± 0.5 vs 2.5 ± 0.5 kg, P = .86) and age (37.2 ± 1.6 vs 37.1 ± 1.9 weeks, P = .74) were similar between groups. There was no difference in metrics of right-sided dimensions and function. However, left-sided dimensions were decreased in infants born <26 weeks, including systolic left ventricle (LV) diameter (1.06 ± 0.20 cm vs 1.12 ± 0.18 cm, P = .02), diastolic LV length (2.85 ± 0.37 vs 3.02 ± 0.57 cm, P = .02), and estimated LV end-diastolic volume (5.36 ± 1.69 vs 6.01 ± 1.79 mL, P = .02).

CONCLUSIONS

In our cohort of very immature infants, birth at the extreme of prematurity was associated with smaller left cardiac dimensions around 36 weeks of corrected age. Future longitudinal prospective studies should evaluate further the impact of prematurity on LV development and performance and their long-term clinical impact.

Cardioprotective Effects of Dexmedetomidine in an Oxidative-Stress In Vitro Model of Neonatal Rat Cardiomyocytes

Preterm birth is a risk factor for cardiometabolic disease. The preterm heart before terminal differentiation is in a phase that is crucial for the number and structure of cardiomyocytes in further development, with adverse effects of hypoxic and hyperoxic events. Pharmacological intervention could attenuate the negative effects of oxygen. Dexmedetomidine (DEX) is an α2-adrenoceptor agonist and has been mentioned in connection with cardio-protective benefits. In this study, H9c2 myocytes and primary fetal rat cardiomyocytes (NRCM) were cultured for 24 h under hypoxic condition (5% O₂), corresponding to fetal physioxia (pO₂ 32-45 mmHg), ambient oxygen (21% O₂, pO₂ ~150 mmHg), or hyperoxic conditions (80% O₂, pO₂ ~300 mmHg). Subsequently, the effects of DEX preconditioning (0.1 µM, 1 µM, 10 µM) were analyzed. Modulated oxygen tension reduced both proliferating cardiomyocytes and transcripts (CycD2). High-oxygen tension induced hypertrophy in H9c2 cells. Cell-death-associated transcripts for caspase-dependent apoptosis (Casp3/8) increased, whereas caspase-independent transcripts (AIF) increased in H9c2 cells and decreased in NRCMs. Autophagy-related mediators (Atg5/12) were induced in H9c2 under both oxygen conditions, whereas they were downregulated in NRCMs. DEX preconditioning protected H9c2 and NRCMs from oxidative stress through inhibition of transcription of the oxidative stress marker GCLC, and inhibited the transcription of both the redox-sensitive transcription factors Nrf2 under hyperoxia and Hif1α under hypoxia. In addition, DEX normalized the gene expression of Hippo-pathway mediators (YAP1, Tead1, Lats2, Cul7) that exhibited abnormalities due to differential oxygen tensions compared with normoxia, suggesting that DEX modulates the activation of the Hippo pathway. This, in the context of the protective impact of redox-sensitive factors, may provide a possible rationale for the cardio-protective effects of DEX in oxygen-modulated requirements on survival-promoting transcripts of immortalized and fetal cardiomyocytes.

Introducing and Implementing Genetic Assessment in Cardio-Obstetrics Clinical Practice: Clinical and Genetic Workup of Patients with Cardiomyopathy

Cardiovascular disease (CVD) during pregnancy varies significantly worldwide, influenced by factors such as access to healthcare, delayed diagnosis, causes, and risk factors. Our study sought to explore the spectrum of CVD present in pregnant women in the United Arab Emirates to better understand this population's unique needs and challenges. Central to our study is an emphasis on the importance of implementing a multidisciplinary approach that involves the collaboration of obstetricians, cardiologists, geneticists, and other healthcare professionals to ensure that patients receive comprehensive and coordinated care. This approach can also help identify high-risk patients and implement preventive measures to reduce the occurrence of adverse maternal outcomes. Furthermore, increasing awareness among women about the risk of CVD during pregnancy and obtaining detailed family histories can help in the early identification and management of these conditions. Genetic testing and family screening can also aid in identifying inherited CVD that can be passed down through families. To illustrate the significance of such an approach, we provide a comprehensive analysis of five women's cases from our retrospective study of 800 women. The findings from our study emphasize the importance of addressing maternal cardiac health in pregnancy and the need for targeted interventions and improvements in the existing healthcare system to reduce adverse maternal outcomes.

Long-Term Transcriptomic Changes and Cardiomyocyte Hyperpolyploidy after Lactose Intolerance in Neonatal Rats

Many cardiovascular diseases originate from growth retardation, inflammation, and malnutrition during early postnatal development. The nature of this phenomenon is not completely understood. Here we aimed to verify the hypothesis that systemic inflammation triggered by neonatal lactose intolerance (NLI) may exert long-term pathologic effects on cardiac developmental programs and cardiomyocyte transcriptome regulation. Using the rat model of NLI triggered by lactase overloading with lactose and the methods of cytophotometry, image analysis, and mRNA-seq, we evaluated cardiomyocyte ploidy, signs of DNA damage, and NLI-associated long-term transcriptomic changes of genes and gene modules that differed qualitatively (i.e., were switched on or switched off) in the experiment vs. the control. Our data indicated that NLI triggers the long-term animal growth retardation, cardiomyocyte hyperpolyploidy, and extensive transcriptomic rearrangements. Many of these rearrangements are known as manifestations of heart pathologies, including DNA and telomere instability, inflammation, fibrosis, and reactivation of fetal gene program. Moreover, bioinformatic analysis identified possible causes of these pathologic traits, including the impaired signaling via thyroid hormone, calcium, and glutathione. We also found transcriptomic manifestations of increased cardiomyocyte polyploidy, such as the induction of gene modules related to open chromatin, e.g., "negative regulation of chromosome organization", "transcription" and "ribosome biogenesis". These findings suggest that ploidy-related epigenetic alterations acquired in the neonatal period permanently rewire gene regulatory networks and alter cardiomyocyte transcriptome. Here we provided first evidence indicating that NLI can be an important trigger of developmental programming of adult cardiovascular disease. The obtained results can help to develop preventive strategies for reducing the NLI-associated adverse effects of inflammation on the developing cardiovascular system.

Association of Preterm Birth With Prevalent and Incident Hypertension, Early-Onset Hypertension, and Cardiovascular Disease in the Women's Health Initiative

Increasing evidence suggests preterm birth is a risk factor for hypertension and cardiovascular disease (CVD) in adulthood. Whether there is effect modification by hypertension on CVD risk is unknown. To investigate the associations between preterm birth, hypertension, and incident CVD, we identified 2,303 women aged 50 to 79 years who self-reported being born preterm from the Women's Health Initiative. Using multivariable logistic regression, prevalent hypertension at enrollment, age at hypertension diagnosis, and antihypertensive medication use were compared by birth status (preterm, full-term). Risk of incident hypertension, coronary heart disease, and CVD were analyzed using multivariable Cox proportional-hazard models. Both models adjusted for age, race/ethnicity, education, smoking, physical activity, body mass index, and diabetes mellitus. Significant associations were found between preterm birth and prevalent hypertension (37% vs 33.1%; adjusted odds ratio 1.26 [95% confidence interval (CI) 1.15 to 1.28] p = <0.0001), early-onset hypertension (<50 years) (14.7% vs 11.7%; adjusted odds ratio 1.31, 95% CI 1.15 to 1.48, p = <0.0001), and incident hypertension (53.2% vs 51%; ajusted hazard ratio 1.10, 95% CI 1.03 to 1.19, p = 0.008). Preterm-born women reported taking more antihypertensive medications (2.9% vs 2.6%, p = 0.04). Preterm birth had a nonsignificant association with CVD risk, but when stratified by prevalent hypertension, women born preterm without hypertension had elevated CVD risk compared with women born full-term without prevalent hypertension. Women with prevalent hypertension, preterm and full-term, had similar magnitudes of elevations in CVD risk. In conclusion, preterm birth increases the risk of hypertension and coronary heart disease. With 10% of the population born preterm, birth history should be assessed as a CVD risk factor.

Effect of preterm birth in rats on proliferation and hyperplasia of cardiomyocytes

Aim. To identify the effect of preterm birth on proliferation and hyperplasia of cardiomyocytes in the early postnatal period of ontogenesis in rats.

Materials and methods. Preterm birth (on day 21 and 21.5 of gestation) in Wistar rats was induced by subcutaneous administration of mifepristone. Immunohistochemistry was used to identify and calculate the number of Ki67-positive and Mklp2-positive cardiomyocytes in the left ventricle of preterm and full-term rats on days 1, 2, 3, 4, 5, and 6 of postnatal ontogenesis. Statistical analysis of morphometric parameters was performed using the Shapiro – Wilk test and Mann – Whitney test with the Bonferroni correction.

Results. We revealed an increase in the number of Ki67-positive cardiomyocytes in the left ventricle of the rats: on day 1 of postnatal ontogenesis (in the rats born on day 21 of gestation) and on days 3–5 of postnatal ontogenesis (in the rats born on day 21.5 of gestation). Preterm birth in rats did not result in a change in the number of Mklp2-positive cardiomyocytes in the left ventricular wall.

Conclusion. A change in the pattern of Ki67 expression by cardiomyocytes in the rats born 12 or 24 hours before full term was demonstrated in the early postnatal period of ontogenesis. An isolated increase in Ki67 expression without a change in Mklp2 expression by cardiomyocytes in the left ventricular wall of preterm rats indicates acceleration of cardiomyocyte hypertrophy. Shorter duration of prenatal development is associated with more pronounced morphological and functional rearrangements in the rat myocardium.

Gestational Diabetes Mellitus and Antenatal Corticosteroid Therapy-A Narrative Review of Fetal and Neonatal Outcomes

BACKGROUND

There, we review the pathogenesis of gestational diabetes mellitus (GDM), its influence on fetal physiology, and neonatal outcomes, as well as the usage of antenatal corticosteroid therapy (ACST) in pregnancies complicated by GDM.

METHODS

MEDLINE and PubMed search was performed for the years 1990-2022, using a combination of keywords on such topics. According to the aim of the investigation, appropriate articles were identified and included in this narrative review.

RESULTS

GDM is a multifactorial disease related to unwanted pregnancy course and outcomes. Although GDM has an influence on the fetal cardiovascular and nervous system, especially in preterm neonates, the usage of ACST in pregnancy must be considered taking into account maternal and fetal characteristics.

CONCLUSIONS

GDM has no influence on neonatal outcomes after ACST introduction. The ACST usage must be personalized and considered according to its gestational age-specific effects on the developing fetus.

Cardiopulmonary Exercise Testing in Childhood in Late Preterms: Comparison to Early Preterms and Term-Born Controls

Background: Late preterm (340−366 weeks gestational age [GA]) infants may have abnormal pulmonary development and possible exercise physiology parameters. We aim to assess the effect of late prematurity on exercise capacity in childhood and to compare it to early preterm (EP) (born < 300 GA), and to term healthy control (TC) (>370 week GA). Methods: Late preterm and early preterm (7−10 years) completed a cardiopulmonary exercise test (CPET) and spirometry and were compared to EP and to TC. Results: Eighty-four children (age 9.6 ± 1.0 years, 48% girls) participated. Twenty-one former LP were compared to 38 EP (15 with Bronchopulmonary dysplasia (BPD) [EP+], 23 without BPD [EP−]) and to 25 TC children. Peak oxygen uptake (peakV̇O2) was statistically lower than in the TC, but within the normal range, and without difference from the EP (LP 90.2 ± 15.1%, TC 112.4 ± 16.9%, p < 0.001; EP+ 97.3 ± 25.5%, EP− 85.4 ± 20.8%, p = 0.016 and p < 0.001, respectively, when compared with TC). Lung function (FEV1) was lower than normal only in the EP+ (75.6 ± 14.9% predicted, compared with 12.5 ± 87.8 in EP−, 87.5 ± 16.9 in LP and 91.0 ± 11.7 in TC). Respiratory and cardiac limitations were similar between all four study groups. Conclusions: This study demonstrated lower exercise capacity (peakV̇O2) in former LP children compared with healthy term children. Exercise capacity in LP was comparable to that of EP, with and without BPD. However, the exercise test parameters, specifically peakV̇O2, were within the normal range, and no significant physiological exercise limitations were found.

Antenatal Glucocorticoid Administration Promotes Cardiac Structure and Energy Metabolism Maturation in Preterm Fetuses

Although the rate of preterm birth has increased in recent decades, a number of preterm infants have escaped death due to improvements in perinatal and neonatal care. Antenatal glucocorticoid (GC) therapy has significantly contributed to progression in lung maturation; however, its potential effects on other organs remain controversial. Furthermore, the effects of antenatal GC therapy on the fetal heart show both pros and cons. Translational research in animal models indicates that constant fetal exposure to antenatal GC administration is sufficient for lung maturation. We have established a premature fetal rat model to investigate immature cardiopulmonary functions in the lungs and heart, including the effects of antenatal GC administration. In this review, we explain the mechanisms of antenatal GC actions on the heart in the fetus compared to those in the neonate. Antenatal GCs may contribute to premature heart maturation by accelerating cardiomyocyte proliferation, angiogenesis, energy production, and sarcoplasmic reticulum function. Additionally, this review specifically focuses on fetal heart growth with antenatal GC administration in experimental animal models. Moreover, knowledge regarding antenatal GC administration in experimental animal models can be coupled with that from developmental biology, with the potential for the generation of functional cells and tissues that could be used for regenerative medical purposes in the future.

Using human induced pluripotent stem cell-derived cardiomyocytes to understand the mechanisms driving cardiomyocyte maturation

Cardiovascular diseases are the leading cause of mortality and reduced quality of life globally. Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) provide a personalized platform to study inherited heart diseases, drug-induced cardiac toxicity, and cardiac regenerative therapy. However, the immaturity of CMs obtained by current strategies is a major hurdle in utilizing hiPSC-CMs at their fullest potential. Here, the major findings and limitations of current maturation methodologies to enhance the utility of hiPSC-CMs in the battle against a major source of morbidity and mortality are reviewed. The most recent knowledge of the potential signaling pathways involved in the transition of fetal to adult CMs are assimilated. In particular, we take a deeper look on role of nutrient sensing signaling pathways and the potential role of cap-independent translation mediated by the modulation of mTOR pathway in the regulation of cardiac gap junctions and other yet to be identified aspects of CM maturation. Moreover, a relatively unexplored perspective on how our knowledge on the effects of preterm birth on cardiovascular development can be actually utilized to enhance the current understanding of CM maturation is examined. Furthermore, the interaction between the evolving neonatal human heart and brown adipose tissue as the major source of neonatal thermogenesis and its endocrine function on CM development is another discussed topic which is worthy of future investigation. Finally, the current knowledge regarding transcriptional mediators of CM maturation is still limited. The recent studies have produced the groundwork to better understand CM maturation in terms of providing some of the key factors involved in maturation and development of metrics for assessment of maturation which proves essential for future studies on in vitro PSC-CMs maturation.

Understanding the Preterm Human Heart: What do We Know So Far?

Globally, preterm birth affects more than one in every 10 live births. Although the short‐term cardiopulmonary complications of prematurity are well known, long‐term health effects are only now becoming apparent. Indeed, preterm birth has been associated with elevated cardiovascular morbidity and mortality in adulthood. Experimental animal models and observational human studies point toward changes in heart morphology and function from birth to adulthood in people born preterm that may contribute to known long‐term risks. Moreover, recent data support the notion of a heterogeneous cardiac phenotype of prematurity, which is likely driven by various maternal, early, and late life factors. This review aims to describe the early fetal‐to‐neonatal transition in preterm birth, the different structural and functional changes of the preterm human heart across developmental stages, as well as potential factors contributing to the cardiac phenotype of prematurity.

The Disease Spectrum and Influencing Factors of NICU in Xiangxi, Underdeveloped Area of China: A 9-Year Retrospective Study

OBJECTIVE

Investigation of the basic conditions and disease spectrum in neonatal intensive care unit (NICU) from 2012 to 2020, in the underdeveloped area of Xiangxi, China.

METHODS

All newborns (N = 16,094) admitted to the NICU of a hospital in the Xiangxi area from 2012 to 2020 were selected for the retrospective study.

RESULTS

The average male/female ratio was 1.43:1, with 9,482 males and 6,612 females admitted to the NICU. The sample comprised 41.02% premature infants, and 56.52% had been delivered via cesarean delivery (CD). The most prevalent diseases diagnosed in the NICU were jaundice (22.01%), respiratory (18.45%) and neurological diseases (17.54%). Over the 9-year study window, the prevalence of jaundice and cardiovascular diseases increased, while respiratory and neurological diseases became less frequent. The prevalence of the remaining diseases remained unchanged. Prevalence of neonatal diseases is influenced by gender, patient sources, delivery methods, gestational age and birth weight (P < 0.05). The prevalence of neonatal diseases was significantly higher in males, infants born via CD, and in infants of lower gestational age and birth weight.

CONCLUSION

The study contributes in-depth information about infant characteristics in an NICU in an undeveloped region of China. In the past 9 years, the average proportion of premature infants in the NICU decreased to 37.38% in 2020, but this figure remains higher than the Chinese national average of 26.2%. Similarly, the CD rate is higher than the Chinese average. The spectrum of neonatal diseases in the NICU in Xiangxi area is drawn, included jaundice, respiratory and neurological diseases, primarily. Through statistical analysis, it is found that the types and prevalence of neonatal diseases are closely related to different gender, gestational age, patient sources, delivery methods, and birth weight (P < 0.05). Newborns of specific gestational age, birth weight and delivery method should be considered "at-risk" and targeted in the formulation of preventive measures. There is a great need to improve the diagnosis and treatment of neonatal diseases-and perinatal health care in general-to ensure improved outcomes for newborns admitted to NICUs in underdeveloped regions.