Longitudinal Changes and Interobserver Variability of Systolic Myocardial Deformation Values in a Prospective Cohort of Healthy Fetuses across Gestation and after Delivery

Perinatal Cardiac Functional Adaptation in Hypoplastic Left Heart Syndrome: A Longitudinal Analysis

BACKGROUND

The perinatal transition is characterized by acute changes in cardiac loading. Compared with normal newborn combined cardiac output (CCO), single right ventricular (RV) output of neonates with hypoplastic left heart syndrome (HLHS) is markedly greater. The aim of this study was to examine the mechanisms of cardiac adaptation that facilitate this perinatal transition from late fetal to early neonatal life in HLHS.

METHODS

Prospectively recruited pregnancies complicated by fetal HLHS (n = 35) and healthy control subjects (Ctrl; n = 17) underwent serial echocardiography in late gestation (38 ± 1 weeks) and 6, 24, and 48 hours after birth. Cardiac function was assessed using conventional, Doppler tissue, and speckle-tracking echocardiography.

RESULTS

Term fetuses with HLHS had RV output comparable with Ctrl CCO via higher stroke volume. Compared with both left ventricular and RV indices of Ctrl, they exhibited globular and dilated right ventricles with reduced relative wall thickness (0.40 ± 0.08 vs 0.49 ± 0.10, P < .01), increased Tei index' (HLHS vs Ctrl left ventricle/Ctrl right ventricle: sphericity index, 0.9 ± 0.25 vs 0.5 ± 0.10/0.6 ± 0.11; RV area index, 28 ± 6 vs 15 ± 3/17 ± 5 cm2/m2; Tei index', 0.65 ± 0.11 vs 0.43 ± 0.07/0.45 ± 0.09; P < .0001 for all). Neonates with HLHS generated elevated RV cardiac output compared with Ctrl CCO via higher heart rate and stroke volume, with further RV dilatation, increased longitudinal systolic strain at 48 hours (-17 ± 4% vs -14 ± 3%/ 14 ± 5%) with reduced circumferential and rotational myocardial deformation and altered diastolic function. Neonates with HLHS also demonstrated right atrial enlargement with increased longitudinal strain: 6 hours (33 ± 12% vs 26 ± 6%), 24 hours (37 ± 15% vs 26 ± 13%), and 48 hours (38 ± 11% vs 24 ± 13%) (P < .0001).

CONCLUSIONS

Term fetuses with HLHS exhibit altered RV geometry and RV systolic and diastolic functional parameters. After birth, further alterations in these cardiac parameters likely reflect adaptation to acutely altered RV loading from increasing cardiac output and pulmonary artery flow demands.

Reference Ranges and Development Patterns of Fetal Myocardial Function Using Speckle Tracking Echocardiography in Healthy Fetuses at 17 to 24 Weeks of Gestation

OBJECTIVE

The purposes of the study were to develop reference ranges and maturation patterns of fetal cardiac function parameters measured by speckle tracking echocardiography (STE) using multiple biometric variables at 17 to 24 weeks' gestation among Thai fetuses and to compare with other previous reports.

STUDY DESIGN

The four-chamber view of the fetal heart in 79 healthy fetuses was suitably analyzed by STE to establish the best-fit regression model. The 95% reference intervals and Z-score equations of fetal cardiac function parameters were computed.

RESULTS

The fractional area change of both ventricles, left ventricular (LV) end-diastolic and end-systolic volumes, LV stroke volume, LV cardiac output (CO), and LV CO per kilogram were all increased according to gestational age (GA) and five fetal biometric measurements. However, the global longitudinal strain, basal-apical length fractional shortening (BAL-FS), BAL annular free wall and septal wall FS, BAL free wall and septal wall annular plane systolic excursions, 24-segment transverse width FS, as well as LV ejection fraction were all independent of GA or other somatic characteristics. There were varying development patterns between fetal right and left ventricles of these cardiac function indices across the gestation period.

CONCLUSION

Our study created Z-score and corresponding centile calculators, 5th and 95th centile reference tables, and corresponding graphs and determined the normal evolution across gestation using multiple somatic growth and age variables between 17 and 24 gestational weeks. These nomograms serve as an essential prerequisite for quantitatively evaluating fetal cardiac contractility and allow for precisely detecting early changes in the fetal heart function.

KEY POINTS

· Most fetal cardiac function measurements were correlated with all the independent variables.. · Fetal ventricular function parameters have their own characteristic maturation changes.. · Racial variability may not occupy an important place for fetal myocardial function during these GA..

Fetal left and right ventricular strain parameters using speckle tracking in congenital heart diseases

Assessment of fetal ventricular function is mostly subjective, and currently, for the objective assessment left ventricular shortening fraction is obtained. However, this by itself is not very reliable. Hence, more tools that can provide an objective assessment are needed to increase the confidence of functional assessment. Speckle tracking imaging can provide one such tool. In this study we sought to establish the normative value of global longitudinal and circumferential strain for our fetal patients and for two major forms of congenital heart diseases, namely atrioventricular canal defects (AVC) and uncorrected dextro-transposition of the great arteries (dTGA) to act as a benchmark. The study was completed via a single center retrospective analysis on 72 fetal echocardiograms (26 normal, 15 dTGA, and 31 AVC). Tomtec Arena™ echocardiography analysis software was used for analysis. In normal fetuses, mean left ventricular (LV) global longitudinal strain (GLS) was - 22.6% (95% CI -24, -21.1) and mean right ventricular (RV) GLS was - 22.1% (95% CI -23.6, -20.6). In AVC patients LV GLS was-26.6% (95% CI -28,-25.3) and mean RV GLS was - 26.5% (95% CI -27.9,-25.2). In dTGA patients LV GLS was - 22.9% (95% CI of -24.8, -21) and RV GLS was - 21.3% (95% CI was - 23.4, -20.8). There was good intra-rater reliability though poor to fair inter-rater reliability. Notwithstanding its current limitations, strain imaging can provide useful information that can increase confidence of cardiac functional assessment in fetal patients. However, to be reliable across the board, further automation and standardization is required.

Left Ventricular Strain, Arch Angulation, and Velocity-Time Integral Ratio Improve Performance of a Clinical Pathway for Fetal Diagnosis of Neonatal Coarctation of the Aorta

INTRODUCTION

Neonatal presentation of coarctation of the aorta (CoA) is a potentially life-threatening condition that is difficult to diagnose in fetal life. We therefore sought to validate and compare novel metrics that may add diagnostic value for fetal CoA, including the diastolic to systolic aortic isthmus VTI ratio (VTId:VTIs), ascending aorta to descending aorta angle (AAo-DAo), transverse aorta to descending aorta angle (TAo-DAo), and LV longitudinal strain (LVS), then to evaluate whether these novel metrics improve specificity to identify fetuses at the highest risk for postnatal CoA without compromising sensitivity.

METHODS

Retrospective cohort study of fetuses followed a prospective clinical pathway and previously classified as mild, moderate, or high-risk for CoA based on standard fetal echo metrics. Novel metrics were retrospectively measured in a blinded manner.

RESULTS

Among fetuses with prenatal concern for CoA, VTId:VTIs, AAo-DAo angle, TAo-DAo angle, and LVS were significantly different between surgical and non-surgical cases (p < 0.01 for all variables). In the subgroup of moderate- and high-risk fetuses, the standard high-risk criteria (flow reversal at the foramen ovale or aortic arch) did not discriminate effectively between surgical and non-surgical cases. VTId:VTIs, AAo-Dao angle, Tao-DAo angle, and LVS all demonstrated greater discrimination than standard high-risk criteria, with specificity of 100% and PPV (positive predictive value) of 78-100%.

CONCLUSIONS

The incorporation of novel metrics added diagnostic value to our clinical pathway for fetal CoA with higher specificity than the previous high-risk criteria. The incorporation of these metrics into the evaluation of fetuses at moderate- or high-risk for surgical CoA may improve prenatal counseling, allow for more consistent surgical planning, and ultimately optimize hospital resource allocation.

The impact of angles of insonation on left and right ventricular global longitudinal strain estimation in fetal speckle tracking echocardiography

OBJECTIVES

Two-dimensional speckle tracking echocardiography has been considered an angle-independent modality. However, current literature is limited and inconclusive on the actual impact of angle of insonation on strain values. Therefore, the primary objective of this study was to assess the impact of angles of insonation on the estimation of fetal left ventricular and right ventricular global longitudinal strain. Secondarily, the impact of different definitions for angles of insonation was investigated in a sensitivity analysis.

METHODS

This is a retrospective analysis of a prospective longitudinal cohort study with 124 healthy subjects. The analyses were based on the four-chamber view ultrasound clips taken between 18+0 and 21+6 weeks of gestation. Angles of insonation were categorized into three groups: up/down, oblique and perpendicular. The mean fetal left and right ventricular and global longitudinal strain values corresponding to these three groups were compared by an ANOVA test corrected for heteroscedasticity.

RESULTS

Fetal left and right ventricular global longitudinal strain values were not statistically different between the three angles of insonation (p-value >0.062 and >0.149, respectively). When applying another definition for angles of insonation in the sensitivity analysis, the mean left ventricular global longitudinal strain value was significantly decreased for the oblique compared to the up/down angle of insonation (p-value 0.041).

CONCLUSIONS

There is no evidence of a difference in fetal left and right ventricular global longitudinal strain between the different angles of insonation in fetal two-dimensional speckle tracking echocardiography.

Advanced imaging of fetal cardiac function

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

Longitudinal Behavior of Left-Ventricular Strain in Fetal Growth Restriction

Fetal growth restriction (FGR) is associated with an increased risk of adverse outcomes resulting from adaptive cardiovascular changes in conditions of placental insufficiency, leading to cardiac deformation and dysfunction, which can be evaluated with 2D speckle tracking echocardiography (2D-STE). The aim of the present study was to evaluate whether reduced fetal growth is associated with cardiac left-ventricle (LV) dysfunction, using 2D-STE software widely used in postnatal echocardiography. A prospective longitudinal cohort study was performed, and global (GLO) and segmental LV longitudinal strain was measured offline and compared between FGR and appropriate-for-gestational-age (AGA) fetuses throughout gestation. All cases of FGR fetuses were paired 1:2 to AGA fetuses, and linear mixed model analysis was performed to compare behavior differences between groups throughout pregnancy. Our study shows LV fetal longitudinal strain in FGR and AGA fetuses differed upon diagnosis and behaved differently throughout gestation. FGR fetuses had lower LV strain values, both global and segmental, in comparison to AGA, suggesting subclinical cardiac dysfunction. Our study provides more data regarding fetal cardiac function in cases of placental dysfunction, as well as highlights the potential use of 2D-STE in the follow-up of cardiac function in these fetuses.

Feasibility of 4D-Spatio Temporal Image Correlation (STIC) in the Comprehensive Assessment of the Fetal Heart Using FetalHQ®

Fetal Heart Quantification (FetalHQ®) is a novel speckle tracking software that permits the study of global and regional ventricular shape and function from a 2D four-chamber-view loop. The 4D-Spatio Temporal Image Correlation (STIC) modality enables the offline analysis of optimized and perfectly aligned cardiac planes. We aimed to evaluate the feasibility and reproducibility of 4D-STIC speckle tracking echocardiography (STE) using FetalHQ® and to compare it to 2D STE. We conducted a prospective study including 31 low-risk singleton pregnancies between 20 and 40 weeks of gestation. Four-chamber view volumes and 2D clips were acquired with an apex pointing at 45° and with a frame rate higher than 60 Hz. Morphometric and functional echocardiography was performed by FetalHQ®. Intra- and interobserver reproducibility were evaluated by the intraclass correlation coefficient (ICC). Our results showed excellent reproducibility (ICC > 0.900) for morphometric evaluation (biventricular area, longitudinal and transverse diameters). Reproducibility was also good (ICC > 0.800) for functional evaluation (biventricular strain, Fractional Area Change, left ventricle volumes, ejection fraction and cardiac output). On the contrary, the study of the sphericity index and shortening fraction of the different ventricular segments showed lower reproducibility (ICC < 0.800). To conclude, 4D-STIC is feasible, reproducible and comparable to 2D echocardiography for the assessment of cardiac morphometry and function.

Importance of frame rate for the measurement of strain and synchrony in fetuses using speckle tracking echocardiography

OBJECTIVES

To assess the influence of frame rate settings on longitudinal strain (LS) and mechanical synchrony (SYN) values in Speckle Tracking Echocardiography (STE) of healthy fetuses.

METHODS

In this prospective study, we collected transversal or apical four-chamber-views of 121 healthy fetuses between 20 and 38 weeks of gestation using three different frame rate (FR) settings (≥ 110, 100 ± 10, 60 ± 10 frames per second). We assessed the segmental and the global LS of both ventricles (2C) and of the left ventricle (LV) offline with QLab 10.8 (Philips Medical Systems, Andover, MA, USA). Inter- and intraventricular SYN were calculated as time difference in peak myocardial strain between the mid-segments of left and right ventricle (interventricular, 2C_Syn) and lateral wall and septum of the left ventricle (intraventricular, LV_Syn), respectively.

RESULTS

In 84.3% STE was feasible at all three FR settings. The LS increased in both views at higher FRs to a statistically noticeable extent. SYN measurements and the absolute differences at patient level between the FR settings showed no statistically noticeable alterations.

CONCLUSIONS

STE is feasible at low and high FR settings. SYN emerges to be a robust parameter for fetal STE as it is less affected by the FR. High FRs enable high temporal resolutions and thus an accurate examination of fetal hearts. Future research for the technical implementation of tailored fetal STE software is necessary for reliable clinical application.

Inter-observer and Inter-vendor Variability in Strain Measurements in Patients with Single Right Ventricular Anatomy

Myocardial strain offers new insights into ventricular performance, There are software packages from several different companies used to ascertain this, and little data is available in patients with single right ventricle (sRV) physiology. We aimed to compare the analysis of two strain software applications using a cohort of patients with sRV for both inter-vendor and inter-observer variability. Echocardiograms from 85 patients with sRV (122 separate studies) were prospectively evaluated. All had Glenn and/or Fontan palliation. Longitudinal 4-chamber (4LS), inflow/outflow (IO), circumferential, and radial strain were assessed using Velocity Vector Imaging (VVI, Seimens, Munich) and Automated Functional Imaging (AFI, General Electric, Boston) software. In a subset of 45 patients (61 separate studies), strain measurements were obtained by two sonographers so a paired "inter-observer" analysis could be performed. A moderate correlation between measurements made by the two systems was observed. Circumferential strain assessment had the highest R value (0.77) with all others having R values < 0.6. Both software packages showed modest inter-observer reproducibility for longitudinal and circumferential strain. VVI intraclass correlation coefficients (ICC) for 4LS and average circumferential strain (ACS) were 0.6 and 0.58, compared to 0.68 and 0.59 for AFI. Other than radial strain and VVI IO inferior strain, mean strain differences between AFI and VVI were ≤ 1%. Inter-observer variability is modest, however, mean differences are minimal suggesting reasonable clinical reliability. Inter-vendor variability is greater and not as clinically reliable. In patients with sRV, serial assessments with strain should be performed using the same software.

Fetal speckle-tracking echocardiography: a comparison between two-dimensional and electronic spatio-temporal image correlation (e-STIC) technique

BACKGROUND

Speckle tracking technology has been applied to assess ventricular deformation throughout the cardiac cycle. An electronic four dimensional probe that allows rapid acquisition of electronic spatio-temporal image correlation volumes (eSTIC) has been recently introduced.

OBJECTIVES

The aim of our study was to investigate whether e-STIC acquisition improves deformation analyses reproducibility.

STUDY DESIGN

We recruited fetuses between 20 and 40 weeks of gestation. We obtained a 2D video clip and an e-STIC volume of a four-chamber view. We focused on left ventricular global strain (LV-GS) and left ventricular ejection fraction (LV-FE). Intraobserver, interobserver and intermethod agreement were assessed by means of intraclass correlation coefficient (ICC) and illustrated by Bland-Altman plots. Systematic differences between measurements were assessed using a paired t-test.

RESULTS

The mean difference between LV-GS values obtained with e-STIC and 2D analysis was -0.10 (95% CI -2.28, 2.08). No systematic differences were found between the two techniques for LV-GS values (p-value = .927). The mean difference between LV-FE values obtained with e-STIC and 2D analysis was 7.55 (95% CI 4.16, 10.95; p-value <.001). The inter-rater reliability of LV-GS was moderate-to-substantial for both e-STIC and 2D. The inter-rater reliability of LV-FE obtained via e-STIC was superior to that obtained via 2D analysis. The intra-rater reliability of LV-GS obtained with e-STIC was superior to that obtained with 2D analysis (ICC 0.857; 95% IC 0.761-0.917). The intra-rater reliability of LV-FE obtained via e-STIC was superior to that obtained via 2D analysis (ICC 0.647; IC 0.51-0.783).

CONCLUSIONS

e-STIC seems to be a better technique than 2D analysis for intra-rater reliability of LV-GS. 4D acquisition might improve intrinsic limitations of speckle tracking echocardiography.

Initial fetal to initial postnatal echocardiogram in uncomplicated atrioventricular septal defects: Do significant changes occur?

BACKGROUND

Yield of serial echocardiography in fetuses with atrioventricular septal defects (fAVSD) has not been well defined. The goal of this study was to document if any major changes occurred from initial fetal to initial postnatal echocardiogram in uncomplicated fAVSD.

METHODS

fAVSD were excluded if initial fetal scan documented complex CHD or any concerns. Changes in ventricular function, valvular regurgitation, or diagnosis between first fetal and first postnatal echocardiogram were recorded.

RESULTS

Fifty-seven fAVSD met criteria. Ninety-six fetal echocardiograms were done in 57 patients. Initial fetal scan was performed at 24.3 ± 3.7 weeks of estimated gestational age. All fAVSD had normal function, 38 had no atrioventricular valve regurgitation (AVVR), and 19 had mild AVVR. First postnatal echocardiogram was performed at 6.3 ± 15.3 days. Fifty-six patients had normal function, 1 patient had mild dysfunction, 16 patients had no AVVR, 36 had mild AVVR, and 5 had moderate AVVR. Three patients (5%) had an improvement in AVVR by one degree, 27 patients (47%) had no change in AVVR, 24 patients (42%) had an increase in AVVR by one degree, and 3 patients (5%) had an increase in AVVR by two degrees. There was no major missed anatomical diagnosis from first prenatal to first postnatal echocardiogram.

CONCLUSION

In fAVSD that had no concerns on their initial fetal echocardiogram, the majority of patients had no major changes noted between their initial fetal echocardiogram and their first postnatal echocardiogram. Repeat fetal echocardiograms may not necessarily be needed in this cohort of patients.

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.

Fetal Speckle-Tracking: Impact of Angle of Insonation and Frame Rate on Global Longitudinal Strain

BACKGROUND

There is a growing body of research on fetal speckle-tracking echocardiography because it is considered to be an angle-independent modality. The primary aim of this study was to investigate whether angle of insonation and acquisition frame rate (FR) influence left ventricular endocardial global longitudinal peak strain (GLS) in the fetus.

METHODS

Four-chamber views of 122 healthy fetuses were studied at three different angles of insonation (apex up/down, apex oblique, and apex perpendicular) at high and low acoustic FRs. GLS was calculated, and a linear mixed-model analysis was used for analysis. Six hundred fifty-six fetal echocardiographic clips were analyzed (288 in the second trimester, at a median gestation of 21 weeks [interquartile range (IQR), 1 week], and 368 in the third trimester, at a median gestation of 36 weeks [IQR, 2 weeks]).

RESULTS

Angle of insonation and FRs were significant determinants of GLS. Ventricular septum perpendicular to the ultrasound beam was associated with higher (more negative) GLS compared with apex up/down (at high FR: -21.8% vs -19.7%, P < .001; at low FR: -24.1% vs -21.4%, P < .001). Higher frames per second (FPS; median 149 FPS [IQR, 33 FPS] = 61 frames per cycle [FPC] [IQR, 17 FPC]) compared with lower FPS (median 51 FPS [IQR, 15 FPS] = 22 FPC [IQR, 7 FPC]) at the same insonation angle resulted in lower GLS (apex up/down: -19.7% vs -21.4%, P < .001; apex oblique: -21.2% vs -22.7%, P < .001; apex perpendicular: -21.8% vs -24.1%, P < .001).

CONCLUSIONS

The present findings show that insonation angle and FR influence GLS significantly. These factors need to be considered when comparing studies with different acquisition protocols, when establishing normative values, and when interpreting pathology. Speckle-tracking echocardiography cannot be considered an angle-independent modality during fetal life.

Behavior of fetal longitudinal myocardial fibers assessed by speckle tracking to obtain strain and strain rate values for low-risk pregnancies

Objective To analyze the behavior of fetal longitudinal myocardial fibers assessed by speckle tracking (STE) after fetal viability. Methods A cross-sectional study was performed in 156 women with normal singleton pregnancies from 22 to 31 weeks of gestation. Strain (S) and strain rate (SR) values were measured in both ventricles during the fetal cardiac cycle. The population was divided into five gestational age groups based on 2-week intervals. The correlations of maternal variables with the S and SR variables and intra-observer analysis were performed. Results There was a significant difference in the S and SR values of the left ventricle (LV) among the gestational age groups (P = 0.007). Significantly higher S and SR values were observed in early age groups demonstrating reductions in LV S and SR values at 26 weeks, followed by stabilization. For the right ventricle (RV), there was no significant difference between gestational age groups. Significant intra-observer agreement was observed for S values of the RV (P = 0.008) and LV (P = 0.0004) and SR values of the RV (P = 0.0001) and LV (P = 0.015). Conclusion Decreases in the S and SR values of the LV occurred after 26 weeks, followed by stabilization. No significant difference was observed in the S or SR value of the RV among the gestational age groups, and no significant association of any maternal variable evaluated with S and SR values was observed. Significant intra-observer agreement was obtained among the results.

Advances in fetal echocardiography: myocardial deformation analysis, cardiac MRI and three-dimensional printing

PURPOSE OF REVIEW

Advances in ultrasound technology have led to new ways of evaluating cardiac function and structure, including myocardial deformation imaging (strain and strain rate), cardiac MRI and three-dimensional (3D) printing. As ultrasound technology has improved, it has become possible to use these modalities to evaluate the fetal heart. This article will review some of the more recent developments in applying these techniques to the evaluation of fetal cardiac structure and function.

RECENT FINDINGS

Myocardial deformation analyses have led to the establishment of normative values for strain and strain rate in the fetal heart and have also been used to evaluate fetal heart function in both fetal disease states and maternal disease states. Technological advances in MRI technology, 3D imaging and 3D printing have opened up new methods of evaluating fetal structural heart disease.

SUMMARY

A deeper understanding of the subtleties of myocardial dysfunction in various fetal and maternal disease states may elucidate the pathophysiology involved and lead to new treatment and/or counseling paradigms that may ultimately affect outcome. Similarly, the ability to image the fetal heart in new ways, including fetal MRI and 3D printing, could potentially change fetal counseling techniques and prenatal planning.

Left ventricular torsional mechanics in term fetuses and neonates

OBJECTIVE

Left ventricular (LV) torsion is an important aspect of cardiac mechanics and is fundamental to normal ventricular function. The myocardial mechanics of the fetal heart and the changes that occur during the transition to the neonatal period have not been explored previously. The aim of this study was to evaluate perinatal changes in LV torsion and its relationship with myocardial function.

METHODS

This was a prospective study of 36 women with an uncomplicated term pregnancy. Fetal and neonatal conventional, spectral tissue Doppler and two-dimensional (2D) speckle tracking echocardiography were performed a few days before and within hours after delivery to measure cardiac indices including LV rotational parameters derived from short-axis views at the base and apex of the heart. Linear regression analysis was used to examine the relationship between LV rotational parameters and cardiac geometric and functional indices in term fetuses and neonates. Perinatal changes in LV rotational parameters were assessed.

RESULTS

There were three patterns of LV twist in term fetuses: those with reversed-apex-type LV twist had the lowest median values of LV torsion (0.1°/cm), with higher values (1.6°/cm) in those with infant-type LV twist and the highest values (4.4°/cm) in those with adult-type LV twist. LV torsion was associated significantly with cardiac geometric and functional indices. Perinatal evaluation revealed a significant increase in LV torsion following delivery in fetuses exhibiting reversed-apex-type LV twist (increase of 2.8°/cm, P = 0.009) and a significant decrease in those with adult-type LV twist (decrease of 3.2°/cm, P = 0.008).

CONCLUSIONS

This study demonstrates the feasibility of 2D speckle tracking imaging for accurate assessment of rotational cardiac parameters in term fetuses. There are unique perinatal patterns of LV twist that demonstrate different values of LV torsion, which was found to correlate with indices of ventricular geometry and myocardial function. Differences in patterns of LV twist may therefore reflect differences in compensatory myocardial adaptation to the physiological environment/loading conditions in late gestation in fetuses and postnatal cardiac adjustment to the acute loading changes that occur at delivery. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Normal fetal cardiac deformation values in pregnancy; a prospective cohort study protocol

Background

Myocardial deformation imaging offers the potential to measure myocardial function. Remodelling, the change in size, shape and function, appears as a result of pressure or volume changes and is thought to be the first sign of fetal adaptation to placental dysfunction. Deformation can be measured using speckle tracking echocardiography (STE). STE in the fetus might be useful for detection and follow up of the fetus endangered by placental dysfunction. Reference values for fetal myocardial deformation during gestation have not been comprehensively described and need further investigation before STE can be introduced in daily clinical practice. The aim of this study is to determine reference values for fetal myocardial deformation throughout gestation in uncomplicated pregnancies.

Methods

A longitudinal cohort will be performed. 150 Women, pregnant from a non-anomalous singleton, will be included from 19 to 21 + 6 weeks gestational age. Thereafter, fetal heart ultrasounds will be performed 4 weekly, until 41 weeks gestational age or delivery. Ultrasound data will be analysed using STE software to determine reference values for fetal cardiac deformation during gestation.

Discussion

Measuring cardiac deformation changes in pregnancy can be a promising tool to detect preclinical cardiac adaptation to placental dysfunction. However, previous studies used different ultrasound scans and STE software resulting in incomparable and contradictory results on deformation values. In this prospective study reference values during pregnancy, cardiac deformation values will be assessed with the same ultrasound and software package in 150 uncomplicated pregnancies.

Trial registration

National Trial Register number: NTR7132. Date of inclusion: 2018/04/06.

Intervendor Discordance of Fetal and Neonatal Myocardial Tissue Doppler and Speckle-Tracking Measurements

BACKGROUND

Fetal and neonatal studies report a wide range of cardiac parameters derived by pulsed-wave Doppler tissue imaging (DTI) and two-dimensional speckle-tracking echocardiographic (STE) imaging. The use of different ultrasound systems and their vendor-specific software compromises the ability to compare echocardiographic findings among various studies. The aim of this study was to evaluate intervendor reproducibility as well as intra- and interobserver repeatability of DTI and STE measurements in normal-term fetuses and neonates.

METHODS

A prospective study was conducted of term fetuses (n = 196) from uncomplicated pregnancies assessed days before the onset of labor and a few hours after birth. Fetal and neonatal DTI and STE parameters were obtained and analyzed using vendor-specific software on three ultrasound systems: Toshiba Aplio MX versus GE Vivid E9 and GE Vivid E9 versus Philips EPIQ. A reproducibility study in fetuses and neonates (n = 118) was performed by systematic scanning with head-to-head comparison.

RESULTS

DTI reproducibility showed moderate to good correlation, with good agreement for fetuses and neonates on Toshiba versus GE (intraclass correlation coefficient [ICC] = 0.4-0.8). Correlation of DTI measurements on GE versus Philips was poor to moderate for fetuses (ICC = 0.1-0.6) and moderate to good for neonates (ICC = 0.5-0.8), with wider limits of agreement. Fetal and neonatal STE parameters revealed very poor correlation (ICC = 0.1-0.3) and agreement among ultrasound vendors. Intra- and interobserver repeatability demonstrated good to excellent correlation of all fetal and neonatal DTI and STE measurements, with good agreement irrespective of the ultrasound platform used.

CONCLUSIONS

These findings demonstrate reliable assessment of fetal and neonatal DTI and STE measurements when performed on the same ultrasound platform, whereas ultrasound machines and software from different vendors give significantly divergent estimates of DTI and STE parameters in fetuses and neonates. These intervendor discrepancies have significant clinical and research implications and should be considered when interpreting and comparing study findings, establishing reference standards, or performing systematic reviews.

Feasibility and Reproducibility of Fetal Left Ventricular Twist Using Two-Dimensional Speckle-Tracking Analysis in a Japanese Population

In fetal echocardiography, conventional parameters for assessing cardiac function are limited because of limited echocardiographic windows or the fetus' position. We aimed to evaluate the feasibility and reproducibility of fetal left ventricular (LV) twist by two-dimensional, speckle-tracking echocardiography (2DSTE) in a Japanese population.We included 55 normal fetuses at gestational ages between 21 and 36 weeks. Subjects with adverse maternal health issues were excluded. LV twist was calculated as the net difference between LV basal and apical rotation at end-systole estimated with 2DSTE.We were able to analyze the 2DSTE images in 44 cases (80%). The mean (±SE) apical rotation, basal rotation, and LV twist were 7.88 ± 0.77, -3.68 ± 0.50, and 11.1 ± 0.75 degrees, respectively. We could not analyze 11 cases (20%) because of poor image quality due to fetal position in five cases (45.5%), failure to track the endocardium because of blurred images in five cases (45.5%), and failure to obtain images of the heart due to the presence of the placenta in front of the fetus in one case (9.1%). There were no significant differences in the demographic data between pregnant women in whom LV twist analysis was feasible and not feasible. The intra- and interobserver intraclass correlation coefficients were 0.67 and 0.64, respectively.LV twist analysis by 2DSTE in the fetus was feasible in a substantial population and may provide new insight into cardiac function during the prenatal period. On the other hand, its reproducibility was moderate and needs to be improved.

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.

Maturational patterns in right ventricular strain mechanics from the fetus to the young infant

AIM

To test the hypothesis that right ventricular (RV) function has age-specific patterns of development, we tracked the evolution of RV strain mechanics by 2D-speckle tracking echocardiography (2DSTE) in healthy subjects from mid-gestation through one year of age.

METHODS

We conducted a prospective longitudinal echocardiography study in 50 healthy subjects at five time periods across gestation (16-20 weeks, 21-25 weeks, 26-30 weeks, 31-35 weeks, and 36-40 weeks) and four time periods following delivery (1 week, 1 month, 6 months, and 1 year of age). We characterized RV function by measuring RV global and free wall longitudinal strain and systolic strain rate, and segmental longitudinal strain at the apical-, mid-, and basal- ventricular levels of the free wall. Possible associations of gestational age, postnatal age, estimated fetal weight, body surface area, gender, and heart rate on strain were investigated.

RESULTS

The magnitudes of RV global and free wall longitudinal strain and global strain rate were decreased throughout gestation (p < 0.05 for all). Following birth, the magnitudes of all measures increased from one week through one year (p < 0.001 for all). RV segmental longitudinal strain maintained a base-to-apex gradient (highest-to-lowest) from mid-gestation through one year (p < 0.001). There was no significant difference in strain patterns based on gender or hear rate.

CONCLUSION

The maturational patterns of RV strain are gestational- and postnatal age- specific. With accepted physiological maturation patterns in healthy subjects, these myocardial deformation parameters can provide a valid basis that allows comparison between health and disease.

Longitudinal Annular Systolic Displacement Compared to Global Strain in Normal Fetal Hearts and Those With Cardiac Abnormalities

OBJECTIVES

The purpose of this study was to compare a new technique that measures the midventricular basal-apical longitudinal diastolic and systolic lengths, computes the longitudinal displacement fractional shortening, and compares it to global strain.

METHODS

Two hundred control fetuses were examined between 20 and 40 weeks' gestation, in whom the longitudinal displacement fractional shortening was computed from end-diastolic and end-systolic lengths measured from the apex to the mid portion of the distance between the level of the basal lateral and septal walls using 2-dimnsional speckle tracking. In addition, global strain was computed using speckle tracking. A correlation analysis was used to compare the longitudinal displacement fractional shortening to global strain. The longitudinal displacement fractional shortening of the right ventricle (RV) and left ventricle (LV) was measured in 10 fetuses with heart abnormalities.

RESULTS

The longitudinal displacement fractional shortening for the RV (mean ± SD, 22.94% ± 4.73%) and LV (21.05% ± 4.21%) was independent of gestational age and other biometric growth parameters, as was global strain (RV, -22.7% ± 4.07%); LV, -22.93% ± 3.52%). The RV longitudinal displacement fractional shortening was greater than that of the LV (P < .024). The correlations between the longitudinal displacement fractional shortening and global strain were 0.95 for the RV and 0.97 for the LV. Comparing the longitudinal displacement fractional shortening and global strain in fetuses with abnormal cardiac findings showed concordant findings in 9 of 10 fetuses.

CONCLUSIONS

The RV and LV longitudinal displacement fractional shortening can be computed from 2-dimensional images of the 4-chamber view and correlated with global strain. The longitudinal displacement fractional shortening was significantly greater for the RV than the LV and was abnormal in fetuses with RV and LV cardiac abnormalities.

Fetal regional myocardial strain rate in the membranous ventricular septum: changes with gestational age and the left ventricular mass and predictive value for a complete membranous ventricular septum (without defect)

To describe the fetal regional myocardial strain rate in the membranous ventricular septum across gestation and to determine their predictive value for a complete membranous ventricular septum (without defect) after delivery. In 1150 fetuses, the peak systolic strain rate (SRs), peak early diastolic strain rate (SRe) and peak late diastolic strain rate (SRa) in the membranous ventricular septum were measured at four time points across gestation (18-20, 24-26, 30-32 and 36-38 weeks). The integrity of the interventricular septum was examined at 12 weeks' postnatal age. The correlations between myocardial strain rates and gestational age as well as fetal left ventricular mass were analyzed, and the performance of myocardial strain rates in predicting a complete membranous ventricular septum was deducted. Strain rate absolute values in the membranous ventricular septum all increased across gestation. They all significantly correlated with gestational age and left ventricular mass. At 24 weeks during pregnancy, the areas under the receiver operating characteristics curve (AUC) for SRe and SRa were all > 0.72 (p < 0.05) in predicting a complete membranous ventricular septum, while the AUC for SRs was only 0.55. The sensitivity, specificity and accuracy of the cut off value (> 1.53 s^-1) for SRe was 62.5, 85.7 and 73.3%, respectively, and the sensitivity, specificity and accuracy of the cut off value (> 1.51 s^-1) for SRa was 75.2, 71.9 and 73.8%, respectively. The changes of myocardial strain rates in the membranous ventricular septum across gestation maybe can be used to predict a complete membranous ventricular septum after delivery.

Deformation imaging and rotational mechanics in neonates: a guide to image acquisition, measurement, interpretation, and reference values

Advances in neonatal cardiac imaging permit a more comprehensive assessment of myocardial performance in neonates that could not be previously obtained with conventional imaging. Myocardial deformation analysis is an emerging quantitative echocardiographic technique to characterize global and regional ventricular function in neonates. Cardiac strain is a measure of tissue deformation and strain rate is the rate at which deformation occurs. These measurements are obtained in neonates using tissue Doppler imaging (TDI) or two-dimensional speckle tracking echocardiography (STE). There is an expanding body of literature describing longitudinal reference ranges and maturational patterns of strain values in term and preterm infants. A thorough understanding of deformation principles, the technical aspects, and clinical applicability is a prerequisite for its routine clinical use in neonates. This review explains the fundamental concepts of deformation imaging in the term and preterm population, describes in a comparative manner the two major deformation imaging methods, provides a practical guide to the acquisition and interpretation of data, and discusses their recognized and developing clinical applications in neonates.

Controversies in the identification and management of acute pulmonary hypertension in preterm neonates

It is increasingly recognized that the abnormal physiologic consequences of pulmonary hypertension (PH) may contribute to poor cardiopulmonary health in premature babies. Conflicting literature has led to clinical uncertainty, pathological misinterpretation, and variability in treatment approaches among practitioners. There are several disorders with overlapping and interrelated presentations, and other disorders with a similar clinical phenotype but diverse pathophysiological contributors. In this review, we provide a diagnostic approach for acute hypoxemic respiratory failure in the preterm neonate, outline the pathophysiological conditions that may present as acute PH, and discuss the implications of high pulmonary vascular resistance (PVR) on the cardiovascular system. Although PVR and respiratory management are highly interrelated, there may be a population of preterm neonates in whom inhaled nitric oxide may improve illness severity and may relate to outcomes. A management approach based on physiology that considers common clinical conundrums is provided. A more comprehensive understanding of the physiology may help in informed decision-making in clinical situations where conclusive scientific evidence is lacking. Regardless, high-quality research is required, and appropriate definition of the target population is paramount. A thoughtful approach to cardiovascular therapy may also provide an avenue to improve neurodevelopmental outcomes while awaiting more clear answers.

Left ventricular rotational mechanics in early infancy: Normal reference ranges and reproducibility of peak values and time to peak values

INTRODUCTION

Left ventricular cardiac twist and torsion values have been described in premature and term neonates, but not in early infancy. Early and late peak untwist rates and time to peak (TTP) values have not been described in infants.

METHODS

53 term infants were enrolled prospectively. The following parameters were obtained by two blinded observers at 1-2months postnatal age: peak twist and torsion (twist indexed to LV length), peak twist rate and torsion rate, TTP twist, early peak untwist rate, TTP early untwist rate, late peak untwist rate, TTP late untwist rate. Reproducibility was assessed using intraclass correlation and Bland Altman analysis.

RESULTS

Intraclass correlation was ≥0.87 for all peak rotational mechanics values. Measures of TTP values had intraclass correlation (ICC) values ≤0.77, with TTP twist rate demonstrating the lowest ICC (0.69). The only measure which demonstrated significant bias was TTP twist rate. Peak twist demonstrated modest correlation (R=0.52, p<0.001) with global circumferential strain, and no correlation with ejection fraction, global longitudinal strain, or left ventricular myocardial performance index.

CONCLUSIONS

Measurements of rotational mechanics and timing to peak values have acceptable reproducibility. Peak twist, twist rate, and early untwist rate values in early infancy are similar to those reported in premature neonates, and higher than those reported in older children. Twist indexed to LV length (torsion) is lower in early infancy than in premature neonates, but higher than in term neonates.