Fetal cardiac function measured by myocardial performance index of small-for-gestational age fetuses

Fetal echocardiographic parameters in pregnancies complicated by diabetes: a case control study

BACKGROUND

At present, the prevalence of pregestational diabetes is 2.2% with an overall prevalence of hyperglycaemia in pregnancy of about 16.2%. Fetuses of diabetic mothers are at risk of functional cardiac abnormalities without structural cardiac anomalies especially in the third trimester. The main aim of this study was to assess the association of diabetes with different fetal echocardiographic parameters.

METHODS

A case control study comprising a total of 120 pregnant women (60 cases and 60 controls). The cases group included fetuses of mothers known to have pre-gestational type 2 diabetes (DM group) while the control group included fetuses of euglycaemic healthy pregnant women. They were examined twice at 23-24 weeks' gestation (visit 1) and followed up at 27-28 weeks' gestation (visit 2). The Modified Myocardial Performance Index (Mod MPI) was obtained in all fetuses. Also, M-mode echocardiography was used to measure the interventricular septum thickness at diastole in a transverse four chamber view.

RESULTS

There was a significant increase in Iso-volumetric contraction time (ICT) (45.4 ms ± 8.9), Iso-volumetric relaxation time (IRT) (54.7 ms ± 11.22), Interventricular septal thickness (IVST) (4.08 mm ± 0.8), aortic acceleration time (AAT) (54.16 ms ± 12.77) and MPI (0.64 ± 0.09) in the diabetic group compared to the normal control group ICT (38.5 ms ± 9.59), IRT (46.13 ms ± 10.29), IVST (3.17 mm ± 0.6), AAT (49.73 ms ± 10.68) and MPI (0.5 ± 0.1) (all P values were < 0.001). When comparing parameters assessed at both visits among diabetic patients, there was a significant increase in IVST in the second visit (4.74 ± 0.78 mm) compared to the first visit (4.08 ± 0.8 mm) (P value < 0.05). The incidence of hypertrophic cardiomyopathy (HCM) was significantly higher in diabetic patients than in the control group. This is was observed in both first and second visit (33.4% and 56.7%) (P value < 0.001).

CONCLUSIONS

Fetuses of diabetic pregnant females show a significant increase in MPI, decrease in E\A ratio and HCM. These alterations in cardiac functions and structure were found to be continuous throughout the period of time between the two visits.

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.

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.

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.

Biochemical tests of placental function versus ultrasound assessment of fetal size for stillbirth and small-for-gestational-age infants

BACKGROUND

Stillbirth affects 2.6 million pregnancies worldwide each year. Whilst the majority of cases occur in low- and middle-income countries, stillbirth remains an important clinical issue for high-income countries (HICs) - with both the UK and the USA reporting rates above the mean for HICs. In HICs, the most frequently reported association with stillbirth is placental dysfunction. Placental dysfunction may be evident clinically as fetal growth restriction (FGR) and small-for-dates infants. It can be caused by placental abruption or hypertensive disorders of pregnancy and many other disorders and factorsPlacental abnormalities are noted in 11% to 65% of stillbirths. Identification of FGA is difficult in utero. Small-for-gestational age (SGA), as assessed after birth, is the most commonly used surrogate measure for this outcome. The degree of SGA is associated with the likelihood of FGR; 30% of infants with a birthweight < 10th centile are thought to be FGR, while 70% of infants with a birthweight < 3rd centile are thought to be FGR. Critically, SGA is the most significant antenatal risk factor for a stillborn infant. Correct identification of SGA infants is associated with a reduction in the perinatal mortality rate. However, currently used tests, such as measurement of symphysis-fundal height, have a low reported sensitivity and specificity for the identification of SGA infants.

OBJECTIVES

The primary objective was to assess and compare the diagnostic accuracy of ultrasound assessment of fetal growth by estimated fetal weight (EFW) and placental biomarkers alone and in any combination used after 24 weeks of pregnancy in the identification of placental dysfunction as evidenced by either stillbirth, or birth of a SGA infant. Secondary objectives were to investigate the effect of clinical and methodological factors on test performance.

SEARCH METHODS

We developed full search strategies with no language or date restrictions. The following sources were searched: MEDLINE, MEDLINE In Process and Embase via Ovid, Cochrane (Wiley) CENTRAL, Science Citation Index (Web of Science), CINAHL (EBSCO) with search strategies adapted for each database as required; ISRCTN Registry, UK Clinical Trials Gateway, WHO International Clinical Trials Portal and ClinicalTrials.gov for ongoing studies; specialist abstract and conference proceeding resources (British Library's ZETOC and Web of Science Conference Proceedings Citation Index). Search last conducted in Ocober 2016.

SELECTION CRITERIA

We included studies of pregnant women of any age with a gestation of at least 24 weeks if relevant outcomes of pregnancy (live birth/stillbirth; SGA infant) were assessed. Studies were included irrespective of whether pregnant women were deemed to be low or high risk for complications or were of mixed populations (low and high risk). Pregnancies complicated by fetal abnormalities and multi-fetal pregnancies were excluded as they have a higher risk of stillbirth from non-placental causes. With regard to biochemical tests, we included assays performed using any technique and at any threshold used to determine test positivity.

DATA COLLECTION AND ANALYSIS

We extracted the numbers of true positive, false positive, false negative, and true negative test results from each study. We assessed risk of bias and applicability using the QUADAS-2 tool. Meta-analyses were performed using the hierarchical summary ROC model to estimate and compare test accuracy.

MAIN RESULTS

We included 91 studies that evaluated seven tests - blood tests for human placental lactogen (hPL), oestriol, placental growth factor (PlGF) and uric acid, ultrasound EFW and placental grading and urinary oestriol - in a total of 175,426 pregnant women, in which 15,471 pregnancies ended in the birth of a small baby and 740 pregnancies which ended in stillbirth. The quality of included studies was variable with most domains at low risk of bias although 59% of studies were deemed to be of unclear risk of bias for the reference standard domain. Fifty-three per cent of studies were of high concern for applicability due to inclusion of only high- or low-risk women.Using all available data for SGA (86 studies; 159,490 pregnancies involving 15,471 SGA infants), there was evidence of a difference in accuracy (P < 0.0001) between the seven tests for detecting pregnancies that are SGA at birth. Ultrasound EFW was the most accurate test for detecting SGA at birth with a diagnostic odds ratio (DOR) of 21.3 (95% CI 13.1 to 34.6); hPL was the most accurate biochemical test with a DOR of 4.78 (95% CI 3.21 to 7.13). In a hypothetical cohort of 1000 pregnant women, at the median specificity of 0.88 and median prevalence of 19%, EFW, hPL, oestriol, urinary oestriol, uric acid, PlGF and placental grading will miss 50 (95% CI 32 to 68), 116 (97 to 133), 124 (108 to 137), 127 (95 to 152), 139 (118 to 154), 144 (118 to 161), and 144 (122 to 161) SGA infants, respectively. For the detection of pregnancies ending in stillbirth (21 studies; 100,687 pregnancies involving 740 stillbirths), in an indirect comparison of the four biochemical tests, PlGF was the most accurate test with a DOR of 49.2 (95% CI 12.7 to 191). In a hypothetical cohort of 1000 pregnant women, at the median specificity of 0.78 and median prevalence of 1.7%, PlGF, hPL, urinary oestriol and uric acid will miss 2 (95% CI 0 to 4), 4 (2 to 8), 6 (6 to 7) and 8 (3 to 13) stillbirths, respectively. No studies assessed the accuracy of ultrasound EFW for detection of pregnancy ending in stillbirth.

AUTHORS' CONCLUSIONS

Biochemical markers of placental dysfunction used alone have insufficient accuracy to identify pregnancies ending in SGA or stillbirth. Studies combining U and placental biomarkers are needed to determine whether this approach improves diagnostic accuracy over the use of ultrasound estimation of fetal size or biochemical markers of placental dysfunction used alone. Many of the studies included in this review were carried out between 1974 and 2016. Studies of placental substances were mostly carried out before 1991 and after 2013; earlier studies may not reflect developments in test technology.

Assessment of the Cardiac Function in Intrauterine Growth-Restricted Fetuses and Appropriate for Gestational Age Fetuses

Aim

Aim of the study is to evaluate the myocardial performance index in intrauterine growth restricted fetuses and compare this index with appropriate for gestational age fetuses.

Materials & Methods

A prospective study was conducted in S.M.S Medical College Jaipur, involving 72 singleton fetuses ≥ 28 weeks of gestation divided into two groups: 36 intrauterine growth restricted fetuses (IUGR) and 36 appropriate for gestational age fetuses (AGA). Myocardial performance index was obtained by fetal echocardiography.

Results

The mean myocardial performance index in the IUGR fetuses and AGA fetuses was statistically significant and that was 0.62 ± 0.02 and 0.45 ± 0.01, respectively; (p value: < 0.0001). These findings suggest that IUGR induces primary cardiac changes, which could explain the increased predisposition to cardiovascular disease in adult life. This study concluded that Fetal echocardiographic parameters (MPI) identify a high risk group within the IUGR fetuses, which could be targeted for early screening of blood pressure and other cardiovascular risk factors, as well as for promoting a healthy diet and physical exercise.

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.

Novel Technique for Measurement of Fetal Right Myocardial Performance Index Using Dual Gate Pulsed-Wave Doppler

OBJECTIVES

To evaluate the reproducibility of the fetal right myocardial performance index determined by simultaneous recording of inflow and outflow using a dual gate pulsed-wave Doppler (DD).

METHODS

This was a prospective study of 39 normal singleton fetuses. Two experienced operators each measured the right myocardial performance index in three ways, twice: (1) separate recording of the inflow and outflow using single-gate pulsed-wave Doppler (PD), (2) simultaneous recordings of the inflow and outflow using tissue Doppler (TD), and (3) simultaneous recordings of the inflow and outflow using DD. Intra- and interoperator reproducibility were assessed with intraclass correlation coefficients. The measurements from all three methods taken by the more experienced operator were compared using Bland-Altman plots and mean differences.

RESULTS

For both operators, intra-operator reproducibility was the highest when using DD, followed by PD, and TD. Interoperator agreement was the highest for PD measurements, followed by DD, and TD. The smallest mean difference was between the PD and DD measurements by the more experienced operator. There was a positive correlation between PD and DD values (r = 0.369, P < .001).

CONCLUSIONS

Dual gate pulsed-wave Doppler may be an effective alternative to the PD or TD methods, and can separately evaluate systolic and diastolic myocardial function.