Cardiovascular hemodynamics and umbilical artery N-terminal peptide of proB-type natriuretic peptide in human fetuses with growth restriction

Molecular regulators of defective placental and cardiovascular development in fetal growth restriction

Placental insufficiency is one of the major causes of fetal growth restriction (FGR), a significant pregnancy disorder in which the fetus fails to achieve its full growth potential in utero. As well as the acute consequences of being born too small, affected offspring are at increased risk of cardiovascular disease, diabetes and other chronic diseases in later life. The placenta and heart develop concurrently, therefore placental maldevelopment and function in FGR may have profound effect on the growth and differentiation of many organ systems, including the heart. Hence, understanding the key molecular players that are synergistically linked in the development of the placenta and heart is critical. This review highlights the key growth factors, angiogenic molecules and transcription factors that are common causes of defective placental and cardiovascular development.

Fetal NT-proBNP levels and their course in severe anemia during intrauterine treatment

PURPOSE

In adults and fetuses, N-terminal pro-B-type natriuretic peptide (NT-proBNP) is a marker of cardiac failure and myocardial remodelling. We examined the effect of anemia and intrauterine transfusion (IUT) on NT-proBNP concentrations in fetuses with anemia and established gestational age-dependent reference values of a control group.

METHODS

We analyzed NT-proBNP levels in anemic fetuses that underwent serial intrauterine transfusions (IUT), focusing on different causes and severity of anemia and comparing the results to a non-anemic control group.

RESULTS

In the control group, the average NT-proBNP concentration was 1339 ± 639 pg/ml, decreasing significantly with increasing gestational age (R = - 74.04, T = - 3.65, p = 0.001). Subjects had significantly higher NT-proBNP concentrations before initiation of IUT therapy (p < 0.001), showing fetuses with parvovirus B19 (PVB19) infection having the highest concentrations. Hydropic fetuses also showed an increased NT-proBNP concentration compared to non-hydropic fetuses (p < 0.001). During the course of therapy, NT-proBNP concentration before subsequent IUT decreased significantly from pathologically high levels, while MoM-Hb and MoM-MCA-PSV remained pathological.

CONCLUSION

NT-pro BNP levels in non-anemic fetuses are higher than in postnatal life, decreasing with ongoing pregnancy. Anemia is a hyperdynamic state and its severity correlates with circulating NT-proBNP levels. Highest concentrations occur in fetuses with hydrops and with PVB19 infection, respectively. Treatment by IUT leads to a normalisation of NT-proBNP concentrations, so the measurement of its levels may be useful in therapy monitoring.

Fetal Left Ventricle Function Evaluated by Two-Dimensional Speckle-Tracking Echocardiography across Clinical Stages of Severity in Growth-Restricted Fetuses

Fetal growth restriction (FGR) can result in adverse perinatal outcomes due to cardiac dysfunction. This study used 2D speckle-tracking echocardiography to assess left ventricle (LV) longitudinal strain across FGR severity stages. A prospective longitudinal cohort study measured global (GLS) and segmental LV longitudinal strain in FGR fetuses, with evaluations conducted at various time points. FGR was classified into subtypes based on published criteria using fetal weight centile and Doppler parameters. A linear mixed model was employed to analyze repeated measures and compare Z-score measurements between groups throughout gestational age. The study included 40 FGR fetuses and a total of 107 evaluations were performed: 21 from small for gestational age (SGA), 74 from the FGR stage I, and 12 from the FGR stage ≥ II. The results indicate that SGA and stage I FGR fetuses exhibit higher LV GLS than stages ≥ II. Throughout gestation, SGA and FGR stage I fetuses showed similar behavior with consistently better LV GLS values when compared to FGR stages ≥ II. No significant differences were observed in LV GLS strain behavior between SGA and FGR stage I. In conclusion, all FGRs show signs of early cardiac dysfunction, with severe cases demonstrating significantly a lower LV GLS when compared to mild cases, suggesting deterioration of cardiac dysfunction with progression of fetal compromise.

Long-term implications of fetal growth restriction

Fetal growth restriction (FGR), or intrauterine growth restriction (IUGR), is a complication of pregnancy where the fetus does not achieve its genetic growth potential. FGR is characterized by a pathological retardation of intrauterine growth velocity in the curve of intrauterine growth. However, the FGR definition is still debated, and there is a lack of a uniform definition in the literature. True IUGR, compared to constitutional smallness, is a pathological condition in which the placenta fails to deliver an adequate supply of oxygen and nutrients to the developing fetus. Infants with IUGR, compared to appropriately grown gestational age infants, have a significantly higher risk of mortality and neonatal complications with long-term consequences. Several studies have demonstrated how suboptimal fetal growth leads to long-lasting physiological alterations for the developing fetus as well as for the newborn and adult in the future. The long-term effects of fetal growth retardation may be adaptations to poor oxygen and nutrient supply that are effective in the fetal period but deleterious in the long term through structural or functional alterations. Epidemiologic studies showed that FGR could be a contributing factor for adult chronic diseases including cardiovascular disease, metabolic syndrome, diabetes, respiratory diseases and impaired lung function, and chronic kidney disease. In this review we discussed pathophysiologic mechanisms of FGR-related complications and potential preventive measures for FGR.

NT-proBNP Concentrations in the Umbilical Cord and Serum of Term Neonates: A Systematic Review and Meta-Analysis

The detection of NT-proBNP levels both in umbilical cord blood (UCB) samples and in serum samples collected from healthy term neonates during the neonatal period. A systematic review of relevant literature in accordance with PRISMA guidelines was conducted. For quality appraisal, the potential risk of bias was assessed using the BIOCROSS evaluation tool. The random-effects and fixed-effects models were used to calculate weighted mean differences with a corresponding 95% confidence interval. A total of forty (40) studies met the inclusion criteria for the systematic review. After further examination, eighteen (18) studies (1738 participants) from the UCB sample group and fourteen (14) studies (393 participants) from the serum sample group were selected to perform a meta-analysis. Using the fixed-effects model, the mean intervals of NT-proBNP in UCB and serum samples were 492 pg/mL (95% CI: 480−503 pg/mL) and 1341 pg/mL (95% CI: 1286−1397 pg/mL), respectively. A higher concentration of ΝΤ-proBNP was observed in the serum sample group compared to the UCB samples (p < 0.001). We present the intervals of NT-proBNP in UCB and in the serum of healthy term neonates. The determination of the potential effect of perinatal factors on the biomarker’s reference range was also aimed.

Fetal Pulmonary Vein Pulsatility Index in the Third Trimester of Pregnancy as a Predictor of Small for Gestational Age

OBJECTIVE

This study aimed to establish whether the increased fetal pulmonary venous pulsatility index (PVPI) in late pregnancy can independently predict small for gestational age (SGA) and to verify its cut point value and efficacy.

METHOD

The PVPI was measured in women with singleton pregnancies between 25 and 39 gestational weeks. Maternal hypertension and diabetes, estimated fetal weight (EFW) and percentile of the corresponding weeks of pregnancy (USG_PER), gestational weeks at delivery, and birth weight and percentile of the corresponding weeks of pregnancy (BABY_PER) were reviewed. To assess whether PVPI was independently correlated with BABY_PER, Pearson's correlation analysis was performed. The cut point value of PVPI for the prediction of SGA was established using a receiver operating characteristic (ROC) curve.

RESULTS

A total of 129 mothers were included in this study. Both USG_PER and PVPI were significantly related to SGA, independently (P <.001 and P = .004, respectively). The cut point value of PVPI was found to be 1.13. The AUCs of PVPI and USG_PER were not significantly different (P = .624). The sensitivity of PVPI was 70.27%, and the specificity was 92.39%.

CONCLUSION

PVPI could predict SGA independently, and the efficacy was comparable to EFW during pregnancy.

Molecular Signaling Mechanisms and Function of Natriuretic Peptide Receptor-A in the Pathophysiology of Cardiovascular Homeostasis

The discovery of atrial, brain, and C-type natriuretic peptides (ANP, BNP, and CNP) and their cognate receptors has greatly increased our knowledge of the control of hypertension and cardiovascular homeostasis. ANP and BNP are potent endogenous hypotensive hormones that elicit natriuretic, diuretic, vasorelaxant, antihypertrophic, antiproliferative, and antiinflammatory effects, largely directed toward the reduction of blood pressure (BP) and cardiovascular diseases (CVDs). The principal receptor involved in the regulatory actions of ANP and BNP is guanylyl cyclase/natriuretic peptide receptor-A (GC-A/NPRA), which produces the intracellular second messenger cGMP. Cellular, biochemical, molecular, genetic, and clinical studies have facilitated understanding of the functional roles of natriuretic peptides (NPs), as well as the functions of their receptors, and signaling mechanisms in CVDs. Transgenic and gene-targeting (gene-knockout and gene-duplication) strategies have produced genetically altered novel mouse models and have advanced our knowledge of the importance of NPs and their receptors at physiological and pathophysiological levels in both normal and disease states. The current review describes the past and recent research on the cellular, molecular, genetic mechanisms and functional roles of the ANP-BNP/NPRA system in the physiology and pathophysiology of cardiovascular homeostasis as well as clinical and diagnostic markers of cardiac disorders and heart failure. However, the therapeutic potentials of NPs and their receptors for the diagnosis and treatment of cardiovascular diseases, including hypertension, heart failure, and stroke have just begun to be expanded. More in-depth investigations are needed in this field to extend the therapeutic use of NPs and their receptors to treat and prevent CVDs.

Right ventricular dysfunction identified by abnormal strain values precedes evident growth restriction in small for gestational age fetuses

OBJECTIVES

Small for gestational age (SGA) fetuses have an increased risk for adverse outcome. Placental insufficiency leads to changes in the circulation, with secondary adaptation of the fetal heart resulting in changed cardiac deformation. This deformation can be measured with 2D speckle tracking echocardiography (2D-STE). SGA is antenatally often undiagnosed. The measurement of deformation changes in the fetal heart might help in the prediction of SGA and identify fetuses in need of more intensive surveillance.

METHODS

In this longitudinal prospective cohort study, global longitudinal strain (GLS) and strain rate (GLSR), measured before 23 weeks gestational age were compared between SGA and appropriate for gestational age (AGA) fetuses, based on birthweight corrected for gestational age at birth.

RESULTS

The fetal heart rate was significantly increased in SGA; 158 beats per minute (146-163) vs 148 (134-156); P = 0.035 in AGA. Right ventricle GLS (RV-GLS) values were significantly increased in SGA; -15.87% (-11.69% to -20.55%) vs -20.24% (-16.29% to -24.28%); p = 0.024, respectively.

CONCLUSION

RV-GLS values, measured with 2D-STE, were significantly increased in SGA, indicating systolic RV dysfunction before 23 weeks gestational age in fetuses who will become SGA later in pregnancy. A large longitudinal prospective cohort study is needed to confirm these findings.

Fetal cardiac remodeling and dysfunction is associated with both preeclampsia and fetal growth restriction

BACKGROUND

Preeclampsia and fetal growth restriction share some pathophysiologic features and are both associated with placental insufficiency. Fetal cardiac remodeling has been described extensively in fetal growth restriction, whereas little is known about preeclampsia with a normally grown fetus.

OBJECTIVE

To describe fetal cardiac structure and function in pregnancies complicated by preeclampsia and/or fetal growth restriction as compared with uncomplicated pregnancies.

STUDY DESIGN

This was a prospective, observational study including pregnancies complicated by normotensive fetal growth restriction (n=36), preeclampsia with a normally grown fetus (n=35), preeclampsia with fetal growth restriction (preeclampsia with a normally grown fetus-fetal growth restriction, n=42), and 111 uncomplicated pregnancies matched by gestational age at ultrasound. Fetal echocardiography was performed at diagnosis for cases and recruitment for uncomplicated pregnancies. Cord blood concentrations of B-type natriuretic peptide and troponin I were measured at delivery. Univariate and multiple regression analysis were conducted.

RESULTS

Pregnancies complicated by preeclampsia and/or fetal growth restriction showed similar patterns of fetal cardiac remodeling with larger hearts (cardiothoracic ratio, median [interquartile range]: uncomplicated pregnancies 0.27 [0.23-0.29], fetal growth restriction 0.31 [0.26-0.34], preeclampsia with a normally grown fetus 0.31 [0.29-0.33), and preeclampsia with fetal growth restriction 0.28 [0.26-0.33]; P<.001) and more spherical right ventricles (right ventricular sphericity index: uncomplicated pregnancies 1.42 [1.25-1.72], fetal growth restriction 1.29 [1.22-1.72], preeclampsia with a normally grown fetus 1.30 [1.33-1.51], and preeclampsia with fetal growth restriction 1.35 [1.27-1.46]; P=.04) and hypertrophic ventricles (relative wall thickness: uncomplicated pregnancies 0.55 [0.48-0.61], fetal growth restriction 0.67 [0.58-0.8], preeclampsia with a normally grown fetus 0.68 [0.61-0.76], and preeclampsia with fetal growth restriction 0.66 [0.58-0.77]; P<.001). Signs of myocardial dysfunction also were observed, with increased myocardial performance index (uncomplicated pregnancies 0.78 z scores [0.32-1.41], fetal growth restriction 1.48 [0.97-2.08], preeclampsia with a normally grown fetus 1.15 [0.75-2.17], and preeclampsia with fetal growth restriction 0.45 [0.54-1.94]; P<.001) and greater cord blood B-type natriuretic peptide (uncomplicated pregnancies 14.2 [8.4-30.9] pg/mL, fetal growth restriction 20.8 [13.1-33.5] pg/mL, preeclampsia with a normally grown fetus 31.8 [16.4-45.8] pg/mL and preeclampsia with fetal growth restriction 37.9 [15.7-105.4] pg/mL; P<.001) and troponin I as compared with uncomplicated pregnancies.

CONCLUSION

Fetuses of preeclamptic mothers, independently of their growth patterns, presented cardiovascular remodeling and dysfunction in a similar fashion to what has been previously described for fetal growth restriction. Future research is warranted to better elucidate the mechanism(s) underlying fetal cardiac adaptation in these conditions.

Assessment of ventricular contractility in fetuses with an estimated fetal weight less than the tenth centile

OBJECTIVE

To determine whether abnormal global, transverse, and longitudinal ventricular contractility of the heart in fetuses with an estimated fetal weight <10th centile is present, irrespective of Doppler studies of the umbilical artery and cerebroplacental ratio.

STUDY DESIGN

This was a retrospective study of 50 fetuses with an estimated fetal weight <10th centile that were classified based on Doppler results from the pulsatility indices of the umbilical artery and middle cerebral artery, and the calculated cerebroplacental ratio (pulsatility indices of the umbilical artery/middle cerebral artery). Right and left ventricular measurements were categorized into 3 groups: (1) global ventricular contractility (fractional area change), (2) transverse ventricular contractility (24-segment transverse fractional shortening), and (3) basal-apical longitudinal contractility (longitudinal strain, longitudinal displacement fractional shortening, and basal lateral and septal wall annular plane systolic excursion). Z scores for the above measurements were computed for fetuses with an estimated fetal weight <10th centile using the mean and standard deviation derived from normal controls. Ventricular contractility measurements were considered abnormal if their Z score values were <5th centile (z score <-1.65) or >95th centile (Z score >1.65), depending on the specific ventricular measurement.

RESULTS

The average gestational age at the time of the examination was 32 weeks 4 days (standard deviation 3 weeks 4 days). None of the 50 study fetuses demonstrated absent or reverse flow of the umbilical artery Doppler waveform. Eighty-eight percent (44/50) of fetuses had one or more abnormal measurements of cardiac contractility of 1 or both ventricles. Analysis of right ventricular contractility demonstrated 78% (39/50) to have 1 or more abnormal measurements, which were grouped as follows: global contractility 38% (19/50), transverse contractility 66% (33/50); and longitudinal contractility 48% (24/50). Analysis of left ventricular contractility demonstrated 1 or more abnormal measurements in 58% (29/50) that were grouped as follows: global contractility 38% (19/50); transverse contractility 40% (20/50); and longitudinal contractility 40% (20/50). Of the 50 study fetuses, 25 had normal pulsatility index of the umbilical artery and cerebroplacental ratios, 80% of whom had 1 or more abnormalities of right ventricular contractility and 56% of whom had 1 or more abnormalities of left ventricular contractility. Abnormal ventricular contractility for these fetuses was present in all 3 groups of measurements; global, transverse, and longitudinal. Those with an isolated abnormal pulsatility index of the umbilical artery (n=11) had abnormalities of transverse contractility of the right ventricular and global contractility in the left ventricle. When an isolated cerebroplacental ratio abnormality was present, the right ventricle demonstrated abnormal global, transverse, and longitudinal contractility, with the left ventricle only demonstrating abnormalities in transverse contractility. When both the pulsatility index of the umbilical artery and cerebroplacental ratio were abnormal (3/50), transverse and longitudinal contractility measurements were abnormal for both ventricles, as well as abnormal global contractility of the left ventricle.

CONCLUSIONS

High rates of abnormal ventricular contractility were present in fetuses with an estimated fetal weight <10th centile, irrespective of the Doppler findings of the pulsatility index of the umbilical artery, and/or cerebroplacental ratio. Abnormalities of ventricular contractility were more prevalent in transverse measurements than global or longitudinal measurements. Abnormal transverse contractility was more common in the right than the left ventricle. Fetuses with estimated fetal weight less than the 10th centile may be considered to undergo assessment of ventricular contractility, even when Doppler measurements of the pulsatility index of the umbilical artery, and cerebroplacental ratio are normal.

Size and shape of the four-chamber view of the fetal heart in fetuses with an estimated fetal weight less than the tenth centile

BACKGROUND

Fetuses with an estimated fetal weight below the 10^th centile have an increased risk of adverse perinatal and long-term outcomes as well as increased rates of cardiac dysfunction, which often alters cardiac size and shape of the 4-chamber view and the individual ventricles. As a result, a simple method has emerged to screen for potential cardiac dysfunction in fetuses with estimated fetal weights <10^th centile by measuring the size and shape of the 4-chamber view and the size of the ventricles.

OBJECTIVE

To determine the number of fetuses with an abnormal size and shape of the 4-chamber view and size of the ventricles in fetuses with an estimated fetal weight <10^th centile.

MATERIALS AND METHODS

This was a retrospective study of 50 fetuses between 25 and 37 weeks of gestation with an estimated fetal weight <10^th centile. Data from their last examination were analyzed. From an end-diastolic image of the 4-chamber view, the largest basal-apical length and transverse width were measured from their corresponding epicardial borders. This allowed the 4-chamber view area and global sphericity index (4-chamber view length/4-chamber view width) to be computed. In addition, tracing along the endocardial borders with speckle tracking software enabled measurements of the right and left ventricular chamber areas and the right ventricle/left ventricle area ratios to be computed. Doppler waveform pulsatility indices from the umbilical (umbilical artery pulsatility index) and middle cerebral arteries (middle cerebral artery pulsatility index) were analyzed, and the cerebroplacental ratio (middle cerebral artery pulsatility index/umbilical artery pulsatility index) computed. Umbilical artery pulsatility indices >90^th and cerebroplacental ratios <10^th centile were considered abnormal. Using data from the control fetuses, the centile for each of the cardiac measurements was categorized by whether it was <10^th or >90^th centile, depending upon the measurement.

RESULTS

Of the 50 fetuses with estimated fetal weight <10^th centile, 50% (n = 25) had a normal umbilical artery pulsatility index and cerebroplacental ratio. These fetuses had significantly more (P < 0.02 to <0.0001) abnormalities of the size and shape of the 4-chamber view than controls. In all, 44% had a 4-chamber view area >90^th centile, 32% had a 4-chamber view global sphericity index <10^th centile, 56% had a 4-chamber view width >90^th centile, and 80% had 1 or more abnormalities of size and/or shape. The remaining 50% of fetuses (n = 25) had abnormalities of 1 or both for the umbilical artery pulsatility index and/or cerebroplacental ratio. These fetuses had significantly higher rates of abnormalities (P <0.05 to <0.0001) than controls for the following 4-chamber view measurements: 36% had a 4-chamber view area >90^th centile; 28% had a 4-chamber view global sphericity index <10^th centile; and 68% had a 4-chamber view width >90^th centile. Only those fetuses with an abnormal umbilical artery pulsatility index had significant changes in ventricular size; 56% had a left ventricular area <10^th centile; 28% had a right ventricular area <10^th centile; 36% had right ventricular/left ventricular area ratio >90^th centile. One or more of the above abnormal measurements were present in 92% of the fetuses.

CONCLUSION

Higher rates of abnormalities of cardiac size and shape of the 4-chamber view were found in fetuses with an estimated fetal weight <10^th centile, regardless of their umbilical artery pulsatility index and cerebroplacental ratio measurements. Those with a normal umbilical artery pulsatility index and an abnormal cerebroplacental ratio had larger and wider measurements of the 4-chamber view. In addition, the shape of the 4-chamber view was more globular or round than in controls. These fetuses may have an increased risk of perinatal complications and childhood and/or adult cardiovascular disease. Screening tools derived from the 4-chamber view, acting as surrogates for ventricular dysfunction, may identify fetuses who could benefit from further comprehensive testing and future preventive interventions.

Genetic Ablation and Guanylyl Cyclase/Natriuretic Peptide Receptor-A: Impact on the Pathophysiology of Cardiovascular Dysfunction

Mice bearing targeted gene mutations that affect the functions of natriuretic peptides (NPs) and natriuretic peptide receptors (NPRs) have contributed important information on the pathogenesis of hypertension, kidney disease, and cardiovascular dysfunction. Studies of mice having both complete gene disruption and tissue-specific gene ablation have contributed to our understanding of hypertension and cardiovascular disorders. These phenomena are consistent with an oligogenic inheritance in which interactions among a few alleles may account for genetic susceptibility to hypertension, renal insufficiency, and congestive heart failure. In addition to gene knockouts conferring increased risks of hypertension, kidney disorders, and cardiovascular dysfunction, studies of gene duplications have identified mutations that protect against high blood pressure and cardiovascular events, thus generating the notion that certain alleles can confer resistance to hypertension and heart disease. This review focuses on the intriguing phenotypes of Npr1 gene disruption and gene duplication in mice, with emphasis on hypertension and cardiovascular events using mouse models carrying Npr1 gene knockout and/or gene duplication. It also describes how Npr1 gene targeting in mice has contributed to our knowledge of the roles of NPs and NPRs in dose-dependently regulating hypertension and cardiovascular events.

Successful use of an artificial placenta to support extremely preterm ovine fetuses at the border of viability

BACKGROUND

Ex vivo uterine environment therapy is an experimental life support platform designed to reduce the risk of morbidity and mortality for extremely preterm infants born at the border of viability (21-24 weeks' gestation). To spare the functionally immature lung, this platform performs gas exchange via a membranous oxygenator connected to the umbilical vessels, and the fetus is submerged in a protective bath of artificial amniotic fluid. We and others have demonstrated the feasibility of extended survival with ex vivo uterine environment therapy therapy in late preterm fetuses; however, there is presently no evidence to show that the use of such a platform can support extremely preterm fetuses, the eventual translational target for therapy of this nature.

OBJECTIVE

The objective of the study was to use our ex vivo uterine environment therapy platform to support the healthy maintenance of 600-700 g/95 days gestational age (equivalent to 24 weeks of human gestation) sheep fetuses. Primary outcome measures were as follows: (1) maintenance of key physiological variables; (2) absence of infection; (3) absence of brain injury; and (4) growth and cardiovascular function patterns matching that of noninstrumented, age-matched in utero controls.

STUDY DESIGN

Singleton fetuses from 8 ewes underwent surgical delivery at 95 days' gestation (term, 150 days). Fetuses were adapted to ex vivo uterine environment therapy and maintained for 120 hours with real-time monitoring of key physiological variables. Umbilical artery blood samples were regularly collected to assess blood gas data, differential counts, inflammation, and microbial load to exclude infection. Brain injury was evaluated by gross anatomical and histopathological approaches after euthanasia. Nine pregnant control animals were euthanized at 100 days' gestation to allow comparative postmortem analyses. Data were tested for mean differences with an analysis of variance.

RESULTS

Seven of 8 ex vivo uterine environment group fetuses (87.5%) completed 120 hours of therapy with key parameters maintained in a normal physiological range. There were no significant intergroup differences (P > .05) in final weight, crown-rump length, and body weight-normalized lung and brain weights at euthanasia compared with controls. There were no biologically significant differences in hematological parameters (total or differential leucocyte counts and plasma concentration of tumor necrosis factor-α and monocyte chemoattractant protein 1) (P > .05). Daily blood cultures were negative for aerobic and anaerobic growth in all ex vivo uterine environment animals. There was no difference in airspace consolidation between control and ex vivo uterine environment animals, and there was no increase in the number of lung cells staining positive for the T-cell marker CD3. There were no increases in interleukin-1, interleukin-6, interleukin-8, tumor necrosis factor-α, and monocyte chemoattractant protein 1 mRNA expression in lung tissues compared with the control group. No cases of intraventricular hemorrhage were observed, and white matter injury was identified in only 1 ex vivo uterine environment fetus.

CONCLUSION

For several decades, there has been little improvement in outcomes of extremely preterm infants born at the border of viability. In the present study, we report the use of artificial placenta technology to support, for the first time, extremely preterm ovine fetuses (equivalent to 24 weeks of human gestation) in a stable, growth-normal state for 120 hours. With additional refinement, the data generated by this study may inform a treatment option to improve outcomes for extremely preterm infants.

Velocity vector imaging echocardiography and NT-proBNP study of fetal cardiac function in pregnancy-induced maternal hypertension

PURPOSE

To investigate whether acute and transient pressure overload in patients with pregnancy-induced hypertension affects cardiac function in fetuses.

METHODS

We enrolled 104 singleton pregnant women with gestational ages ranging 30 to 33 weeks, visiting for prenatal care. Among them, 34 had gestational hypertension (GH), 32 had preeclampsia (PE), and 38 were healthy and formed the control group. Conventional echocardiographic and velocity vector imaging (VVI) variables were prospectively collected. Blood levels of N-terminal pro-brain natriuretic peptide (NT-proBNP) were measured from cord blood drawn at birth.

RESULTS

The fetuses of mothers with preeclampsia had significantly lower left (LV) and right ventricle (RV) diastolic strain rate (SRd) and RV strain (S) and systolic strain rate (SRs) than controls. LV and RV S, SRd, and SRS were not different in fetuses of mothers with GH and controls. The NT-proBNP levels were higher in fetuses of patients with PE than in GH and controls.

CONCLUSIONS

In the third trimester of pregnancy, fetal biventricular function and NT-proBNP levels are not significantly influenced by GH. Fetuses of mothers with PE present signs of LV and RV diastolic dysfunction, right ventricular systolic dysfunction, and elevated NT-pro-BNP levels. VVI echocardiography appears more sensitive than conventional echocardiography to evaluate fetal cardiac function.

Mitochondrial implications in human pregnancies with intrauterine growth restriction and associated cardiac remodelling

Intrauterine growth restriction (IUGR) is an obstetric complication characterised by placental insufficiency and secondary cardiovascular remodelling that can lead to cardiomyopathy in adulthood. Despite its aetiology and potential therapeutics are poorly understood, bioenergetic deficits have been demonstrated in adverse foetal and cardiac development. We aimed to evaluate the role of mitochondria in human pregnancies with IUGR. In a single‐site, cross‐sectional and observational study, we included placenta and maternal peripheral and neonatal cord blood mononuclear cells (PBMC and CBMC) from 14 IUGR and 22 control pregnancies. The following mitochondrial measurements were assessed: enzymatic activities of mitochondrial respiratory chain (MRC) complexes I, II, IV, I + III and II + III, oxygen consumption (cell and complex I‐stimulated respiration), mitochondrial content (citrate synthase [CS] activity and mitochondrial DNA copy number), total ATP levels and lipid peroxidation. Sirtuin3 expression was evaluated as a potential regulator of bioenergetic imbalance. Intrauterine growth restriction placental tissue showed a significant decrease of MRC CI enzymatic activity (P < 0.05) and CI‐stimulated oxygen consumption (P < 0.05) accompanied by a significant increase of Sirtuin3/β‐actin protein levels (P < 0.05). Maternal PBMC and neonatal CBMC from IUGR patients presented a not significant decrease in oxygen consumption (cell and CI‐stimulated respiration) and MRC enzymatic activities (CII and CIV). Moreover, CS activity was significantly reduced in IUGR new‐borns (P < 0.05). Total ATP levels and lipid peroxidation were preserved in all the studied tissues. Altered mitochondrial function of IUGR is especially present at placental and neonatal level, conveying potential targets to modulate obstetric outcome through dietary interventions aimed to regulate Sirtuin3 function.

Z-score reference ranges for pulsed-wave Doppler indices of the cardiac outflow tracts in normal fetuses

To determine Z-score equations and reference ranges for Doppler flow velocity indices of cardiac outflow tracts in normal fetuses. A prospective cross-sectional echocardiographic study was performed in 506 normal singleton fetuses from 18 to 40 weeks. Twelve pulsed-wave Doppler (PWD) measurements were derived from fetal echocardiography. The regression analysis of the mean and the standard deviation (SD) for each parameter were performed against estimated fetal weight (EFW) and gestational age (GA), in order to construct Z-score models. The correlation between these variables and fetal heart rate were also investigated. Strong positive correlations were found between the twelve PWD indices and the independent variables. A linear-quadratic regression model was the best description of the mean and SD of most parameters, with the exception of the velocity time interval (VTI) of ascending aorta against EFW, which was best fitted by a fractional polynomial. Z-score equations and reference values for PWD indices of fetal cardiac outflow tracts were proposed against GA and EFW, which may be useful for quantitative assessment of potential hemodynamic alternations, particularly in cases of intrauterine growth retardation and structural cardiac defects.

Factors affecting N-terminal pro-B-type natriuretic peptide levels in preterm infants and use in determination of haemodynamic significance of patent ductus arteriosus

This study aimed to investigate factors affecting N-terminal pro-B-type natriuretic peptide (NTproBNP) in preterm infants and the ability of NTproBNP to predict haemodynamically significant patent ductus arteriosus (HsPDA). Prospective cohort study of 51 infants < 30 weeks gestation. Blood NTproBNP and heart ultrasound were performed on day of life 3, 10, 28 and 36 weeks corrected age. NTproBNP levels analysed for prediction of HsPDA. The effect of gestational age, ventilation, hypoxia, bronchopulmonary dysplasia (BPD), creatinine and haemoglobin levels on NTproBNP levels were investigated. Infants with HsPDA had higher mean (SD) day 3 NTproBNP (1840 pmol/L (1058) versus 178 pmol/L (140) p < 0.001). Receiver operator curves of day 3 NTproBNP for prediction of day 3 and day 10 HsPDA had an area under the curve of 0.98 and 0.94, respectively. A chosen day 3 NTproBNP value of ≥ 287 pmol/L for the prediction of day 3 HsPDA correctly classified 92% (sensitivity 92%, specificity 92%). NTproBNP demonstrated only modest ability to predict severe BPD. Chronological but not gestational age affected NTproBNP. Ventilation, hypoxia and haemoglobin levels did not influence NTproBNP but creatinine level was positively correlated.

CONCLUSION

Day 3 NTproBNP is a useful biomarker to predict HsPDA and may be a valuable tool in future trial design. What is Known: • NTproBNP is a cardiac hormone used to diagnose and monitor cardiac dysfunction in adults and has been shown to be higher in premature infants with haemodynamically significant ductus arteriosus (HsPDA). What is new: • NTproBNP is highly predictive of ultrasound-defined HsPDA and may be a useful tool for further triage • Early NTproBNP higher in infants who develop severe BPD and with renal impairment but not affected by gestational age, recent exposure to hypoxia or haemoglobin levels while late levels unexpectedly higher in those without BPD or HsPDA.

Physiological adaptation of the growth-restricted fetus

The growth-restricted fetus in utero is exposed to a hostile environment and suffers undernutrition and hypoxia. To cope with the stress, the fetus changes its physiological functions. These adaptive changes aid intrauterine survival; however, they can lead to permanent functional and structural changes that can contribute to the development of serious chronic diseases later in life. Epigenetic mechanisms are an important part of the pathophysiological processes behind this "developmental origin of adult diseases." The dominant cardiovascular adaptive change is the redistribution of blood flow in hypoxic fetuses, with preferential supply of blood to the fetal brain, myocardium, and adrenal glands. The proportion of blood from the umbilical vein to the ductus venosus and foramen ovale increases, which increases the cardiac output of the left heart ventricle. The increased perfusion of fetal brain can be followed with Doppler ultrasound as increased diastolic velocities and decreased pulsatility index in the middle cerebral artery.

Long-term cardiovascular consequences of fetal growth restriction: biology, clinical implications, and opportunities for prevention of adult disease

In the modern world, cardiovascular disease is a leading cause of death for both men and women. Epidemiologic studies consistently have suggested an association between low birthweight and/or fetal growth restriction and increased rate of cardiovascular mortality in adulthood. Furthermore, experimental and clinical studies have demonstrated that sustained nutrient and oxygen restriction that are associated with fetal growth restriction activate adaptive cardiovascular changes that might explain this association. Fetal growth restriction results in metabolic programming that may increase the risk of metabolic syndrome and, consequently, of cardiovascular morbidity in the adult. In addition, fetal growth restriction is strongly associated with fetal cardiac and arterial remodeling and a subclinical state of cardiovascular dysfunction. The cardiovascular effects ocurring in fetal life, includes cardiac morphology changes, subclinical myocardial dysfunction, arterial remodeling, and impaired endothelial function, persist into childhood and adolescence. Importantly, these changes have been described in all clinical presentations of fetal growth restriction, from severe early- to milder late-onset forms. In this review we summarize the current evidence on the cardiovascular effects of fetal growth restriction, from subcellular to organ structure and function as well as from fetal to early postnatal life. Future research needs to elucidate whether and how early life cardiovascular remodeling persists into adulthood and determines the increased cardiovascular mortality rate described in epidemiologic studies.

Cord Blood Biomarkers of Cardiac Dysfunction and Damage in Term Growth-Restricted Fetuses Classified by Severity Criteria

OBJECTIVE

To assess cardiovascular function and damage in term small-for-gestational-age (SGA) and intrauterine growth-restricted (IUGR) fetuses by echocardiography and biomarkers in cord blood.

METHODS

This was a cohort study including 60 normal fetuses and 47 term small fetuses subclassified as small for gestational age (SGA) with estimated fetal weight (EFW) between the 3rd and 9th centiles and normal fetoplacental Doppler (n = 14) or intrauterine growth restriction (IUGR, n = 33) if EFW <3rd centile or EFW <10th centile together with cerebroplacental ratio <5th and/or mean uterine artery pulsatility index >95th centile. Fetal echocardiography included left myocardial performance index (MPI) and annular plane systolic excursion. Fetal B-type natriuretic peptide (BNP), troponin-I, heart-type fatty acid-binding proteins (H-FABP), and homocysteine concentrations were measured in cord blood collected at delivery.

RESULTS

Both SGA and IUGR cases presented echocardiographic signs of systolic and diastolic dysfunction with increased MPI (mean controls 0.43 [SD 0.12], SGA 0.47 [0.03], and IUGR 0.57 [0.08], p < 0.01) and decreased mitral annular plane systolic excursion (controls 6.0 mm [1.0], SGA 5.5 mm [0.6], and IUGR 4.9 mm [0.8], p = 0 01). IUGR fetuses presented increased levels of cord blood BNP (controls 17.2 pg/mL [11.5], SGA 22.4 pg/mL [10.7], and IUGR 31.2 pg/mL [26.8], p < 0.01). Troponin I was increased in both SGA and IUGR cases (controls 0.004 ng/mL [0.007], SGA 0.012 ng/mL [0.02], and IUGR 0.018 ng/mL [0.05], p < 0.01). H-FABP and homocysteine showed similar values among groups.

CONCLUSIONS

Cardiac dysfunction and cell damage is a common feature of term SGA and IUGR fetuses despite of the severity criteria for perinatal outcome. Further research is needed to evaluate the potential long-term consequences on their cardiovascular system.

Cardiac Morphology and Function in Preterm Growth Restricted Infants: Relevance for Clinical Sequelae

OBJECTIVES

To assess cardiac morphology and function in preterm infants with fetal growth restriction (FGR) compared with an appropriate for gestational age cohort, and to ascertain clinical correlation with neonatal sequelae.

STUDY DESIGN

With informed consent, 20 infants born between 28 and 32 weeks of gestational age and birthweight (BW) <10th percentile were compared using conventional and tissue Doppler echocardiography with 20 preterm appropriate for gestational age infants. Total duration of respiratory support was recorded.

RESULTS

The gestational age and BW of the infants with FGR and appropriate for gestational age infants were 29.8 ± 1.3 weeks vs 30 ± 0.9 weeks (P = .78) and 923.4 ± 168 g vs 1403 ± 237 g (P < .001), respectively. Preterm infants with FGR had significantly greater interventricular septal hypertrophy, greater free wall thickening, and lower sphericity indices (1.53 ± 0.15 vs 1.88 ± 0.2; P < .001), signifying globular and hypertrophied hearts. The transmitral E/A ratio and isovolumic relaxation time, markers of diastolic function, were significantly increased in the FGR cohort (0.84 ± 0.05 vs 0.78 ± 0.03 [P < .001] and 61.4 ± 4.1 ms vs 53.2 ± 3.2 ms [P < .001], respectively). Ejection fraction, as measured by the rate corrected mean velocity of circumferential fiber shortening was reduced (1.93 ± 0.4 circ/second vs 2.77 ± 0.5 circ/second; P < .001) in the FGR cohort. On follow-up, the total duration of respiratory support was significantly longer in the FGR cohort, and correlated with tissue Doppler E/E' (r = 0.65; P = .001), mean velocity of circumferential fiber shortening (r = -0.64; P = .001) and mitral annular peak systolic excursion (r = -0.57; P = .008).

CONCLUSIONS

Preterm infants with FGR have altered cardiac function evident within days after birth, which is associated with respiratory sequelae.

N-terminal pro-B-type natriuretic peptide in amniotic fluid of fetuses with known or suspected cardiac load

Background

Myocardial dysfunction occurs in a variety of fetal disorders. Findings from adult cardiology, where n-terminal pro-B-type natriuretic peptide (nt-proBNP) is an established biomarker of left ventricular dysfunction have been extended to fetal life. Since fetal blood sampling is technically challenging we investigated amniotic fluid nt-proBNP for its suitability to diagnose fetal myocardial dysfunction.

Methods

Ultrasound, Doppler examination and echocardiography was applied to classify cases and controls. Amniotic fluid nt-proBNP to amniotic fluid total protein ratio was calculated and compared to the gestational age-dependent reference intervals. In a subset of cases, fetal and maternal plasma nt-proBNP levels were determined.

Results

Specimen from 391 fetuses could be analyzed (171 cases, 220 controls). There was a high correlation between amniotic fluid and fetal blood nt-proBNP levels (r = 0.441 for cases; r = 0.515 for controls), whereas no correlation could be detected between maternal and fetal (blood and amniotic fluid) nt-proBNP concentrations. Specificity and positive likelihood ratio of amniotic fluid nt-proBNP to amniotic fluid total protein ratio were high (0.97 and 4.3, respectively).

Conclusion

Amniotic fluid nt-proBNP measurement allows diagnostic confirmation of fetal myocardial dysfunction. It may serve as a useful adjunct in addition and correlation to existing tests of myocardial function, particularly in the context of invasive fetal therapy, where access to the amniotic cavity is part of the procedure.

Persistence of Cardiac Remodeling in Preadolescents With Fetal Growth Restriction

BACKGROUND

Fetal growth restriction (FGR) affects 5% to 10% of newborns and is associated with increased cardiovascular mortality in adulthood. We evaluated whether prenatal cardiovascular changes previously demonstrated in FGR persist into preadolescence.

METHODS AND RESULTS

A cohort study of 58 FGR (defined as birth weight below 10th centile) and 94 normally grown fetuses identified in utero and followed-up into preadolescence (8-12 years of age) by echocardiography and 3-dimensional shape computational analysis. Compared with controls, FGR preadolescents had a different cardiac shape, with more spherical and smaller hearts. Left ventricular ejection fraction was similar among groups, whereas FGR had decreased longitudinal motion (decreased mitral annular systolic peak velocities: control median, 0.11 m/s [interquartile range, 0.09-0.12] versus FGR median 0.09 m/s [interquartile range, 0.09-0.10]; P<0.01) and impaired relaxation (isovolumic relaxation time: control, 0.21 ms [interquartile range, 0.12-0.35] versus FGR, 0.35 ms [interquartile range, 0.20-0.46]; P=0.04). Global longitudinal strain was decreased (control mean, -22.4% [SD, 1.37] versus FGR mean, -21.5% [SD, 1.16]; P<0.001) compensated by an increased circumferential strain and with a higher prevalence of postsystolic shortening in FGR as compared with controls. These differences persisted after adjustment for parental ethnicity and smoking, prenatal glucocorticoid administration, preeclampsia, gestational age at delivery, days in intensive care unit, sex, age, and body surface area at evaluation.

CONCLUSIONS

This study provides evidence that cardiac remodeling induced by FGR persists until preadolescence with findings similar to those reported in their prenatal life and childhood. The findings support the hypothesis of primary cardiac programming in FGR for explaining the association between low birth weight and cardiovascular risk in adulthood.

A review of superior vena cava flow measurement in the neonate by functional echocardiography

Neonatologists have begun using superior vena cava flow as assessed by functional echocardiography to facilitate real-time decision-making on cardiovascular care. This review aims to describe the basis of the technique, summarise the evidence for its use and compare the technique to existing clinical, biochemical and radiological techniques for assessing neonatal circulatory status.

CONCLUSION

Although echocardiographic measurements of superior vena cava flow, like other measures of perfusion, are not perfect, their noninvasive nature and ability to facilitate real-time decision-making means that at present, they remain the best available methodology of monitoring central perfusion in the neonatal population.

Myocardial dysfunction in children with intrauterine growth restriction: an echocardiographic study

Introduction

The prevalence of intrauterine growth restriction (IUGR) is about 3–10% of live-born newborns and can be as high as 20% in developing countries. It may result in the occurrence of cardiovascular diseases later in life.

Methods

The aim of this study was echocardiographic evaluation, with the use of conventional and tissue Doppler parameters, of cardiac function in children born with IUGR, and comparison with healthy peers born as normally grown foetuses.

Results

In the IUGR group, E wave and E/A ratio were significantly lower compared to the control group. A wave, isovolumetric relaxation time, deceleration time, myocardial performance index as well as E/E′ septal and E/E′ lateral indices were significantly higher compared to healthy peers.

Conclusion

Children with IUGR presented with subclinical myocardial dysfunction.

Intrauterine growth restriction: impact on cardiovascular development and function throughout infancy

Intrauterine growth restriction (IUGR) refers to the situation where a fetus does not grow according to its genetic growth potential. One of the main causes of IUGR is uteroplacental vascular insufficiency. Under these circumstances of chronic oxygen and nutrient deprivation, the growth-restricted fetus often displays typical circulatory changes, which in part represent adaptations to the suboptimal intrauterine environment. These fetal adaptations aim to preserve oxygen and nutrient supply to vital organs such as the brain, the heart, and the adrenals. These prenatal circulatory adaptations are thought to lead to an altered development of the cardiovascular system and "program" the fetus for life long cardiovascular morbidities. In this review, we discuss the alterations to cardiovascular structure, function, and control that have been observed in growth-restricted fetuses, neonates, and infants following uteroplacental vascular insufficiency. We also discuss the current knowledge on early life surveillance and interventions to prevent progression into chronic disease.

Clinical application of fetal left modified myocardial performance index in the evaluation of fetal growth restriction

OBJECTIVE

This study aims to evaluate cardiac function in fetuses with intrauterine growth restriction (IUGR) compared with healthy fetuses, using the left modified myocardial performance index (MPI) and the association between MPI and perinatal outcome.

METHODS

Pregnant women between 34 and 39 weeks of gestation, who met the criteria for IUGR and were scheduled for delivery at an Egyptian tertiary medical center, were prospectively enrolled in the study. Women in the same gestational-age group with uncomplicated pregnancies were included as a control group. MPI was measured in all fetuses. The IUGR group was analyzed based on normal and abnormal umbilical artery (UA) Doppler. Perinatal outcomes were recorded.

RESULTS

The mean left MPI was significantly higher in IUGR fetuses with abnormal UA Doppler (mean 0.58±SD 0.093) compared with healthy fetuses (mean 0.45±SD 0.070) (P<0.001). IUGR fetuses with abnormal left MPI showed significantly worse perinatal outcome and increased morbidity compared with the control group. IUGR fetuses with abnormal left MPI also showed significantly worse perinatal outcome compared with IUGR fetuses with normal MPI (whether the UA Doppler was normal or abnormal). The fetal MPI was associated with the severity of fetal compromise in IUGR fetuses based on the perinatal outcome.

CONCLUSION

MPI is a potentially useful tool in evaluating fetuses with suspected IUGR, which is crucial in classifying IUGR pregnancies into critical and non-critical cases and in predicting neonatal outcome.

Perinatal inflammation: a common factor in the early origins of cardiovascular disease?

Cardiovascular disease continues to be the leading cause of global morbidity and mortality. Traditional risk factors account for only part of the attributable risk. The origins of atherosclerosis are in early life, a potential albeit largely unrecognized window of opportunity for early detection and treatment of subclinical cardiovascular disease. There are robust epidemiological data indicating that poor intrauterine growth and/or prematurity, and perinatal factors such as maternal hypercholesterolaemia, smoking, diabetes and obesity, are associated with adverse cardiovascular intermediate phenotypes in childhood and adulthood. Many of these early-life risk factors result in a heightened inflammatory state. Inflammation is a central mechanism in the development of atherosclerosis and cardiovascular disease, but few studies have investigated the role of overt perinatal infection and inflammation (chorioamnionitis) as a potential contributor to cardiovascular risk. Limited evidence from human and experimental models suggests an association between chorioamnionitis and cardiac and vascular dysfunction. Early life inflammatory events may be an important mechanism in the early development of cardiovascular risk and may provide insights into the associations between perinatal factors and adult cardiovascular disease. This review aims to summarise current data on the early life origins of atherosclerosis and cardiovascular disease, with particular focus on perinatal inflammation.

Fetal cardiac function in late-onset intrauterine growth restriction vs small-for-gestational age, as defined by estimated fetal weight, cerebroplacental ratio and uterine artery Doppler

OBJECTIVE

Among late-onset small fetuses, a combination of estimated fetal weight (EFW), cerebroplacental ratio (CPR) and mean uterine artery (UtA) pulsatility index (PI) can predict a subgroup of fetuses with poor perinatal outcome; however, the association of these criteria with fetal cardiac structure and function is unknown. Our aim was to determine the presence and severity of signs indicating cardiac dysfunction in small fetuses, classified as intrauterine growth-restricted (IUGR) or small-for-gestational age (SGA), according to EFW, CPR and UtA-PI.

METHODS

A cohort of 209 late-onset small fetuses that were delivered > 34 weeks of gestation was divided in two categories: SGA (n = 59) if EFW was between the 3(rd) and 9(th) centiles with normal CPR and UtA-PI; and IUGR (n = 150) if EFW was < 3(rd) centile, or < 10(th) centile with a CPR < 5(th) centile and/or UtA-PI > 95(th) centile. The small population was compared with 150 appropriately grown fetuses (controls). Fetal cardiac morphometry and function were assessed by echocardiography using two-dimensional M-mode, conventional and tissue Doppler.

RESULTS

Compared with controls, both IUGR and SGA fetuses showed larger and more globular hearts (mean left sphericity index ± SD: controls, 1.8 ± 0.3; SGA, 1.5 ± 0.2; and IUGR, 1.6 ± 0.3; P < 0.01) and showed signs of systolic and diastolic dysfunction, including decreased tricuspid annular plane systolic excursion (mean ± SD: controls, 8.2 ± 1.1; SGA, 7.4 ± 1.2; and IUGR, 6.9 ± 1.1; P < 0.001) and increased left myocardial performance index (mean ± SD: controls, 0.45 ± 0.14; SGA, 0.51 ± 0.08; and IUGR, 0.57 ± 0.1; P < 0.001).

CONCLUSIONS

Despite a perinatal outcome comparable to that of normal fetuses, the population of so-defined SGA fetuses showed signs of prenatal cardiac dysfunction. This supports the concept that at least a proportion of them are not 'constitutionally small' and that further research is needed.

Reference intervals for N-terminal pro-B-type natriuretic peptide in amniotic fluid between 10 and 34 weeks of gestation

BACKGROUND

In adult and pediatric cardiology, n-terminal pro-B-type natriuretic peptide (nt-proBNP) serves as biomarker in the diagnosis and management of cardiovascular dysfunction. Elevated levels of circulating nt-proBNP are present in fetal conditions associated with myocardial pressure or volume load. Compared to fetal blood sampling, amniocentesis is technically easier and can be performed from early pregnancy onwards. We aimed to investigate amniotic fluid (AF) nt-proBNP concentrations in normal pregnancies between 10 and 34 weeks of gestation.

METHODS

Nt-proBNP and total protein (TP) was measured in AF by chemiluminescence assay (photometry, respectively). To adjust for a potential dilutional effect, the AF-nt-proBNP/AF-TP ratio was analyzed. Reference intervals were constructed by regression modeling across gestational age.

RESULTS

132 samples were analyzed. A negative correlation between AF-nt-proBNP/AF-TP ratio and gestational age was observed. Curves for the mean and the 5% and 95% reference interval between 10 and 34 weeks of gestation were established.

CONCLUSION

In normal pregnancy, nt-proBNP is present in AF and decreases during gestation. Our data provide the basis for research on AF-nt-proBNP as biomarker in fetal medicine.

Cardiac dysfunction is associated with altered sarcomere ultrastructure in intrauterine growth restriction

OBJECTIVE

The purpose of this study was to assess whether abnormal cardiac function in human fetuses with intrauterine growth restriction (IUGR) is associated with ultrastructural differences in the cardiomyocyte sarcomere.

STUDY DESIGN

Nine severe early-onset IUGR fetuses and 9 normally grown fetuses (appropriate growth for gestational age) who died in the perinatal period were included prospectively. Cardiac function was assessed by echocardiography and levels of B-type natriuretic peptide and troponin-I. Heart sections were imaged by second harmonic generation microscopy, which allowed unstained visualization of cardiomyocyte's sarcomere length.

RESULTS

Echocardiographic and biochemical markers showed signs of severe cardiac dysfunction in IUGR fetuses. Second harmonic generation microscopy demonstrated a significantly shorter sarcomere length in IUGR as compared with appropriate growth for gestational age fetuses.

CONCLUSION

IUGR is associated with changes in the cardiomyocyte contractile machinery in the form of shorter sarcomere length, which could help to explain the cardiac dysfunction previously documented in IUGR.

Aortic and carotid intima-media thickness in term small-for-gestational-age newborns and relationship with prenatal signs of severity

OBJECTIVE

To assess carotid and aortic intima-media thickness (IMT) in term small-for-gestational-age (SGA) newborns with and without prenatal signs of severity.

METHODS

This prospective study comprised 67 cases diagnosed prenatally and 134 normally grown newborns. Cases were subclassified into SGA with no signs of severity and those with signs of severity, defined as a birth weight below the 3(rd) percentile or abnormal uterine artery Doppler or cerebroplacental ratio. Blood pressure and vascular IMT were evaluated.

RESULTS

SGA newborns showed a non-significant trend for higher values of blood pressure. IMT values were significantly increased in SGA newborns, with and without signs of severity, compared with controls. The magnitude of the increase was higher in SGA newborns with signs of severity.

CONCLUSIONS

Vascular IMT was increased in SGA newborns, irrespective of the presence or absence of prenatal signs of severity. This finding challenges the notion of 'constitutionally small' SGA, and supports the premise that the majority of SGA newborns have true growth restriction and suffer fetal cardiovascular programming.

Correlation analysis of ductus venosus velocity indices and fetal cardiac function

OBJECTIVE

To examine the relationships between the ductus venosus (DV) pulsatility index for veins (PIV), individual DV velocity ratios and diastolic and global myocardial cardiac function.

METHODS

Doppler measurements of the DV, atrioventricular (AV) valves and ventricular in- and outflow were analyzed. The DV-PIV and velocity ratios for individual phases (systole (S), end-systolic relaxation (v), early diastole (D), atrial systole (a), and S/v, S/D, S/a, v/D, v/a and D/a ratios) were calculated. The ratio of early and late diastolic peak velocities across AV valves was calculated (E/A ratio). Left modified myocardial performance index (MPI) was calculated from time intervals between valve clicks defining isovolumetric contraction/relaxation and ejection times. All values were transformed to Z-scores. The distributions of DV velocity ratios and DV-PIV were correlated with cardiac Doppler parameters.

RESULTS

A total of 1163 examinations from 213 fetuses, most of which were at risk for cardiac dysfunction, were included in the study. In 742 the PIV was normal and in 421 PIV was elevated > 2 SD above the normal mean. The DV-PIV correlated with velocity ratios (P < 0.0001) but not with E/A ratios and the MPI. S/v and v/D ratios were related to tricuspid and mitral E/A ratios and left ventricular MPI. The S/D ratio was only related to both E/A ratios. There was no relationship between a-wave-related velocity ratios and cardiac function.

CONCLUSIONS

Velocity ratios of the DV show relationships with cardiac function that are not reflected by the PIV alone. In cases of suspected fetal cardiac dysfunction based on elevated DV-PIV, analysis of velocity ratios or direct cardiac evaluation is suggested to determine the underlying pathophysiology.

Cardiac function and arterial indices in infants born small for gestational age: analysis by speckle tracking

AIM

To compare strain indices between small for gestational age (SGA) infants and asymptomatic appropriate for gestational age (AGA) infants and to ascertain correlations with arterial biophysical properties.

METHODS

In this prospective observational echocardiographic study, 20 inborn term SGA infants weighing <3rd centile for gestational age were compared with 20 AGA infants. Demographic and echocardiographic data were analysed regarding cardiac strain and strain rate and arterial indices (stiffness, impedance and strain elastic modulus). Correlations between variables were assessed using Pearson's coefficient of correlation.

RESULTS

Ponderal index was significantly lower in SGA infants (24.6 ± 2.9 vs. 29.5 ± 2.5). Left ventricular global longitudinal strain (GLS) was noted to be significantly impaired in the SGA infants (-15.9% ± 2.1 vs. -21.3% ± 2.8, p < 0.001). A basal to apical gradient was noted in segmental strain. Arterial biophysical measurements were significantly altered in the SGA infants. Significant correlations were noted between GLS and arterial stiffness (r = -0.4, p = 0.03), weight-indexed stiffness (r = -0.45, p = 0.02) and pressure-strain elastic modulus (r = -0.49, p = 0.01).

CONCLUSION

Impairment in myocardial deformation was noted in the presence of altered arterial biophysical properties in the SGA infants.

Early detection of prenatal cardiocirculatory compromise in small for gestational age infants

BACKGROUND

Impairment of gas and substrate exchange through the placenta leads to fetal hypoxia and growth restriction. Oxygenation of vital organs is maintained with preferential perfusion at the expense of less vital organs, challenging the fetal cardiovascular system.

OBJECTIVES

To identify cardiovascular compromise in preterm small for gestational age (SGA) infants using the cardiac biomarker B-type natriuretic peptide (BNP), which indicates the workload of the myocardium.

METHODS

In this retrospective case-control study, 26 SGA infants born at less than 32 weeks of gestation from October 2009 to October 2010 were matched for gestational age and month of birth with 26 appropriate for gestational age (AGA) infants. Antenatal Doppler ultrasound was used to identify fetal hemodynamic changes by determination of the pulsatility index (PI) of the middle cerebral artery (MCA-PI), umbilical artery (UA-PI) and veins of the ductus venosus (DV-PIV). These indices were compared with BNP levels obtained within 6 h after birth.

RESULTS

Antenatal PIs of MCA, UA and DV were significantly related to elevated BNP levels after birth in SGA infants, but not in AGA infants (SGA: MCA-PI = r(2) 0.23, p < 0.05; UA-PI = r(2) 0.46, p < 0.01; DV-PIV = r(2) 0.31, p < 0.05). Furthermore, signs of perinatal (chronic) asphyxia coincided with elevated levels of BNP. SGA was related to more postnatal cardiocirculatory complications. No significant relations between postnatal cardiac ultrasound measurements, placenta size and BNP were found.

CONCLUSION

BNP levels were elevated early after birth in SGA infants and corresponded positively with Doppler indices of circulatory compromise. This suggests an increased workload of the myocardium.

Cardiac function and arterial biophysical properties in small for gestational age infants: postnatal manifestations of fetal programming

OBJECTIVE

To investigate the differences in cardiac function and arterial biophysical properties between term-born appropriate for gestational age (AGA) infants and small for gestational age (SGA) infants. Our hypothesis was that adaptation to intrauterine growth restriction induces changes in cardiac and arterial indices.

STUDY DESIGN

This was a prospective observational echocardiographic evaluation of cardiac and arterial indices in SGA infants and AGA infants. Demographic and echocardiographic data were compared between 20 inborn term SGA infants with birth weight <3rd percentile for gestational age and 20 AGA infants.

RESULTS

The Ponderal index was significantly lower and blood pressure was significantly higher in the SGA infants compared with the AGA infants. Left ventricular output was lower in the SGA infants (170 ± 31 mL/kg/min vs 197 ± 39 mL/kg/min). Diastolic dysfunction was greater in the SGA infants (ie, reduced E and A wave velocities, higher E/A ratio [1.08 ± 0.16 vs 0.85 ± 0.07], and prolonged isovolumic relaxation time [73 ± 6.2 ms vs 62.6 ± 3.6 ms]). Aortic intima-media thickness was significantly greater in the SGA infants (822 ± 105 μm vs 694 ± 52 μm), as were arterial wall stiffness index and input impedance.

CONCLUSION

Cardiac function and arterial biophysical properties were altered in the SGA infants. The findings complement the information on the association between in utero growth and cardiovascular morbidity in later life.

Cord blood B-type natriuretic peptide levels in placental insufficiency: correlation with fetal Doppler and pH at birth

OBJECTIVE

To examine the correlation of cardiac B-type natriuretic peptide (BNP) concentrations in umbilical cord blood at birth with fetal Doppler parameters and pH at birth.

STUDY DESIGN

Prospective cross-sectional study with the following inclusion criteria: women with a singleton pregnancy, placental insufficiency characterized by increased pulsatility index (PI) of the umbilical artery (UA), intact membranes, and absence of fetal abnormalities. The exclusion criteria kept out cases of newborns with postnatal diagnosis of abnormality and cases in which the blood analysis was not performed. The Doppler parameters used were the UA PI, middle cerebral artery (MCA) PI, cerebroplacental ratio (CPR), and ductus venosus (DV) PI for veins (PIV), all converted into zeta scores. Blood samples were obtained from the umbilical cord immediately after delivery to measure the pH of the UA and the BNP.

RESULTS

Thirty-two pregnancies with placental insufficiency were included, 21 (65%) with positive diastolic flow and 11 (35%) with absent or reversed end diastolic flow in the UA. The concentration of BNP correlated significantly with the UA PI z-score (rho=0.43, P=0.016), the CPR z-score (rho=-0.35, P=0.048), the DV PIV z-score (rho=0.61, P<0.001), pH at birth (rho=-0.39, P=0.031), and gestational age (rho=-0.51, P=0.003). In the multiple regression analysis, antenatal parameters were included; the DV PIV z-score (P=0.008) was found to be an independent parameter correlating with BNP at birth. Correlation between BNP and the DV PIV z-score was borne out by the regression equation Log[BNP]=2.34+0.13*DV (F=18.8, P<0.001). Correlation between BNP and pH at birth was confirmed by the regression equation Log[BNP]=21.36-2.62*pH (F=7.69, P=0.01).

CONCLUSION

The results suggest that fetal cardiac dysfunction identified by BNP concentrations at birth correlated independently with changes in DV PIV and correlated negatively with pH values at birth.

Cardiac blood flow measurements in stable full term small for gestational age neonates

BACKGROUND

Cardiac blood flow measurements are useful in the haemodynamic management of neonates. Cardiac blood flows can be estimated with functional echocardiography as follows; flow in Superior Vena Cava (SVC), Right Ventricular Outflow (RVO) and Left Ventricular Outflow (LVO). Studies in preterm infants have shown that abnormal superior vena cava flow is associated with poor neurodevelopmental outcomes. To date, normative data on LVO, RVO and SVC flows has been established for term appropriate for gestational age neonates and preterm neonates, but no data is available on RVO, LVO and SVC flows for term small for gestational age neonates.

OBJECTIVE

To determine Right Ventricular Output (RVO), Left Ventricular Output (LVO) and Superior Vena Cava (SVC) flow after the transitional period in stable full term Small for Gestational Age (SGA) neonates.

DESIGN

Observational study.

SETTING

A tertiary care, perinatal centre in western Maharashtra, India.

PARTICIPANTS

Full term (37 to 41 weeks) small for gestational age (weight below 10th percentile for gestational age) infants who were born during the study period.

METHODS

RVO, LVO and SVC flows were measured by functional echocardiography on day 7 of life in stable full term SGA neonates from January 2011 to August 2011. Infants who required respiratory or cardiovascular support and intensive care unit admissions for any indication and those with a clinical suspicion of an infection within 48 hours after data collection were excluded from the study.

STATISTICAL ANALYSES

Unpaired t-test was used to compare SVC flow between symmetric and asymmetric SGA neonates.

MAIN OUTCOME MEASURE

Measurements of RVO, LVO and SVC in term SGA neonates on day 7 of life.

RESULTS

We performed measurements in 52 term SGA neonates with a median (range) birth weight of 2.190 (1.600-2.410) kg. Fifty two measurements were analyzed on day 7. The mean (SD) RVO, LVO and SVC flows were 255.59 (57.42) , 214.61 (52.04) and 126.28 (31.23) mL/kg/min.

CONCLUSION

This study provides RVO, LVO and SVC flow values in a cohort of stable term SGA neonates after the transitional period.

Cardiorenal syndrome is present in human fetuses with severe, isolated urinary tract malformations

OBJECTIVE

We analyzed the association between renal and cardiovascular parameters in fetuses with isolated severe urinary tract malformations.

METHODS

39 fetuses at a mean gestational age of 23.6 weeks with nephropathies or urinary tract malformations and markedly impaired or absent renal function were prospectively examined. Fetal echocardiography was performed, and thicknesses of the interventricular septum, and left and right ventricular wall were measured. Blood flow velocity waveforms of the umbilical artery, middle cerebral artery, and ductus venosus were obtained by color Doppler ultrasound. Concentrations of circulating n-terminal pro-B-type natriuretic peptide (nt-proBNP), cystatin C, ß2-microglobulin, and hemoglobin were determined from fetal blood samples.

RESULTS

Malformations included 21 cases of obstructive uropathy, 10 fetuses with bilateral nephropathy, and 8 cases of bilateral renal agenesis. Marked biventricular myocardial hypertrophy was present in all cases. The ratio between measured and gestational age-adjusted normal values was 2.01 (interventricular septum), 1.85, and 1.78 (right and left ventricular wall, respectively). Compared to controls, levels of circulating nt-proBNP were significantly increased (median (IQR) 5035 ng/L (5936 ng/L) vs. 1874 ng/L (1092 ng/L); p<0.001). Cystatin C and ß2-microglobulin concentrations were elevated as follows (mean ± SD) 1.85±0.391 mg/L and 8.44±2.423 mg/L, respectively (normal range 1.66±0.202 mg/L and 4.25±0.734 mg/L, respectively). No correlation was detected between cardiovascular parameters and urinary tract morphology and function. Despite increased levels of nt-proBNP cardiovascular function was preserved, with normal fetal Doppler indices in 90.2% of cases.

CONCLUSION

Urinary tract malformations resulting in severe renal impairment are associated with biventricular myocardial hypertrophy and elevated concentrations of circulating nt-proBNP during fetal life. Cardiovascular findings do not correlate with kidney function or morphology.

B-type natriuretic peptide levels are correlated with birth-weight discordance in monochorionic-diamniotic twins without twin-twin transfusion syndrome

OBJECTIVE

To determine whether B-type natriuretic peptide (BNP) levels in umbilical cord blood (UCB) and amniotic fluid (AF) are correlated with birth-weight discordances in monochorionic-diamniotic twins.

STUDY DESIGN

The UCB-BNP and AF-BNP levels were determined at birth in 36 twin-pairs without twin-twin transfusion syndrome (TTTS).

RESULT

Both the UCB-BNP and the AF-BNP levels were significantly higher among twins with either a birth-weight discordance ≥20% (141.6 versus 52.9 pg ml(-1) for UCB-BNP, 38.0 versus 17.2 pg ml(-1) for AF-BNP) or cardiac dysfunction at birth (167.2 versus 56.3 pg ml(-1) for UCB-BNP, 34.9 versus 19.0 pg ml(-1) for AF-BNP), compared with neonates without the respective characteristics. The UCB-BNP and AF-BNP levels in both the larger and the smaller twins were significantly correlated with birth-weight discordance.

CONCLUSION

Cardiac dysfunction occurs in both larger and smaller co-twins with increasing birth-weight discordances, even in the absence of TTTS.

Use of cardiac biomarkers in neonatology

Cardiac biomarkers are used to identify cardiac disease in term and preterm infants. This review discusses the roles of natriuretic peptides and cardiac troponins. Natriuretic peptide levels are elevated during atrial strain (atrial natriuretic peptide (ANP)) or ventricular strain (B-type natriuretic peptide (BNP)). These markers correspond well with cardiac function and can be used to identify cardiac disease. Cardiac troponins are used to assess cardiomyocyte compromise. Affected cardiomyocytes release troponin into the bloodstream, resulting in elevated levels of cardiac troponin. Cardiac biomarkers are being increasingly incorporated into clinical trials as indicators of myocardial strain. Furthermore, cardiac biomarkers can possibly be used to guide therapy and improve outcome. Natriuretic peptides and cardiac troponins are potential tools in the diagnosis and treatment of neonatal disease that is complicated by circulatory compromise. However, clear reference ranges need to be set and validation needs to be carried out in a population of interest.

Evaluation of cardiac functions in term small for gestational age newborns with mild growth retardation: a serial conventional and tissue Doppler imaging echocardiographic study

BACKGROUND

The aim of this study is to evaluate the cardiac functions of term small for gestational age (SGA) babies with mild growth retardation by echocardiography during the postnatal period.

METHODS AND RESULTS

Thirty term SGA (2271±207 g/38-41 weeks (mean 39.5 weeks)) and 30 term AGA (3298±338 g/38-41 weeks (mean 39 weeks)) newborns as the control group, with normal general health status and with no nutritional problems were evaluated at three time points, on the 3rd postnatal day, at the 3rd and the 6th months. In the initial analysis, heart rate, left ventricular end diastolic diameter index (LVEdDI), cardiac index (CI), all E/A, Em/Am and E/Em ratios, pulsed wave Doppler myocardial performance index (MPI), and tissue Doppler imaging MPI values were higher in SGA babies than the control group. In the last analysis, only heart rate, LVEdDI and CI values were different between SGA and control groups.

CONCLUSIONS

Systolic and diastolic cardiac dysfunctions were determined in SGA babies with mild growth retardation during the first 6 months of postnatal period. Any disease that affects the hemodynamic stability of these patients during postnatal period may lead to early progressive deterioration in cardiac functions. Furthermore, many of the cardiac functions of these babies have been improved about the 6th month period, and high levels of heart rate and LVEdDI may be suggested as an indicator of cardiac remodeling.

Circulating N-terminal pro-B-type natriuretic peptide in fetal anemia before and after treatment

BACKGROUND

N-terminal pro-B-type natriuretic peptide (ntproBNP) is an established marker of heart failure in adult cardiology. We analyzed nt-proBNP in the circulation of fetuses with increased volume load secondary to anemia and investigated the effect of treatment on nt-proBNP concentration.

METHODS

Fetuses undergoing intrauterine transfusion (IUT) were examined. nt-proBNP was measured before IUT and correlated with hemoglobin concentrations, ultrasonographic findings, and Doppler measurements of the peak systolic velocity of the middle cerebral artery (MCA-PSV).

RESULTS

A total of 27 patients (7 with hydrops) and 78 controls were examined. nt-proBNP was markedly elevated in anemia (P < 0.001). Concentrations were highest in hydropic fetuses (P < 0.03); no differences were present in hemoglobin and MCA-PSV values between hydropic and nonhydropic cases. In fetuses undergoing multiple IUTs nt-proBNP normalized after the third IUT, whereas hemoglobin and MCA-PSV remained abnormal.

CONCLUSION

Levels of circulating nt-proBNP correlate well with the degree of myocardial workload in the hyperdynamic state of fetal anemia. We hypothesize that normalization of nt-proBNP after serial transfusions is an indicator of myocardial adjustment to chronic anemia. nt-proBNP measurement may be useful in the management of fetal anemia, particularly in cases at risk of hydrops and fetuses requiring multiple transfusions.

Fetal myocardial tissue Doppler indices before birth physiologically change in proportion to body size adjusted for gestational age in low-risk term pregnancies

BACKGROUND

Few studies have investigated the relationship between myocardial tissue Doppler parameters and fetal size adjusted for gestational age and its trend has been controversial.

AIMS

To investigate fetal cardiac function before birth using tissue Doppler imaging (TDI: indicated by the prime symbol (')) in low-risk term pregnancies by comparing the TDI parameters with gestational age-specific birth weight percentiles and z scores.

STUDY DESIGN AND MEASUREMENTS

Interventricular septum, left and right ventricular myocardial peak early diastolic (E'), late diastolic (A') and systolic (S') velocities, E'/A' ratios, myocardial performance index (MPI') and umbilical artery pulsatility index were measured within three days before birth in 76 low-risk term pregnancies, including appropriate for gestational age (AGA, n=50), small for gestational age (SGA, n=10), and large for gestational age (LGA, n=16) subjects.

RESULTS

Myocardial peak velocities showed higher in the LGA and lower in the SGA compared with the AGA group, and All S' positively correlated with birth weight (r=0.51-0.57). All z scores of S' demonstrated a positive correlation with birth weight z score (Spearman r=0.45-0.53). MPI' was significantly higher in the SGA and lower in the LGA compared with the AGA group. All MPI' negatively correlated with birth weight (r=-0.55 to -0.65). All z scores of MPI' showed a negative correlation with birth weight z score (Spearman r=-0.40 to -0.56).

CONCLUSIONS

Fetal myocardial peak velocities and MPI' physiologically changed in proportion to body size adjusted for gestational age in low-risk term pregnancies.

Fetal cardiac function: technical considerations and potential research and clinical applications

Fetal echocardiography was initially used to detect structural anomalies but has more recently also been proposed to assess fetal cardiac function. This review summarizes technical issues and limitations in fetal cardiac function evaluation, as well as its potential research and clinical applications. Functional echocardiography has been demonstrated to select high-risk populations and to be associated with outcome in several fetal conditions including intrauterine growth restriction, twin-to-twin transfusion syndrome, maternal diabetes, and congenital diaphragmatic hernia. Fetal heart evaluation is challenging due to the smallness and high heart rate of the fetus and restricted access to the fetus far from the transducer. Due to these limitations and differences in cardiac function which are related to fetal maturation, cardiovascular parameters should be validated in the fetus and used with caution. Despite these precautions, in expert hands and with appropriate ultrasound equipment, evaluation of cardiac function is feasible in most fetuses. Functional fetal echocardiography is a promising tool that may soon be incorporated into clinical practice. Research is warranted to further refine the contribution of fetal cardiac assessment to the diagnosis, monitoring, or prediction of outcomes in various fetal conditions.