Fetal myocardial performance index in assessment and management of small-for-gestational-age fetus: a cohort and nested case-control study

Fetal epicardial fat thickness and modified myocardial performance index in late-onset fetal growth restriction

AIM

In our study, we aimed to investigate the value of fetal epicardial fat thickness (EFT) and modified myocardial performance index (mod-MPI) in fetal growth restriction (FGR) that develops after the 32nd week of gestation.

MATERIALS AND METHODS

Fifty-six pregnant women who met the inclusion and exclusion criteria were included in the study and were divided into two groups: pregnancies diagnosed with FGR after the 32nd week of gestation (FGR group) and those without (control group). Demographic and obstetric histories, ultrasonographic and clinical characteristics, fetal EFT and mod-MPI values, and neonatal outcomes of the groups were recorded, and comparisons were made between the groups. Additionally, the diagnostic performance of fetal EFT value in late FGR was investigated.

RESULTS

The FGR group had fetal EFT that was statistically significantly lower (1.11 ± 0.21 vs. 1.34 ± 0.23, p = 0.001). The FGR group had a significantly lower isovolumetric contraction time (ICT) (31.04 ± 6.88 vs. 35.14 ± 7.58, p = 0.048). The two groups' isovolumetric relaxation time (IRT), ejection time (ET), and mod-MPI values (p values 0.871, 0.55, and 0.750, respectively) were comparable. Receiver operating characteristic (ROC) analysis at a cutoff of 1.2 revealed 76.1% sensitivity and 74.2% specificity, respectively, for the diagnostic performance of the fetal EFT value in late-onset FGR. There was a positive predictive value (PPV) and negative predictive value (NPV) of 64.0% and 83.8%, respectively.

CONCLUSION

We found that fetal EFT was significantly lower in FGR and may be useful in diagnosing FGR. However, we observed that mode-MPI did not change in FGR.

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.

Fetal cardiac alterations in the late-onset growth-restricted fetuses: A prospective case-control study

AIM

Fetal growth restriction (FGR) has significant consequences on cardiac functions. This study aims to evaluate cardiac functional parameters in late-onset (FGR) fetuses and compare those appropriate for gestational age (AGA) fetuses.

MATERIAL AND METHODS

Fifty-six singleton pregnancies were involved in this prospective case-control study. Delphi consensus was used to define late-onset FGR. We compared the E/A ratio, left myocardial performance index (MPI) and tricuspid annular plane systolic excursion (TAPSE) in late-onset FGR cases and gestational age-matched AGA fetuses.

RESULTS

Twenty-eight late-onset FGR and 28 AGA fetuses were enrolled. The mean gestational age in the late-onset FGR group was 34.1 ± 2.3 weeks and 34.4 ± 2.1 in controls. The E/A ratio was 0.88 ± 0.09 in AGA fetuses, 0.79 ± 0.11 in the late-onset FGR group, and significantly lower in late-onset FGR fetuses (p: 0.012). Left MPI was 0.51 ± 0.09 in AGA and 0.62 ± 0.11 in the late-onset FGR group. Left MPI was markedly higher in late-onset FGR fetuses (p: 0.024). TAPSE was 7.4 ± 2.9 mm in controls and 5.2 ± 1.8 in the late-onset FGR group, and it was significantly shorter in the late-onset FGR fetuses (p: 0.016).

CONCLUSION

Late-onset FGR is associated with cardiac remodeling and dysfunction. Fetal echocardiography may be beneficial to detect those subtle cardiac changes.

Cardiac time intervals and myocardial performance index for prediction of twin-twin transfusion syndrome

Objectives

To explore whether intertwin discordance in myocardial performance index (MPI) or cardiac time intervals enables the prediction of twin–twin transfusion syndrome (TTTS) in monochorionic diamniotic (MCDA) pregnancies with amniotic fluid discordance.

Methods

Prospective cohort study of MCDA pregnancies with amniotic fluid discordance ≥4 cm. Serial ultrasound examinations consisted of evaluation of amniotic fluid, fetal Dopplers and fetal cardiac function.

Results

We included 21 “future‐TTTS” (group I), 18 selective fetal growth restriction (sFGR; group II) and 20 uncomplicated MCDA twin pairs (group III). Group I had a higher intertwin difference in left ventricle (LV) MPI and right ventricle (RV) MPI compared to group II and III. The intertwin difference in global heart relaxation time was significantly higher in group I compared to group III. Future recipient twins had significantly higher contraction times of the global heart and RV and lower relaxation times of the global heart and RV compared to the “expected recipients” in group II and III.

Conclusion

Intertwin discordance in LV‐MPI and RV‐MPI differentiate between TTTS and MCDA pregnancies with transient discordant amniotic fluid volume. Cardiac time intervals identify future recipient twins. The clinical utility of cardiac time intervals and MPI should be investigated in large prospective studies.

What’s already known about this topic?

Previous attempts to find improved methods to stratify the risk for twin–twin transfusion syndrome (TTTS) include different measures of fetal cardiac dysfunction, but results have been disappointing so far.

What does this study add?

Intertwin discordance in myocardial performance index differentiates between future TTTS and monochorionic diamniotic pregnancies with discordant amniotic fluid volume without TTTS.

Cardiac time intervals can help to identify future recipient twins.

Reference Ranges for Pulsed-Wave Doppler of the Fetal Cardiac Inflow and Outflow Tracts from 13 to 36 Weeks' Gestation

BACKGROUND

Doppler assessment of ventricular filling and outflow tract velocities is an integral part of fetal echocardiography, to assess diastolic function, systolic function, and outflow tract obstruction. There is a paucity of prospective data from a large sample of normal fetuses in the published literature. The authors report reference ranges for pulsed-wave Doppler flow of the mitral valve, tricuspid valve, aortic valve, and pulmonary valve, as well as heart rate, in a large number of fetuses prospectively examined at a single tertiary fetal cardiology center.

METHODS

The study population comprised 7,885 fetuses at 13 to 36 weeks' gestation with no detectable abnormalities from pregnancies resulting in normal live births. Prospective pulsed-wave Doppler blood flow measurements were taken of the mitral, tricuspid, aortic, and pulmonary valves. The fetal heart rate was recorded at the time of each assessment. Regression analysis, with polynomial terms to assess for linear and nonlinear contributors, was used to establish the relationship between each measurement and gestational age.

RESULTS

The measurement for each cardiac Doppler measurement was expressed as a Z score (difference between observed and expected values divided by the fitted SD corrected for gestational age) and percentile. Analysis included calculation of gestation-specific SDs. Regression equations are provided for the cardiac inflow and outflow tracts.

CONCLUSIONS

This study establishes reference ranges for fetal cardiac Doppler measurements and heart rate between 13 to 36 weeks' gestation that may be useful in clinical practice.

Normal reference ranges for fetal cardiac function: Assessed by modified Doppler myocardial performance index (Mod MPI) in the Egyptian population

AIM

To develop gestational age-based reference ranges for the modified Doppler myocardial performance index (Mod MPI) and to examine the maternal characteristics that affect this measurement.

METHODS

This was a cross-sectional study, comprised of 1021 healthy pregnancies between 20+0 to 35+6 weeks' gestation. They were all undergoing ultrasound examination in Cairo Fetal Medicine Unit (CAIFM) in Cairo University, Egypt from 1st April 2017 till 1st April 2019. Mod MPI was obtained used method described by Friedman et al. (2003). Median and SD models were fitted between Mod MPI and gestational age. The distributions of Mod MPI Z-scores were examined in relation to maternal characteristics RESULTS: The normal Mod MPI in second and third trimester (20 + 1 to 35 + 6 weeks' gestation) was 0.408 ± 0.08. Mod MPI was not affected by maternal age, body mass index (BMI) or parity (p value 0.5, 0.6 and 0.2 respectively).

CONCLUSION

This study established normal reference ranges for Mod MPI according to gestational age and generated a graph with 5th,10th, 90th and 95th centiles. Maternal characteristics as age, BMI or parity do not affect value of Mod MPI.

Sex differences and the effects of intrauterine hypoxia on growth and in vivo heart function of fetal guinea pigs

We hypothesized that the physiological adaptations of the fetus in response to chronic intrauterine hypoxia depend on its sex and the gestational age of exposure. Pregnant guinea pigs were exposed to room air (normoxia, NMX) or 10.5% O₂ (hypoxia, HPX) at either 25 days (early onset) or 50 days (late onset) of gestation until term (~65 days). We evaluated the effects of HPX on hemodynamic and cardiac function indices using Doppler ultrasound and determined sex-related differences in near-term fetuses. Indices of uterine/umbilical artery pulsatility (PI index) and fetal heart systolic and diastolic function [Tei index and passive filling (E-wave) to filling due to atrial contraction (A-wave) (E/A ratios), respectively] were measured in utero and fetal body (FBW) and organ weights measured from extracted fetuses. Both early- and late-onset HPX decreased FBW in both males and females, had no effect on placenta weights, and increased placenta weight-to-FBW ratios. Early- but not late-onset HPX increased uterine artery PI, but neither HPX condition affected umbilical artery PI. Early-onset HPX increased left ventricle E/A ratios in both males and females, whereas late-onset HPX increased the right ventricle E/A ratio in females only. Hypoxia had no effect on the Tei index in either sex. Early- and late-onset HPX induce placental insufficiency and fetal growth restriction and increase diastolic filling depending on the sex, with female fetuses having a greater capacity than males to compensate for intrauterine hypoxia.

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

BACKGROUND

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

OBJECTIVE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Utility of the modified myocardial performance index in growth-restricted fetuses

OBJECTIVES

The modified myocardial performance index (Mod-MPI) can be used to assess myocardial function. Fetal growth restriction can affect fetal myocardial function, thereby altering the Mod-MPI. The results of previous studies on the utility of the Mod-MPI in growth-restricted fetuses are conflicting. The aim of this study was to calculate the left modified-MPI in growth-restricted fetuses and to compare the results with those of healthy fetuses.

METHODS

This was a prospective cross-sectional case-control study. In total, 40 women with growth-restricted fetuses and 40 women with fetuses of normal weight (controls) at 29-39 gestational weeks were enrolled in the study. An experienced obstetrician calculated the Mod-MPI for each fetus. Women with systemic diseases or fetuses with chromosomal/structural abnormalities were excluded from the study. The results of Mod-MPI measurements of the two groups were compared.

RESULTS

The mean single deepest vertical pocket (SDVP) of amniotic fluid, estimated fetal weight (EFW), and isovolumetric relaxation time (IRT) was significantly lower in the fetal growth restriction (FGR) group as compared with these parameters in the control group (P < .05). The uterine artery (UtA) pulsatility index (PI) was significantly higher in the FGR group as compared with that in the control group (P < .05). There were six cases of absent end-diastolic flow (AED) in the FGR group. There were no statistically significant between-group differences in the Mod-MPI, isovolumetric contraction time (ICT), and ejection time (ET) (P > .05). There was also no statistically significant correlation between the Mod-MPI in the fetuses with AED and the control group for Mod-MPI (P > .05).

CONCLUSION

The utility of the Mod-MPI in FGR remains unclear. Future studies with larger populations are needed to determine the utility of the Mod-MPI as a predictor of cardiac compromise in FGR.

Assessment of fetal modified myocardial performance index in early-onset and late-onset fetal growth restriction

Aim

To investigate the changes of modified myocardial performance index (Mod‐MPI) in early‐onset and late‐onset fetal growth restriction (FGR) cases, and its association with adverse perinatal outcome.

Methods

This was a prospective study on 77 early‐onset and 100 late‐onset FGR cases. Hundred normal fetuses were matched as control groups for early‐onset and late‐onset FGR groups, respectively. Mod‐MPI and vessel Doppler parameters including umbilical artery (UA), ductus venosus (DV), and middle cerebral artery (MCA) were measured. Perinatal outcomes were followed up. Mod‐MPI of FGR cases were compared in normal Doppler, abnormal Doppler, and control groups. The association of Mod‐MPI and perinatal outcome was investigated, and further efficacy of Mod‐MPI predicting adverse outcome was studied.

Results

Compared with control groups, both abnormal and normal Doppler groups showed increased Mod‐MPI in early‐onset and late‐onset FGR, respectively. Mod‐MPI had no significant difference between abnormal and normal Doppler groups. Mod‐MPI was associated with adverse outcome in early‐onset FGR (OR = 3.307) and late‐onset FGR (OR = 3.412). The sensitivity and specificity of Mod‐MPI predicting adverse outcome were 60% and 80% when cutoff value was 0.47 in early‐onset FGR. And they were 65% and 70% when cutoff value was 0.50 in late‐onset FGR.

Conclusion

Fetal growth restriction fetuses had increased Mod‐MPI. Mod‐MPI could be used to predict adverse perinatal outcome of FGR fetuses. Mod‐MPI was an effective parameter to supplement vessels’ Doppler parameters in monitoring FGR.

Prospective longitudinal assessment of the fetal left modified Myocardial Performance Index

INTRODUCTION

The fetal left modified Myocardial Performance Index (Mod-myocardial performance index (MPI)) is a measure of systolic versus diastolic time intervals obtained from a single cardiac cycle with ultrasound. It is a measure of global ventricular function and has been investigated for potential utility in fetal conditions associated with cardiac dysfunction.

OBJECTIVES

The objective of this study is to compare values from a precisely replicated fetal left Mod-MPI technique to published reference ranges.

METHODS

Three hundred and sixty-five nulliparae prospectively underwent fetal left Mod-MPI measurement at 27⁺⁰-29⁺⁰ and 35⁺⁰-37⁺⁰ weeks' gestation. Measurements from pregnancies complicated by gestational diabetes mellitus, preeclampsia, or a small-for-gestational-age (<10th centile) infant were excluded. Mod-MPI values were compared with three published references created using similar measurement techniques.

RESULTS

Compared with one selected reference, at 29⁺⁰ and 35⁺⁰-37⁺⁰ weeks' gestation, 90-100% of our values fell within the 5th-95th percentile range as expected. Thus, this reference range was validated for our population in late pregnancy. However, the expected level of concordance was not seen at 27⁺⁰-28⁺⁶ weeks'. The other two references to which we compared our Mod-MPI values demonstrated poor concordance, especially at 27⁺⁰-29⁺⁰ weeks'. Pearson interobserver correlation was also improved at 35⁺⁰-37⁺⁰ weeks' at 0.434, compared with 0.083 at 27⁺⁰-29⁺⁰ weeks' gestation.

CONCLUSIONS

Concordance and interobserver variability between our cohort and similar populations were both improved at 35⁺⁰-37⁺⁰ weeks' compared with 27⁺⁰-29⁺⁰ weeks' gestation. Overall, variable Mod-MPI reproducibility across gestations limits clinical application, especially earlier in pregnancy. Manual Mod-MPI measurement should be considered most reliable in late pregnancy until automated MPI measurement is possible.