Assessment of fetal compromise by Doppler ultrasound investigation of the fetal circulation. Arterial, intracardiac, and venous blood flow velocity studies

Does the use of angiogenic biomarkers for the management of preeclampsia and fetal growth restriction improve outcomes?: Challenging the current status quo

Monitoring and timing of delivery in preterm preeclampsia and fetal growth restriction is one of the biggest challenges in Obstetrics. Finding the optimal time of delivery of these fetuses usually involves a trade-off between the severity of the disease and prematurity. So far, most clinical guidelines recommend the use of a combination between clinical, laboratory and ultrasound markers to guide the time of delivery. Angiogenic biomarkers, especially placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1), have gained significant attention in recent years for their potential role in the prediction and diagnosis of placenta-related disorders including preeclampsia and fetal growth restriction. Another potential clinical application of the angiogenic biomarkers is for the differential diagnosis of patients with chronic kidney disease, as this condition shares similar clinical features with preeclampsia. Consequently, angiogenic biomarkers have been advocated as tools for monitoring and deciding the optimal time of the delivery of fetuses affected by placental dysfunction. In this clinical opinion, we critically review the available literature on PlGF and sFlt-1 for the surveillance and time of the delivery in fetuses affected by preterm preeclampsia and fetal growth restriction. Moreover, we explore the use of angiogenic biomarkers for the differentiation between chronic kidney disease and superimposed preeclampsia.

Fetal cardiac functional changes in pregnancies with Behcet's disease: A case-control study

BACKGROUND

Behcet's disease usually progresses with remission during pregnancy, but early subtle changes might be detected in the heart of these fetuses due to inflammation.

AIMS

We aimed to evaluate the cardiac functions in fetuses of pregnant women with Behcet's disease (BD).

STUDY DESIGN

Prospective case-control study.

SUBJECTS

This prospective study enrolled pregnant women diagnosed with Behcet's disease before pregnancy. Twenty-four pregnancies with Behcet's disease and 48 healthy pregnancies were included at 32-34 gestational weeks.

OUTCOME MEASURES

Pulsed-wave Doppler and tissue Doppler imaging (TDI) were used to assess cardiac functions.

RESULTS

Right ventricle (RV) E (early) wave and left ventricle (LV) E were significantly increased in pregnancies with BD (p = .008, p = .041, respectively). Decreased right ventricle E' (peak systolic velocity) was detected with TDI in the case group (6.2 ± 0.5, p < .001). E/E' ratios for RV and LV were significantly increased in the case group (p < .001, p = .001, respectively). The correlation between the duration of the disease and fetal cardiac functions was also evaluated. For RV, E (r = 0.735, p < .001), E' (r = -0.735, p < .001), E/E' (r = 0.894, p < .001), were strongly correlated with the disease duration. The study also showed the correlation between disease duration and LV E' (r = -0.735, p = .005), LV E (r = 0.750, p < .001), and LV E/E' (r = 0.820, p < .001).

CONCLUSION

This is the first study to evaluate the fetal cardiac functions in fetuses of pregnancies with BD. Although BD usually progresses with remission during pregnancy, early subclinical diastolic changes might occur in the heart of these fetuses due to inflammation.

Color Doppler ultrasound in high-low risk pregnancies and its relationship to fetal outcomes: a cross-sectional study

Objective

To calculate the multivessel color Doppler indices in high-risk and low-risk pregnancies and relate these to fetal outcomes.

Methods

The investigation involved 60 patients who were pregnant. The patients were separated into groups according to assessment of low and high risk. The patients underwent color Doppler ultrasonography to detect the maternal and fetal blood vessels, and the measured Doppler indices were then analyzed for any association with fetal outcomes.

Results

The gestational stages (in weeks) of the participants at the respective times of investigation and delivery were 32.06 ± 2.98 and 36.2 ± 1.78 in the low-risk group and 29.21 ± 1.95 and 29.83 ± 1.86 in the high-risk group. The pulsatility index (PI), resistive index (RI), and systolic/diastolic ratio (SD) decreased with gestation length in the low-risk group, whereas in the high-risk group, these values increased in the uterine and umbilical arteries. With increased gestational stage, MCA-PSV (peak systolic velocity) in the middle cerebral artery (MCA) increased, while PI decreased. Pulsatile and reversal flow of the uterine vein, the vein of Galen, and the umbilical vein were noted in high-risk pregnancies, and these negatively affected the fetal outcome. The fetal venous parameters were more specific and sensitive for predicting an unfavorable fetal outcome than the arterial factors, with a greater negative predictive value.

Conclusion

The results of our study indicate that abnormal Doppler indices of the blood vessels in high-risk pregnant patients will result in adverse clinical outcomes. Therefore, the patients can be monitored and managed accordingly using Doppler ultrasonography.

Human induced pluripotent stem cell-derived closed-loop cardiac tissue for drug assessment

Human iPSC-derived cardiomyocytes (hiPSC-CMs) exhibit functional immaturity, potentially impacting their suitability for assessing drug proarrhythmic potential. We previously devised a traveling wave (TW) system to promote maturation in 3D cardiac tissue. To align with current drug assessment paradigms (CiPA and JiCSA), necessitating a 2D monolayer cardiac tissue, we integrated the TW system with a multi-electrode array. This gave rise to a hiPSC-derived closed-loop cardiac tissue (iCT), enabling spontaneous TW initiation and swift pacing of cardiomyocytes from various cell lines. The TW-paced cardiomyocytes demonstrated heightened sarcomeric and functional maturation, exhibiting enhanced response to isoproterenol. Moreover, these cells showcased diminished sensitivity to verapamil and maintained low arrhythmia rates with ranolazine-two drugs associated with a low risk of torsades de pointes (TdP). Notably, the TW group displayed increased arrhythmia rates with high and intermediate risk TdP drugs (quinidine and pimozide), underscoring the potential utility of this system in drug assessment applications.

Polystyrene micro- and nanoplastics cause placental dysfunction in mice†

Maternal exposure to microplastics and nanoplastics has been shown to result in fetal growth restriction in mice. In this study, we investigated the placental and fetal hemodynamic responses to plastics exposure in mice using high-frequency ultrasound. Healthy, pregnant CD-1 dams were given either 106 ng/L of 5 μm polystyrene microplastics or 106 ng/L of 50 nm polystyrene nanoplastics in drinking water throughout gestation and were compared with controls. Maternal exposure to both microplastics and nanoplastics resulted in evidence of placental dysfunction that was highly dependent on the particle size. The umbilical artery blood flow increased by 48% in the microplastic-exposed group and decreased by 25% in the nanoplastic-exposed group compared to controls (p < 0.05). The microplastic- and nanoplastic-exposed fetuses showed a significant decrease in the middle cerebral artery pulsatility index of 10% and 13%, respectively, compared to controls (p < 0.05), indicating vasodilation of the cerebral circulation, a fetal adaptation that is part of the brain sparing response to preserve oxygen delivery. Hemodynamic markers of placental dysfunction and fetal hypoxia were more pronounced in the group exposed to polystyrene nanoplastics, suggesting nanoplastic exposure during human pregnancy has the potential to disrupt fetal brain development, which in turn may cause suboptimal neurodevelopmental outcomes.

Maternal plasma syndecan-1: a biomarker for fetal growth restriction

OBJECTIVE

The identification of fetal growth disorders is an important clinical priority given that they increase the risk of perinatal morbidity and mortality as well as long-term diseases. A subset of small-for-gestational-age (SGA) infants are growth-restricted, and this condition is often attributed to placental insufficiency. Syndecan-1, a product of the degradation of the endothelial glycocalyx, has been proposed as a biomarker of endothelial damage in different pathologies. During pregnancy, a "specialized" form of the glycocalyx-the "syncytiotrophoblast glycocalyx"-covers the placental villi. The purpose of this study was to determine whether the concentration of maternal plasma syndecan-1 can be proposed as a biomarker for fetal growth restriction.

STUDY DESIGN

A cross-sectional study was designed to include women with normal pregnancy (n = 130) and pregnant women who delivered an SGA neonate (n = 50). Doppler velocimetry of the uterine and umbilical arteries was performed in women with an SGA fetus at the time of diagnosis. Venipuncture was performed within 48 h of Doppler velocimetry and plasma concentrations of syndecan-1 were determined by a specific and sensitive immunoassay.

RESULTS

(1) Plasma syndecan-1 concentration followed a nonlinear increase with gestational age in uncomplicated pregnancies (R² = 0.27, p < .001); (2) women with a pregnancy complicated with an SGA fetus had a significantly lower mean plasma concentration of syndecan-1 than those with an appropriate-for-gestational-age fetus (p = .0001); (3) this difference can be attributed to fetal growth restriction, as the mean plasma syndecan-1 concentration was significantly lower only in the group of women with an SGA fetus who had abnormal umbilical and uterine artery Doppler velocimetry compared to controls (p = .00071; adjusted p = .0028). A trend toward lower syndecan-1 concentrations was also noted for SGA with abnormal uterine but normal umbilical artery Doppler velocimetry (p = .0505; adjusted p = .067); 4) among women with an SGA fetus, those with abnormal umbilical and uterine artery Doppler findings had a lower mean plasma syndecan-1 concentration than women with normal Doppler velocimetry (p = .02; adjusted p = .04); 5) an inverse relationship was found between the maternal plasma syndecan-1 concentration and the umbilical artery pulsatility index (r = -0.5; p = .003); and 6) a plasma syndecan-1 concentration ≤ 850 ng/mL had a positive likelihood ratio of 4.4 and a negative likelihood ratio of 0.24 for the identification of a mother with an SGA fetus who had abnormal umbilical artery Doppler velocimetry (area under the ROC curve 0.83; p < .001).

CONCLUSION

Low maternal plasma syndecan-1 may reflect placental diseases and this protein could be a biomarker for fetal growth restriction. However, as a sole biomarker for this condition, its accuracy is low.

Cerebroplacental hemodynamics in fetuses with transposition of the great arteries and usefulness in predicting neonatal condition

OBJECTIVES

Literature on cerebroplacental hemodynamics in fetuses with transposition of the great arteries (TGA) is scarce and provides conflicting results regarding the presence of a brain-sparing effect. The aims of this study were to examine Doppler parameters in the middle cerebral artery (MCA) and umbilical artery (UA) in a large cohort of fetuses with TGA, and to assess their possible utility in predicting the need for urgent balloon atrial septostomy (BAS) in the neonate.

METHODS

This was a retrospective observational study of fetuses diagnosed with TGA between 2008 and 2022 and an age-matched cohort of normal fetuses, conducted in a single tertiary fetal cardiology center. Medical records and echocardiographic examinations were reviewed to collect demographic, sonographic and follow-up data. Selected Doppler parameters were compared between fetuses with TGA and normal fetuses, as well as between TGA fetuses with and those without an associated ventricular septal defect (VSD), to assess the impact of this congenital heart defect on cerebroplacental circulation. Additionally, Doppler indices in patients with a restrictive foramen ovale (FO) were analyzed to identify potential predictors of the need for urgent BAS.

RESULTS

A total of 541 examinations of 159 fetuses with TGA performed between 19 and 40 weeks' gestation and 1300 examinations of 1215 age-matched normal fetuses were included in the study. MCA pulsatility index (PI) and UA-PI followed expected trends throughout pregnancy, with slightly higher values observed in TGA fetuses, albeit within the limits for the normal population. Cerebroplacental ratio (CPR) values were similar in normal and TGA fetuses. The presence of a small VSD did not have a clinically significant impact on Doppler parameters. Peak systolic velocity (PSV) in the MCA increased gradually after 35 weeks' gestation, especially in fetuses that did not develop restriction of the FO after birth. MCA-PSV values below 1.16 multiples of the median measured at 38 weeks or later predicted the need for urgent BAS with 81.4% sensitivity and 52.4% specificity.

CONCLUSIONS

MCA-PI, UA-PI and CPR values in fetuses with TGA usually fall within normal limits throughout pregnancy. The presence of a small VSD does not affect the Doppler parameters significantly. MCA-PSV increases in TGA fetuses after 35 weeks, and its value measured at the last prenatal examination (ideally after 37 weeks) may serve as an additional predictive factor for the need for urgent BAS. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

A key role for NLRP3 signaling in preterm labor and birth driven by the alarmin S100B

Preterm birth remains the leading cause of neonatal morbidity and mortality worldwide. A substantial number of spontaneous preterm births occur in the context of sterile intra-amniotic inflammation, a condition that has been mechanistically proven to be triggered by alarmins. However, sterile intra-amniotic inflammation still lacks treatment. The NLRP3 inflammasome has been implicated in sterile intra-amniotic inflammation; yet, its underlying mechanisms, as well as the maternal and fetal contributions to this signaling pathway, are unclear. Herein, by utilizing a translational and clinically relevant model of alarmin-induced preterm labor and birth in Nlrp3-/- mice, we investigated the role of NLRP3 signaling by using imaging and molecular biology approaches. Nlrp3 deficiency abrogated preterm birth and the resulting neonatal mortality induced by the alarmin S100B by impeding the premature activation of the common pathway of labor as well as by dampening intra-amniotic and fetal inflammation. Moreover, Nlrp3 deficiency altered leukocyte infiltration and functionality in the uterus and decidua. Last, embryo transfer revealed that maternal and fetal Nlrp3 signaling contribute to alarmin-induced preterm birth and neonatal mortality, further strengthening the concept that both individuals participate in the complex process of preterm parturition. These findings provide novel insights into sterile intra-amniotic inflammation, a common etiology of preterm labor and birth, suggesting that the adverse perinatal outcomes resulting from prematurity can be prevented by targeting NLRP3 signaling.

Evaluation of electrocardiographic parameters in amputee football players

OBJECTIVE

The present study aimed to compare electrocardiographic (ECG) parameters of amputee football players (AF) with football players without disability (FP) and sedentary individuals without disability (SI).

METHODS

A total of 32 participants (AF = 9, FP = 11, SI = 12) were included in the study. ECG parameters including P-wave amplitude, P-wave duration, PR interval, QRS duration, RR interval, QT interval, corrected-QT interval (QTc), ST segment duration, Tp-e duration, Tp-e/QT and Tp-e/QTc ratios were assessed in all the study participants by using a 12-lead ECG device. OneWay ANOVA Test was used for statistical analysis.

RESULTS

Of all ECG parameters, P-wave amplitude and QTc were significantly higher in the AF group in comparison to FP and SI groups. QRS duration was found to be lower in the AF group when compared to FP and SI groups. Myocardial repolarization parameters including Tp-e duration, Tp-e/QT and Tp-e/QTc ratios were similar between groups, as were other parameters such as P-wave duration, PR interval, RR interval, QRS duration and QT interval.

CONCLUSION

It was found that some ECG parameters of amputee football players differ from those with non-disabled players and non-disabled sedentary individuals. These different parameters were within normal limits.

Recasting Current Knowledge of Human Fetal Circulation: The Importance of Computational Models

Computational hemodynamic simulations are becoming increasingly important for cardiovascular research and clinical practice, yet incorporating numerical simulations of human fetal circulation is relatively underutilized and underdeveloped. The fetus possesses unique vascular shunts to appropriately distribute oxygen and nutrients acquired from the placenta, adding complexity and adaptability to blood flow patterns within the fetal vascular network. Perturbations to fetal circulation compromise fetal growth and trigger the abnormal cardiovascular remodeling that underlies congenital heart defects. Computational modeling can be used to elucidate complex blood flow patterns in the fetal circulatory system for normal versus abnormal development. We present an overview of fetal cardiovascular physiology and its evolution from being investigated with invasive experiments and primitive imaging techniques to advanced imaging (4D MRI and ultrasound) and computational modeling. We introduce the theoretical backgrounds of both lumped-parameter networks and three-dimensional computational fluid dynamic simulations of the cardiovascular system. We subsequently summarize existing modeling studies of human fetal circulation along with their limitations and challenges. Finally, we highlight opportunities for improved fetal circulation models.

Advanced imaging of fetal cardiac function

Over recent decades, a variety of advanced imaging techniques for assessing cardiovascular physiology and cardiac function in adults and children have been applied in the fetus. In many cases, technical development has been required to allow feasibility in the fetus, while an appreciation of the unique physiology of the fetal circulation is required for proper interpretation of the findings. This review will focus on recent advances in fetal echocardiography and cardiovascular magnetic resonance (CMR), providing examples of their application in research and clinical settings. We will also consider future directions for these technologies, including their ongoing technical development and potential clinical value.

The potential of 1.5 T magnetic resonance imaging for the evaluation of fetal anomalies of the great vessels

Purpose

To determine the efficacy of 1.5 T magnetic resonance imaging (MRI) for the diagnosis of anomalies of the fetal great arteries with comparison to fetal ultrasound, and to compare image quality between 1.5 T and 3.0 T MRI in fetal imaging of the great arteries.

Methods

We compared the results of postnatal exam or surgery and evaluated the application value of prenatal 1.5 T MRI in the assessment of fetal great-vessel anomalies. To further determine the diagnostic potential of 1.5 T MRI, 23 pregnant women with suspected fetal cardiovascular abnormalities who had undergone ultrasound and 3.0 T MRI were enrolled and compared, respectively.

Results

Prenatal MRI was superior to ultrasound in demonstrating aortic arch and branch abnormalities (sensitivity, 92.86% vs. 83.33%; specificity, 66.67% vs. 20%). The mean quality ratings for fetal MRI at 1.5 T was higher than 3.0 T (P < 0.001). Other than the fast scan speed afforded by 3.0 T MRI, the signal noise ratio (SNR) of 1.5 T MRI were higher than those of 3.0 T MRI; however, the difference in contrast to noise ratio (CNR) between the two imaging modalities was not statistically significant.

Conclusions

1.5 T MRI can achieve an overall assessment of fetal great-vessel anomalies, especially aortic arch and branch abnormalities. Therefore, 1.5 T MRI can be considered a supplementary imaging modality for the prenatal assessment of extracardiac great vessels malformations.

The Effect of External Cephalic Version on Fetal Circulation: A Prospective Cohort Study

External cephalic version (ECV) is a cost-effective and safe treatment option for breech presentation at term. Following ECV, fetal well-being is assessed via a non-stress test (NST). An alternative option to identify signs of fetal compromise is via the Doppler indices of the umbilical artery (UA), middle cerebral artery (MCA) and ductus venosus (DV). Inclusion criteria were an uncomplicated pregnancy with breech presentation at term. Doppler velocimetry of the UA, MCA and DV were performed up to 1 h before and up to 2 h after ECV. The study included 56 patients who underwent elective ECV with a success rate of 75%. After ECV, the UA S/D ratio, UA pulsatility index (PI) and UA resistance index (RI) were increased compared to before the ECV (p = 0.021, p = 0.042, and p = 0.022, respectively). There were no differences in the Doppler MCA and DV before or after ECV. All patients were discharged after the procedure. ECV is associated with changes in the UA Doppler indices that might reflect interference in placental perfusion. These changes are probably short-term and have no detrimental effects on the outcomes of uncomplicated pregnancies. ECV is safe; yet it is a stimulus or stress that can affect placental circulation. Therefore, careful case selection for ECV is important.

Comparison of cardiac morphology and function in small for gestational age fetuses and fetuses with late-onset fetal growth retardation

OBJECTIVES

To compare cardiac structural and functional findings of fetuses with fetal growth restriction (FGR) and small for gestational age (SGA).

METHODS

In this prospective cohort study, patients were classified into three groups using Delphi procedure according to fetal weight, umbilical, uterine artery Doppler and cerebroplacental ratio. Fetal cardiac ultrasonographic morphology and Doppler examination was performed to all pregnant women at 36 weeks of gestation.

RESULTS

Seventy three patients were included in the study. There were one (6.7%) patient in the control group, 2 (13.3%) in the SGA group and 12 (80%) in the FGR group who needed neonatal intensive care unit (NICU) and NICU requirement was significantly higher in FGR fetuses (p<0.001). Left spherical index was found to be lower only among FGR fetuses (p=0.046). Left ventricular wall thickness was decreased and the right/left ventricular wall ratio was increased in FGR fetuses (p=0.006, p<0.001). Tricuspid/mitral valve ratio and mitral annular plane systolic excursion value was lower in FGR fetuses (p=0.034, p=0.024 respectively). Also, myocardial performance index was remarkably higher in FGR group (p=0.002).

CONCLUSIONS

We detected cardiac morphological changes in cases of both SGA and FGR-more pronounced in the FGR cases. Findings related to morphological changes on the left side in FGR cases were considered secondary to volume increase in FGR cases as an indicator of a brain-protective effect. In the FGR group, both systolic and diastolic dysfunctions were detected in the left heart.

Peripheral chemoreflex activation and cardiac function during hypoxemia in near-term fetal sheep without placental compromise

A drop in arterial oxygen content activates fetal chemoreflex including an increase in sympathetic activity leading to peripheral vasoconstriction and redistribution of blood flow to protect the brain, myocardium, and adrenal glands. By using a chronically instrumented fetal sheep model with intact placental circulation at near-term gestation, we investigated the relationship between peripheral chemoreflex activation induced by hypoxemia and central hemodynamics. A total of 17 Åland landrace sheep fetuses at 115-128/145 gestational days were instrumented. Carotid artery was catheterized in 10 fetuses and descending aorta in 7 fetuses. After a 4-day recovery, baseline measurements of fetal arterial blood pressures, blood gas values, and fetal cardiovascular hemodynamics by pulsed Doppler ultrasonography were obtained under isoflurane anesthesia. Comparable data to baseline were collected 10 min (acute hypoxemia) and 60 min (prolonged hypoxemia) after maternal hypo-oxygenation to saturation level of 70%-80% was achieved. During prolonged hypoxemia, pH and base excess (BE) were lower and lactate levels were higher in the descending aorta than in the carotid artery. During hypoxemia mean arterial blood pressure (MAP) in the descending aorta increased, whereas in the carotid artery, MAP decreased. In addition, right pulmonary artery pulsatility index values increased, and the diastolic component in the aortic isthmus blood flow velocity waveform became more retrograde, thus decreasing the aortic isthmus antegrade/retrograde blood flow (AoI Net Flow) ratio. Both fetal ventricular cardiac outputs were maintained even during prolonged hypoxemia when significant fetal metabolic acidemia developed. Fetal chemoreflex activation induced by hypoxemia decreased the perfusion pressure in the cerebral circulation. Fetal weight-indexed left ventricular cardiac output (LVCO) or AoI Net Flow ratio did not correlate with a drop in carotid artery blood pressure.NEW & NOTEWORTHY During fetal hypoxemia with intact placental circulation, peripheral chemoreflex was activated, as demonstrated by an increase in the descending aorta blood pressure, pulmonary vasoconstriction, and an increase in retrograde diastolic AoI blood flow, while both ventricular cardiac outputs remained stable. However, perfusion pressure in the cerebral circulation decreased. These changes were seen even during prolonged hypoxemia when significant metabolic acidosis developed. Weight-indexed LVCO or AoI Net Flow ratio did not correlate with a drop in carotid artery blood pressure.

Hemodynamic Changes in Umbilical Artery and Middle Cerebral Artery With Oligohydramnios in Third Trimester of Pregnancy

Objective:

The objective of this study was to determine the hemodynamic changes in the umbilical artery (UA) and middle cerebral artery (MCA) with oligohydramnios, during third trimester of pregnancy.

Materials and Methods:

A cross-sectional descriptive study was done in a perinatal ultrasound center, over a 9-month period. The participant sample size was 64, and all of the women were conveniently consented and selected for the study. All individuals were referred for obstetrical sonography in the third trimester, with oligohydramnios. All fetal anomalies, such as a neural tube defect, dwarfism, an abdominal wall defect, were excluded from the study.

Results:

The mean systolic to diastolic (S/D) ratio for the UA was 3.01, within a range of 1.49 to 5.60 (± 0.79 SD). The mean pulsatility index (PI), of the UA, was 1.11, within a range of 0.41 to 5.51 cm (± 0.64 SD). The mean resistive index (RI) of the UA was 0.66, within a range of 0.33 to 1.25 cm (± 0.13 SD). The mean S/D ratio of the MCA was 5.68, within a range of 2.05 to 26.10 (± 3.10 SD). The mean PI of the MCA was 1.67 within a range of 0.75 to 2.55 cm (± 0.45 SD). The mean resistive index (RI), of the UA, was 0.82 within a range of 0.51 to 1.77 cm (± 0.82 SD).

Conclusion:

The Doppler indices may rise as pregnancy advances, especially in fetuses with oligohydramnios. In these types of patients, the flow within the MCA may decrease, with an increase in the gestational age. Consequently, it appears that oligohydramnios may lead to vascular remodeling of the UA and MCA.

Differences in Biometric Fetal Weight Estimation Accuracy and Doppler Examination Results in Uncomplicated Term Singleton Pregnancies between Vertex and Breech Presentation

Doppler examination of the umbilical artery and the fetal middle cerebral artery is evaluated predominantly in pregnancies with fetuses in cephalic presentation and never has been elucidated in breech presentation. Evidence on the accuracy of fetal weight estimation in dependence of the fetal presentation is controversial. Nevertheless, clinical decisions including recommendations for a cesarean section or labor induction based on these examinations are applied to pregnancies with fetuses in breech presentation. The objective of this study was to investigate the influence of the fetal presentation on fetal weight estimation accuracy, umbilical artery and middle cerebral artery resistance indices (RI) in a prospective case control study. Ultrasound examinations in 305 uncomplicated term pregnancies (153 vertex presentations, 152 breech) were investigated. Non-parametric variables were compared using Pearson’s chi² test and Wilcoxon chi² test, depending on variable scaling. Fetal weight estimation accuracy was not significantly different between vertex presentation group (VP) (6.97%) and breech presentation group (BP) (7.96%, p = 0.099). Fetal head circumference measurements were significantly larger in BP (350 mm vs. 341 mm in VB, p > 0.0001) while abdominal circumferences were significantly smaller (VP: 338 mm, BP: 331 mm, p = 0.0039) and weight estimation was not significantly different. Umbilical artery RIs were not significantly different between VP (54.5) and BP (55.3, p = 0.354). Fetal middle cerebral artery RIs also showed no significant differences (VP: 71.2, BP: 70.7, p = 0.335). Our study shows that fetal Doppler (RI) and weight estimation ultrasound originally calibrated in cephalic pregnancies are applicable to pregnancies with fetuses in breech presentation.

The usefulness of ultrasound before induction of labor

The indications for induction of labor have been consistently on the rise. These indications are mainly medical (maternal or fetal) or social or related to convenience or maternal preferences. With the increase in the prevalence of these indications, the incidence rates of induction of labor are expected to rise continuously. This poses a substantial workload and financial burden on maternity healthcare systems. Failure rates of induction of labor are relatively high, especially when considering the maternal, fetal, and neonatal risks associated with emergency cesarean deliveries in cases of failure. Therefore, it is essential for obstetricians to carefully select women who are eligible for induction of labor, particularly those with no clinical contraindication and who have a reasonable chance of ending up with a successful noncomplicated vaginal delivery. Ultrasound has an established role in the various areas of obstetrical care. It is available, accessible, easy to perform, and acceptable to the patient. In addition, the learning curve for skillful obstetrical ultrasound scanning is rather easy to fulfill. Ultrasound has always had an important role in the assessment of maternal and fetal well-being. Indeed, it has been extensively explored as a reliable, reproducible, and objective tool in the management of labor. In this review, we aimed to provide a comprehensive update on the different applications and uses of ultrasound before induction of labor for the prediction of its success and the potential improvement of its health-related maternal and fetal outcomes.

Update on fetal cardiovascular magnetic resonance and utility in congenital heart disease

Background

Congenital heart disease (CHD) is the most common birth defect, affecting approximately eight per thousand newborns. Between one and two neonates per thousand have congenital cardiac lesions that require immediate post-natal treatment to stabilize the circulation, and the management of these patients in particular has been greatly enhanced by prenatal detection. The antenatal diagnosis of CHD has been made possible through the development of fetal echocardiography, which provides excellent visualization of cardiac anatomy and physiology and is widely available. However, late gestational fetal echocardiographic imaging can be hampered by suboptimal sonographic windows, particularly in the setting of oligohydramnios or adverse maternal body habitus.

Main body

Recent advances in fetal cardiovascular magnetic resonance (CMR) technology now provide a feasible alternative that could be helpful when echocardiography is inconclusive or limited. Fetal CMR has also been used to study fetal circulatory physiology in human fetuses with CHD, providing new insights into how these common anatomical abnormalities impact the distribution of blood flow and oxygen across the fetal circulation. In combination with conventional fetal and neonatal magnetic resonance imaging (MRI) techniques, fetal CMR can be used to explore the relationship between abnormal cardiovascular physiology and fetal development. Similarly, fetal CMR has been successfully applied in large animal models of the human fetal circulation, aiding in the evaluation of experimental interventions aimed at improving in utero development. With the advent of accelerated image acquisition techniques, post-processing approaches to correcting motion artifacts and commercial MRI compatible cardiotocography units for acquiring gated fetal cardiac imaging, an increasing number of CMR methods including angiography, ventricular volumetry, and the quantification of vessel blood flow and oxygen content are now possible.

Conclusion

Fetal CMR has reached an exciting stage whereby it may now be used to enhance the assessment of cardiac morphology and fetal hemodynamics in the setting of prenatal CHD.

Sex differences in fetal Doppler parameters during gestation

BACKGROUND

Fetal sex is known to affect pregnancy outcomes. In current clinical practice, monitoring of fetal well-being is based on Doppler ultrasound measurements of major placental and fetal vessels. The objective of this study was to investigate the effect of fetal sex on Doppler parameters throughout gestation in healthy pregnancy.

METHODS

A prospective study was conducted in 240 pregnant women with ultrasound examinations at a 4-weekly interval between 12 and 38 weeks of gestation. Pulsed Doppler spectra were collected for the umbilical arteries (UAs), middle cerebral artery (MCA), descending abdominal aorta (DAo), and ductus venosus (DV). Linear mixed effects models were used to determine if the pulsatility indices (PIs) of these vessels depended on gestational age and fetal sex.

RESULTS

While there were no differences in the MCA PI and DV PIV over gestation between female and male fetuses, the trajectory of the UA and DAo PIs differed by fetal sex (p = 0.02 and p = 0.01, respectively).

CONCLUSIONS

Doppler ultrasound parameters were found to be dependent on fetal sex for some vessels and not for others in healthy pregnancies. Further investigations are needed to understand the physiological mechanisms for these sex differences and the relevance for disease processes in pregnancy.

Reference ranges of fetal superior vena cava blood flow velocities and pulsatility index in the second half of pregnancy: a longitudinal study

Background

Fetal superior vena cava (SVC) is essentially the single vessel returning blood from the upper body to the heart. With approximately 80-85% of SVC blood flow representing cerebral venous return, its interrogation may provide clinically relevant information about fetal brain circulation. However, normal reference values for fetal SVC Doppler velocities and pulsatility index are lacking. Our aim was to establish longitudinal reference intervals for blood flow velocities and pulsatility index of the SVC during the second half of pregnancy.

Methods

This was a prospective study of low-risk singleton pregnancies. Serial Doppler examinations were performed approximately every 4 weeks to obtain fetal SVC blood velocity waveforms during 20–41 weeks. Peak systolic (S) velocity, diastolic (D) velocity, time-averaged maximum velocity (TAMxV), time-averaged intensity-weighted mean velocity (TAMeanV), and end-diastolic velocity during atrial contraction (A-velocity) were measured. Pulsatility index for vein (PIV) was calculated.

Results

SVC blood flow velocities were successfully recorded in the 134 fetuses yielding 510 sets of observations. The velocities increased significantly with advancing gestation: mean S-velocity increased from 24.0 to 39.8 cm/s, D-velocity from 13.0 to 19.0 cm/s, and A-velocity from 4.8 to 7.1 cm/s. Mean TAMxV increased from 12.7 to 23.1 cm/s, and TAMeanV from 6.9 to 11.2 cm/s. The PIV remained stable at 1.5 throughout the second half of pregnancy.

Conclusions

Longitudinal reference intervals of SVC blood flow velocities and PIV were established for the second half of pregnancy. The SVC velocities increased with advancing gestation, while the PIV remained stable from 20 weeks to term.

Extracardiac Doppler indices predict perinatal mortality in fetuses with Ebstein anomaly and tricuspid valve dysplasia

OBJECTIVES

Ebstein anomaly and tricuspid valve dysplasia (EA/TVD) carry high perinatal mortality. Past studies have focused on cardiac predictors of mortality; we sought to describe the fetal echo (FE) extracardiac Dopplers in this cohort and determine their association with perinatal mortality.

METHOD

Fetuses with EA/TVD at 23 centers from 2005-2011 were included for retrospective study. Doppler pattern and velocity of the umbilical artery (UA), umbilical vein (UV), ductus venosus (DV), and middle cerebral artery (MCA) were collected. Bivariate and multivariate analyzes were performed. The primary outcome measure was perinatal mortality, defined as fetal demise or neonatal death.

RESULTS

Of 190 cases that met eligibility criteria, alterations were seen in 50% of UA, 16% of UV, 48% of DV, and 8% of MCA Doppler indices on the last FE (median 27.4 weeks). Independent predictors of perinatal mortality included abnormal UA Doppler pattern of absence or reversed end diastolic flow (OR 9.7) and UV velocity z score <1 (OR 2.5), in addition to diagnosis <32 weeks (OR 4.2) and tricuspid valve (TV) annulus z score ≥6 (OR 5.3).

CONCLUSION

Abnormal UA Doppler pattern and decreased UV velocity are independent predictors of perinatal mortality in EA/TVD fetuses and should be used to refine mortality risk and guide perinatal management.

Umbilical and Middle Cerebral Artery Doppler Measurements in Fetuses With Congenital Heart Block

OBJECTIVES

In fetal congenital complete heart block, the slow fetal heart rate prolongs the diastolic phase of the cardiac cycle, which may affect Doppler measurements that are typically used to quantify placental function. We here describe the umbilical artery (UA) and middle cerebral artery (MCA) Dopplers in a cohort of fetuses with heart block, hypothesizing that values will be increased but nevertheless remain associated with placental function and fetal outcome.

METHODS

We retrospectively reviewed Doppler measurements of the UA and MCA pulsatility index (PI) and resistance index in fetuses with complete heart block. The cerebroplacental ratio (CPR) was calculated as a marker of central redistribution. Measurements were transformed to Z scores and compared between fetuses born with a normal weight (appropriate for gestational age [AGA]) to those with fetal growth restriction (FGR) and correlated with a composite adverse outcome consisting of FGR, fetal death, or preterm birth prior to 34 weeks' gestation.

RESULTS

Fifty-four fetuses were included. There were 36 (67%) live births, 8 (22%) stillbirths, and 10 (19%) pregnancy terminations. Of those born alive, 14 (39%) had FGR. The UA PI decreased with gestational age and was higher in FGR compared with AGA fetuses (P < .001). Twenty-three percent of AGA fetuses developed absent end-diastolic flow in the UA. The MCA PI did not change with gestation and did not differ between AGA and FGR fetuses. The CPR was lower in FGR than in AGA fetuses (-2.43 ± 0.85 vs -1.44 ± 1.04, P = .006). The UA PI and resistance index were strongly correlated with the composite adverse outcome (P < .001).

CONCLUSIONS

The UA and MCA PI are significantly elevated in fetuses with complete heart block. The UA Doppler indices and CPR nevertheless still reflect placental function. Longitudinal measurements may be useful in monitoring well-being in fetuses with heart block.

Fetal whole heart blood flow imaging using 4D cine MRI

Prenatal detection of congenital heart disease facilitates the opportunity for potentially life-saving care immediately after the baby is born. Echocardiography is routinely used for screening of morphological malformations, but functional measurements of blood flow are scarcely used in fetal echocardiography due to technical assumptions and issues of reliability. Magnetic resonance imaging (MRI) is readily used for quantification of abnormal blood flow in adult hearts, however, existing in utero approaches are compromised by spontaneous fetal motion. Here, we present and validate a novel method of MRI velocity-encoding combined with a motion-robust reconstruction framework for four-dimensional visualization and quantification of blood flow in the human fetal heart and major vessels. We demonstrate simultaneous 4D visualization of the anatomy and circulation, which we use to quantify flow rates through various major vessels. The framework introduced here could enable new clinical opportunities for assessment of the fetal cardiovascular system in both health and disease.

Effects of altered photoperiod due to COVID-19 lockdown on pregnant women and their fetuses

Maternal circadian rhythms provide highly important input into the entrainment and programming of fetal and newborn circadian rhythms. The light-dark cycle is an important regulator of the internal biological clock. Even though pregnant women spend a greater part of the day at home during the latter stages of pregnancy, natural light exposure is crucial for the fetus. The current recommended COVID-19 lockdown might dramatically alter normal environmental lighting conditions of pregnant women, resulting in exposure to extremely low levels of natural daylight and high-intensity artificial light sources during both day and night. This article summarizes the potential effects on pregnant woman and their fetuses due to prolonged exposure to altered photoperiod and as consequence altered circadian system, known as chronodisruption, that may result from the COVID-19 lockdown.

Fetal brain hemodynamics in pregnancies at term: correlation with gestational age, birthweight and clinical outcome

INTRODUCTION

The primary aim of this study was to ascertain the strength of association between cerebral blood flow assessed in anterior (ACA), middle (MCA), and posterior (PCA) cerebral arteries and the following clinical outcomes: small for gestational age (SGA), induction of labor (IOL) for oligohydramnios and caesarean section (CS) for nonreassuring fetal status (NRFS) during labor.

MATERIAL AND METHODS

Retrospective analysis of prospectively collected data on consecutive singleton pregnancies from 40 0/7 to 41 6/7 week of gestation. UA, ACA, MCA, PCA pulsatility index (PI) were measured from 40 weeks of gestations. Furthermore, the ratios between cerebral blood flow and UA (CPR, ACA/UA and PCA/UA) were calculated and correlated with the observed outcomes.

RESULTS

Two hundred twenty-four singleton pregnancies were included in the study. Mean PI of either ACA (p = .04), MCA (p = .008), and PCA (p = .003) were lower in the SGA compared to non-SGA group; furthermore, mean PCA PI was significantly lower than MCA PI (p = .04). Furthermore, CPR (p = .016), ACA/UA (p = .02), and PCA/UA (p = .003) were significantly lower in the SGA group compared to controls. UA, ACA, MCA, and PCA PI were higher in women undergoing IOL for oligohydramnios compared to controls. Logistic regression analysis showed that CPR and PCA/UA ratio were independently associated with SGA. SGA, ACA PI, and ACA/UA were independently associated with CS for NRFS. Finally, birthweight centile, were independently associated with IOL oligohydramnios. Despite this, the predictive accuracy of Doppler in detecting any of the explored outcome was only poor to moderate.

CONCLUSION

Redistribution of cerebral blood flow at term is significantly associated with SGA, IOL for oligohydramnios and CS for NRFS in labor. However, the predictive accuracy of Doppler at term is only poor to moderate, thus advising against its use in clinical practice as a standalone screening test for adverse perinatal outcome in pregnancies at term. Key Message Redistribution of cerebral blood flow at term is significantly associated with SGA, IOL for oligohydramnios and CS for NRFS in labor.

The controversial role of the ductus venosus in hypoxic human fetuses

The ductus venosus plays a critical role in circulatory adaptation to hypoxia in fetal growth restriction but the mechanisms still remain controversial. Increased shunting of blood through the ductus venosus under hypoxic conditions has been shown in animal and human studies. The hemodynamic laws governing the accelerated flow in this vessel suggest that any dilation at its isthmus, which increases the blood flow shunting to the heart, is associated with a low, absent or reversed a-wave and a high pulsatility index. Cardiac dysfunction associated with increased atrial pressure as well as reduced ventricular compliance might be predominant mechanisms determining the profile of ductus venosus velocity waveforms in severe fetal growth restriction with signs of hypoxic compromise. Understanding the pathophysiology of the ductus venosus will underpin translation of the hypotheses developed through biostatistics toward explaining with more confidence Doppler changes in the fetal circulation in predicting clinical outcomes.

Foramen ovale blood flow and cardiac function after main pulmonary artery occlusion in fetal sheep

NEW FINDINGS

What is the central question of this study? At near-term gestation, foramen ovale blood flow accounts for a significant proportion of fetal left ventricular output. Can the foramen ovale increase its volume blood flow when right ventricular afterload is increased by main pulmonary artery occlusion? What is the main finding and its importance? Foramen ovale volume blood flow increased during main pulmonary artery occlusion. However, this increase was attributable to an increase in fetal heart rate, because left ventricular stroke volume remained unchanged. These findings suggest that the foramen ovale has a limited capacity to increase its volume blood flow.

ABSTRACT

The foramen ovale (FO) accounts for the majority of fetal left ventricular (LV) output. Increased right ventricular afterload can cause a redistribution of combined cardiac output between the ventricles. To understand the capability of the FO to increase its volume blood flow and thus LV output, we mechanically occluded the main pulmonary artery in seven chronically instrumented near-term sheep fetuses. We hypothesized that FO volume blood flow and LV output would increase during main pulmonary artery occlusion. Fetal cardiac function and haemodynamics were assessed by pulsed and tissue Doppler at baseline, 15 and 60 min after occlusion of the main pulmonary artery and 15 min after occlusion was released. Fetal ascending aorta and central venous pressures and blood gas values were monitored. Main pulmonary artery occlusion initially increased fetal heart rate (P < 0.05) from [mean (SD)] 158 (7) to 188 (23) beats min^-1 and LV cardiac output (P < 0.0001) from 629 (198) to 776 (283) ml min^-1 . Combined cardiac output fell (P < 0.0001) from 1524 (341) to 720 (273) ml min^-1 . During main pulmonary artery occlusion, FO volume blood flow increased (P < 0.001) from 507 (181) to 776 (283) ml min^-1 . This increase was related to fetal tachycardia, because LV stroke volume did not change. Fetal ascending aortic blood pressure remained stable. Central venous pressure was higher (P < 0.05) during the occlusion than after it was released. During the occlusion, fetal pH decreased and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>P</mml:mi> <mml:mrow><mml:mi>C</mml:mi> <mml:msub><mml:mi>O</mml:mi> <mml:mn>2</mml:mn></mml:msub> </mml:mrow> </mml:msub> </mml:math> increased. Left ventricular systolic dysfunction developed while LV diastolic function was preserved. Right ventricular systolic and diastolic function deteriorated after the occlusion. In conclusion, the FO has a limited capacity to increase its volume blood flow at near-term gestation.

Fetal dynamic phase-contrast MR angiography using ultrasound gating and comparison with Doppler ultrasound measurements

OBJECTIVES

To investigate the feasibility of fetal phase-contrast (PC)-MR angiography of the descending aorta (AoD) using an MR-compatible Doppler ultrasound sensor (DUS) for fetal cardiac gating and to compare velocimetry with Doppler ultrasound measurements.

METHODS

In this prospective study, 2D PC-MR angiography was performed in 12 human fetuses (mean gestational age 32.8 weeks) using an MR-compatible DUS for gating of the fetal heart at 1.5 T. Peak flow velocities in the fetal AoD were compared with Doppler ultrasound measurements performed on the same day. Reproducibility of PC-MR measurements was tested by repeated PC-MR in five fetuses.

RESULTS

Dynamic PC-MR angiography in the AoD was successfully performed in all fetuses using the DUS, with an average fetal heart rate of 140 bpm (range 129-163). Time-velocity curves revealed typical arterial blood flow patterns. PC-MR mean flow velocity and mean flux were 21.2 cm/s (range 8.6-36.8) and 8.4 ml/s (range 3.2-14.6), respectively. A positive association between PC-MR mean flux and stroke volume with gestational age was obtained (r = 0.66, p = 0.02 and r = 0.63, p = 0.03). PC-MR and Doppler ultrasound peak velocities revealed a highly significant correlation (r = 0.8, p < 0.002). Peak velocities were lower for PC-MR with 69.1 cm/s (range 39-125) compared with 96.7 cm/s (range 60-142) for Doppler ultrasound (p < 0.001). Reproducibility of PC-MR was high (p > 0.05).

CONCLUSION

The MR-compatible DUS for fetal cardiac gating allows for PC-MR angiography in the fetal AoD. Comparison with Doppler ultrasound revealed a highly significant correlation of peak velocities with underestimation of PC-MR velocities. This new technique for direct fetal cardiac gating indicates the potential of PC-MR angiography for assessing fetal hemodynamics.

KEY POINTS

• The developed MR-compatible Doppler ultrasound sensor allows direct fetal cardiac gating and can be used for prenatal dynamic cardiovascular MRI. • The MR-compatible Doppler ultrasound sensor was successfully applied to perform intrauterine phase-contrast MR angiography of the fetal aorta, which revealed a highly significant correlation with Doppler ultrasound measurements. • As fetal flow hemodynamics is an important parameter in the diagnosis and management of fetal pathologies, fetal phase-contrast MR angiography may offer an alternative imaging method in addition to Doppler ultrasound and develop as a second line tool in the evaluation of fetal flow hemodynamics.

Reference values of the ductus venosus pulsatility index for pregnant women between 11 and 13+6 weeks of gestation

Purpose: The ductus venosus pulsatility index velocity (DV PIV) has become a popular ultrasonographic measurement during the first trimester of pregnancy. The value of the DV PIV has been the topic of ongoing discussion in the literature, and its reference value in the normal population has not yet been established. Therefore, we aimed to determine a reference value for the DV PIV.Materials and Methods: We retrospectively evaluated our records of first-trimester ultrasonography performed between 2016 and 2017. Our inclusion criteria were as follows: singleton pregnancy; crown-rump length (CRL) between 45 and 84 mm; absence of structural abnormalities on the ultrasound examination; and absence of chromosomal abnormalities. Records of 820 patients were evaluated. According to the inclusion criteria, records of 458 patients were included in this study. All ultrasound examinations were performed by a single operator with the Voluson E8 (5- to 8-MHz 3 D transducer; General Electric Healthcare, Little Chalfont, UK) via the transabdominal route. Gestational weeks were designated according to CRL measurements at the beginning of the examination. Nuchal translucency (NT), nasal bone visualization (NB), tricuspid valve regurgitation (TR), "a"-wave pattern, DV PIV, S-wave (peak systolic velocity), D-wave (peak diastolic velocity), a-wave (atrial contraction in late diastole), and time-averaged maximum velocity (TAMXV) measurements were performed. To evaluate the DV Doppler images, a mid-sagittal view of the fetal profile was obtained. Color Doppler and pulse Doppler gate were used in the distal portion of the umbilical sinus, and at least three typical DV waveforms were detected. The SPSS 21.0 statistical program (IBM, Armonk, NY) was used to analyze variables.Results: The mean age, body mass index, CRL, gestational age, and NT values were 30.3 years (range, 18-45), 23.9 kg/m² (range, 15.5-46.6), 59.5 mm (range, 45-79), 12.3 weeks (range, 11.2-13.6), and 1.58 mm (range, 0.73-2.62), respectively. The median gravidity and parity were 2 (1-8) and 0 (0-4), respectively. The "a"-wave pattern was identified in all cases, but TR was not detected in any of the cases. Measurements of DV PIV with a Gaussian distribution were suitable according to the Shapiro-Wilk test (p = .252). The mean DV PIV was 0.98, and the fifth and 95th percentiles were 0.73 and 1.22 (±2 SD), respectively. A statistical analysis of our cohort revealed that DV PIV values less than 0.73 and more than 1.22 were beyond the normal range. The mean S-wave, D-wave, a-wave, and TAMXV values were 31.18, 25.64, 8.68, and 22.72 cm/s, respectively.Conclusions: The value of DV PIV measurements is debated in the literature. Using our cohort, we defined the means and ranges of DV PIV. Determining the normal ranges of DV PIV could be helpful to anticipate congenital or chromosomal abnormalities. Further studies are needed to demonstrate the clinical importance of DV PIV, especially for patients with abnormal DV PIV measurements.

Restricted physical activity in pregnancy reduces maternal vascular resistance and improves fetal growth

OBJECTIVES

To test the efficacy of maternal activity restriction for reducing peripheral vascular resistance in normotensive pregnant women with raised total vascular resistance (TVR) and to evaluate its effect on fetal growth.

METHODS

This was a prospective case-control study of 30 women enrolled between 27 and 29 weeks' gestation. All patients met the following criteria: normal blood pressure before and during pregnancy, TVR between 1300 and 1400 dynes × s/cm⁵ at enrolment, normal fetal Doppler parameters at enrolment and abdominal circumference between the 10^th and 25^th centiles. Patients were assigned to activity restriction (activity-restriction group; n = 15) or no treatment (control group; n = 15) and were assessed after 4 weeks for TVR and fetal growth.

RESULTS

TVR at enrolment and estimated fetal weight centile were similar in the activity-restriction group vs controls (1358 ± 26 vs 1353 ± 30 dynes × s/cm⁵ ; 18^th  ± 4 vs 19^th  ± 4 centile; P = NS). After 4 weeks, the activity-restriction group compared with controls showed significantly lower TVR (1165 ± 159 vs 1314 ± 190 dynes × s/cm⁵ ; P < 0.05), which was associated with higher estimated fetal weight centile (25^th  ± 5 vs 20^th  ± 5 centile; P < 0.05). TVR was lower and estimated fetal weight centile higher for the activity-restriction group after 4 weeks compared with at enrolment.

CONCLUSIONS

In normotensive pregnant women with raised TVR, maternal activity restriction appears to be effective in reducing TVR and therefore enhancing fetal growth. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

In Vivo Evaluation of the Cardiovascular System of Mouse Embryo and Fetus Using High Frequency Ultrasound

Genetically engineered mice have been widely used for studying cardiovascular development, physiology and diseases. In the past decade, high frequency ultrasound imaging technology has been significantly advanced and applied to observe the cardiovascular structure, function, and blood flow dynamics with high spatial and temporal resolution in mice. This noninvasive imaging approach has made possible longitudinal studies of the mouse embryo/fetus in utero. In this chapter, we describe detailed methods for: (1) the assessment of the structure, function, and flow dynamics of the developing heart of the mouse embryo during middle gestation (E10.5-E13.5); and (2) the measurement of flow distribution throughout the circulatory system of the mouse fetus at late gestation (E17.5). With the described protocols, we are able to illustrate the main cardiovascular structures and the corresponding functional and flow dynamic events at each stage of development, and generate baseline physiological information about the normal mouse embryo/fetus. These data will serve as the reference material for the identification of cardiovascular abnormalities in numerous mouse models with targeted genetic manipulations.

Behaviour of the Foramen Ovale Flow in Fetuses with Intrauterine Growth Restriction

Background

Foramen ovale (FO) flow may be altered in IUGR. This study was designed to test this hypothesis.

Methods

Forty pregnant women (24–38 weeks) were divided into 3 groups: group I (IUGR), group II (adequate growth and maternal hypertension), and group III (normal controls). Impedance across the FO was assessed by the FO pulsatility index (FOPI): (systolic velocity − presystolic velocity)/mean velocity. Statistical analysis utilized ANOVA, Tukey test, and ROC curves.

Results

Mean FOPI in IUGR fetuses (n = 15) was 3.70 ± 0.99 (3.15–4.26); in the group II (n = 12), it was 2.84 ± 0.69 (2.40–3.28), and in the group III (n = 13), it was 2.77 ± 0.44 (2.50–3.04) (p=0.004). FOPI and UtA RI were correlated (r = 0.375, p=0.017), as well as FOPI and UA RI (r = 0.356, p=0.024) and, inversely, FOPI and MCA RI (r = −0.359, p=0.023).

Conclusions

The FO flow pulsatility index is increased in fetuses with IUGR, probably as a result of impaired left ventricular diastolic function.

Prenatal Echocardiographic Predictors of Postnatal Management Strategy in the Fetus with Right Ventricle Hypoplasia and Pulmonary Atresia or Stenosis

Fetuses with pulmonary atresia or pulmonary stenosis with intact ventricular septum manifest variable degrees of right ventricle hypoplasia and inadequacy. We studied the relationship between prenatal echocardiographic parameters and their progression through gestation as potential predictors of postnatal single-ventricle or two-ventricle care strategy. Serial fetal echocardiograms of pulmonary atresia (n = 28) or severe pulmonary stenosis (n = 8) and intact ventricular septum were reviewed. Measurements included tricuspid valve and mitral valve diameter and Z scores, degree of tricuspid regurgitation, presence of subaortic stenosis, presence of coronary artery fistulae, and Doppler pulsatility indices in middle cerebral and umbilical artery. Data were compared between first and last fetal studies. Subjects were divided based on postnatal course of single- or two-ventricle repair. Tricuspid valve size of those destined for single ventricle is smaller than of those destined for a two-ventricle repair at first study (26w, Z score -4.22 v -1.83, p < 0.001) and at final study (35w, -4.94 v -1.42, p < 0.001). Tricuspid valve and right ventricle grow in those destined for two ventricle, but not single-ventricle palliation. Tricuspid valve Z score = -3 at first or last study discriminated between single- or two-ventricle repair, except in two unusual cases with significant subaortic stenosis. Tricuspid valve Doppler-derived parameters of middle cerebral artery and umbilical artery did not distinguish between groups. In the fetus with pulmonary atresia or stenosis and intact ventricular septum, tricuspid valve Z score ≥-3, presence of important tricuspid regurgitation, absence of coronary fistulae, and absence of subaortic stenosis are associated with a two-ventricle postnatal strategy.

A complex association between DNA methylation and gene expression in human placenta at first and third trimesters

The human placenta is a maternal-fetal organ essential for normal fetal development and maternal health. During pregnancy, the placenta undergoes many structural and functional changes in response to fetal needs and environmental exposures. Previous studies have demonstrated widespread epigenetic and gene expression changes from early to late pregnancy. However, on the global level, how DNA methylation changes impact on gene expression in human placenta is not yet well understood. We performed DNA methylome analysis by reduced representation bisulfite sequencing (RRBS) and gene expression analysis by RNA-Seq for both first and third trimester human placenta tissues. From first to third trimester, 199 promoters (corresponding to 189 genes) and 2,297 gene bodies were differentially methylated, with a clear dominance of hypermethylation (96.8% and 93.0% for promoters and gene bodies, respectively). A total of 2,447 genes were differentially expressed, of which 77.2% were down-regulated. Gene ontology analysis using differentially expressed genes were enriched for cell cycle and immune response functions. The correlation between DNA methylation and gene expression was non-linear and complex, depending on the genomic context (promoter or gene body) and gene expression levels. A wide range of DNA methylation and gene expression changes were observed at different gestational ages. The non-linear association between DNA methylation and gene expression indicates that epigenetic regulation of placenta development is more complex than previously envisioned.

The impact of intrauterine growth restriction on respiratory outcomes

BACKGROUND

Intrauterine growth restriction (IUGR) is caused by fetal growth below what is normal for its genetic potential. Recent studies have shown a distinct association between changes in umbilical artery flow in IUGR subjects and an increased risk of respiratory morbidity and consequently, higher mortality. The aim of this study was to find the impact of IUGR on the respiratory outcomes of premature neonates born with less than 32 weeks gestational age.

METHODS

This retrospective cohort study targeted infants born with less than 32 weeks of gestation, admitted at NCIU, between January 2010 and December 2016. Each selected IUGR case was matched according to gestational age and sex with an appropriate birthweight newborn at a 1:2 ratio, within a 12-month period.

RESULTS

The study involved 126 neonates, 42 with IUGR, and 84 control subjects. IUGR was not identified as a predictor of Bronchopulmonary Dysplasia (BDP) (OR 4.80, 95% CI: 1.14-20.21, P=0.033). Abnormal umbilical artery flow (OR 4.80, 95% CI: 1.14-20.21, P=0.033) and late onset sepsis (OR 3.31, 95% CI: 1.04-10.56, P=0.044) were significantly associated with BDP.

CONCLUSIONS

It is essential to recognize changes in the umbilical artery flow, especially in high-risk pregnancies such as IUGR, since these represent an a priori risk marker for the development of BDP. The individual and combined effect of IUGR, alterations on umbilical artery flow and extreme prematurity has not yet been completely clarified on the impact on lung morbidity, requiring a larger number of studies.

Online versus offline spatiotemporal image correlation (STIC) M-mode for the evaluation of cardiac longitudinal annular displacement in fetal growth restriction

PURPOSE

Our first aim was to compare online M-mode with offline spatiotemporal image correlation (STIC) M-mode for assessing longitudinal annular displacement (LAD) in growth-restricted fetuses (FGR). Our second aim was to compare LAD measures of FGR cases with controls.

MATERIALS AND METHODS

Prospective study including 40 FGR cases (defined estimated fetal weight and birth weight <10th centile) and 72 normally grown fetuses matched to cases by gestational age at scan. LAD was measured with online M-mode and offline STIC M-mode at the left and right ventricular free walls and septum in all fetuses.

RESULTS

FGR cases had a significant decrease in LAD by STIC in all sites as compared to controls (e.g. right LAD in FGR mean 6.7 mm (SD 1.2) versus controls 7.2 mm (1.2), p = .033). There was a non-significant trend for lower values in FGR when using online M-mode (e.g. right LAD in FGR 6.9 mm (1.5) versus controls 7.4 mm (1.5), p = .084).

CONCLUSIONS

STIC M-mode seems a better method than online M-mode for detecting subtle changes in myocardial motion. STIC presents more precise results and allows an ideal placement of the M-mode arrow. These results confirm previous data suggesting decreased longitudinal motion in FGR.

Fetal intrapericardial teratoma: natural history and management including successful in utero surgery

BACKGROUND

Intrapericardial teratoma is a rare, lethal tumor often detected in fetal life. Tumor mass and pericardial effusion cause cardiac tamponade that, if relieved, could be life-saving. Optimal timing of intervention and methods for effective fetal treatment are unknown.

OBJECTIVE

We describe our single-center experience with fetal intrapericardial teratoma including the first report of successful in utero surgical resection with survival to term.

STUDY DESIGN

We reviewed our database for suspected fetal intrapericardial teratoma. On fetal ultrasound and echocardiography tumor size was estimated by calculation of an ellipse and analyzed in relation to Doppler-derived fetal cardiac output, venous flow patterns, hydrops, and outcome.

RESULTS

Eight fetuses with suspected intrapericardial teratoma were seen from 2009 through 2015. Gestational age at initial presentation ranged from 21-34 (median 26) weeks. Two cases mimicked the appearance of intrapericardial teratoma, but had no serial change in cardiac output over time and were ultimately determined to be other types of tumor. In 6 cases of true intrapericardial teratoma, tumor growth was extremely rapid and associated with progressive decline in cardiac output (to <400 mL/kg/min) manifesting in hydrops and death if left untreated. One case was treated successfully at 31 weeks through ex utero intrapartum delivery with tumor resection while on placental support. Another case underwent open fetal surgery and resection at 24 weeks, with resumption of gestation until delivery at 37 weeks with excellent outcome.

CONCLUSION

Fetal intrapericardial teratoma can be successfully managed utilizing serial surveillance and by treatment in a timely manner prior to the predictable onset of hydrops, determined through increasing tumor size and a declining cardiac output. Surgical resection in utero is possible, with good results.

Effect of corticosteroids on cardiac function in growth-restricted fetuses

OBJECTIVE

To determine the acute effects of corticosteroids on the cardiovascular system in growth-restricted fetuses.

METHODS

This was a prospective cohort study conducted at a tertiary hospital between January 2011 and October 2013. Fetal cardiovascular function in fetuses with intrauterine growth restriction (IUGR) was assessed immediately before and 24 h after the first dose of betamethasone, administered in routine management of IUGR. Fetal arterial and venous Dopplers were assessed. Fetal cardiac function was evaluated by tissue Doppler echocardiography, with the assessment of both left and right ventricular function by calculating myocardial performance index (MPI') and E':A' ratios. Values were compared before and after exposure.

RESULTS

Seventeen patients were included at a mean gestational age of 34 + 1 (range, 29 + 1 to 37 + 4) weeks. Fifteen fetuses were below the 5(th) percentile and two were below the 10(th) percentile for estimated fetal weight and abdominal circumference and all had no interval growth during a 2-week period. There was a decrease in right MPI' (from 0.56 to 0.47; P = 0.007) after corticosteroid exposure but no change in left MPI' (from 0.49 to 0.48). Right MPI' was higher than left MPI' before exposure (0.56 vs 0.49, respectively; P = 0.001), but not after exposure (P = 0.55). There was no change in left or right ventricular E':A' ratios and no difference was detected in umbilical artery, middle cerebral artery or ductus venosus pulsatility index following administration of corticosteroids.

CONCLUSIONS

Corticosteroids altered right-sided, but not left-sided, tissue Doppler MPI' in IUGR fetuses, with no detectable change in arterial or venous Doppler pulsatility indices. Before exposure, the mean right MPI' was higher than the left. However, after exposure, there was no difference, suggesting that corticosteroids may reverse the negative effect of IUGR on fetal heart function. Large prospective studies with a larger sample size are needed to confirm this finding. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Four-dimensional live imaging of hemodynamics in mammalian embryonic heart with Doppler optical coherence tomography

Hemodynamic analysis of the mouse embryonic heart is essential for understanding the functional aspects of early cardiogenesis and advancing the research in congenital heart defects. However, high-resolution imaging of cardiac hemodynamics in mammalian models remains challenging, primarily due to the dynamic nature and deep location of the embryonic heart. Here we report four-dimensional micro-scale imaging of blood flow in the early mouse embryonic heart, enabling time-resolved measurement and analysis of flow velocity throughout the heart tube. Our method uses Doppler optical coherence tomography in live mouse embryo culture, and employs a post-processing synchronization approach to reconstruct three-dimensional data over time at a 100 Hz volume rate. Experiments were performed on live mouse embryos at embryonic day 9.0. Our results show blood flow dynamics inside the beating heart, with the capability for quantitative flow velocity assessment in the primitive atrium, atrioventricular and bulboventricular regions, and bulbus cordis. Combined cardiodynamic and hemodynamic analysis indicates this functional imaging method can be utilized to further investigate the mechanical relationship between blood flow dynamics and cardiac wall movement, bringing new possibilities to study biomechanics in early mammalian cardiogenesis. Four-dimensional live hemodynamic imaging of the mouse embryonic heart at embryonic day 9.0 using Doppler optical coherence tomography, showing directional blood flows in the sinus venosus, primitive atrium, atrioventricular region and vitelline vein.

A Review of Fetal Circulation and the Segmental Approach in Fetal Echocardiography

The incidence of congenital heart disease is generally estimated at 8 in 1000 live births. Fifty percent of these neonates will have “minor” defects—easily corrected with some intervention. The remainder will account for 30% of perinatal deaths and nearly 50% of lethal malformations in childhood. The purpose of this review is to outline essential guidelines for a thorough fetal echocardiogram and how it differs from the fetal cardiac imaging included as part of an obstetric sonographic examination. Specific values for both the anatomic and blood flow velocity measurements recommended are typically related to gestational age and method of acquisition. Multiple references exist in the literature that define these values.

A liposomal Gd contrast agent does not cross the mouse placental barrier

The trans-placental permeability of liposomal Gadolinium (Gd) nanoparticle contrast agents was evaluated in a pregnant mouse model. Pregnant Balb/c mice at 16.5 (±1) days of gestation were imaged using a 3D Spoiled Gradient Echo method at 9.4 T using two contrast agents: a clinically approved Gd chelate, Multihance^® (gadobenate dimeglumine), and a novel experimental liposomal Gd agent. A Dynamic Contrast Enhancement (DCE) protocol was used to capture the dynamics of contrast entry and distribution in the placenta, and clearance from circulation. A blinded clinical radiologist evaluated both sets of images. A reference region model was used to measure the placental flow and physiological parameters; volume transfer constant (K^trans), efflux rate constant (K^ep). The Gd content of excised placentae and fetuses was measured, using inductively coupled plasma mass spectrometry (ICP-MS). MRI images of pregnant mice and ICP-MS analyses of placental and fetal tissue demonstrated undetectably low transplacental permeation of the liposomal Gd agent, while the clinical agent (Multihance) avidly permeated the placental barrier. Image interpretation and diagnostic quality was equivalent between the two contrast agents. Additional testing to determine both maternal and fetal safety of liposomal Gd is suggested.

Ductus venosus Doppler in the assessment of fetal cardiovascular health: an updated practical approach

The ductus venosus has a central role in the distribution of highly oxygenated umbilical venous blood to the heart. Its waveform is related to the pressure-volume changes in the cardiac atria and it is therefore important in the monitoring of any fetal condition that may affect forward cardiac function. The cardiovascular parameters that can influence forward cardiac function include afterload, myocardial performance and preload. Decreased forward flow during atrial systole (a-wave) is the most sensitive and ubiquitous finding when any of these parameters is affected. In contrast, decreased forward velocities during end-systolic relaxation (v-wave) are more specifically related to myocardial performance. The ductus venosus pulsatility index alone does not accurately reflect cardiac function, and in cases of suspected fetal cardiac dysfunction, echocardiography is required to identify the underlying mechanism. The role of ductus venosus Doppler in the assessment of fetal growth restriction, supraventricular tachycardia, fetal hydrops, complicated monochorionic twins and congenital heart disease is discussed with these considerations in mind.

Utility of ductus venosus blood flow in the study of cardiac function in fetuses with intracardiac echogenic focus

PURPOSE

The purpose of this study was to investigate fetal ductus venosus (DV) wave velocities, DV velocity ratios, and DV diastolic time intervals to derive additional information on fetal cardiac function in the presence of an intracardiac echogenic focus (IEF).

METHODS

Seventy fetuses at 19-28 weeks of gestation with an IEF and 63 control fetuses were screened using two-dimensional and power Doppler echocardiography. DV wave velocities, DV velocity ratios, and diastolic time intervals were measured. The aortic peak velocity, pulmonary artery peak velocity, left ventricular shortening fraction, and right ventricular shortening fraction, atrioventricular early-diastolic filling velocity (E), atrial contraction velocity (A), and E/A ratio were also measured.

RESULTS

The study and control groups were similar in terms of maternal age, body mass index, and gestational age in weeks at the time of examination (p > 0.05). Significant between-group differences were found in DV v-descent (p = 0.03) and a-wave velocities (p = 0.04).

CONCLUSIONS

Although the presence of an IEF in the fetal heart does not influence conventional measurements (DV velocity ratios and DV diastolic time intervals), it is associated with changes in DV v-descent and a-wave velocities. These changes may be indirectly related to reduced end-systolic relaxation and augmented atrial contraction in the fetal heart. We therefore suggest examination of DV flow velocities in fetuses with IEF.

Effect of resveratrol on metabolic and cardiovascular function in male and female adult offspring exposed to prenatal hypoxia and a high-fat diet

Prenatal hypoxia, a common outcome of pregnancy complications, predisposes offspring to the development of metabolic and cardiovascular disorders in later life. We have previously observed that resveratrol improved cardiovascular and metabolic health in adult male rat offspring exposed to prenatal hypoxia and a postnatal high-fat (HF) diet; however, the effects of resveratrol in female rat offspring are not known. Our aim was to identify the mechanism(s) by which resveratrol may prevent metabolic and cardiac dysfunction in both male and female rat offspring exposed to prenatal hypoxia and a postnatal HF diet. Offspring that experienced normoxia or hypoxia in utero were fed a HF diet or a HF diet supplemented with resveratrol for 9 weeks following weaning. Body composition, metabolic function, in vivo cardiac function and ex vivo cardiac susceptibility to ischaemia-reperfusion (I/R) injury were assessed at 12 weeks of age. Prenatal hypoxia impaired metabolic function in male, but not female, rat offspring fed a HF diet and this was improved by resveratrol supplementation. Prenatal hypoxia also led to reduced recovery from cardiac I/R injury in male, and to a lesser extent in female, rat offspring fed a HF diet. Indices of cardiac oxidative stress after I/R were enhanced in both male and female rat offspring exposed to prenatal hypoxia. Resveratrol improved cardiac recovery from I/R injury and attenuated superoxide levels in both male and female rat offspring. In conclusion, prenatal hypoxia impaired metabolic and cardiac function in a sex-specific manner. Resveratrol supplementation may improve metabolic and cardiovascular health in adult male and female rat offspring exposed to prenatal hypoxia.

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.

Characterization of early changes in fetoplacental hemodynamics in a diet-induced rabbit model of IUGR

Intrauterine growth restriction (IUGR) is associated with adverse perinatal outcomes and late-onset diseases in offspring. Eating disorders, voluntary caloric restriction and maternal undernutrition can all induce IUGR but a relevant model is required to measure all its possible consequences. In this work, pregnant rabbits were used as an IUGR model. Control females (n=4) received ad libitum diet throughout pregnancy, whereas underfed females (n=5) were restricted to 50% of their daily requirements. Offspring size was measured by ultrasonography and in vivo at birth. Hemodynamic features of the umbilical cords and middle cerebral arteries (systolic peak velocity, end diastolic velocity, pulsatility index and resistance index) were characterized by Doppler ultrasonography. At day 21, maternal underfeeding resulted in a significant reduction of fetal size (occipito-nasal length). At birth, the size of kits from the underfed group was significantly lower (lower crown-rump length, biparietal and transversal thoracic diameters) and a reduced weight with respect to the control group. Feed restriction altered blood flow perfusion compared with does fed ad libitum (significant higher systolic peak, time-averaged mean velocities and lower end diastolic velocity). Fetuses affected by IUGR presented with compensative brain-sparing effects when compared with the control group. In conclusion, the present study supports using rabbits and the underfeeding approach as a valuable model for IUGR studies. These results may help to characterize IUGR alterations due to nutrient restriction of mothers in future research.