Elevated Blood Pressure with Reduced Left Ventricular and Aortic Dimensions in Adolescents Born Extremely Preterm

Echocardiography Assessment of Left Ventricular Function in Extremely Preterm Infants, Born at Less Than 28 Weeks' Gestation, With Bronchopulmonary Dysplasia and Systemic Hypertension

BACKGROUND

The survival of smaller and more immature premature infants has been associated with lifelong cardiorespiratory comorbidities. Infants with bronchopulmonary dysplasia (BPD) undergo routine screening echocardiography to evaluate for development of chronic pulmonary hypertension, a late manifestation of pulmonary vascular disease.

METHODS

Our aim was to evaluate left ventricular (LV) performance in infants with BPD and pulmonary vascular disease who developed systemic hypertension. We hypothesized that infants with hypertension were more likely to have impaired LV performance. We present a single-center cross-sectional study of premature infants born at less than 28 0/7 weeks' gestational age with a clinical diagnosis of BPD. Infants were categorized by the systolic arterial pressure (SAP) at time of echocardiography as hypertensive (SAP ≥90 mm Hg) or normotensive (SAP <90 mm Hg). Sixty-four patients were included.

RESULTS

Infants with hypertension showed altered LV diastolic function with prolonged tissue Doppler imaging-derived isovolumic relaxation time (54.2 ± 5.1 vs 42.9 ± 8.2, P < .001), lower E:A, and higher E:e'. Indices of left heart volume/pressure loading (left atrium:aorta and LV end-diastolic volume [6.1 ± 2 vs 4.2 ± 1.2, P < .001]) were also higher in the hypertensive group. Finally, infants in the hypertensive group had higher pulmonary vascular resistance index (4.42 ± 1.1 vs 3.69 ± 0.8, P = .004).

CONCLUSIONS

We conclude that extremely preterm infants with BPD who develop systemic hypertension are at risk of abnormal LV diastolic dysfunction. Increased pulmonary vascular resistance index in the hypertensive group may relate to pulmonary venous hypertension secondary to LV dysfunction. This is an important consideration in this cohort when selecting the physiologically most appropriate treatment.

Prematurity and Low Birth Weight and Their Impact on Childhood Growth Patterns and the Risk of Long-Term Cardiovascular Sequelae

Preterm birth (before 37 completed weeks of gestation) is a global health problem, remaining the main reason for neonatal mortality and morbidity. Improvements in perinatal and neonatal care in recent decades have been associated with a higher survival rate of extremely preterm infants, leading to a higher risk of long-term sequelae in this population throughout life. Numerous surveillance programs for formerly premature infants continue to focus on neurodevelopmental disorders, while long-term assessment of the impact of preterm birth and low birth weight on child growth and the associated risk of cardiovascular disease in young adults is equally necessary. This review will discuss the influence of prematurity and low birth weight on childhood growth and cardiovascular risk in children, adolescents and young adults. The risk of cardiovascular and metabolic disorders is increased in adult preterm survivors. In early childhood, preterm infants may show elevated blood pressure, weakened vascular growth, augmented peripheral vascular resistance and cardiomyocyte remodeling. Increased weight gain during the early postnatal period may influence later body composition, promote obesity and impair cardiovascular results. These adverse metabolic alterations contribute to an increased risk of cardiovascular incidents, adult hypertension and diabetes. Preterm-born children and those with fetal growth restriction (FGR) who demonstrate rapid changes in their weight percentile should remain under surveillance with blood pressure monitoring. A better understanding of lifelong health outcomes of preterm-born individuals is crucial for developing strategies to prevent cardiovascular sequelae and may be the basis for future research to provide effective interventions.

DNA methylation patterns at birth predict health outcomes in young adults born very low birthweight

Background

Individuals born very low birthweight (VLBW) are at increased risk of impaired cardiovascular and respiratory function in adulthood. To identify markers to predict future risk for VLBW individuals, we analyzed DNA methylation at birth and at 28 years in the New Zealand (NZ) VLBW cohort (all infants born < 1500 g in NZ in 1986) compared with age-matched, normal birthweight controls. Associations between neonatal methylation and cardiac structure and function (echocardiography), vascular function and respiratory outcomes at age 28 years were documented.

Results

Genomic DNA from archived newborn heel-prick blood (n = 109 VLBW, 51 controls) and from peripheral blood at ~ 28 years (n = 215 VLBW, 96 controls) was analyzed on Illumina Infinium MethylationEPIC 850 K arrays. Following quality assurance and normalization, methylation levels were compared between VLBW cases and controls at both ages by linear regression, with genome-wide significance set to p < 0.05 adjusted for false discovery rate (FDR, Benjamini-Hochberg). In neonates, methylation at over 16,400 CpG methylation sites differed between VLBW cases and controls and the canonical pathway most enriched for these CpGs was Cardiac Hypertrophy Signaling (p = 3.44E⁻¹¹). The top 20 CpGs that differed most between VLBW cases and controls featured clusters in ARID3A, SPATA33, and PLCH1 and these 3 genes, along with MCF2L, TRBJ2-1 and SRC, led the list of 15,000 differentially methylated regions (DMRs) reaching FDR-adj significance. Fifteen of the 20 top CpGs in the neonate EWAS showed associations between methylation at birth and adult cardiovascular traits (particularly LnRHI). In 28-year-old adults, twelve CpGs differed between VLBW cases and controls at FDR-adjusted significance, including hypermethylation in EBF4 (four CpGs), CFI and UNC119B and hypomethylation at three CpGs in HIF3A and one in KCNQ1. DNA methylation GrimAge scores at 28 years were significantly greater in VLBW cases versus controls and weakly associated with cardiovascular traits. Four CpGs were identified where methylation differed between VLBW cases and controls in both neonates and adults, three reversing directions with age (two CpGs in EBF4, one in SNAI1 were hypomethylated in neonates, hypermethylated in adults). Of these, cg16426670 in EBF4 at birth showed associations with several cardiovascular traits in adults.

Conclusions

These findings suggest that methylation patterns in VLBW neonates may be informative about future adult cardiovascular and respiratory outcomes and have value in guiding early preventative care to improve adult health.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13148-023-01463-3.

Impact of Suspected Preterm Labor during Pregnancy on Cardiometabolic Profile and Neurodevelopment during Childhood: A Prospective Cohort Study Protocol

Introduction: Suspected preterm labor (SPL), defined as the presence of regular and painful uterine contractions and cervical shortening, represents a prenatal insult with potential long-term consequences. However, despite recent evidence demonstrating suboptimal neurodevelopment at 2 years in this population, it remains underestimated as a significant risk factor for neurodevelopmental disorders or other chronic diseases. The aim of this study is to assess the impact of suspected preterm labor during pregnancy on cardiometabolic profile and neurodevelopment during childhood (6–8 years). Methods and analysis: Prospective cohort study including children whose mothers suffered suspected preterm labour during pregnancy and paired controls. Neurodevelopmental, cardiovascular, and metabolic assessments will be performed at 6–8 years of age. A trained psychologist will carry out the neurodevelopment assessment including intelligence, visual perception, and behavioral assessment. Body composition and physical fitness assessment will be performed by one trained pediatrician and nurse. Finally, cardiovascular evaluation, including echocardiography and blood pressure, will be performed by two pediatric cardiologists. Data regarding perinatal and postnatal characteristics, diet, lifestyle, and weekly screen time of the child will be obtained from medical history and direct interviews with families. Primary outcome measures will include body mass index and adiposity, percentage of fat mass and total and regional lean mass, bone mineral content and density, cardiorespiratory resistance, isometric muscle strength, dynamic lower body strength, systolic and diastolic blood pressure, left ventricle (LV) systolic and diastolic function, general intelligence index, visuospatial working memory span, oculomotor control test, index of emotional, and behavioral problems.

Cardiovascular Morbidities in Adults Born Preterm: Getting to the Heart of the Matter!

Advances in perinatal and neonatal care have led to improved survival of preterm infants into adulthood. However, the shift in focus to long-term health in adults born preterm requires a clear understanding of the impact of prematurity on developing organ systems and the development of adult-oriented disease. A less well-recognized area of risk for surviving preterm infants is their cardiometabolic health. Epidemiologic evidence has linked preterm birth to the development of systemic hypertension, type 2 diabetes, metabolic syndrome, heart failure, and ischemic heart disease. Of more significant concern is that the risk of cardiometabolic disorders is higher in adults born preterm compared to full-term infants. The interconnected nature of the cardio-pulmonary system means worsening morbidity and mortality in adults born preterm. Addressing the problems of adults born preterm holistically would help promote cardiovascular health, wellness, and quality of life over their lifetime. Recognizing that adults born preterm are a unique subset of the population is a challenge in the current healthcare environment. Addressing issues relevant to adults born preterm in the clinically and research domain, using technology to characterize cardiopulmonary physiology and exercise tolerance, developing screening tools for early diagnosis and treatment, and robust follow-up of these infants with access to longitudinal data would improve both the quality and longevity of life in adults born preterm.

Hypersensitivity of Zebrafish htr2b Mutant Embryos to Sertraline Indicates a Role for Serotonin Signaling in Cardiac Development

ABSTRACT

Selective serotonin reuptake inhibitors (SSRIs) are antidepressants prescribed in 10% of pregnancies in the United States. Maternal use of SSRIs has been linked to an elevated rate of congenital heart defects, but the exact mechanism of pathogenesis is unknown. Previously, we have shown a decrease in cardiomyocyte proliferation, left ventricle size, and reduced cardiac expression of the serotonin receptor 5-HT 2B in offspring of mice exposed to the SSRI sertraline during pregnancy, relative to offspring of untreated mice. These results suggest that disruption of serotonin signaling leads to heart defects. Supporting this conclusion, we show here that zebrafish embryos exposed to sertraline develop with a smaller ventricle, reduced cardiomyocyte number, and lower cardiac expression of htr2b relative to untreated embryos. Moreover, zebrafish embryos homozygous for a nonsense mutation of htr2b ( htr2bsa16649 ) were sensitized to sertraline treatment relative to wild-type embryos. Specifically, the ventricle area was reduced in the homozygous htr2b mutants treated with sertraline compared with wild-type embryos treated with sertraline and homozygous htr2b mutants treated with vehicle control. Whereas long-term effects on left ventricle shortening fraction and stroke volume were observed by echocardiography in adult mice exposed to sertraline in utero, echocardiograms of adult zebrafish exposed to sertraline as embryos were normal. These results implicate the 5-HT 2B receptor functions in heart development and suggest zebrafish are a relevant animal model that can be used to investigate the connection between maternal SSRI use and elevated risk of congenital heart defects.

Early life determinants of arterial stiffness in neonates, infants, children and adolescents: A systematic review and meta-analysis

BACKGROUND AND AIMS

Certain exposures and risk factors during the first 1,000 days of life are known to influence future cardiovascular disease (CVD) risk. Pulse wave velocity (PWV) is a measure of arterial stiffness and a recognised surrogate marker of CVD. We performed a systematic review and meta-analyses to investigate whether early life exposures were associated with increased PWV compared with controls in youth.

METHODS

Databases AMED, MEDLINE, EMBASE, CINAHL and Scopus were searched from inception until February 2022.

ELIGIBILITY CRITERIA

observational controlled studies in youth aged <20 years with risk factors/exposure during the first 1,000 days and PWV measurement. This review is registered with PROSPERO (CRD42019137559). Outcome data were pooled using random-effects meta-analysis. Meta-regression was used to investigate potential confounders.

RESULTS

We identified 24 eligible studies. Age of participants ranged from 1-day to 19-years at time of PWV assessment. Exposures included pre-term birth, small for gestational age (SGA), maternal diabetes and assisted reproductive technologies, none of which were significantly associated with PWV in meta-analysis. Sub-group analysis by age demonstrated increased PWV in childhood and adolescence in those exposed to maternal diabetes or born SGA. In meta-regression of pre-term studies, higher prevalence of SGA was associated with increased PWV compared with controls (p = 0.034, R² = 1).

CONCLUSIONS

We found limited evidence that youth exposed to maternal diabetes or born SGA have increased PWV, consistent with increased future CVD risk. These changes in PWV appear to manifest in later childhood and adolescence. Further research is required to better understand the observed relationships.

Cardiac cycle: an observational/interventional study protocol to characterise cardiopulmonary function and evaluate a home-based cycling program in children and adolescents born extremely preterm

INTRODUCTION

Extremely preterm (EP)/extremely low birthweight (ELBW) individuals may have an increased risk for adverse cardiovascular outcomes. Compared with term-born controls, these individuals have poorer lung function and reduced exercise capacity. Exercise interventions play an important role in reducing cardiopulmonary risk, however their use in EP/ELBW cohorts is unknown. This study, cardiac cycle, aims to characterise the cardiopulmonary system of children and adolescents who were born EP compared with those born at term, following acute and chronic exercise bouts.

METHODS AND ANALYSIS

The single-centre study comprises a home-based exercise intervention, with physiological characterisation at baseline and after completion of the intervention. Fifty-eight children and adolescents aged 10-18 years who were born EP and/or with ELBW will be recruited. Cardiopulmonary function assessed via measures of blood pressure, arterial stiffness, capillary density, peak oxygen consumption, lung clearance indexes and ventricular structure/function, will be compared with 58 age-matched and sex-matched term-born controls at baseline and post intervention. The intervention will consist of a 10-week stationary cycling programme, utilising Zwift technology.

ETHICS AND DISSEMINATION

The study is approved by the Ethics Committee of the Royal Children's Hospital Melbourne under HREC2019.053. Results will be disseminated via peer-reviewed journal regardless of outcome.

TRIAL REGISTRATION NUMBER

12619000539134, ANZCTR.

Subclinical Changes in Left Heart Structure and Function at Preschool Age in Very Low Birth Weight Preterm Infants

Background

Survivors of preterm birth are at risk of long-term cardiovascular consequences. The objective of this prospective observational study was to assess left heart function at preschool age in preterm children with very low birth weight (VLBW).

Methods

We recruited children aged 5–6 years from preterm infants and full-term children. All subjects underwent conventional echocardiography and speckle-tracking echocardiography. The results were compared between the preterm and term groups.

Results

Eighty-seven VLBW preterm children and 29 term controls were included in the study. After adjusting for body surface area, the preterm group compared to the full-term group had significantly smaller left ventricular (LV) end-diastolic and end-systolic internal dimensions (31.2 vs. 33.5 mm, p = 0.048; and 20.0 vs. 21.6 mm, respectively; p = 0.024), lower LV end-diastolic and end-systolic volumes (38.8 vs. 46.3 mL, p = 0.024; and 12.8 vs. 15.6 mL, respectively; p = 0.008). Left atrial (LA) maximal and minimal volume were also significantly smaller in the preterm group (15.4 vs. 18.9 mL, p = 0.017; and 6.2 vs 7.5 mL, respectively; p = 0.018). LV global longitudinal strain (−21.4 vs. −23.2%, p < 0.0001) and systolic strain rate (−1.30 vs. −1.37 /s, p = 0.001) were significantly lower in the preterm group than in the term control group. LA longitudinal strain was decreased (43.9 vs. 52.8%, p < 0.0001) and left atrial stiffness index (0.17 vs. 0.14, p < 0.0001) was increased in preterm infants. However, all the measurements in both groups were within normal range.

Conclusions

Subclinical changes of left heart structure and function were found in VLBW infants at preschool age. Additional long-term follow-ups of the cardiovascular outcomes are needed in this vulnerable population.

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.

Educational Review: The Impact of Perinatal Oxidative Stress on the Developing Kidney

Oxidative stress occurs when there is an imbalance between reactive oxygen species/reactive nitrogen species and antioxidant systems. The interplay between these complex processes is crucial for normal pregnancy and fetal development; however, when oxidative stress predominates, pregnancy related complications and adverse fetal programming such as preterm birth ensues. Understanding how oxidative stress negatively impacts outcomes for the maternal-fetal dyad has allowed for the exploration of antioxidant therapies to prevent and/or mitigate disease progression. In the developing kidney, the negative impact of oxidative stress has also been noted as it relates to the development of hypertension and kidney injury mostly in animal models. Clinical research addressing the implications of oxidative stress in the developing kidney is less developed than that of the neurodevelopmental and respiratory conditions of preterm infants and other vulnerable neonatal groups. Efforts to study the oxidative stress pathway along the continuum of the perinatal period using a team science approach can help to understand the multi-organ dysfunction that the maternal-fetal dyad sustains and guide the investigation of antioxidant therapies to ameliorate the global toxicity. This educational review will provide a comprehensive and multidisciplinary perspective on the impact of oxidative stress during the perinatal period in the development of maternal and fetal/neonatal complications, and implications on developmental programming of accelerated aging and cardiovascular and renal disease for a lifetime.

Cardiac structure and function in very preterm-born adolescents compared to term-born controls: A longitudinal cohort study

BACKGROUND

There is emerging evidence of differences in cardiac structure and function in preterm-born adults and increased risk of heart failure. However, there is a paucity of data in populations who have been exposed to modern intensive care and the impact of perinatal factors is unclear.

AIMS

To compare echocardiographic measures of cardiac structure and function in a regional cohort of 17-year-olds born very preterm compared to term-born peers and the influence of perinatal factors.

STUDY DESIGN

Observational longitudinal cohort study.

SUBJECTS

A regional cohort of ninety-one 17-year-olds born at <32 weeks gestation compared to sixty-two term-born controls.

OUTCOME MEASURES

Echocardiographic measures of cardiac structure and function.

RESULTS

Left ventricular and right atrial volume and left ventricular mass, indexed to body surface area, were significantly smaller in preterm-born adolescents compared to term-born controls even when adjusted for sex. There were no between group differences in cardiac function. Within those born preterm we found a significant association between gestational age and birthweight z-score and measures of cardiac function at 17 years. Within the preterm group, those with a diagnosis of bronchopulmonary dysplasia had higher left ventricular posterior wall thickness, higher mitral deceleration time and lower left atrial area and tricuspid annular plane of systolic excursion.

CONCLUSIONS

Adolescents born very prematurely, who have received modern intensive care, have measurable differences in heart structure compared to their term-born peers but heart function is preserved. For those born preterm, gestational age, birthweight and bronchopulmonary dysplasia are associated with differences in cardiac function.

Cardiovascular impact and sequelae of bronchopulmonary dysplasia

The development, growth, and function of the cardiac, pulmonary, and vascular systems are closely intertwined during both fetal and postnatal life. In utero, placental, environmental, and genetic insults may contribute to abnormal pulmonary alveolarization and vascularization that increase susceptibility to the development of bronchopulmonary dysplasia (BPD) in preterm infants. However, the shared milieu of stressors may also contribute to abnormal cardiac or vascular development in the fetus and neonate, leading to the potential for cardiovascular dysfunction. Further, cardiac or pulmonary maladaptation can potentiate dysfunction in the other organ, amplify the risk for BPD in the neonate, and increase the trajectory for overall neonatal morbidity. Beyond infancy, there is an increased risk for systemic and pulmonary vascular disease including hypertension, as well as potential cardiac dysfunction, particularly within the right ventricle. This review will focus on the cardiovascular antecedents of BPD in the fetus, cardiovascular consequences of preterm birth in the neonate including associations with BPD, and cardiovascular impact of prematurity and BPD throughout the lifespan.

Right Ventricular Structure and Function in Young Adults Born Preterm at Very Low Birth Weight

Being born preterm (PT, <37 weeks gestation) or at very low birth weight (VLBW, <1500 g) is associated with increased rates of cardiopulmonary disorders in childhood. As survivors age, late cardiac effects, including right ventricular (RV) remodelling and occult pulmonary hypertension are emerging. In this population-based study, we aimed to investigate right heart structure and function in young adults born PT at VLBW compared to normal-weight term-born controls. The New Zealand VLBW Study has followed all infants born in 1986 with birth weight <1500 g. All were born preterm from 24 to 37 weeks. A total of 229 (71% of survivors) had echocardiograms aged 26–30 years which were compared to age-matched, term-born, normal-weight controls (n = 100). Young adults born preterm at very low birth weight exhibited smaller RV dimensions compared to term-born peers. Standard echocardiographic measures of RV function did not differ, but mildly reduced function was detected by RV longitudinal strain. This difference was related to birth weight and gestational age but not lung function or left ventricular function. Echocardiographic strain imaging may be an important tool to detect differences in RV function preterm and VLBW.

The high-risk factors of different severities of bronchopulmonary dysplasia (BPD) based on the national institute of child health and human development (NICHD) diagnosis criteria in 2018

Objective

To investigate the clinical characteristics of preterm infants with different severities of bronchopulmonary dysplasia (BPD) and disclose the high-risk factors of exacerbating BPD.

Methods

Collection of clinical data of 91 preterm infants admitted to the NICU and diagnosed with BPD, categorized in groups according to the disease severity: 41 mild cases,, 24 moderate cases, and 26 severe cases. Comparison and analysis of perinatal risk factors, treatment, complications and prognosis of the infants with different severity degrees.

Results

The severe group had a higher proportion of infants with congenital heart disease (CHD) higher than the moderate group (P < 0.05), and a higher ratio of pneumonia and mechanical ventilation (MV) ≥ seven days than the mild group (P < 0.05). The severe group also presented higher reintubation incidence than both the mild and moderate groups (P < 0.05). The groups presented different (P < 0.05) incidence rates of hemodynamically significant patent ductus arteriosus (hsPDA) . Ridit analysis suggested that the premature infants (PIs) with hsPDA, multiple microbial pulmonary infections, or Klebsiella pneumoniae pneumonia had more severe illness.

Conclusion

CHD, hsPDA, MV ≥ seven days, reintubation, pneumonia, especially multiple microbial pulmonary infections, and Klebsiella pneumoniae pneumonia are correlated with the severity of BPD and can be used as BPD progression predictor.

Decreased ventricular size and mass mediate the reduced exercise capacity in adolescents and adults born premature

BACKGROUND

Premature birth is associated with lower levels of cardiorespiratory fitness (CRF) but the underlying mechanisms responsible remain unclear. This study assessed whether differences in cardiac morphology or function mediate differences in CRF among adolescents and young adults born preterm.

METHODS

Adolescents and young adults born moderately to extremely premature (gestational age ≤ 32 weeks or birth weight < 1500 g) and age-matched term born participants underwent resting cardiac MRI and maximal exercise testing. Mediation analysis assessed whether individual cardiovascular variables accounted for a significant proportion of the difference in maximal aerobic capacity between groups.

RESULTS

Individuals born preterm had lower VO2max than those born term (41.7 ± 8.6 v 47.5 ± 8.7, p < 0.01). Several variables differed between term and preterm born subjects, including systolic and diastolic blood pressure, mean pulmonary artery pressure, indexed left ventricular end-diastolic volume (LVEDVi), right ventricular end-diastolic volume (RVEDVi), LV mass (LVMi), LV stroke volume index (LVSVi), and LV strain (p < 0.05 for all). Of these variables, LVEDVi, RVEDVi, LVSVi, LVMi, and LV longitudinal strain were significantly related to VO2max (p < 0.05 for all). Significant portions of the difference in VO2max between term and preterm born subjects were mediated by LVEDVi (74.3%, p = 0.010), RVEDVi (50.6%, p = 0.016), and LVMi (43.0%, p = 0.036).

CONCLUSIONS

Lower levels of CRF in adolescents and young adults born preterm are mediated by differences in LVEDVi, RVEDVi, and LVMi. This may represent greater risk for long-term cardiac morbidity and mortality in preterm born individuals.

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

Preterm birth coincides with a key developmental window of cardiac growth and maturation, and thus has the potential to influence long-term cardiac function. Individuals born preterm have structural cardiac remodelling and altered cardiac growth and function by early adulthood. The evidence linking preterm birth and cardiovascular disease in later life is mounting. Advances in the perinatal care of preterm infants, such as glucocorticoid therapy, have improved survival rates, but at what cost? This review highlights the short-term and long-term impact of preterm birth on the structure and function of the heart and focuses on the impact of antenatal and postnatal glucocorticoid treatment on the immature preterm heart.

Postnatal Expression Profile of MicroRNAs Associated with Cardiovascular Diseases in 3- to 11-Year-Old Preterm-Born Children

(1) Background: Preterm-born children have an increased cardiovascular risk with the first clinical manifestation during childhood and/or adolescence. (2) Methods: The occurrence of overweight/obesity, prehypertension/hypertension, valve problems or heart defects, and postnatal microRNA expression profiles were examined in preterm-born children at the age of 3 to 11 years descending from preterm prelabor rupture of membranes (PPROM) and spontaneous preterm birth (PTB) pregnancies. The whole peripheral blood gene expression of 29 selected microRNAs associated with cardiovascular diseases was the subject of our interest. (3) Results: Nearly one-third of preterm-born children (32.43%) had valve problems and/or heart defects. The occurrence of systolic and diastolic prehypertension/hypertension was also inconsiderable in a group of preterm-born children (27.03% and 18.92%). The vast majority of children descending from either PPROM (85.45%) or PTB pregnancies (85.71%) had also significantly altered microRNA expression profiles at 90.0% specificity. (4) Conclusions: Postnatal microRNA expression profiles were significantly influenced by antenatal and early postnatal factors (gestational age at delivery, birth weight of newborns, and condition of newborns at the moment of birth). These findings may contribute to the explanation of increased cardiovascular risk in preterm-born children. These findings strongly support the belief that preterm-born children should be dispensarized for a long time to have access to specialized medical care.

Association between Neonatal Intakes and Hyperglycemia, and Left Heart and Aortic Dimensions at 6.5 Years of Age in Children Born Extremely Preterm

Survivors of extremely preterm birth (gestational age < 27 weeks) have been reported to exhibit an altered cardiovascular phenotype in childhood. The mechanisms are unknown. We investigated associations between postnatal nutritional intakes and hyperglycemia, and left heart and aortic dimensions in children born extremely preterm. Postnatal nutritional data and echocardiographic dimensions at 6.5 years of age were extracted from a sub-cohort of the Extremely Preterm Infants in Sweden Study (EXPRESS; children born extremely preterm between 2004-2007, n = 171, mean (SD) birth weight = 784 (165) grams). Associations between macronutrient intakes or number of days with hyperglycemia (blood glucose > 8 mmol/L) in the neonatal period (exposure) and left heart and aortic dimensions at follow-up (outcome) were investigated. Neonatal protein intake was not associated with the outcomes, whereas higher lipid intake was significantly associated with larger aortic root diameter (B = 0.040, p = 0.009). Higher neonatal carbohydrate intake was associated with smaller aorta annulus diameter (B = -0.016, p = 0.008). Longer exposure to neonatal hyperglycemia was associated with increased thickness of the left ventricular posterior wall (B = 0.004, p = 0.008) and interventricular septum (B = 0.004, p = 0.010). The findings in this study indicate that postnatal nutrition and hyperglycemia may play a role in some but not all long-lasting developmental adaptations of the cardiovascular system in children born extremely preterm.

Altered Right Ventricular Filling at Four-dimensional Flow MRI in Young Adults Born Prematurely

Purpose

To use four-dimensional (4D) flow MRI to measure intraventricular flow in young adults who were born prematurely to investigate mechanisms that may account for increased heart failure risk in this population.

Materials and Methods

In this secondary analysis of a prospective study, a total of 56 young adults participated in an observational cardiac 4D flow MRI study from 2016 to 2020. There were 35 participants who had been born moderately to extremely prematurely (birth weight <1500 g or gestational age ≤32 weeks; 23 women; mean age, 26 years ± 4) and 21 term-born participants (11 women; mean age, 25 years ± 3). Participants underwent cardiac MRI, including cine cardiac structure and function assessment, as well as 4D flow MRI. In each ventricle, normalized kinetic energy (KE/end diastolic volume) and flow through the atrioventricular valve were computed and compared between term-born and preterm participants at systolic and diastolic (early diastolic filling rate [E wave] and late diastolic filling [atrial contraction] rate [A wave]) time points by using Wilcoxon rank-sum tests.

Results

Preterm-born participants had lower right ventricular (RV) E wave/A wave (E/A) KE ratios (2.4 ± 1.7 vs 3.5 ± 1.4; P <.01) and lower E/A peak filling rate ratios (computed from RV volume-time curves; 2.3 ± 1.3 vs 3.5 ± 2.5; P = .03). Additionally, viscous energy dissipation was increased during systole (5.7 µW/mL ± 3.0 vs 4.2 µW/mL ± 1.6; P = .03), increased during late diastole (3.9 µW/mL ± 4.0 vs 2.2 µW/mL ± 1.6; P = .03), and summed over the cardiac cycle (2.4 µJ/mL ± 1.0 vs 1.9 µJ/mL ± 0.6; P = .02) in preterm relative to term participants.

Conclusion

These results suggest that RV diastolic filling is altered in young adults who were born moderately to severely prematurely.Supplemental material is available for this article. Keywords: Adults, Cardiac, Comparative Studies, MR-Imaging, Right Ventricle © RSNA, 2021.

Sildenafil administration improves right ventricular function on 4D flow MRI in young adults born premature

Extreme preterm birth conveys an elevated risk of heart failure by young adulthood. Smaller biventricular chamber size, diastolic dysfunction, and pulmonary hypertension may contribute to reduced ventricular-vascular coupling. However, how hemodynamic manipulations may affect right ventricular (RV) function and coupling remains unknown. As a pilot study, 4D flow MRI was used to assess the effect of afterload reduction and heart rate reduction on cardiac hemodynamics and function. Young adults born premature were administered sildenafil (a pulmonary vasodilator) and metoprolol (a β blocker) on separate days, and MRI with 4D flow completed before and after each drug administration. Endpoints include cardiac index (CI), direct flow fractions, and ventricular kinetic energy including E/A wave kinetic energy ratio. Sildenafil resulted in a median CI increase of 0.24 L/min/m2 (P = 0.02), mediated through both an increase in heart rate (HR) and stroke volume. Although RV ejection fraction improved only modestly, there was a significant increase (4% of end diastolic volume) in RV direct flow fraction (P = 0.04), consistent with hemodynamic improvement. Metoprolol administration resulted in a 5-beats/min median decrease in HR (P = 0.01), a 0.37 L/min/m2 median decrease in CI (P = 0.04), and a reduction in time-averaged kinetic energy (KE) in both ventricles (P < 0.01), despite increased RV diastolic E/A KE ratio (P = 0.04). Despite reduced right atrial workload, metoprolol significantly depressed overall cardiac systolic function. Sildenafil, however, increased CI and improved RV function, as quantified by the direct flow fraction. The preterm heart appears dependent on HR but sensitive to RV afterload manipulations.NEW & NOTEWORTHY We assessed the effect of right ventricular afterload reduction with sildenafil and heart rate reduction with metoprolol on cardiac hemodynamics and function in young adults born premature using 4D flow MRI. Metoprolol depressed cardiac function, whereas sildenafil improved cardiac function including right ventricular direct flow fraction by 4D flow, consistent with hemodynamic improvement. This suggests that the preterm heart is dependent on heart rate and sensitive to right ventricular afterload changes.

Preterm Birth With Neonatal Interventions Accelerates Collagen Deposition in the Left Ventricle of Lambs Without Affecting Cardiomyocyte Development

Background

Adults born preterm (< 37 weeks’ gestation) exhibit altered cardiac growth and are susceptible to cardiac dysfunction. Sheep studies have shown that moderate preterm birth results in maladaptive structural remodelling of the cardiac ventricles. The aim of this study was to examine ventricular structure in lambs born at a greater severity of preterm birth and ventilated postnatally.

Methods

Former-preterm lambs delivered at 128 days’ gestation, and mechanically ventilated for a week after birth, were compared with unventilated lambs born at term (150 days’ gestation), at 2 months (term: n = 10, former-preterm: n = 8), and 5 months (term: n = 9, former-preterm: n = 8) term-equivalent age. The right ventricle and left ventricle plus septum were analysed using immunohistochemistry, histology, and stereology.

Results

Cardiomyocyte number, cross-sectional area, proliferation, and apoptosis were not affected by preterm birth or age. Left ventricle plus septum interstitial collagen levels increased with age (P = 0.0015) and were exacerbated by preterm birth (P = 0.0006; 2 months term: 0.57% ± 0.07%, former-preterm: 1.44% ± 0.18%; 5 months term: 1.37% ± 0.25%, former-preterm: 2.15% ± 0.31%). Right ventricle interstitial collagen levels increased with age (P = 0.012) but were not affected by preterm birth.

Conclusion

This study is the first to explore the effect of preterm birth combined with modern neonatal interventions on the ventricular myocardium in lambs. There was no adverse impact on cardiomyocyte growth in early postnatal life. Of concern, however, there was increased collagen deposition in the preterm hearts, which has the potential to induce cardiac dysfunction, especially if it becomes exaggerated with ageing.

Preterm birth and cardiac function in adulthood

Preterm birth affects 1 in 10 pregnancies worldwide, with increasing survival rates over the last 30 years. However, as this new generation of long-term survivors approaches middle age, recent studies have revealed increased cardiovascular risk factors and higher rates of ischaemic heart disease and heart failure. Cardiovascular imaging has identified smaller cardiac chamber size, changes in myocardial mass and impaired ventricular function, particularly under physiological stress. Accordingly, this population should be recognised as having a higher risk of heart failure as they age. In this review, we present current evidence for increased rates of heart failure and evidence of alterations in cardiac structure and function in those born preterm. We discuss potential mechanisms to explain this risk including greater frequency of co-morbidities known to be associated with heart failure. We also explore potential mechanistic links specific to the preterm-born population, including the impact of premature birth on myocardial and vascular development and the effects of perinatal haemodynamic changes and chronic lung disease on the developing heart. We highlight gaps in our knowledge and consider implications for patient management relevant to the adult physician.

Left Ventricle Structure and Function in Young Adults Born Very Preterm and Association with Neonatal Characteristics

Preterm birth increases risk of cardiovascular disease and early death. A body of evidence suggests left ventricle (LV) echocardiographic alterations in children and adults born preterm. We aimed to determine if neonatal characteristics were associated with alterations in LV structure and function in preterm adults. We evaluated a cohort of 86 young adults born preterm below 30 weeks of gestation, and 85 full-term controls. We determined LV dimensions and function using tissue Doppler imaging, conventional and speckle tracking echocardiography (STE). Adults born preterm had smaller LV dimensions, but these differences did not remain after adjustment for body surface area (BSA), which was smaller in the preterm group. Stroke volume and cardiac output were reduced even after adjustment for BSA. We found a smaller e’ wave in the preterm group, but other markers of systolic and diastolic function did not differ. Use of antenatal steroids may be associated with a further reduced cardiac output in those born preterm. Adults born preterm show alterations in markers of LV dimensions and function. Identification of these markers may represent opportunities for early prevention of cardiovascular events in this at-risk population.

Neonatal hyperoxia inhibits proliferation and survival of atrial cardiomyocytes by suppressing fatty acid synthesis

Preterm birth increases the risk for pulmonary hypertension and heart failure in adulthood. Oxygen therapy can damage the immature cardiopulmonary system and may be partially responsible for the cardiovascular disease in adults born preterm. We previously showed that exposing newborn mice to hyperoxia causes pulmonary hypertension by 1 year of age that is preceded by a poorly understood loss of pulmonary vein cardiomyocyte proliferation. We now show that hyperoxia also reduces cardiomyocyte proliferation and survival in the left atrium and causes diastolic heart failure by disrupting its filling of the left ventricle. Transcriptomic profiling showed that neonatal hyperoxia permanently suppressed fatty acid synthase (Fasn), stearoyl-CoA desaturase 1 (Scd1), and other fatty acid synthesis genes in the atria of mice, the HL-1 line of mouse atrial cardiomyocytes, and left atrial tissue explanted from human infants. Suppressing Fasn or Scd1 reduced HL-1 cell proliferation and increased cell death, while overexpressing these genes maintained their expansion in hyperoxia, suggesting that oxygen directly inhibits atrial cardiomyocyte proliferation and survival by repressing Fasn and Scd1. Pharmacologic interventions that restore Fasn, Scd1, and other fatty acid synthesis genes in atrial cardiomyocytes may, thus, provide a way of ameliorating the adverse effects of supplemental oxygen on preterm infants.

Association of Bronchopulmonary Dysplasia and Right Ventricular Systolic Function in Young Adults Born Preterm

BACKGROUND

Adults born preterm are at a higher risk of cardiopulmonary disease and premature death. Preterm birth is associated with abnormalities in right ventricular (RV) structure and function, but the impact of bronchopulmonary dysplasia (BPD), a common complication of extremely preterm birth, on these parameters remains unknown.

RESEARCH QUESTION

Are preterm birth and BPD associated with alterations in RV structure and function in early adulthood?

STUDY DESIGN AND METHODS

Echocardiographic and spirometry data were obtained from the Health of Adults Born Preterm Investigation (HAPI). RV structure and performance were evaluated by using echocardiography, and respiratory function was assessed by using spirometry.

RESULTS

The study comprised 86 young adults born preterm before 30 weeks of gestation, including 28 with moderate to severe BPD, and 85 adults of the same age born full term. Individuals were assessed at a mean age of 23 years. RV systolic function was altered in the preterm group, with lower tricuspid annular plane systolic excursion and lower RV s' and RV outflow tract velocity time integral values, especially in those born preterm with BPD. Nine (36%) participants born preterm with BPD, six (13%) participants born preterm without BPD, and six (8%) participants born full term had a tricuspid annular plane systolic excursion value < 16 mm, a marker of RV systolic dysfunction (P value for the comparison between preterm no BPD and BPD, .032). No difference was found in RV diastolic function or estimates of pulmonary artery pressure between groups. Although respiratory function was altered in those born preterm, and more so in the case of BPD, no association was observed between spirometry indices of respiratory function and RV systolic function.

INTERPRETATION

Preterm birth is associated in adulthood with alterations in RV systolic function, which are more pronounced in the case of BPD.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov; No.: NCT03261609; URL: www.clinicaltrials.gov.

Asthma prevalence, lung and cardiovascular function in adolescents born preterm

Our main objective was to study respiratory evolution and pulmonary and cardiac function in adolescents born preterm in the post-surfactant era. Observational cross-sectional study, comparing very preterm (< 32 weeks) and moderately-late preterm adolescents (≥ 32 weeks) (74 each group). We recorded respiratory symptoms, spirometry and functional echocardiogram. Very preterm adolescents required more respiratory admissions (45.9% vs. 28.4%) (p = 0.03, OR 2.1, CI95% 1.1–4.2) and had more current asthma (21.6% vs. 9.5%, p = 0.04, OR 2.3, CI95% 1.1–5.2). Preterm subjects with intrauterine growth restriction (IUGR) presented lower FEV₁ (88.7 ± 13.9 vs. 95.9 ± 13.3, p = 0.027) and lower FVC (88.2 ± 13.6 vs. 95.5 ± 13.3, p = 0.025). When assessing right ventricle, very preterm showed a greater E/E’ ratio (p = 0.02) and longer myocardial performance index (MPI) (p = 0.001). Adolescents with IUGR showed less shortening fraction (p = 0.016), worse E/E′ ratio (p = 0.029) and longer MPI (p = 0.06). Regarding left ventricle, very preterm showed less E′ wave velocity (p = 0.03), greater E/E′ ratio (p = 0.005) and longer MPI (p < 0.001). Gestational age < 32 weeks is independently associated with current asthma in adolescence. Children 13–14 years old born very preterm required more respiratory admissions and had poorer diastolic and global function of both ventricles. IUGR is a risk factor for poorer lung function in preterm adolescents, regardless gestational age.

Cardiovascular Health Profile at Age 25 Years in Adults Born Extremely Preterm or Extremely Low Birthweight

Being born extremely preterm (EP; <28 weeks' gestation) or extremely low birthweight (ELBW; <1000 g birthweight) may predict increased cardiometabolic risk in adulthood, but other early life predictors are less well described. We aimed to (1) compare cardiovascular health profiles between 165 adults born EP/ELBW and 127 controls at age 25 years, drawn from a prospective longitudinal cohort study, recruited at birth in 1991 to 1992; and (2) in the EP/ELBW group, determine early life associations of cardiovascular health. Cardiovascular health profiles were calculated individually for measures of anthropometry, abdominal visceral fat, blood pressure, fasting plasma glucose, insulin, lipids, C-reactive protein, vascular indices, exercise tolerance and smoking status, and summed for an overall score. Cardiovascular health profiles were compared between groups; using logistic regression (individual scores) and the Mann-Whitney U test (cumulative score). Compared with controls, adults born EP/ELBW had less favorable cardiovascular health profiles; individually for abdominal visceral fat (odds ratio, 0.56 [95% CI, 0.33-0.96], P=0.03), blood pressure (odds ratio 0.38 [95% CI, 0.23-0.63], P<0.001), exercise capacity (odds ratio 0.37 [95% CI, 0.22-0.63], P<0.001), and fasting glucose (odds ratio 0.51 [95% CI, 0.31-0.84], P=0.01) and overall (median [interquartile range] 10 [7-11] versus 11 [9-12], P=0.007). Male sex predicted unfavorable abdominal visceral fat, blood pressure and fasting glucose, and favorable exercise capacity. Greater increases in weight Z scores between 2 and 8, and 8 and 18 years predicted less favorable profiles of exercise capacity and visceral fat. Longer-term follow-up is critical to determine the cardiovascular sequelae of adults born EP/ELBW.

Cardiovascular risk factors in those born preterm - systematic review and meta-analysis

Emerging evidence demonstrates a link between preterm birth (PTB) and later life cardiovascular disease (CVD). We conducted a systematic review and meta-analysis to compare conventional CVD risk factors between those born preterm and at term. PubMed, CINAHL, SCOPUS, and EMBASE databases were searched. The review protocol is registered in PROSPERO (CRD42018095005). CVD risk factors including systolic blood pressure (SBP), diastolic blood pressure (DBP), body mass index, lipid profile, blood glucose, and fasting insulin among those born preterm (<37 weeks' gestation) were compared with those born at term (≥37 weeks' gestation). Subgroup analyses based on gender, age, gestational at birth (<32 weeks' gestation and <28 weeks' gestation), and PTB associated with small for gestational age or average for gestational age were also performed. Fifty-six studies provided data on 308,987 individuals. Being born preterm was associated with 3.26 mmHg (95% confidence interval [CI] 2.08 to 4.44) higher mean SBP and 1.32 mmHg (95% CI: 0.61 to 2.04) higher mean DBP compared to being born at term. Subgroup analyses demonstrated that SBP was higher among (a) preterm compared to term groups from early adolescence until adulthood; (b) females born preterm but not among males born preterm compared to term controls; and (c) those born at <32 weeks or <28 weeks compared to term. Our meta-analyses demonstrate higher SBP and DBP among those born preterm compared to term. The difference in SBP is evident from early adolescence until adulthood.

Cardiovascular Outcomes in Young Adulthood in a Population-Based Very Low Birth Weight Cohort

OBJECTIVES

To assess differences in left heart structure and function, and endothelial function in a national cohort of very low birth weight (VLBW) young adults and term-born controls.

STUDY DESIGN

The New Zealand VLBW study is a prospective, population-based, longitudinal cohort study which included all infants born <1500 g in 1986. The VLBW cohort (n = 229; 71% of survivors) and term-born controls (n = 100), were assessed at age 26-30 years. Measures of left heart structure and function were evaluated by echocardiography, vascular function was assessed using blood pressure, reactive hyperemia index, and arterioventricular coupling by calculating left ventricular (LV) and arterial elastance.

RESULTS

Compared with controls, those born VLBW had smaller LVs, even when indexed for body surface area (mean LV mass, 89.7 ± 19.3 g/m² vs 95.0 ± 22.3 g/m² [P = .03]; LV end-diastolic volume, 58.3 ± 10.9 mL/m² vs 62.4 ± 12.4 mL/m² [P = .002]; and LV end-systolic volume, 20.8 ± 4.9 mL/m² vs 22.6 ± 5.8 mL/m² [P = .004]). VLBW participants had lower stroke volume (median, 37.2 mL/m² [IQR, 33-42 mL/m²] vs median, 40.1 mL/m² [IQR, 34-45 mL/m²]; P = .0059) and cardiac output (mean, 4.8 ± 1.2 L/min vs 5.1 ± 1.4 L/min; P = .03), but there was no difference in ejection fraction. The VLBW group had higher LV elastance (3.37 ± 0.88 mm Hg/mL vs 2.86 ± 0.75 mm Hg/mL; P < .0001) and arterial elastance (1.84 ± 0.4 vs 1.6 ± 0.4; P < .0001) and lower reactive hyperemia index (0.605 ± 0.28 vs 0.688 ± 0.31; P = .041). These measures were influenced by birth weight and sex, but we found limited associations with other perinatal factors.

CONCLUSIONS

Being born preterm and VLBW is associated with differences in cardiovascular structure and function in adulthood. This population may be more vulnerable to cardiovascular pathology as they age.

TRIAL REGISTRATION

Australian Clinical Trials Registry ACTRN12612000995875.

Arterial Structure and Stiffness Are Altered in Young Adults Born Preterm

OBJECTIVE

Preterm birth has been associated with changes in arterial structure and function. Association with complications occurring during the neonatal period, including bronchopulmonary dysplasia, on vascular outcomes in adulthood is unknown. Approach and Results: We evaluated a cohort of 86 adults born preterm (below 30 weeks of gestation), compared to 85 adults born term, at a mean age of 23 years. We performed ultrasonographic assessment of the dimensions of the ascending aorta, carotid and brachial arteries, and estimated flow-mediated dilation, carotid-femoral pulse wave velocity, augmentation index corrected for heart rate, and carotid intima-media thickness. All analyses were performed with and without adjustment for potential confounding variables, including height, sex, and body mass index. Ascending aorta diameter in diastole was smaller in the preterm group, but carotid and brachial arteries were similar. Carotid and brachial strain, a marker of arterial distensibility, was smaller in the preterm group, while carotid-femoral pulse wave velocity, was similar between groups, indicating similar aortic stiffness. Carotid intima-media thickness, endothelial function flow-mediated dilation, blood nitrite, and nitrate levels were similar between groups. Individuals with bronchopulmonary dysplasia had lower brachial artery strain suggesting long-term association of this neonatal complication with vascular structure. Diastolic blood pressure was higher in the preterm group and was associated with decreased brachial and carotid distensibility.

CONCLUSIONS

Young adults born preterm display alterations in arterial distensibility that are associated with a history of bronchopulmonary dysplasia.

Impact of the Vulnerable Preterm Heart and Circulation on Adult Cardiovascular Disease Risk

Preterm birth accounts for over 15 million global births per year. Perinatal interventions introduced since the early 1980s, such as antenatal glucocorticoids, surfactant, and invasive ventilation strategies, have dramatically improved survival of even the smallest, most vulnerable neonates. As a result, a new generation of preterm-born individuals has now reached early adulthood, and they are at increased risk of cardiovascular diseases. To better understand the sequelae of preterm birth, cardiovascular follow-up studies in adolescents and young adults born preterm have focused on characterizing changes in cardiac, vascular, and pulmonary structure and function. Being born preterm associates with a reduced cardiac reserve and smaller left and right ventricular volumes, as well as decreased vascularity, increased vascular stiffness, and higher pressure of both the pulmonary and systemic vasculature. The purpose of this review is to present major epidemiological evidence linking preterm birth with cardiovascular disease; to discuss findings from clinical studies showing a long-term impact of preterm birth on cardiac remodeling, as well as the systemic and pulmonary vascular systems; to discuss differences across gestational ages; and to consider possible driving mechanisms and therapeutic approaches for reducing cardiovascular burden in individuals born preterm.

Changes in the Preterm Heart From Birth to Young Adulthood: A Meta-analysis

CONTEXT

Preterm birth is associated with incident heart failure in children and young adults.

OBJECTIVE

To determine the effect size of preterm birth on cardiac remodeling from birth to young adulthood.

DATA SOURCES

Data sources include Medline, Embase, Scopus, Cochrane databases, and clinical trial registries (inception to March 25, 2020).

STUDY SELECTION

Studies in which cardiac phenotype was compared between preterm individuals born at <37 weeks' gestation and age-matched term controls were included.

DATA EXTRACTION

Random-effects models were used to calculate weighted mean differences with corresponding 95% confidence intervals.

RESULTS

Thirty-two observational studies were included (preterm = 1471; term = 1665). All measures of left ventricular (LV) and right ventricular (RV) systolic function were lower in preterm neonates, including LV ejection fraction (P = .01). Preterm LV ejection fraction was similar from infancy, although LV stroke volume index was lower in young adulthood. Preterm LV peak early diastolic tissue velocity was lower throughout development, although preterm diastolic function worsened with higher estimated filling pressures from infancy. RV longitudinal strain was lower in preterm-born individuals of all ages, proportional to the degree of prematurity (R ² = 0.64; P = .002). Preterm-born individuals had persistently smaller LV internal dimensions, lower indexed LV end-diastolic volume in young adulthood, and an increase in indexed LV mass, compared with controls, of 0.71 g/m² per year from childhood (P = .007).

LIMITATIONS

The influence of preterm-related complications on cardiac phenotype could not be fully explored.

CONCLUSIONS

Preterm-born individuals have morphologic and functional cardiac impairments across developmental stages. These changes may make the preterm heart more vulnerable to secondary insults, potentially underlying their increased risk of early heart failure.

Association Between Preterm Birth and Arrested Cardiac Growth in Adolescents and Young Adults

Importance

Premature birth is associated with substantially higher lifetime risk for cardiovascular disease, including arrhythmia, ischemic disease, and heart failure, although the underlying mechanisms are poorly understood.

Objective

To characterize cardiac structure and function in adolescents and young adults born preterm using cardiac magnetic resonance imaging (MRI).

Design, Setting, and Participants

This cross-sectional cohort study at an academic medical center included adolescents and young adults born moderately to extremely premature (20 in the adolescent cohort born from 2003 to 2004 and 38 in the young adult cohort born in the 1980s and 1990s) and 52 age-matched participants who were born at term and underwent cardiac MRI. The dates of analysis were February 2016 to October 2019.

Exposures

Premature birth (gestational age ≤32 weeks) or birth weight less than 1500 g.

Main Outcomes and Measures

Main study outcomes included MRI measures of biventricular volume, mass, and strain.

Results

Of 40 adolescents (24 [60%] girls), the mean (SD) age of participants in the term and preterm groups was 13.3 (0.7) years and 13.0 (0.7) years, respectively. Of 70 adults (43 [61%] women), the mean (SD) age of participants in the term and preterm groups was 25.4 (2.9) years and 26.5 (3.5) years, respectively. Participants from both age cohorts who were born prematurely had statistically significantly smaller biventricular cardiac chamber size compared with participants in the term group: the mean (SD) left ventricular end-diastolic volume index was 72 (7) vs 80 (9) and 80 (10) vs 92 (15) mL/m2 for adolescents and adults in the preterm group compared with age-matched participants in the term group, respectively (P < .001), and the mean (SD) left ventricular end-systolic volume index was 30 (4) vs 34 (6) and 32 (7) vs 38 (8) mL/m2, respectively (P < .001). Stroke volume index was also reduced in adolescent vs adult participants in the preterm group vs age-matched participants in the term group, with a mean (SD) of 42 (7) vs 46 (7) and 48 (7) vs 54 (9) mL/m2, respectively (P < .001), although biventricular ejection fractions were preserved. Biventricular mass was statistically significantly lower in adolescents and adults born preterm: the mean (SD) left ventricular mass index was 39.6 (5.9) vs 44.4 (7.5) and 40.7 (7.3) vs 49.8 (14.0), respectively (P < .001). Cardiac strain analyses demonstrated a hypercontractile heart, primarily in the right ventricle, in adults born prematurely.

Conclusions and Relevance

In this cross-sectional study, adolescents and young adults born prematurely had statistically significantly smaller biventricular cardiac chamber size and decreased cardiac mass. Although function was preserved in both age groups, these morphologic differences may be associated with elevated lifetime cardiovascular disease risk after premature birth.

Retinal and Renal Microvasculature in Relation to Central Hemodynamics in 11-Year-Old Children Born Preterm or At Term

Background Prematurity disrupts the perinatal maturation of the microvasculature and macrovasculature and confers high risk of vascular dysfunction later in life. No previous studies have investigated the crosstalk between the microvasculature and macrovasculature in childhood. Methods and Results In a case-control study, we enrolled 55 children aged 11 years weighing <1000 g at birth and 71 matched controls (October 2014-November 2015). We derived central blood pressure (BP) wave by applanation tonometry and calculated the forward/backward pulse waves by an automated pressure-based wave separation algorithm. We measured the renal resistive index by pulsed wave Doppler and the central retinal arteriolar equivalent by computer-assisted program software. Compared with controls, patients had higher central systolic BP (101.5 versus 95.2 mm Hg, P<0.001) and backward wave amplitude (15.5 versus 14.2 mm Hg, P=0.029), and smaller central retinal arteriolar equivalent (163.2 versus 175.4 µm, P<0.001). In multivariable analyses, central retinal arteriolar equivalent was smaller with higher values (+1 SD) of central systolic BP (-2.94 µm; 95% CI, -5.18 to -0.70 µm [P=0.011]) and forward (-2.57 µm; CI, -4.81 to -0.32 µm [P=0.026]) and backward (-3.20 µm; CI, -5.47 to -0.94 µm [P=0.006]) wave amplitudes. Greater renal resistive index was associated with higher backward wave amplitude (0.92 mm Hg, P=0.036). Conclusions In childhood, prematurity compared with term birth is associated with higher central systolic BP and forward/backward wave amplitudes. Higher renal resistive index likely moves reflection points closer to the heart, thereby explaining the inverse association of central retinal arteriolar equivalent with central systolic BP and backward wave amplitude. These observations highlight the crosstalk between the microcirculation and macrocirculation in children. Registration URL: http://www.clinicaltrials.gov. Unique Identifier: NCT02147457.

Early impact of moderate preterm birth on the structure, function and gene expression of conduit arteries

NEW FINDINGS

What is the central question of this study? What is the immediate impact of moderate preterm birth on the structure and function of major conduit arteries using a pre-clinical sheep model? What is the main finding and its importance? Postnatal changes in conduit arteries, including a significant decrease in collagen within the thoracic aortic wall (predominately males), narrowed carotid arteries, reduced aortic systolic blood flow, and upregulation of the mRNA expression of cell adhesion and inflammatory markers at 2 days of age in preterm lambs compared to controls, may increase the risk of cardiovascular impairment in later life.

ABSTRACT

The aim of this work was to compare the structure and function of the conduit arteries of moderately preterm and term-born lambs and to determine whether vascular injury-associated genes were upregulated. Time-mated ewes were induced to deliver either preterm (132 ± 1 days of gestation; n = 11 females and n = 10 males) or at term (147 ± 1 days of gestation; n = 10 females and n = 5 males). Two days after birth, ultrasound imaging of the proximal ascending aorta, main, right and left pulmonary arteries, and right and left common carotid arteries was conducted in anaesthetized lambs. Lambs were then killed and segments of the thoracic aorta and left common carotid artery were either snap frozen for real-time PCR analyses or immersion-fixed for histological quantification of collagen, smooth muscle and elastin within the medial layer. Overall there were few differences in vascular structure between moderately preterm and term lambs. However, there was a significant decrease in the proportion of collagen within the thoracic aortic wall (predominantly in males), narrowing of the common carotid arteries and a reduction in peak aortic systolic blood flow in preterm lambs. In addition, there was increased mRNA expression of the cell adhesion marker P-selectin in the thoracic aortic wall and the pro-inflammatory marker IL-1β in the left common carotid artery in preterm lambs, suggestive of postnatal vascular injury. Early postnatal differences in the function and structure of conduit arteries and evidence of vascular injury in moderately preterm offspring may place them at greater risk of cardiovascular impairment later in life.

Dilated hypertrophy: a distinct pattern of cardiac remodeling in preterm infants

BACKGROUND

Young adults born preterm have remodeled hearts, i.e., altered cardiac shape and size with impaired cardiac function. At present, the natural history and pattern of prematurity related cardiac remodeling are not clearly established. The aim of this study was to compare the left ventricle (LV) geometry and function of preterm infants at 36 weeks postmenstrual age (PMA) with gestation matched newborn infants.

METHODS

LV end diastolic volume index (LV EDVI), LV mass index (LVMI), relative wall thickness (RWT), and sphericity index (SI) were prospectively obtained with echocardiography. LV geometry was classified according to the Gaasch method. LV function was assessed by determining ejection fraction (EF), longitudinal strain (LS), mitral annulus systolic motion (s'), and estimated LV filling pressure (E/e').

RESULTS

Eighty-three preterm infants between 23 and 29 weeks gestation, and 40 infants of 36 weeks gestation at birth were analysed. LV EDVI, LVMI, SI, LS, s', and E/e' were higher in preterm group while RWT and EF were comparable between groups. LV showed normal geometry in 55.4%, physiological enlargement in 23% and dilated hypertrophy in 21.6% preterm infants.

CONCLUSION

At 36 week, preterm infants have significantly dilated, hypertrophied, and more spherical LV with impaired diastolic function compared with PMA matched newborn infants.

Persistent metagenomic signatures of early-life hospitalization and antibiotic treatment in the infant gut microbiota and resistome

Hospitalized preterm infants receive frequent and often prolonged exposures to antibiotics because they are vulnerable to infection. It is not known whether the short-term effects of antibiotics on the preterm infant gut microbiota and resistome persist after discharge from neonatal intensive care units. Here, we use complementary metagenomic, culture-based and machine learning techniques to study the gut microbiota and resistome of antibiotic-exposed preterm infants during and after hospitalization, and we compare these readouts to antibiotic-naive healthy infants sampled synchronously. We find a persistently enriched gastrointestinal antibiotic resistome, prolonged carriage of multidrug-resistant Enterobacteriaceae and distinct antibiotic-driven patterns of microbiota and resistome assembly in extremely preterm infants that received early-life antibiotics. The collateral damage of early-life antibiotic treatment and hospitalization in preterm infants is long lasting. We urge the development of strategies to reduce these consequences in highly vulnerable neonatal populations.

Bimodal right ventricular dysfunction after postnatal hyperoxia exposure: implications for the preterm heart

Rats exposed to postnatal hyperoxia develop right ventricular (RV) dysfunction, mild pulmonary hypertension, and dysregulated cardiac mitochondrial biogenesis when aged to one year, with the degree of cardiac dysfunction and pulmonary hypertension similar to that previously described in young adults born preterm. Here, we sought to understand the impact of postnatal hyperoxia exposure on RV hemodynamic and mitochondrial function across the life span. In Methods, pups from timed-pregnant Sprague-Dawley rats were randomized to normoxia or hyperoxia [fraction of inspired oxygen (FIO2), 0.85] exposure for the first 14 days of life, a commonly used model of chronic lung disease of prematurity. RV hemodynamic and mitochondrial function were assessed by invasive measurement of RV pressure-volume loops and by high-resolution respirometry at postnatal day 21 (P21), P90, and P365. In Results, at P21, hyperoxia-exposed rats demonstrated severe pulmonary hypertension and RV dysfunction, accompanied by depressed mitochondrial oxidative capacity. However, significant upregulation of mitochondrial biogenesis at P21 as well as improved afterload led to complete RV hemodynamic and mitochondrial recovery at P90. Mitochondrial DNA mutations were significantly higher by P90 and associated with significant late RV mitochondrial and hemodynamic dysfunction at P365. In conclusion, there appears to be a "honeymoon period" where cardiac hemodynamic and mitochondrial function normalizes following postnatal hyperoxia exposure, only to decline again with ongoing aging. This finding may have significant implications if a long-term pulmonary vascular screening program were to be developed for children or adults with a history of severe prematurity. Further investigation into the mechanisms of recovery are warranted.NEW & NOTEWORTHY Premature birth is associated with increased risk for cardiac dysfunction and failure throughout life. Here, we identify bimodal right ventricular dysfunction after postnatal hyperoxia exposure. Mitochondrial biogenesis serves as an early adaptive feature promoting recovery of cardiac hemodynamic and mitochondrial function. However, the accumulation of mitochondrial DNA mutations results in late mitochondrial and right ventricular dysfunction. This bimodal right ventricular dysfunction may have important implications for the development of screening programs in the preterm population.

Impact of early life AT1 blockade on adult cardiac morpho-functional changes and the renin-angiotensin system in a model of neonatal high oxygen-induced cardiomyopathy

We previously reported that neonatal blockade of angiotensin II AT₁ receptor prevents cardiac changes in 4 weeks rats with neonatal hyperoxia-induced cardiomyopathy, a recognized model of prematurity-related deleterious conditions. Considering the importance of AT₁ receptor and the renin angiotensin system (RAS) in normal development, the present study aimed to investigate the adult effects of neonatal AT₁ blockade on left ventricle (LV) in rats exposed to neonatal hyperoxia. Sprague-Dawley pups were exposed to 80% O₂ or room air from days 3-10. AT₁ blocker (losartan) or H₂O were given by gavage from day 8-10. LV function (echo and intraventricular pressure), histology and expression of RAS components were examined in 15-16 weeks old adult males. Losartan treatment prevented myocardial fibrosis, LV wall thickening and stroke volume reduction in rats exposed to high O₂ in the neonatal period. However, Losartan treatment of O₂-exposed pups led to reduced ejection fraction (EF) and fractional shortening (FS), and did not prevent changes in diastolic function. Losartan also did not prevent increased LV AT₂ and decreased angiotensin-(1-7) Mas receptors expression observed in high O₂-exposed rats. Neonatal Losartan attenuated long-term impact of neonatal hyperoxia but also led to decreased EF and FS. Increased AT₂ and decreased Mas receptor expression observed in O₂-exposed group were unaffected by Losartan treatment. Our results show that early life Losartan treatment aimed at preventing cardiac consequences of neonatal deleterious conditions may also comprise detrimental effects that require further investigation prior to clinical translation in developing children.

Increased aortic wave reflection contributes to higher systolic blood pressure in adolescents born preterm

OBJECTIVE

To evaluate the wave reflection characteristics in the aortic arch and common carotid artery of ex-preterm adolescents and assess their relationship to central blood pressure in a cohort followed prospectively since birth.

METHODS

Central blood pressures, pulse wave velocity, augmentation index, microvascular reactive hyperemia, arterial distensibility, compliance and stiffness index, and also aortic and carotid wave intensity were measured in 18-year-olds born extremely preterm at below 28 weeks' gestation (n = 76) and term-born controls (n = 42).

RESULTS

Compared with controls, ex-preterm adolescents had higher central systolic (111 ± 11 vs. 105 ± 10 mmHg; P < 0.001) and diastolic blood pressures (73 ± 7 vs. 67 ± 7 mmHg; P < 0.001). Although conventional measures of arterial function and biomechanics such as pulse wave velocity and augmentation index were no different between groups, wave intensity analysis revealed elevated backward compression wave area (-0.39 ± 0.21 vs. -0.29 ± 0.17 W/m/s × 10; P = 0.03), backward compression wave pressure change (9.0 ± 3.5 vs. 6.6 ± 2.5 mmHg; P = 0.001) and reflection index (0.44 ± 0.15 vs. 0.32 ± 0.08; P < 0.001) in the aorta of ex-preterm adolescents compared with controls. These changes were less pronounced in the carotid artery. On multivariable analysis, forward and backward compression wave areas were the only biomechanical variables associated with central systolic pressure.

CONCLUSIONS

Ex-preterm adolescents demonstrate elevated wave reflection indices in the aortic arch, which correlate with central systolic pressure. Wave intensity analysis may provide a sensitive novel marker of evolving vascular dysfunction in ex-preterm survivors.

Reduced Aortic Distensibility is Associated With Higher Aorto-Carotid Wave Transmission and Central Aortic Systolic Pressure in Young Adults After Coarctation Repair

Background The long-term prognosis of patients with repaired aortic coarctation is characterized by high rates of cardiovascular and cerebrovascular disease related to hypertension, the basis of which remains unclear. To define potential underlying mechanisms, we investigated aortic and carotid arterial biomechanics and wave dynamics, and determinants of aortic systolic blood pressure, in young adults after coarctation repair. Methods and Results Aortic arch and carotid biomechanics, wave intensity and wave power, and central aortic blood pressure, were derived from echocardiography and brachial blood pressure in 43 young adults after coarctation repair and 42 controls. Coarctation subjects had higher brachial and central systolic blood pressure ( P=0.04), while aortic compliance was lower and characteristic impedance (Zc) higher. Although carotid intima-media thickness was higher ( P<0.001), carotid biomechanics were no different. Carotid forward compression wave power was higher and was negatively correlated with aortic compliance ( R2=0.42, P<0.001) and distensibility ( R2=0.37, P=0.001) in coarctation subjects. Aortic wave power and wave reflection indices were no different in control and coarctation patients, but coarctation patients with elevated aortic Zc had greater aorto-carotid transmission of forward compression wave power ( P=0.006). Aortic distensibility was the only independent predictor of central aortic systolic blood pressure on multivariable analysis. Conclusions Young adults following coarctation repair had a less compliant aorta, but no change in carotid biomechanics. Reduced aortic distensibility was related to greater transmission of aortic forward wave energy into the carotid artery and higher central aortic systolic blood pressure. These findings suggest that reduced aortic distensibility may contribute to later cardiovascular and cerebrovascular disease after coarctation repair.

Postnatal nutritional intakes and hyperglycemia as determinants of blood pressure at 6.5 years of age in children born extremely preterm

BACKGROUND

Adverse developmental programming by early-life exposures might account for higher blood pressure (BP) in children born extremely preterm. We assessed associations between nutrition, growth and hyperglycemia early in infancy, and BP at 6.5 years of age in children born extremely preterm.

METHODS

Data regarding perinatal exposures including nutrition, growth and glycemia status were collected from the Extremely Preterm Infants in Sweden Study (EXPRESS), a population-based cohort including infants born <27 gestational weeks during 2004-2007. BP measurements were performed at 6.5 years of age in a sub-cohort of 171 children (35% of the surviving children).

RESULTS

Higher mean daily protein intake (+1 g/kg/day) during postnatal weeks 1-8 was associated with 0.40 (±0.18) SD higher diastolic BP. Higher mean daily carbohydrate intake (+1 g/kg/day) during the same period was associated with 0.18 (±0.05) and 0.14 (±0.04) SD higher systolic and diastolic BP, respectively. No associations were found between infant growth (weight, length) and later BP. Hyperglycemia and its duration during postnatal weeks 1-4 were associated primarily with higher diastolic BP z-scores.

CONCLUSIONS

These findings emphasize the importance of modifiable early-life exposures, such as nutrition and hyperglycemia, in determining long-term outcomes in children born extremely preterm.

Endothelial colony-forming cell therapy for heart morphological changes after neonatal high oxygen exposure in rats, a model of complications of prematurity

Very preterm birth is associated with increased cardiovascular diseases and changes in myocardial structure. The current study aimed to investigate the impact of endothelial colony-forming cell (ECFC) treatment on heart morphological changes in the experimental model of neonatal high oxygen (O2 )-induced cardiomyopathy, mimicking prematurity-related conditions. Sprague-Dawley rat pups exposed to 95% O2 or room air (RA) from day 4 (P4) to day 14 (P14) were randomized to receive (jugular vein) exogenous human cord blood ECFC or vehicle at P14 (n = 5 RA-vehicle, n = 8 RA-ECFC, n = 8 O2 -vehicle and n = 7 O2 -ECFC) and the hearts collected at P28. Body and heart weights and heart to body weight ratio did not differ between groups. ECFC treatment prevented the increase in cardiomyocyte surface area in both the left (LV) and right (RV) ventricles of the O2 group (O2 -ECFC vs. O2 -vehicle LV: 121 ± 13 vs. 179 ± 21 μm2 , RV: 118 ± 12 vs. 169 ± 21 μm2 ). In O2 rats, ECFC treatment was also associated with a significant reduction in interstitial fibrosis in both ventricles (O2 -ECFC vs. O2 -vehicle LV: 1.07 ± 0.47 vs. 1.68 ± 0.41% of surface area, RV: 1.01 ± 0.74 vs. 1.77 ± 0.67%) and in perivascular fibrosis in the LV (2.29 ± 0.47 vs. 3.85 ± 1.23%) but in not the RV (1.95 ± 0.95 vs. 2.74 ± 1.14), and with increased expression of angiogenesis marker CD31. ECFC treatment had no effect on cardiomyocyte surface area or on tissue fibrosis of RA rats. Human cord blood ECFC treatment prevented cardiomyocyte hypertrophy and myocardial and perivascular fibrosis observed after neonatal high O2 exposure. ECFC could constitute a new regenerative therapy against cardiac sequelae caused by deleterious conditions of prematurity.

Endothelial Colony-Forming Cells in Young Adults Born Preterm: A Novel Link Between Neonatal Complications and Adult Risks for Cardiovascular Disease

BACKGROUND

Preterm birth is linked to cardiovascular risks and diseases. Endothelial progenitor cells play a critical role in vascular development and repair. Cord blood endothelial progenitor cells of preterm-born infants, especially endothelial colony-forming cells (ECFC), show enhanced susceptibility to prematurity-related pro-oxidant stress. Whether ECFC dysfunction is present in adulthood following preterm birth is unknown.

METHODS AND RESULTS

This cross-sectional observational study includes 55 preterm-born (≤29 gestational weeks) young adults (18-29 years old, 38% male) and 55 sex- and age-matched full-term controls. ECFC were isolated from peripheral blood; cell proliferative and vascular cord formation capacities were assessed in vitro. Daytime systolic blood pressure was higher, whereas glucose tolerance and body mass index were lower in preterm-born subjects. ECFC colonies grew in culture for 62% of full-term- and 58% of preterm-born participants. Preterm-born participants have formed ECFC colonies later in culture and have reduced proliferation compared with controls. Only in preterm-born individuals, we observed that the later the ECFC colony grows in culture, the worse was overall ECFC function. In addition, in preterms, elevated systolic blood pressure significantly correlated with reduced ECFC proliferation (r_S=-0.463; P=0.030) and numbers of branches formed on matrigel (r_S=-0.443; P=0.039). In preterm-born subjects, bronchopulmonary dysplasia was associated with impaired ECFC function, whereas exposure to antenatal steroids related to better ECFC function.

CONCLUSIONS

This study is the first to examine ECFC in preterm-born adults and to demonstrate ECFC dysfunction compared with full-term controls. In the preterm-born group, ECFC dysfunction was associated with bronchopulmonary dysplasia, the major prematurity-related neonatal morbidity, and with increased systolic blood pressure into adulthood.

Glucocorticoids, antenatal corticosteroid therapy and fetal heart maturation

Glucocorticoids are essential in mammals to mature fetal organs and tissues in order to survive after birth. Hence, antenatal glucocorticoid treatment (termed antenatal corticosteroid therapy) can be life-saving in preterm babies and is commonly used in women at risk of preterm birth. While the effects of glucocorticoids on lung maturation have been well described, the effects on the fetal heart remain less clear. Experiments in mice have shown that endogenous glucocorticoid action is required to mature the fetal heart. However, whether the potent synthetic glucocorticoids used in antenatal corticosteroid therapy have similar maturational effects on the fetal heart is less clear. Moreover, antenatal corticosteroid therapy may increase the risk of cardiovascular disease in adulthood. Here, we present a narrative review of the evidence relating to the effects of antenatal glucocorticoid action on the fetal heart and discuss the implications for antenatal corticosteroid therapy.

Neonatal Growth Restriction Slows Cardiomyocyte Development and Reduces Adult Heart Size

Prematurity is associated with reduced cardiac dimensions and an increased risk of cardiovascular disease. While prematurity is typically associated with ex utero neonatal growth restriction (GR), the independent effect of neonatal GR on cardiac development has not been established. We tested the hypothesis that isolated neonatal GR decreases cardiomyocyte growth and proliferation, leading to long-term alterations in cardiac morphology. C57BL/6 mice were fostered in litters ranging in size from 6 to 12 pups to accentuate normal variation in neonatal growth. Regardless of litter size, GR was defined by a weight below the 10th percentile. On postnatal day 8, Ki67 immunoreactivity, cardiomyocyte nucleation status and cardiomyocyte profile area were assessed. For adult mice, cardiomyocyte area was determined, along with cardiac dimensions by echocardiography and cardiac fibrosis by Masson's trichrome stain. On day 8, cardiomyocytes from GR versus control mice were significantly smaller and less likely to be binucleated with evidence of persistent cell cycle activity. As adults, GR mice continued to have smaller cardiomyocytes, as well as decreased left ventricular volumes without signs of fibrosis. Neonatal GR reduces cardiomyocyte size, delays the completion of binucleation, and leads to long-term alterations in cardiac morphology. Clinical studies are needed to ascertain whether these results translate to preterm infants that must continue to grow and mature in the midst of the increased circulatory demands that accompany their premature transition to an ex utero existence. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc.

Neonatal hyperoxia depletes pulmonary vein cardiomyocytes in adult mice via mitochondrial oxidation

Supplemental oxygen given to preterm infants has been associated with permanently altering postnatal lung development. Now that these individuals are reaching adulthood, there is growing concern that early life oxygen exposure may also promote cardiovascular disease through poorly understood mechanisms. We previously reported that adult mice exposed to 100% oxygen between postnatal days 0 and 4 develop pulmonary hypertension, defined pathologically by capillary rarefaction, dilation of arterioles and veins, cardiac failure, and a reduced lifespan. Here, Affymetrix Gene Arrays are used to identify early transcriptional changes that take place in the lung before pulmonary capillary rarefaction. We discovered neonatal hyperoxia reduced expression of cardiac muscle genes, including those involved in contraction, calcium signaling, mitochondrial respiration, and vasodilation. Quantitative RT-PCR, immunohistochemistry, and genetic lineage mapping using Myh6^CreER; Rosa26^RmT/mG mice revealed this reflected loss of pulmonary vein cardiomyocytes. The greatest loss of cadiomyocytes was seen within the lung followed by a graded loss beginning at the hilum and extending into the left atrium. Loss of these cells was seen by 2 wk of age in mice exposed to ≥80% oxygen and was attributed, in part, to reduced proliferation. Administering mitoTEMPO, a scavenger of mitochondrial superoxide during neonatal hyperoxia prevented loss of these cells. Since pulmonary vein cardiomyocytes help pump oxygen-rich blood out of the lung, their early loss following neonatal hyperoxia may contribute to cardiovascular disease seen in these mice, and perhaps in people who were born preterm.