Techniques for assessing cardiac output and fetal cardiac function

How Automated Techniques Ease Functional Assessment of the Fetal Heart: Applicability of MPI+™ for Direct Quantification of the Modified Myocardial Performance Index

(1) Objectives: In utero functional cardiac assessments using echocardiography have become increasingly important. The myocardial performance index (MPI, Tei index) is currently used to evaluate fetal cardiac anatomy, hemodynamics and function. An ultrasound examination is highly examiner-dependent, and training is of enormous significance in terms of proper application and subsequent interpretation. Future experts will progressively be guided by applications of artificial intelligence, on whose algorithms prenatal diagnostics will rely on increasingly. The objective of this study was to demonstrate the feasibility of whether less experienced operators might benefit from an automated tool of MPI quantification in the clinical routine. (2) Methods: In this study, a total of 85 unselected, normal, singleton, second- and third-trimester fetuses with normofrequent heart rates were examined by a targeted ultrasound. The modified right ventricular MPI (RV-Mod-MPI) was measured, both by a beginner and an expert. A calculation was performed semiautomatically using a Samsung Hera W10 ultrasound system (MPI+™, Samsung Healthcare, Gangwon-do, South Korea) by taking separate recordings of the right ventricle's in- and outflow using a conventional pulsed-wave Doppler. The measured RV-Mod-MPI values were assigned to gestational age. The data were compared between the beginner and the expert using a Bland-Altman plot to test the agreement between both operators, and the intraclass correlation was calculated. (3) Results: The mean maternal age was 32 years (19 to 42 years), and the mean maternal pre-pregnancy body mass index was 24.85 kg/m² (ranging from 17.11 to 44.08 kg/m²). The mean gestational age was 24.44 weeks (ranging from 19.29 to 36.43 weeks). The averaged RV-Mod-MPI value of the beginner was 0.513 ± 0.09, and that of the expert was 0.501 ± 0.08. Between the beginner and the expert, the measured RV-Mod-MPI values indicated a similar distribution. The statistical analysis showed a Bland-Altman bias of 0.01136 (95% limits of agreement from -0.1674 to 0.1902). The intraclass correlation coefficient was 0.624 (95% confidence interval from 0.423 to 0.755). (4) Conclusions: For experts as well as for beginners, the RV-Mod-MPI is an excellent diagnostic tool for the assessment of fetal cardiac function. It is a time-saving procedure, offers an intuitive user interface and is easy to learn. There is no additional effort required to measure the RV-Mod-MPI. In times of reduced resources, such assisted systems of fast value acquisition represent clear added value. The establishment of the automated measurement of the RV-Mod-MPI in clinical routine should be the next level in cardiac function assessment.

A Computer-Aided Markov Random Field Segmentation Algorithm for Assessing Fetal Ventricular Chambers

Congenital heart disease (CHD) is the most widely occurring congenital defect and accounts to about 28% of the overall congenital defects. Analysis of the development of the fetal heart thus plays an important role for detection of abnormality in early stages and to take corrective measures. Cardiac chamber analysis is one of the important diagnosing methods. Segmentation of the cardiac chambers must be done appropriately to avoid false interpretations. Effective segmentation of fetal ventricular chambers is a challenging task as the speckle noise inherent in ultrasound images cause blurring of the boundaries of anatomical structures. Several segmentation techniques have been proposed for extracting the fetal cardiac chambers. This article discusses the performance evaluation of automated, probability based segmentation approach, and Markov random field (MRF) for segmenting the fetal ventricular chambers of ultrasonic cineloop sequences. 837 ultrasonic biometery sequences of various gestations were collected from local diagnostic center after due ethical clearance and used for the study. In order to assess the efficiency of the segmentation technique, four metrics such as dice coefficient, true positive ratio (TPR), false positive ratio (FPR), similarity ratio (SIR), and precision (PR) were used. In order to perform ground truth validation, 56% of the data used in this study were annotated by clinical experts. The automated segmentation yielded comparable results with manual annotation. The technique results in average value of 0.68 for Dice coefficient, 0.723 for TPR, 0.604 for SIR, and 0.632 for PR.

Global longitudinal reference ranges for fetal myocardial deformation in the second half of pregnancy

PURPOSE

To construct longitudinal fetal reference ranges for global longitudinal myocardial deformation (strain and strain rate) of the left and right ventricles in the second half of pregnancy.

METHODS

A prospective, observational, longitudinal study of 120 women with uncomplicated singleton pregnancies. The participants underwent ultrasonographic scans every 4 weeks from enrolment (18-28 weeks) until delivery. Strain and strain rate were measured at each examination using velocity vector imaging. Changes in strain and strain rate as functions of gestational age (GA) were modeled using Bayesian mixed effects models.

RESULTS

A total of 406 assessments of global longitudinal strain and strain rate were performed for 120 women. Global longitudinal strain and strain rate decreased with increasing GA in the left ventricle. There was, however, no change in strain measurements of the right ventricle over the same gestational time frame. Posterior predictive distributions were used to derive reference centiles for each week of GA.

CONCLUSION

Assessment of myocardial deformation of the fetal heart is easily performed and may be useful for quantitative assessment of heart function, particularly in fetuses at risk of cardiac dysfunction.

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.

Reference ranges for the left ventricle modified myocardial performance index, respective time periods, and atrioventricular peak velocities between 20 and 36 + 6 weeks of gestation

Objective: To establish reference ranges for the fetal left ventricle (LV) modified myocardial performance index (Mod-MPI), respective time periods, and right and left atrioventricular peak velocities between 20 and 36 + 6 weeks of gestation.Methods: This cross-sectional study evaluated 360 low-risk singleton pregnancies between 20 and 36 + 6 weeks of gestation. The LV Mod-MPI was calculated as (isovolumetric contraction time + isovolumetric relaxation time)/ejection time. Polynomial regression was used to obtain the best-fit using Mod-MPI and atrioventricular peak velocity measurements and gestational age (GA) with adjustments using the coefficient of determination (R²). The intra- and interobserver reliability was evaluated using the concordance correlation coefficient (CCC).Results: LV Mod-MPI (R² = 0.026, p = .002) and isovolumetric relaxation time (IRT) (R² = 0.036, p < .001) significantly increased with advancing GA. Isovolumetric contraction time (ICT) and ejection time (ET) did not significantly change with GA. RV and LV E wave, A wave, and E/A ratio significantly increased with GA (p < .001). The mean of each parameter ranged as follows: LV Mod-MPI (0.44-0.47 s), IRT (0.041-0.045 s), ICT (0.032-0.034 s), ET (0.167-0.167 s), RV E (30.2-46.91 cm/s), RV A (47.1-60.7 cm/s), RV E/A (0.65-0.78 cm/s), LV E (27.0-41.4 cm/s), LV A (43.2-53.8 cm/s), and LV E/A (0.63-0.78 cm/s). Only LV A wave measurements demonstrated an intraobserver CCC >0.80. The remaining intra- and interobserver reproducibility parameters demonstrated lower CCC.Conclusions: Reference values were replicated for the fetal LV Mod-MPI and LV and RV transvalvular peak velocities between 20 and 36 + 6 weeks of gestation.

Z-Score Reference Ranges for Fetal Heart Functional Measurements in a Large Brazilian Pregnant Women Sample

The objective of this study was to determine the reference values for fetal heart functional measurements at 24 and 34 weeks of gestation and to develop Z-score equations for all measurements. A single-center, prospective, cross-sectional study with normal fetuses between 24 and 34 weeks of gestation was performed. All pregnant women underwent a comprehensive fetal Doppler echocardiogram with anatomical and functional analysis. Measurements of left and right cardiac output, combined cardiac output, mitral and tricuspid valve flow, inferior vena cava flow, and pulmonary vein flow were performed. The Shapiro-Wilk test and histogram evaluation were performed on all variables. Linear regression was used to assess the relationships between measurements and gestational age. A total of 612 pregnant women with singleton and normal fetuses were included. We assessed the reference values and percentiles of cardiac function as a function of gestational age. The variables that were not normally distributed were subjected to logarithmic or square root transformation. Eleven Z-score equations were developed, with equations for left and right ventricle output and combined cardiac output that were dependent on gestational age and with other equations that were independent of gestational age. The present study produced a large database, allowing the demonstration of reference values and percentiles as well as the development of Z-score equations to facilitate the echocardiographic evaluation of fetal heart function.

Atrial and ventricular ejection force of the fetal heart: Which of the four chambers is the dominant?

Background/Aim:

This study aimed to measure and compare the ejection force of the cardiac chambers in healthy singleton fetuses and to investigate the relationship of ejection force of cardiac chambers with gestational age, fetal sex, and fetal heart rate.

Patients and Methods:

A prospective study was performed on 68 singleton fetuses with a gestational age of 17–34 weeks. Atrial and ventricular ejection force was measured. Measurements were repeated in 18 of the fetuses to assess intraobserver reliability.

Results:

The right atrium had the highest ejection force of all the cardiac chambers. Ejection force of both atria and ventricles increased with gestational age.

Conclusion:

The right atrium is the dominant chamber of the fetal heart in 17–34 weeks of gestation. Comparison of our values with previous studies indicates that left atrial ejection force almost doubles in the 1^st month after birth. This study highlights the crucial role of the right atrium in the fetal cardiac function during 17–34 weeks of gestation.

Assessing the consequences of gestational diabetes mellitus on offspring's cardiovascular health: MySweetHeart Cohort study protocol, Switzerland

INTRODUCTION

Gestational diabetes mellitus (GDM) is a state of glucose intolerance with onset during pregnancy. GDM carries prenatal and perinatal risks as well as long-term risks for the mother and her child. GDM may be involved in the foetal programming of long-term cardiovascular health. However, evidence is sparse and the effect of GDM on cardiovascular health is unknown. To address these issues, we will conduct MySweetHeart Cohort study. The objectives are to assess the effect of GDM on offspring's cardiovascular health early in life by using surrogate markers of cardiovascular disease and atherosclerosis.

METHODS AND ANALYSIS

This is a cohort study of 100 offspring of women with GDM and 100 offspring of women without GDM. At inclusion, a baseline assessment of the mothers will be conducted through means of self-report questionnaires, a researcher-administrated interview, blood pressure and anthropometric measurements, and a maternal blood sampling. Between the 30th and 34th weeks of gestation, a foetal echography will be performed to assess the foetal cardiac structure and function, the fetomaternal circulation and the hepatic volume. At birth, maternal and neonatal characteristics will be assessed. An echocardiography will be performed to assess cardiac structure and function 2-7 days after birth; carotid intima-media thickness will be also measured to assess vascular structure. MySweetHeart Cohort is linked to MySweetHeart Trial (clinicaltrials.gov/ct2/show/NCT02890693), a randomised controlled trial assessing the effect of a multidimensional interdisciplinary lifestyle and psychosocial intervention to improve the cardiometabolic and mental health of women with GDM and their offspring. A long-term follow-up of children is planned.

ETHICS AND DISSEMINATION

Ethical approval has been obtained through the state Human Research Ethics Committee of the Canton de Vaud (study number 2016-00745). We aim to disseminate the findings through regional, national and international conferences and through peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov (clinicaltrials.gov/ct2/show/NCT02872974).

Prediction of pregnancy complication occurrence using fetal cardiac output assessments made by ultrasonography at 20 to 24 weeks of gestation

Objective

To evaluate the importance of assessment of fetal cardiac output (CO) for the prediction of complications of pregnancy.

Methods

We evaluated 65 fetuses and all of them had a fetal cardiac scan at 20 to 24 weeks of pregnancy. To measure CO, diameters (d) of the left right ventricle outflow tract were measured just above the valves. Each left CO (LCO) and right CO (RCO) was derived using the following equation: CO = velocity time integral × π × d²/4 × heart rate. Pregnancy complications included gestational hypertensive disorders, fetal growth restriction (FGR) and preterm birth (PTB) caused from preterm labor or preterm premature rupture of membrane (PPROM).

Results

There were 23 cases with one more pregnancy complication (FGR, 9; gestational hypertensive disorders, 8; PTB caused from PTB or PPROM, 12). The LCO was lower in complication group than in normal group (88±53 vs. 117±48 mL/min, P=0.028). The RCO to the LCO ratio (RCO/LCO) was higher in complication group (2.43±1.69 vs. 1.48±0.81, P=0.001). Regression analysis demonstrated that RCO/LCO was a significant predictor of pregnancy complication; Odds ratio was 7.76 (95% CI, 1.15 to 52.21; P=0.029). The area under the receiver-operating characteristic curve for prediction of pregnancy complications from LCO was 0.71. The diagnostic cut-off value of LCO was 80 mL/min. The area under the receiver-operating characteristic curve from RCO/LCO was 0.68 and cut-off value was 1.41.

Conclusion

This study demonstrated that pregnancy complications can be suspected based on fetal CO assessments at a GA of 20 to 24 weeks.

Effect of cordocentesis on fetal myocardial performance

OBJECTIVE

To compare fetal Tei index before, immediately after and 30 min after cordocentesis for prenatal diagnosis.

PATIENTS AND METHODS

Pregnant women undergoing prenatal diagnostic cordocentesis in the early mid-trimester underwent measurement of the fetal Tei index of both right and left ventricles just before cordocentesis, immediately after and at 30 min after the procedure.

RESULTS

A total of 143 singleton women underwent cordocentesis at a median gestational age of 19 weeks (range 16-23). The most common indication was fetal risk of beta-thalassemia/hemoglobin E disease (42%, 60 cases). Immediately after cordocentesis, fetal Tei index and all its components at both ventricles were significantly altered when compared with the baseline values (p < 0.001). At 30 min after cordocentesis, components of the Tei index had significantly improved but 5/6 had not completely recovered. No serious procedure-related short-term complications were observed in the study.

CONCLUSION

Cordocentesis has a negative impact on fetal hemodynamics as indicated by worsening of the Tei index. Although the adverse effect seems to be temporary, the recovery time may be longer than 30 min. © 2016 John Wiley & Sons, Ltd.

Tissue Doppler imaging in fetuses with aortic stenosis and evolving hypoplastic left heart syndrome before and after fetal aortic valvuloplasty

OBJECTIVES

Fetal aortic valvuloplasty can improve filling and reduce afterload of the left ventricle in critical aortic stenosis. Success of an intrauterine intervention is currently measured by technical success, clinical survival and eventual postnatal biventricular physiology. In the present study we investigated the use of tissue Doppler imaging (TDI) to evaluate changes in ventricular function assessed before and after prenatal aortic valvuloplasty.

METHODS

Between October 2008 and December 2012, cardiac function was assessed by TDI before and after intervention in 23 fetuses that underwent technically successful valvuloplasty for critical aortic stenosis and in which postnatal outcome was known. The measurements were transformed into gestational age-independent Z-scores where appropriate.

RESULTS

Mean ± SD gestational age at intervention was 27.5 ± 3.1 weeks. Of the 23 fetuses, 14 had biventricular outcome. Before intervention all left ventricular (LV) TDI-derived parameters and mitral annular plane systolic excursion (MAPSE) were severely abnormal. It was possible to demonstrate considerably improved cardiac function after technically successful valvuloplasty. Among fetuses with postnatal biventricular outcome, TDI-derived LV myocardial peak velocity during early diastole (E') and myocardial peak velocity during systole in the ejection phase (S') significantly increased, E'/myocardial peak velocity during late diastole with atrial contraction (A') increased towards normal values, and LV transmitral-to-mitral-annular diastolic velocity ratio (E/E') and myocardial performance index (MPI') decreased but remained abnormally elevated. In addition, right ventricular A', S' and MPI' significantly improved after intervention.

CONCLUSION

Technically successful fetal aortic valvuloplasty led to significantly improved myocardial performance. It was possible to use TDI to detect distinct changes in ventricular function and TDI-derived parameters correlated with a biventricular outcome after birth. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

The impact of total bile acid levels on fetal cardiac function in intrahepatic cholestasis of pregnancy using fetal echocardiography: a tissue Doppler imaging study

AIM

The aim of this study was to assess total bile acid (TBA) levels and its impact on systolic and diastolic functions in fetuses of mothers with intrahepatic cholestasis of pregnancy (ICP) using tissue Doppler imaging (TDI), and to explore the correlation between TBA levels and fetal cardiac function.

SUBJECTS AND METHODS

The study employed 98 pregnant women with ICP who were divided into two groups according to their bile acid levels. Fifty pregnant women without ICP represented the control group.

RESULTS

Significant differences in the myocardial tissue velocities of both mitral and tricuspid valves were found between the fetuses of mothers with ICP and TBA levels of <40 mmol/L and the control group, versus fetuses of mothers with ICP and TBA levels >40 mmol/L. There was a significant increase in neonatal respiratory distress, meconium staining and neonatal TBAs in group II compared to the control group and group I. There was a correlation between maternal TBA levels and preterm delivery, APGAR scores and neonatal TBA levels at birth. There was also a positive correlation between maternal TBA and fetal myocardial tissue velocities of both mitral and tricuspid, and fetal diastolic myocardial tissue Doppler velocities.

CONCLUSION

ICP is a very serious condition especially when maternal TBA levels are >40 mmol/L. Fetal echocardiography with tissue Doppler is a useful tool for fetal assessment in patients with ICP. It could be an indication of induction of labor in cases of ICP and bile acid levels ≥40 mol/L. Neonatal echocardiography is mandatory for follow-up and management of these neonates.

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.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Automated region mask for four-chamber fetal heart biometry

This letter proposes an automated region mask for the detection of cardiac chambers from ultrasonic fetal heart biometry. The fetal biometry consists of two dimensional ultrasonic cine-loop sequences of apical four chamber view of fetal heart, which are comparatively The clinical motion information of individual frame is extracted by keeping a constant frame rate of 25 frames per second (fps). The region mask is designed based on the superimposition of motion information from a set of consecutive frames that belong to one cardiac cycle followed by connected component labelling. The borders and edges of all four chambers are thus recognized leading to formation of binary region mask. Experimental study based on second trimester cine-loop sequences confirms the suitability of the proposed technique for detection of heart chambers.