Changes in myocardial performance index and aortic isthmus and ductus venosus Doppler in term, small-for-gestational age fetuses with normal umbilical artery pulsatility index

Influence of pre-existing maternal diabetes mellitus on fetal myocardial performance index and systolic-to-diastolic duration ratio: a prospective cohort study

OBJECTIVE

To evaluate the influence of pre-existing maternal diabetes mellitus on fetal myocardial performance index and systolic-to-diastolic duration ratio.

METHODS

Prospective cohort study included 179 pregnant women between 20 and 36w6d, divided into 3 groups: Group 1 (120, normal), Group 2 (31, type 1 diabetes mellitus), and Group 3 (28, type 2 diabetes mellitus). Systolic-to-diastolic duration ratio was calculated as the sum of isovolumic contraction time and ejection time divided by the sum of isovolumic relaxation time and ventricular filling time. Spectral Doppler was used to assess left ventricle systolic-to-diastolic duration ratio. Tissue Doppler was used to assess right ventricular filling time. Using spectral Doppler, left ventricle myocardial performance index was calculated as the sum of isovolumic contraction time and isovolumic relaxation time divided by ejection time.

RESULTS

Pre-existing maternal diabetes mellitus had a significant influence on fasting glucose levels (p < 0.001), left ventricle isovolumic contraction time (p < 0.001), left ventricle ejection time (p = 0.025), and left ventricle myocardial performance index (p < 0.001). Group 2 had higher left ventricle isovolumic contraction time (0.036 vs. 0.031 sec, p = 0.001) and left ventricle myocardial performance index (0.487 vs. 0.453, p = 0.003) compared with Group 1. Group 3 showed higher left ventricle myocardial performance index (0.492 vs. 0.449, p = 0.006) and lower left ventricle ejection time (0.161 vs. 0.169 sec, p = 0.038) than Group 1. Left ventricle systolic-to-diastolic duration (p = 0.704), right ventricle systolic-to-diastolic duration ratio' (p = 0.757), left ventricle isovolumic contraction time (p = 0.163), left ventricle ejection time (p = 0.093), and left ventricle myocardial performance index (p = 0.087) were not useful parameters in predicting composite neonatal outcomes.

CONCLUSION

Pre-existing maternal diabetes mellitus had significant influence on fetal left ventricle myocardial performance index, but no effect on systolic-to-diastolic duration ratio. Systolic-to-diastolic duration ratio was not useful in predicting adverse perinatal outcomes.

Fetal cardiovascular function in a late-onset SGA and FGR cohort: CURIOSA study

The measurement of fetal cardiovascular function parameters is not yet established in prenatal diagnostics. Now that the research field of fetal programming is becoming increasingly important, this might change. Fetal cardiovascular changes have been described above all in early/severe fetal growth restriction (FGR). The aim of this study was to investigate functional echocardiographic parameters in fetuses with late-onset small for gestational age (SGA)/FGR.A prospective cohort of SGA fetuses (including FGR) and a control group with similar distribution of gestational age were studied. Parameters of systolic, diastolic, and global cardiac function, morphometry and measurements of the fetal abdominal aorta were collected.A total of 149 SGA fetuses and 143 control fetuses were included from 32 weeks until term. The total SGA group was further divided into SGA 3rd-10th (fetuses between the 3rd and 10th weight percentile) and FGR subgroups. In the total SGA group, relative right and left ventricular wall thickness, left E/A ratio, isovolumetric contraction time and left myocardial performance index were significantly increased compared to controls after adjustment for gestational age. MAPSE, TAPSE, ejection time, left cardiac output, and abdominal aortic distensibility were significantly lower. The changes were more pronounced in the FGR subgroup.Even in a group of late-onset SGA/FGR, echocardiographic parameters are already altered in utero.

Feasibility of automated measurement of fetal right ventricular modified myocardial performance index with development of reference values and clinical application

To establish normal reference ranges for fetal right ventricular modified myocardial performance index (RV Mod-MPI) using automatic synchronization of the RV inflow and outflow images (MPI+TM). Additionally, we aimed to clinically apply RV Mod-MPI to investigate its changes in fetal right congenital diaphragmatic hernia (CDH) compared to normal fetuses. This prospective study included uncomplicated singleton pregnancies between 16 and 38 weeks of gestational age. Cases with any maternal or fetal complications that developed during the enrollment period were excluded. Two experienced operators measured the RV Mod-MPI using the automated and manual methods. The intraclass correlation coefficients (ICC) were calculated for intra- and inter-operator reproducibility. The mean differences between the manual and automated measurements were also compared. The RV Mod-MPI was then compared between the right CDH fetuses and normal fetuses. Seventy normal fetuses were analyzed for the feasibility of an automated system, and 364 examinations from 272 fetuses were analyzed for developing the normal references. The automated system showed significantly higher intra- and inter-operator reproducibility of Mod-MPI than those of manual measurements (ICC = 0.962 vs. 0.913 and 0.961 vs. 0.889, respectively). The mean difference in Mod-MPI between the manual and automated method was 0.0002 ± 0.0586 with a 95% confidence interval of -0.0095-0.0099. The Mod-MPI and isovolumetric relaxation time increased throughout the gestational weeks. The isovolumetric contraction time increased until 24 weeks of gestation and then slightly decreased afterwards, and the ejection time also increased until 31 weeks of gestation and then decreased. There was no significant difference in the Mod-MPI between right CDH and normal fetuses. The automated system showed high inter- and intra-operator reproducibility. Furthermore, the normal reference values of Mod-MPI for each gestational age were established. Our results suggest that the automated system might be clinically feasible for evaluating fetal cardiac function.

Fetal Aortic Blood Flow Velocity and Power Doppler Profiles in the First Trimester: A Comprehensive Study Using High-Definition Flow Imaging

OBJECTIVES

This study aimed to establish reference values for fetal aortic isthmus blood flow velocity and associated indices during the first trimester, utilizing a novel ultrasonographic technique known as high-definition flow imaging (HDFI). Additionally, the correlation between Doppler profiles of aortic blood flow and key fetal parameters, including nuchal thickness (NT), crown-rump length (CRL), and fetal heartbeat (FHB), was investigated.

METHODS

A total of 262 fetuses were included in the analysis between December 2022 and December 2023. Utilizing 2D power Doppler ultrasound images, aortic blood flow parameters were assessed, including aortic peak systolic velocity (PS), aortic end-diastolic velocity (ED), aortic time average maximal velocity (TAMV), and various indices such as aortic systolic velocity/diastolic velocity (S/D), aortic pulsatile index (PI), aortic resistance index (RI), aortic isthmus flow velocity index (IFI), and aortic isthmic systolic index (ISI). Concurrently, fetal FHB, NT, and CRL were evaluated during early trimester Down syndrome screening.

RESULTS

Significant findings include a positive correlation between gestational age (GA) and PS (PS = 3.75 × (GA) - 15.4, r2 = 0.13, p < 0.01), ED (ED = 0.42 × (GA) - 0.61, r2 = 0.04, p < 0.01), PI (PI = 0.07 × (GA) + 1.03, r2 = 0.04, p < 0.01), and TAMV (TAMV = 1.23 × (GA) - 1.66, r2 = 0.08, p < 0.01). In contrast, aortic ISI demonstrated a significant decrease (ISI = -0.03 × (GA) + 0.57, r2 = 0.05, p < 0.05) with gestational age. No significant correlation was observed for aortic RI (p = 0.33), S/D (p = 0.39), and IFI (p = 0.29) with gestational age. Aortic PS exhibited positive correlations with NT (0.217, p = 0.001) and CRL (0.360, p = 0.000) but a negative correlation with FHB (-0.214, p = 0.001). Aortic PI demonstrated positive correlations with CRL (0.208, p = 0.001) and negative correlations with FHB (-0.176, p = 0.005). Aortic TAMV showed positive correlations with NT (0.233, p = 0.000) and CRL (0.290, p = 0.000) while exhibiting a negative correlation with FHB (-0.141, p = 0.026). Aortic ISI demonstrated negative correlations with NT (-0.128, p = 0.045) and CRL (-0.218, p = 0.001) but a positive correlation with FHB (0.163, p = 0.010).

CONCLUSIONS

Power Doppler angiography with Doppler ultrasound demonstrates the ability to establish accurate reference values for fetal aortic blood flow during the first trimester of pregnancy. Notably, aortic PS, TAMV, and ISI exhibit significant correlations with NT, CRL, and FHB, with ISI appearing more relevant than IFI, PS, TAMV, and FHB. The utilization of HDFI technology proves advantageous in efficiently detecting the site of the aortic isthmus compared to traditional color Doppler mode in early second trimesters.

Fetal Doppler in monochorionic pregnancies complicated by twin-to-twin transfusion syndrome and selective in utero growth restriction

BACKGROUND

Monochorionic (MC) twin pregnancies may be complicated by placental pathologies that impact fetal cardiac function, such as twin-twin transfusion syndrome (TTTS) and selective intrauterine growth-restriction (sIUGR). In the TTTS, the unbalanced blood flow through placental anastomoses lead a recipient volume overload, hypertension and hypertrophic cardiomyopathy and the donor twin experiences hypovolemia and hypertension due to increased placental resistance and poor renal perfusion. When MC pregnancies were complicated by sIUGR, the increase of placental resistances lead to complex fetal compensatory mechanisms with redistribution of cardiac output to vital organs. Increased placental vascular resistances, hypoxia and hemodynamic compensation mechanisms lead to higher pre and/or afterload for both ventricles, right cardiac failure and eventually left cardiac failure observed just before fetal death.

OBJECTIVES

The purpose of this study was to describe the anomalies of umbilical, ductal and aortic isthmic Doppler as well as left and right myocardial performance index (MPI) across various clinical phenotypes of MC twin pregnancies, uncomplicated or complicated by TTTS or sIUGR, in order to help differentiating these conditions and to improve the understanding of TTTS and sIUGR pathophysiology.

STUDY DESIGN

Aortic isthmic systolic index (ISI), umbilical artery pulsatility index (UAPI), ductus venosus pulsatility index (DVPI), and MPI were studied in uncomplicated MC twins (control group) and cases of sIUGR or TTTS.

RESULTS

The measurements were obtained in 113 pregnancies (24 uncomplicated, 22 sIUGR, 51 TTTS). In comparison with controls, the sIUGR smaller twin sets had lower ISI and higher UAPI, and the larger twin had higher ISI. The TTTS donor and recipient had lower ISI, higher UAPI and DVPI. Compared to the co-twin, the ISI values were lower in the sIUGR smaller twin and the TTTS donor had lower ISI and MPI. Comparing TTTS and sIUGR, the recipient had higher DVPI and MPI than the sIUGR larger twin.

CONCLUSIONS

The Doppler anomalies observed in the smaller twin reflected increased placental blood flow resistance, presumably due to abnormal feto-fetal transfusion in TTTS and to unequal placental sharing in sIUGR. Early hemodynamic changes suggestive of cardiac overload in the recipient twin may help to differentiate TTTS and sIUGR.

Linking the Perinatal Environment to Neonatal Cardiovascular Outcomes

Cases of high-risk pregnancies continue to rise throughout the United States and globally, increasing rates of maternal and neonatal morbidity. Common pregnancy complications and morbidities include preterm birth, hypertensive disorders, fetal growth restriction, diabetes mellitus, and chorioamnionitis. Exposure to these perinatal conditions contributes to cardiac morbidities in the fetus and neonate, including altered cardiac growth, congenital heart disease, and cardiac dysfunction. Significant research has demonstrated lasting effects of these pregnancy complications, with increased rates of cardiac morbidities seen in children and adults after these perinatal exposures. The link between the perinatal environment and long-term outcomes has not been fully elucidated. The aim of this review is to discuss the current understanding of the implications of a high-risk pregnancy on fetal and neonatal cardiac development.

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.

The role of the fetal biophysical profile in the management of fetal growth restriction

Growth-restricted fetuses are at risk of hypoxemia, acidemia, and stillbirth because of progressive placental dysfunction. Current fetal well-being, neonatal risks following delivery, and the anticipated rate of fetal deterioration are the major management considerations in fetal growth restriction. Surveillance has to quantify the fetal risks accurately to determine the delivery threshold and identify the testing frequency most likely to capture future deterioration and prevent stillbirth. From the second trimester onward, the biophysical profile score correlates over 90% with the current fetal pH, and a normal score predicts a pH >7.25 with a 100% positive predictive value; an abnormal score on the other hand predicts current fetal acidemia with similar certainty. Between 30% and 70% of growth-restricted fetuses with a nonreactive heart rate require biophysical profile scoring to verify fetal well-being, and an abnormal score in 8% to 27% identifies the need for delivery, which is not suspected by Doppler findings. Future fetal well-being is not predicted by the biophysical profile score, which emphasizes the importance of umbilical artery Doppler and amniotic fluid volume to determine surveillance frequency. Studies with integrated surveillance strategies that combine frequent heart rate monitoring with biophysical profile scoring and Doppler report better outcomes and stillbirth rates of between 0% and 4%, compared with those between 8% and 11% with empirically determined surveillance frequency. The variations in clinical behavior and management challenges across gestational age are better addressed when biophysical profile scoring is integrated into the surveillance of fetal growth restriction. This review aims to provide guidance on biophysical profile scoring in the in- and outpatient management of fetal growth restriction.

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.

Fetal Cardiac Function: Myocardial Performance Index

The Myocardial Performance Index (MPI) or Tei index, presented by Tei in 1995, is the ratio of the sum of the duration of the isovolumetric contraction time (ICT) and isovolumetric relaxation time (IRT) to the duration of the ejection time (ET). The Modified Myocardial Performance Index (Mod-MPI), proposed in 2005, is considered a reliable and useful tool in the study of fetal heart function in several conditions, such as growth restriction, twin-twin transfusion syndrome, maternal diabetes, preeclampsia, intrahepatic cholestasis of pregnancy, and adverse perinatal outcomes. Nevertheless, clinical translation is currently limited by poorly standardised methodology as variations in the technique, machine settings, caliper placement, and specific training required can result in significantly different MPI values. This review aims to provide a survey of the relevant literature on MPI, present a strict methodology and technical considerations, and propose future research.

Second-trimester cardiovascular biometries in growth-restricted fetuses; a multicenter cohort study

BACKGROUND

Intrauterine growth restriction is associated with an increased risk of cardiovascular changes neonatally. However, the underlying pathways are poorly understood, and it is not clear whether the dysfunction is already present in the fetus.

OBJECTIVE

This study aimed to investigate fetal cardiac dimensions assessed from images at the second trimester anatomy scan from fetuses classified postnatally as small for gestational age and intrauterine growth restricted and compare them with appropriate for gestational age fetuses.

STUDY DESIGN

This was a substudy from The Copenhagen Baby Heart Study, a prospective, multicenter cohort study including fetuses from the second trimester of pregnancy in Copenhagen from April 2016 to October 2018. The mothers were recruited at the second trimester anatomy scan that included extended cardiovascular image documentation followed by consecutively measured heart biometries by 2 investigators blinded for the pregnancy outcome. The fetuses were classified postnatally as small for gestational age and intrauterine growth restricted according to the International Society of Ultrasound in Obstetrics and Gynecology 2020 guidelines using birthweight and with a retrospective assessment of Doppler flow. The mean differences in the cardiovascular biometries were adjusted for gestational age at the time of the second trimester scan and the abdominal circumference. The z-scores were calculated, and the comparisons were Bonferroni corrected (significance level of P<.005). Receiver operating characteristic curves were computed after performing backward regression on several maternal characteristics and biomarkers.

RESULTS

We included 8278 fetuses, with 625 (7.6%) of them being small for gestational age and 289 (3.5%) being intrauterine growth restricted. Both small for gestational age and intrauterine growth restricted fetuses had smaller heart biometries, including the diameter at the location of the aortic valve (P<.005), the ascending aorta in the 3-vessel view (P<.005), and at the location of the pulmonary valve (P<.005). The intrauterine growth restricted group had significantly smaller hearts with respect to length and width (P<.005) and smaller right and left ventricles (P<.005). After adjusting for the abdominal circumference, the differences in the aortic valve and the pulmonary valve remained significant in the intrauterine growth restricted group. Achievement of an optimal receiver operating characteristic curve included the following parameters: head circumference, abdominal circumference, femur length, gestational age, pregnancy associated plasma protein-A multiples of median, nullipara, spontaneous conception, smoking, body mass index <18.5, heart width, and pulmonary valve with an area under the curve of 0.91 (0.88-0.93) for intrauterine growth restricted cases.

CONCLUSION

Intrauterine growth restricted fetuses had smaller prenatal cardiovascular biometries, even when adjusting for abdominal circumference. Our findings support that growth restriction is already associated with altered cardiac growth at an early stage of pregnancy. The heart biometries alone did perform well as a screening test, but combined with other factors, it increased the sensitivity and specificity for intrauterine growth restriction.

Left myocardial performance index in monochorionic diamniotic twin pairs complicated by selective fetal growth restriction with abnormal umbilical artery Doppler

OBJECTIVE

To evaluate left myocardial performance index (MPI) and its time intervals in monochorionic diamniotic (MCDA) twin pairs complicated by selective fetal growth restriction (sFGR) with abnormal (persistent -type II- or intermittent -type III- absent or reversed end-diastolic flow) umbilical artery Doppler.

METHODS

Retrospective study including 16 MCDA twin pairs with sFGR type II, 26 MCDA twin pairs with sFGR type III and 42 gestational age-matched uncomplicated MCDA twin pairs in a single tertiary center. Left isovolumetric contraction time (ICT), ejection time (ET), and isovolumetric relaxation time (IRT) were measured and MPI calculated by conventional Doppler at diagnosis of sFGR.

RESULTS

In sFGR type II, the smaller twin had shorter ET and prolonged IRT and MPI, while the larger twin showed prolonged ICT and MPI as compared to uncomplicated MCDA twins. In sFGR type III, the smaller twin had shorter ICT and ET, while the larger twin showed prolonged ICT, IRT, and MPI in comparison to controls.

CONCLUSION

A differential pattern of MPI time intervals could be observed in MCDA twins with sFGR type II and III. All twins had echocardiographic signs of pressure/volume overload, except the smaller twin type III with shorter systolic times probably reflecting reduced volume load.

Cardiac function in fetal growth restriction

Fetal growth restriction (FGR) is defined as the inability of the fetus to reach its growth potential. According to the onset of the disease is defined early (<32 weeks) or late (≥32 weeks). FGR is associated with an increased risk of adverse short- and long-term outcomes, including hypoxemic events and neurodevelopmental delay compared to normally grown fetuses and increased risk of complications in the infanthood and adulthood. The underlying cause of FGR is placental insufficiency leading to chronic fetal hypoxia that affects cardiac hemodynamic with different mechanism in early and late onset growth restriction. In early onset FGR adaptive mechanisms involve the diversion of the cardiac output preferentially in favor of the brain and the heart, while abnormal arterial and venous flow manifest in the case of further worsening of fetal hypoxia. In late FGR the fetal heart shows a remodeling of its shape and function mainly related to a reduction of umbilical vein flow. In this review we discuss the modifications occurring at the level of the fetal cardiac hemodynamic in fetuses with early and late FGR.

Reference values for left and right ventricular systolic-to-diastolic duration ratio (SDR) found using both spectral and tissue Doppler of fetal heart between 20 and 36+6 weeks of gestation

PURPOSE

To establish reference values for the systolic-to-diastolic duration ratio (SDR) of the left ventricle (LV) using spectral Doppler, as well as for the SDR' of the interventricular septum (SEP), LV, and right ventricles (RV) using tissue Doppler of the fetal heart.

METHOD

This prospective and cross-sectional study evaluated 374 low-risk singleton pregnancies from 20 to 36 + 6 weeks of gestation. The ventricular filling time (FT) was obtained from LV inflow using spectral Doppler. Tissue Doppler was used to assess the FT of each ventricle by placing the cursor at the atrioventricular junction marked by the mitral and tricuspid valves, respectively. SDR was calculated as the sum of the isovolumic contraction time (ICT) and the ejection time (ET) divided by the sum of the isovolumic relaxation time (IRT) and the ventricular FT. We used regression analysis to obtain the best-fit model polynomial equation for the parameters. The concordance correlation coefficient (CCC) was used to assess intra- and inter-observer reproducibility.

RESULTS

SDR and SDR' LV showed a progressive decrease with gestational age (GA); the SDR' RV and SDR' SEP did not show a significant decrease with advancing GA. The SDR LV (r = 0.29, p < 0.0001), SDR' RV (r = 0.21, p < 0.0001), SDR' LV (r = 0.20, p = 0.0001), and SDR' SEP (r = 0.25, p < 0.0001) showed a significant weak positive correlation with fetal heart rate. The inter-observer SDR' SEP measurements demonstrated poor reproducibility (CCC: 0.50), whereas intra-observer SRD LV measurements demonstrated moderate reproducibility (CCC: 0.78).

CONCLUSIONS

Reference values for SDR SEP, LV, and RV using spectral and tissue Doppler of fetal heart were established between 20 and 36+6 weeks of gestation.

Doppler studies of placental function

Placental-associated diseases account for most cases of adverse perinatal outcome in developing countries. Doppler evaluation has been incorporated as a predictive parameter at early pregnancy for high-risk placental disease, in the diagnosis and management of those fetuses with impaired intrauterine growth and for the evaluation of fetal wellbeing in those high-risk pregnancies. Uterine Doppler at second trimester predicts most instances of early-onset preeclampsia and intrauterine growth restriction. However, the growing evidence of an effective early propylactic strategy, has turned Uterine Doppler an essential parameter to be included in first trimester predictive algorithms. Umbilical artery Doppler helps in the identification of small-for-gestational-age fetuses at higher risk, and is one of the essential vessels in the assessment of fetal hypoxia impairment, especially in the early cases. It helps in the decision timing for ending the pregnancy improving thus perinatal outcomes. Moreover, in high-risk pregnancies, umbilical artery Doppler has demonstrated to reduce the risk of perinatal deaths and the risk of obstetric interventions. On the other hand, middle cerebral artery Doppler reflects fetal adaptation to hypoxia, and with the cerebroplacental ratio, they improve the detection of fetuses a high risk of adverse perinatal outcome, mostly of those late small fetuses, where most instances of adverse outcome occur in fetuses with normal umbilical artery. Ductus venosous Doppler waveform is a surrogate parameter of the fetal base-acid status. Its use has demonstrated to improve perinatal outcomes, mainly reducing the risk of fetal intrauterine death. Alone or in combination with computerized CTG, it helps tailoring the best moment to end the pregnancy among early cases.

Fetal myocardial performance index in pregnancies with idiopathic mildly increased amniotic fluid volume

PURPOSE

To evaluate modified myocardial performance index (MPI), or Tei index, in fetuses of pregnancies with idiopathic mildly increased amniotic fluid index (AFI).

METHODS

We studied 25 cases (24-40 weeks) with idiopathic mildly increased AFI, and 25 gestational age- and fetal gender-matched healthy controls. Fetal echocardiographic variables and Doppler-derived indices were recorded, including left and right MPI, left isovolumetric contraction time (IVCT), left ejection time (ET), left isovolumetric relaxation time (IVRT), aortic and pulmonary arterial peak systolic velocity (PSV), left and right E/A ratios, middle cerebral artery (MCA) pulsatility index (PI), and umbilical artery (UA) PI.

RESULTS

The mean left MPI (0.52 vs 0.41, P < .0001) and right MPI (0.50 vs 0.42, P < .001) were higher, and mean IVCT (37.7 vs 25.9, P < .0001) was longer in cases than in controls. However, there were no significant differences between the two groups in IVRT (45.2 vs 43.2, P = .381), ET (160.2 vs 170.0, P = .079), aortic PSV (P = .073), left E/A (P = .080), pulmonary artery PSV (P = .061), right E/A (P = .054), MCA PI (P = .259), UA PI (P = .685), and cerebroplacental ratio (P = .645).

CONCLUSION

Pregnancies with idiopathic mildly increased AFI were associated with a significant increase in the fetal MPI of both left and right ventricles.

A review of fetal cardiac monitoring, with a focus on low- and middle-income countries

There is limited evidence regarding the utility of fetal monitoring during pregnancy, particularly during labor and delivery. Developed countries rely on consensus 'best practices' of obstetrics and gynecology professional societies to guide their protocols and policies. Protocols are often driven by the desire to be as safe as possible and avoid litigation, regardless of the cost of downstream treatment. In high-resource settings, there may be a justification for this approach. In low-resource settings, in particular, interventions can be costly and lead to adverse outcomes in subsequent pregnancies. Therefore, it is essential to consider the evidence and cost of different fetal monitoring approaches, particularly in the context of treatment and care in low-to-middle income countries. This article reviews the standard methods used for fetal monitoring, with particular emphasis on fetal cardiac assessment, which is a reliable indicator of fetal well-being. An overview of fetal monitoring practices in low-to-middle income counties, including perinatal care access challenges, is also presented. Finally, an overview of how mobile technology may help reduce barriers to perinatal care access in low-resource settings is provided.

Reference ranges of filling time and systolic-to-diastolic time index of the left ventricle, right ventricle, and interventricular septum using both spectral and tissue Doppler of fetal heart between 20 and 36 + 6 weeks of gestation

OBJECTIVE

The objective of this study is to determine the reference ranges for filling time (FT) and systolic-to-diastolic time index (SDI) of the left ventricle (LV) by using spectral Doppler, and FT' and SDI' of the LV, right ventricle, and interventricular septum (IVS) by using tissue Doppler of the fetal heart.

STUDY DESIGN

This prospective and cross-sectional study included 360 low-risk singleton pregnancies between 20 and 36 + 6 weeks of gestation. The SDI/SDI' is the sum of the ejection time, isovolumic contraction time, and isovolumic relaxation time (IRT) divided by the FT. We measured FT/FT' from the beginning of the opening click of the E wave of the mitral valve to the closing click of the A wave of the mitral valve. We used regression analysis to obtain the best-fit model polynomial equation for the parameters. Additionally, we assessed intra- and inter-observer reproducibility by using concordance correlation coefficient (CCC).

RESULTS

There was a weak correlation among FT LV (r = 0.31, p < 0.0001), SDI LV (r = -0.23, p < 0.0001), and gestational age (GA). Additionally, there was a very weak positive correlation among FT' RV (r = 0.09, p = 0.0001), FT' LV (r = 0.07, p < 0.0001), FT' IVS (r = 0,08, p < 0.0001), and GA. In contrast, there was a very weak negative correlation among SDI' LV (r=-0.09, p < 0.0001), SDI' IVS (r=-0.05, p < 0.0021), and GA. There was no significative correlation between SDI' RV (r=-0.06, p < 0.081) and GA. Poor/very poor intra- and inter-observer reliability was observed for all the parameters (CCC = 0.19-0.79), whereas moderate intra- and inter-observer agreement was observed for all parameters (CCC = 0.37-0.72).

CONCLUSIONS

The reference ranges for FT and SDI were determined by using spectral and tissue Doppler of the fetal heart and showed a poor reproducibility.

Aortic Isthmus Doppler Velocimetry in Fetuses with Intrauterine Growth Restriction: A Literature Review

Intrauterine growth restriction (IUGR) is associated with poor perinatal prognosis and a higher risk of stillbirth, neonatal death, and cerebral palsy. Its detection and the evaluation of its severity by new Doppler velocimetric parameters, such as aortic isthmus (AoI), are of great relevance for obstetrical practice. The AoI is a vascular segment that represents a point of communication between the right and left fetal circulations. It is considered to be a functional arterial shunt that reflects the relationship between the systemic and cerebral impedances, and has recently been proposed as a tool to detect the status of hemodynamic balance and prognosis of IUGR in fetuses. In the present review, we noticed that in healthy fetuses, the AoI net flow is always antegrade, but in fetuses with IUGR the deterioration of placental function leads to progressive reduction in its flow until it becomes mostly retrograde; this point is associated with a drastic reduction in oxygen delivery to the brain. The more impaired the AoI flow is, the greater is the risk of impairment in the Doppler velocimetry of other vessels; and the alterations of the AoI Doppler seem to precede other indicators of severe hypoxemia. Although there seems to be an association between the presence of retrograde flow in the AoI and the risk of long-term neurologic disability, its role in the prediction of perinatal morbi-mortality remains unclear. The AoI Doppler seems to be a promising tool in the management of fetuses with IUGR, but more studies are needed to investigate its employment in clinical practice.

Evaluation of Hemodynamic Changes in Fetuses With Isolated Mild-to-Moderate Ventriculomegaly by Transabdominal Ultrasound

OBJECTIVES

To investigate fetal hemodynamic alterations using transabdominal ultrasound in fetuses with isolated mild-to-moderate ventriculomegaly (VM).

METHODS

Fetuses diagnosed with isolated mild-to-moderate VM by transabdominal ultrasound were evaluated for hemodynamic changes, including changes in fetal cardiac function, the umbilical artery, the ductus venosus, and the middle cerebral artery. The fetuses with isolated mild-to-moderate VM were divided into 2 groups, namely, before 32 weeks' gestation (20 weeks-31 weeks 6 days) and after 32 weeks' gestation (32-38 weeks), and matched to corresponding healthy control fetuses.

RESULTS

The 53 fetuses with VM before 32 weeks had a longer mean isovolumetric relaxation time (IRT; mean ± SD, 42.9 ± 6.8 versus 40.4 ± 5.0 milliseconds; P < .05) and an apparently higher modified myocardial performance index 0.46 ± 0.06 versus 0.43 ± 0.05; P < .01) than the healthy control fetuses. The 43 fetuses with VM after 32 weeks had a significantly longer mean IRT (45.5 ± 6.7 versus 40.9 ± 7.2 milliseconds; P < .01) and a lower UA pulsatility index (0.81 ± 0.13 versus 0.89 ± 0.11; P < .01). The optimal cutoff levels for the IRT in the prediction of adverse perinatal outcomes were 40 and 43 milliseconds before and after 32 weeks, respectively (sensitivity, 100% versus 100%; specificity, 40.4% versus 50.0%; area under the curve, 0.601 versus 0.748; 95% confidence interval, 0.457-0.733 versus 0.590-0.869; P = .291 versus .005).

CONCLUSIONS

Some fetuses with isolated mild-to-moderate VM may have impaired cardiac function, characterized by a higher modified myocardial performance index or longer IRT. This finding might be useful for improving fetal surveillance.

Correlation between fetoplacental Doppler indices and measurements of cardiac function in term fetuses

OBJECTIVE

Redistribution of cardiac output (CO) is responsible for the brain-sparing effect seen during periods of fetal stress. Our aim was to investigate prospectively the correlation between fetoplacental Doppler indices and measurements of cardiac function in uncomplicated term singleton pregnancy.

METHODS

This was a prospective observational study of normotensive women with appropriately grown, non-anomalous singleton pregnancy. Participants underwent fortnightly ultrasound examinations from 36 weeks' gestation until delivery, and intrapartum and neonatal outcomes were recorded. The correlation between fetoplacental Doppler indices and various measurements of cardiac function was evaluated.

RESULTS

The study cohort comprised 273 singleton pregnancies. The cerebroplacental ratio (CPR) was correlated positively with left ventricular CO (LVCO) (P < 0.001, rho = 0.29), left-to-right ventricular CO ratio (LVCO/RVCO; P < 0.001, rho = 0.41), global left ventricular strain (P < 0.01, rho = 0.17) and global right ventricular strain (P < 0.001, rho = 0.22). The CPR was correlated inversely with the left ventricular myocardial performance index (P < 0.01, rho = -0.18) and the RVCO (P < 0.001, rho = -0.28). The LVCO and global left ventricular strain were correlated positively with umbilical venous flow (P = 0.04, rho = 0.18 and P < 0.001, rho = 0.25, respectively). There was minimal or no correlation between either the mean uterine artery pulsatility index (PI) or umbilical artery PI with any cardiac indices.

CONCLUSION

The fetal CPR, middle cerebral artery PI and umbilical venous flow are correlated positively with LVCO, LVCO/RVCO and global left ventricular strain in low-risk term pregnancies. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Managing fetal growth restriction: surveillance tests and their interpretation

The main challenges in pregnancies affected by fetal growth restriction consist in identifying signs of disease progression and determining the appropriate timing of delivery. The risk of continuing the pregnancy must be balanced with the risk of prematurity, which depends on gestational age. To allow appropriate monitoring of the growth-restricted fetus, several surveillance tests are available. These include ultrasound Doppler velocimetry of feto-placental vessels, cardiotocography, and amniotic fluid evaluation. It is well known that the combination of tests performs better than each test alone to predict fetal deterioration. The interpretation of test results depends on the gestational age and on the nature of the growth disorder (early- vs. late-onset disease). Appropriate knowledge on the surveillance tests interpretation and the frequency at which they need to be performed is crucial in managing fetal growth restriction, in order to produce better outcome and prevent stillbirth, and at the same time to avoid unnecessary interventions.

Modified myocardial performance index and its prognostic significance for adverse perinatal outcome in early and late onset fetal growth restriction

Objective: To compare the fetal modified myocardial performance index (Mod-MPI) in appropriately grown, early (EO) and late onset (LO) fetal growth restricted (FGR) fetuses and to assess its prognostic significance for adverse perinatal outcome.Study design: In a prospective case-control study, Mod-MPI was performed in 22 and 51 fetuses with EO and LO-FGR fetuses, respectively. Mod-MPI values of FGR fetuses were compared against gestation-matched controls (34 for EO-, and 32 for LO-FGR, respectively). Correlation testing related with poor perinatal outcomes were performed.Results: Incidences of pathologic uterine artery Doppler rate, cesarean section rate, 5-min Apgar score < 7, neonatal intensive care unit (NICU) admission and perinatal mortality were significantly higher in the EO-FGR group (p < .001). There was a decrease in Mod-MPI with gestational age in the normal (Pearson's r = 0.401, p < .001), and growth-restricted fetuses (Pearson's r = 0.248, p = .034). Mean Mod-MPI values were significantly higher in both EO- and LO-FGR group than gestation-matched controls (p < .001). There was no significant correlation between Mod-MPI values and perinatal deaths (Pearson's r = 0.004, p = .987) and 5-min Apgar score < 7 (Pearson's r = 0.391, p = .088) in the EO-FGR fetuses. There was a significant negative correlation between Mod-MPI values and cerebroplacental ratio (CPR) values (Pearson's r = -0.288, p = .041); however no significant correlation between Mod-MPI values and 5-min Apgar score< 7, and fetal distress during labor (Pearson's r = 0.149, p = 0.297) in the LO-FGR fetuses was noted.Conclusion: EO and LO-FGR fetuses have significantly higher Mod-MPI values, demonstrating prenatal cardiac dysfunction. Evaluating Mod-MPI is not so effective in predicting poor perinatal outcome in both EO and LO-FGR fetuses.

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.

Differential Changes in Myocardial Performance Index and Its Time Intervals in Donors and Recipients of Twin-to-Twin Transfusion Syndrome before and after Laser Therapy

OBJECTIVE

To evaluate left myocardial performance index (MPI) and time intervals in fetuses with twin-to-twin transfusion syndrome (TTTS) before and after laser surgery.

METHODS

Fifty-one fetal pairs with TTTS and 47 uncomplicated monochorionic twin pairs were included. Left ventricular isovolumetric contraction time (ICT), ejection time (ET), and isovolumetric relaxation time (IRT) were measured using conventional Doppler.

RESULTS

Recipients showed prolonged ICT (46 ± 12 vs. 31 ± 8 vs. 30 ± 5 ms; p < 0.001) and IRT (51 ± 9 vs. 43 ± 8 vs. 43 ± 5 ms; p < 0.001) and higher MPI (0.57 ± 0.12 vs. 0.47 ± 0.09 vs. 0.44 ± 0.05; p < 0.001) than donors and controls. Donors showed shorter ET than recipients and controls (157 ± 12 vs. 169 ± 10 vs. 168 ± 10 ms; p < 0.001) and higher MPI than controls (0.47 ± 0.09 vs. 0.44 ± 0.05; p = 0.006). Preoperative MPI changes were observed in all TTTS stages. Time intervals partially improved after surgery.

CONCLUSION

Donor and recipient twins had higher MPI due to different changes in the time intervals, possibly reflecting the state of hypovolemia in the donor and hypervolemia and pressure overload in the recipient.

Assessment of Fetal Myocardial Performance Index in Women with Placenta Previa

Background

This study investigated whether fetuses of placenta previa pregnancies have cardiac dysfunction by use of a modified myocardial performance index (Mod-MPI).

Material/Methods

A prospective cross-sectional study was conducted including 178 fetuses at 28–40 weeks of gestation. Eighty-nine fetuses of mothers with placenta previa and without pregnancy complications were recruited (placenta previa group) and matched with 89 fetuses of mothers with normal pregnancies (control group). Fetal cardiac function parameters and perinatal outcomes as well as the Mod-MPI were compared between the 2 groups.

Results

The median Mod-MPI was significantly increased in fetuses of mothers with placenta previa compared with controls (0.47±0.05 vs. 0.45±0.05; P<0.01). Among fetuses of mothers with or without placenta previa, the Mod-MPI was significantly higher in the incomplete placenta previa group compared with the complete placenta previa group and control group (P<0.01). An increased Mod-MPI in placenta previa pregnancies was independently associated with fetal cord pH <7.2 (odds ratio, 4.8; 95% confidence interval, 0.98–23.54; P=0.003).

Conclusions

There is impairment of fetal cardiac function in pregnancies with placenta previa. An increased MPI was independently associated with adverse perinatal outcomes to some extent in the placenta previa pregnancies.

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.

Quantification of mechanical dyssynchrony in growth restricted fetuses and normal controls using speckle tracking echocardiography (STE)

PURPOSE

To evaluate longitudinal mechanical dyssynchrony in normally grown fetuses by speckle tracking echocardiography (STE) and to compare longitudinal mechanical dyssynchrony in fetal growth restriction (FGR) with normal controls.

MATERIALS AND METHODS

A prospective study was performed on 30 FGR and 62 normally grown fetuses, including 30 controls matched by gestational age, using STE and a transversal four-chamber view. Data analysis was carried out with a high frame rate of about 175 frames/s. Dyssynchrony was analyzed offline with QLab 9 (Philips Medical Systems, Andover, MA, USA) as time differences between peaks in strain of both ventricles and the septum. Inter- and intraventricular and intraseptal dyssynchrony were obtained and inter- and intraobserver reliability was analyzed.

RESULTS

Longitudinal mechanical dyssynchrony was feasible in all cases, with high inter- and intraobserver reliability. Levels of inter- and intraventricular dyssynchrony were higher in the FGR than in the control group.

CONCLUSION

Speckle tracking echocardiography (STE) is a reliable technique for cardiac function assessment in the fetal heart. Interventricular dyssynchrony could be a potential parameter for early detection of subclinical myocardial dysfunction before other parameters demand intervention. The future clinical role of longitudinal mechanical dyssynchrony needs to be verified in larger studies and with a technique customized for prenatal echocardiography.

Fetal growth restriction: current knowledge

BACKGROUND

Fetal growth restriction (FGR) is a condition that affects 5-10% of pregnancies and is the second most common cause of perinatal mortality. This review presents the most recent knowledge on FGR and focuses on the etiology, classification, prediction, diagnosis, and management of the condition, as well as on its neurological complications.

METHODS

The Pubmed, SCOPUS, and Embase databases were searched using the term "fetal growth restriction".

RESULTS

Fetal growth restriction (FGR) may be classified as early or late depending on the time of diagnosis. Early FGR (<32 weeks) is associated with substantial alterations in placental implantation with elevated hypoxia, which requires cardiovascular adaptation. Perinatal morbidity and mortality rates are high. Late FGR (≥32 weeks) presents with slight deficiencies in placentation, which leads to mild hypoxia and requires little cardiovascular adaptation. Perinatal morbidity and mortality rates are lower. The diagnosis of FGR may be clinical; however, an arterial and venous Doppler ultrasound examination is essential for diagnosis and follow-up. There are currently no treatments to control FGR; the time at which pregnancy is interrupted is of vital importance for protecting both the mother and fetus.

CONCLUSION

Early diagnosis of FGR is very important, because it enables the identification of the etiology of the condition and adequate monitoring of the fetal status, thereby minimizing risks of premature birth and intrauterine hypoxia.

Relationship between general movements in neonates who were growth restricted in utero and prenatal Doppler flow patterns

OBJECTIVE

To investigate whether Doppler pulsatility indices (PIs) of the fetal circulation in cases of fetal growth restriction (FGR) are associated with the general movements (GMs) of the neonate after birth.

METHODS

This was a prospective observational cohort study including pregnancies with FGR diagnosed between June 2012 and September 2014. A diagnosis of FGR was based on an abdominal circumference or estimated fetal weight < 10^th percentile (in conjuction with abnormal Doppler) or declining fetal growth of at least 30 percentiles with respect to previous size measurements. Doppler parameters of the umbilical artery (UA), fetal middle cerebral artery (MCA) and ductus venosus (DV) were measured maximally 1 week prior to delivery. Cerebroplacental ratio (CPR) was calculated as MCA-PI divided by UA-PI. We assessed the quality of neonatal GMs 7 days after birth, around the due date if cases were born preterm, and at 3 months post-term. We performed a detailed analysis of the motor repertoire by calculating a motor optimality score (MOS).

RESULTS

Forty-eight FGR cases were included with a median gestational age at delivery of 35 (range, 26-40) weeks. UA-PI, MCA-PI and CPR correlated strongly (ρ, -0.374 to 0.472; P < 0.01) with the MOS on day 7 after birth, but DV-PI did not. Doppler PI measurements did not correlate with MOS at 3 months post-term.

CONCLUSION

Fetal arterial Doppler measurements are associated with the quality of neonatal GMs 1 week after birth, but this association is no longer evident at 3 months post-term. Brain sparing in particular is associated strongly with GMs of an abnormal quality. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Effect of Hypoxemia with or without Increased Placental Vascular Resistance on Fetal Left and Right Ventricular Myocardial Performance Index in Chronically Instrumented Sheep

Myocardial performance index (MPI) is increased in growth-restricted fetuses with placental insufficiency, but it is unknown if this is due to fetal hypoxemia or increased placental vascular resistance (R_plac). We used chronically instrumented sheep fetuses (n = 24). In 12 fetuses, placental embolization was performed 24 h before experiments. On the day of the experiment, left (LV) and right (RV) ventricular MPIs were obtained by pulsed Doppler at baseline and in the hypoxemia and recovery phases. At baseline, R_plac was greater and fetal pO₂ lower in the placental embolization group, but RV and LV MPIs were comparable to those of the control group. During hypoxemia, mean LV MPI increased significantly only in fetuses with an intact placenta (0.34 vs. 0.46), returning to baseline during the recovery phase. Right ventricular MPI was unaffected. We conclude that fetal LV function is sensitive to acute hypoxemia. Exposure to chronic hypoxemia could pre-condition the fetal heart and protect its function with worsening hypoxemia.

An integrated approach to fetal growth restriction

Fetal growth restriction (FGR) is among the most common complications of pregnancy. FGR is associated with placental insufficiency and poor perinatal outcomes. Clinical management is challenging because of variability in clinical presentation. Fetal smallness (estimated fetal weight <10th centile for gestational age) remains the best clinical surrogate for FGR. However, it is commonly accepted that not all forms of fetal smallness represent true FGR. In a significant subset of small fetuses, there is no evidence of placental involvement, perinatal outcomes are nearly normal, and they are clinically referred to as "only" small for gestational age (SGA). Doppler may improve the clinical management of FGR; however, the need to use several parameters sometimes results in a number of combinations that may render interpretation challenging when translating into clinical decisions. We propose that the management of FGR can be simplified using a sequential approach based on three steps: (1) identification of the "small fetus," (2) differentiation between FGR and SGA, and (3) timing of delivery according to a protocol based on stages of fetal deterioration.

Early onset fetal growth restriction

Fetal growth restriction remains a challenging entity with significant variations in clinical practice around the world. The different etiopathogenesis of early and late fetal growth restriction with their distinct progression of fetal severity and outcomes, compounded by doctors and patient anxiety adds to the quandary involving its management. This review summarises the literature around diagnosing and monitoring early onset fetal growth restriction (early onset FGR) with special emphasis on optimal timing of delivery as guided by recent research advances.

Human fetal growth restriction: a cardiovascular journey through to adolescence

Intrauterine growth restriction has been noted to adversely impact morbidity and mortality in the neonatal period as well as cardiovascular well-being in adolescence and adulthood. Recent data based on a wide range of ultrasound parameters during fetal and neonatal life has noted early and persistent involvement of the cardiovascular system. Some of these measures are predictive of long-term morbidities. Assessment of vascular mechanics is a new and novel concept in this population, and opens up avenues for diagnosis, monitoring and evaluation of the likely effectiveness of interventions. Prevention of these adverse vascular and cardiac outcomes secondary to fetal growth restriction may be feasible and of clinical relevance. This review focuses on growth restriction in humans with respect to cardiovascular remodeling and dysfunction during fetal life, persistence of functional cardiac impairment during early childhood and adolescence, and possible preventive strategies.

The Aortic Isthmus: A Significant yet Underexplored Watershed of the Fetal Circulation

The aortic isthmus (AoI) is a unique fetal watershed with a waveform reflecting its complex haemodynamic physiology. The systolic component represents left and right ventricular systolic ejection, and the diastolic component represents comparative downstream vascular impedance between the brachiocephalic and subdiaphragmatic fetal circulations. Several indices have been devised to quantify different components of the waveform, including the pulsatility index, resistance index, isthmic flow index, and recently the isthmic systolic index. There have been promising preliminary studies applying these indices to both cardiac (congenital) and extracardiac pathologies, including intrauterine growth restriction and twin-twin transfusion syndrome. However, the waveform's multifactorial origin has proven to be challenging, and the difficulty in separating various components of the waveform could explain that AoI evaluation does not have a clear clinical utility. Further research is underway to realise the full potential of this vessel in fetal cardiac and haemodynamically compromised pathological conditions. In this review article we outline the physiological origin of this Doppler waveform, describe in detail the various published indices, summarise the published literature to date, and finally outline potential future research and hopefully clinical applications.

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.

Fetal left modified myocardial performance index measured by the Auto Mod-MPI system: development of reference values and application to recipients of twin-to-twin transfusion syndrome

OBJECTIVES

To establish normal reference ranges for the fetal left modified myocardial performance index (Mod-MPI) measured by the Auto Mod-MPI system and evaluate Mod-MPI changes in recipients of twin-to-twin transfusion syndrome (TTTS) before and after fetoscopic laser coagulation.

METHODS

This was a prospective longitudinal study of normal singleton fetuses from 12.0 to 40.0 weeks of gestation. TTTS cases treated by laser coagulation were reviewed for Mod-MPI measurements of recipients. All measurements were performed using the Auto Mod-MPI system by a single experienced operator.

RESULTS

Among a total 447 examinations from 222 fetuses, we were unable to measure the Mod-MPI in two cases, and therefore, 445 examinations were analyzed. The median Mod-MPI consistently increased from 0.44 to 0.56 throughout gestation. The median isovolumetric contraction time (ICT) and isovolumetric relaxation time (IRT) also increased with advancing gestational age. The ejection time (ET) increased until 27 weeks of gestation and decreased thereafter. In the 30 recipients, Mod-MPI, ICT, and IRT increased before laser coagulation and significantly decreased after laser coagulation.

CONCLUSION

Normal reference values for left Mod-MPI were established using the Auto Mod-MPI system, and these might be useful for assessing cardiac function in TTTS. © 2016 John Wiley & Sons, Ltd.

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.

The (Pulsed-Wave) Doppler Fetal Myocardial Performance Index: Technical Challenges, Clinical Applications and Future Research

Functional cardiovascular assessment is becoming an increasingly important tool in the study of fetal pathology. The myocardial performance index (MPI) is a parameter measuring global myocardial function. Since its introduction, several studies have proposed methods to improve its reproducibility and have constructed normative reference ranges. Fetal heart evaluation using the MPI is technically challenging, requiring specific training and expertise, and a consensus has yet to be reached on the method of delineating the time periods used to calculate the index. Despite these limitations, it has been shown to be a useful and highly sensitive parameter of dysfunction in a number of fetal pathologies. Further research is warranted into the effect of pathology on MPI, parameters of unilateral cardiac strain that utilise MPI, and automation of the MPI to encourage incorporation of the MPI as a useful tool in clinical practice.

Shining light in dark corners: diagnosis and management of late-onset fetal growth restriction

Fetal growth restriction (FGR) is the single biggest risk factor for stillbirth. In the absence of any effective treatment for fetal growth restriction, the mainstay of management is close surveillance and timely delivery. While such statements are almost self-evident, the daily clinical challenge of late-onset fetal growth restriction remains; the competing priorities of minimising stillbirth risk, while avoiding excessive obstetric intervention and the neonatal sequelae of iatrogenic preterm birth. This dilemma is made harder because the tools for late-onset FGR diagnosis and surveillance compare poorly to those used in early-onset FGR; screening tests in early pregnancy have limited predictive value; most cases escape clinical detection, a phenomenon set to worsen given the obesity epidemic; there is a failure of consensus on the definition of small for gestational age, and ancillary tools, such as umbilical artery Doppler--of value in identification of preterm FGR--are less useful in the late-preterm period and at term. Most importantly, the problem is common; 96% of all births occur after 32 weeks. This means a poor noise/signal ratio of any test or management algorithm will inevitably have large clinical consequences. Into such a dark corner, we cast some light; a summary on diagnostic criteria, new developments to improve the diagnosis of late-onset FGR and a suggested approach to management.

Timing of delivery and neonatal outcomes for small-for-gestational-age fetuses

OBJECTIVES

To investigate whether antenatal recognition of small-for-gestational-age (SGA) fetuses with normal maternal and fetal Doppler values delivered after 34 weeks' gestation is associated with changes in the risk of adverse maternal and neonatal outcomes.

METHODS

In this retrospective study, we included 313 singleton SGA fetuses and 313 appropriate-for-gestational-age control fetuses born between 34 and 42 weeks' gestation from 2009 to 2012. Small-for-gestational-age fetuses identified before delivery (n = 124), for whom antenatal surveillance was performed until delivery (estimated fetal weight twice weekly and Doppler evaluation of the fetal compartment once weekly), were compared to those not identified at delivery (n = 189). The latter group did not undergo antenatal surveillance for several reasons (women for whom a sonographic evaluation or gynecologic consultation was not performed in the third trimester and incorrect sonographic biometric evaluation in the third trimester). Main outcome measures were mode of delivery, perinatal complications, and neonatal intensive care unit admission. The risk of serious fetal complications was assessed by cross-tabulation analysis adjusted for gestational age and degree of SGA.

RESULTS

Prenatally recognized SGA fetuses were smaller and delivered earlier than unrecognized SGA fetuses (P< .05). Fetal acidemia (pH <7.10) was significantly more common in unrecognized SGA fetuses (3.7% versus 0%). Small-for-gestational-age fetuses at or below the 3rd percentile were more commonly recognized prenatally and hospitalized in the neonatal intensive care unit. Unrecognized SGA fetuses also had worse fetal outcomes compared to controls (P< .05). Recognized and unrecognized SGA fetuses were born significantly more frequently by cesarean delivery (P < .05). No significant differences in perinatal outcomes were found between recognized SGA deliveries with or without medical induction.

CONCLUSIONS

Antenatal recognition of SGA fetuses delivered after 34 weeks' gestation might improve perinatal outcomes. Medical induction of labor did not modify neonatal outcomes among prenatally recognized SGA fetuses.

A computational model of the fetal circulation to quantify blood redistribution in intrauterine growth restriction

Intrauterine growth restriction (IUGR) due to placental insufficiency is associated with blood flow redistribution in order to maintain delivery of oxygenated blood to the brain. Given that, in the fetus the aortic isthmus (AoI) is a key arterial connection between the cerebral and placental circulations, quantifying AoI blood flow has been proposed to assess this brain sparing effect in clinical practice. While numerous clinical studies have studied this parameter, fundamental understanding of its determinant factors and its quantitative relation with other aspects of haemodynamic remodeling has been limited. Computational models of the cardiovascular circulation have been proposed for exactly this purpose since they allow both for studying the contributions from isolated parameters as well as estimating properties that cannot be directly assessed from clinical measurements. Therefore, a computational model of the fetal circulation was developed, including the key elements related to fetal blood redistribution and using measured cardiac outflow profiles to allow personalization. The model was first calibrated using patient-specific Doppler data from a healthy fetus. Next, in order to understand the contributions of the main parameters determining blood redistribution, AoI and middle cerebral artery (MCA) flow changes were studied by variation of cerebral and peripheral-placental resistances. Finally, to study how this affects an individual fetus, the model was fitted to three IUGR cases with different degrees of severity. In conclusion, the proposed computational model provides a good approximation to assess blood flow changes in the fetal circulation. The results support that while MCA flow is mainly determined by a fall in brain resistance, the AoI is influenced by a balance between increased peripheral-placental and decreased cerebral resistances. Personalizing the model allows for quantifying the balance between cerebral and peripheral-placental remodeling, thus providing potentially novel information to aid clinical follow up.

Intrauterine growth restriction (IUGR) is one of the leading causes of perinatal mortality and can be defined as a low birth weight together with signs of chronic hypoxia or malnutrition. It is mostly due to placental insufficiency resulting in a chronic restriction of oxygen and nutrients to the fetus. IUGR leads to cardiac dysfunction in utero which can persist postnatally. Under these altered conditions, IUGR fetuses redistribute their blood in order to maintain delivery of oxygenated blood to the brain, known as brain sparing. Given that, in the fetus the aortic isthmus (AoI) is a key arterial connection between the cerebral and placental circulations, quantifying AoI blood flow has been proposed to assess this brain sparing effect in clinical practice. However, which remodeling or redistribution processes in the cardiovascular systems induce the observed changes in AoI flow in IUGR fetuses is not fully understood. We developed a computational model of the fetal circulation, including the key elements related to fetal blood redistribution. Using measured cardiac outflow profiles to allow personalization, we can recreate and better understand the blood flow changes in individual IUGR fetuses.

Influence of equipment and settings on myocardial performance index repeatability and definition of settings to achieve optimal reproducibility

OBJECTIVE

To compare left myocardial performance index (MPI) values and reproducibility using different settings and ultrasound equipment in order to standardize optimal machine settings.

METHODS

Left MPI was prospectively evaluated by one observer performing conventional Doppler in 62 fetuses (28-36 weeks of gestational age) using different settings (changing sweep speed, gain and wall motion filter (WMF)) and two different ultrasound devices (Siemens Antares, Siemens; Voluson 730 Expert, GE Medical Systems). Intraclass coefficients of agreement (ICCs) were calculated using Bland-Altman analysis.

RESULTS

Using baseline settings on the Siemens, mean (SD) MPI was 0.44 (0.05) with an ICC of 0.81. Decreasing the sweep speed resulted in decreasing average MPI values (0.43) and decreasing ICC (0.61). Lowering gain also influenced average MPI values (0.46) and ICC (0.76). Raising gain resulted in similar MPI values (0.45) with better ICC (0.90) compared with baseline settings. Raising wall motion filter (WMF) provided the best ICC (0.94) compared with the other settings. Changing the ultrasound equipment resulted in an ICC of 0.64. The optimal settings to achieve the highest reproducibility in measurement of MPI were sweep speed 8, gain 60 dB and WMF 281 Hz for Siemens Antares and sweep speed 5, gain -10 dB and WMF 210 Hz for Voluson 730 Expert.

CONCLUSION

Changing ultrasound settings or equipment may affect the calculation and repeatability of measurement of MPI values. Strict standardization of methods decreases the variability of this parameter for fetal cardiac function assessment.

Ultrasound assessment of fetal cardiac function

Introduction: Fetal heart evaluation with US is feasible and reproducible, although challenging due to the smallness of the heart, the high heart rate and limited access to the fetus. However, some cardiac parameters have already shown a strong correlation with outcomes and may soon be incorporated into clinical practice. Materials and Methods: Cardiac function assessment has proven utility in the differential diagnosis of cardiomyopathies or prediction of perinatal mortality in congenital heart disease. In addition, some cardiac parameters with high sensitivity such as MPI or annular peak velocities have shown promising results in monitoring and predicting outcome in intrauterine growth restriction or congenital diaphragmatic hernia. Conclusion: Cardiac function can be adequately evaluated in most fetuses when appropriate expertise, equipment and time are available. Fetal cardiac function assessment is a promising tool that may soon be incorporated into clinical practice to diagnose, monitor or predict outcome in some fetal conditions. Thus, more research is warranted to further define specific protocols for each fetal condition that may affect cardiac function.