Myocardial strain can be measured from first trimester fetal echocardiography using velocity vector imaging

How automated techniques ease functional assessment of the fetal heart: Applicability of two-dimensional speckle-tracking echocardiography for comprehensive analysis of global and segmental cardiac deformation using fetalHQ®

BACKGROUND

Prenatal echocardiographic assessment of fetal cardiac function has become increasingly important. Fetal two-dimensional speckle-tracking echocardiography (2D-STE) allows the determination of global and segmental functional cardiac parameters. Prenatal diagnostics is relying increasingly on artificial intelligence, whose algorithms transform the way clinicians use ultrasound in their daily workflow. The purpose of this study was to demonstrate the feasibility of whether less experienced operators can handle and might benefit from an automated tool of 2D-STE in the clinical routine.

METHODS

A total of 136 unselected, normal, singleton, second- and third-trimester fetuses with normofrequent heart rates were examined by targeted ultrasound. 2D-STE was performed separately by beginner and expert semiautomatically using a GE Voluson E10 (FetalHQ®, GE Healthcare, Chicago, IL). Several fetal cardiac parameters were calculated (end-diastolic diameter [ED], sphericity index [SI], global longitudinal strain [EndoGLS], fractional shortening [FS]) and assigned to gestational age (GA). Bland-Altman plots were used to test agreement between both operators.

RESULTS

The mean maternal age was 33 years, and the mean maternal body mass index prior to pregnancy was 24.78 kg/m2. The GA ranged from 16.4 to 32.0 weeks (average 22.9 weeks). Averaged endoGLS value of the beginner was -18.57% ± 6.59 percentage points (pp) for the right and -19.58% ± 5.63 pp for the left ventricle, that of the expert -14.33% ± 4.88 pp and -16.37% ± 5.42 pp. With increasing GA, right ventricular endoGLS decreased slightly while the left ventricular was almost constant. The statistical analysis for endoGLS showed a Bland-Altman-Bias of -4.24 pp ± 8.06 pp for the right and -3.21 pp ± 7.11 pp for the left ventricle. The Bland-Altman-Bias of the ED in both ventricles in all analyzed segments ranged from -.49 mm ± 1.54 mm to -.10 mm ± 1.28 mm, that for FS from -.33 pp ± 11.82 pp to 3.91 pp ± 15.56 pp and that for SI from -.38 ± .68 to -.15 ± .45.

CONCLUSIONS

Between both operators, our data indicated that 2D-STE analysis showed excellent agreement for cardiac morphometry parameters (ED and SI), and good agreement for cardiac function parameters (EndoGLS and FS). Due to its complexity, the application of fetal 2D-STE remains the domain of scientific-academic perinatal ultrasound and should be placed preferably in the hands of skilled operators. At present, from our perspective, an implementation into clinical practice "on-the-fly" cannot be recommended.

Feasibility and reliability of fetal two dimensional speckle tracking echocardiography at 16 weeks gestational age: A pilot study

BACKGROUND

Fetal two-dimensional speckle tracking echocardiography (2D-STE) is an emerging technique for assessing fetal cardiac function by measuring global longitudinal strain. Alterations in global longitudinal strain may serve as early indicator of pregnancy complications, making 2D-STE a potentially valuable tool for early detection. Early detection can facilitate timely interventions to reduce fetal and maternal morbidity and mortality. Therefore, the aim of this study was to investigate the feasibility of performing 2D-STE at 16 weeks gestational age.

METHODS

This pilot study utilized 50 ultrasound clips of the fetal four-chamber view recorded between 15+5 and 16+2 weeks gestational age from a prospective cohort study. A strict protocol assessed three parameters essential for 2D-STE analysis: fetal four-chamber view ultrasound clip quality, region of interest, and frame rates. Two independent researchers measured global longitudinal strain in all adequate fetal four-chamber view ultrasound clips to determine inter- and intra-operator reliability.

RESULTS

Out of the 50 ultrasound clips, 37 (74%) were feasible for 2D-STE analysis. The inter-operator reliability for global longitudinal strain measurements of the left and right ventricles was moderate (ICC of 0.64 and 0.74, respectively), while the intra-operator reliability was good (ICC of 0.76 and 0.79, respectively).

CONCLUSIONS

Our findings demonstrate that fetal 2D-STE analysis at 16 weeks gestational age is feasible when adhering to a strict protocol. However, further improvements are necessary to enhance the inter- and intra-operator reliability of 2D-STE at this gestational age.

Fetal echocardiography changes of the right ventricle of well-controlled gestational diabetes mellitus

BACKGROUND

There is few evidence of right ventricular (RV) function in fetuses with gestational diabetes mellitus (GDM). Therefore, the aim of this study was to assess the RV function of fetuses using routine and two-dimensional speckle-tracking echocardiography (2D STE) to determine the effects of well-controlled GDM in the third trimester.

METHODS

We used a Philips Epiq7C ultrasound instrument to obtain RV data sets from 63 subjects from July 2019 to February 2022. We compared the free wall thickness (FWT), fractional area change (FAC), Tei index (TEI), tricuspid annular plane systolic excursion (TAPSE) and free wall longitudinal strain(FWLS)of the RV in mothers with well-controlled GDM and normal gestational age-matched fetuses.

RESULTS

63 third trimester fetuses (32 GDM; 31 healthy controls) met the enrolment criteria. Significant differences in fetal RV were detected between the GDM and control groups for the FAC (36.35 ± 6.19 vs. 41.59 ± 9.11; P = 0.008) and the FWLS (-18.28 ± 4.23 vs. -20.98 ± 5.49; P = 0.021). There was a significant difference among the segmental strains of the base, middle and apex of the RV free wall in the healthy controls (P = 0.003), but in the GDM group, there was no statistical difference (p = 0.076). RV FWLS had a strong correlation with FAC (r = 0.467; P = 0.0002).

CONCLUSIONS

In well-controlled GDM, there was measurable fetal RV hypertrophy and significant systolic function decline, indicating the presence of ventricular remodeling and dysfunction. 2D-STE can evaluate the RV free wall contraction in a more comprehensive way.

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.

Right ventricular systolic function and associated anatomic risk factors in fetuses with transposition of the great arteries: Evaluation by velocity vector imaging

Objectives

The aim of this study was to evaluate right ventricular (RV) systolic function in fetuses with transposition of the great arteries (TGA) using velocity vector imaging (VVI) and to investigate the impact of different factors on RV systolic function in TGA fetuses.

Methods

This was a retrospective cross-sectional study of fetuses referred to our tertiary center between 2015 and 2019. Maternal and fetal baseline characteristics and conventional echocardiographic and myocardial deformation indices were collected in fetuses with TGA at 20-28 weeks' gestation, which were compared with normal fetuses with comparable gestational age (GA). RV deformational parameters including global and regional longitudinal peak systolic strain, strain rate, and velocity were measured using off-line speckle tracking analysis. The univariate and multivariate linear regression analyses were established to evaluate the independent risk factors for RV global longitudinal systolic strain (RVGLSs) and strain rate (RVGLSRs).

Results

In total, 78 fetuses with TGA [including 49 fetuses with complete transposition of the great arteries (d-TGA) and 29 fetuses with Taussig-Bing anomaly (TBA)] and 49 normal fetuses were included. Compared with normal controls, global and most regional RV longitudinal systolic peak velocity, strain, and strain rate were lower in d-TGA and TBA fetuses (P < 0.05). Compared with normal controls, global and most regional RV longitudinal systolic strain was lower in d-TGA fetuses without pulmonary stenosis (PS) and ventricular septal defect (VSD), while RVGLSs and RVGLSRs were lower in TBA fetuses without PS. The VSD was an independent determinant of RVGLSRs (P = 0.024) in the d-TGA group. Additionally, PS was an independent determinant of RVGLSs and RVGLSRs (P = 0.012, P = 0.027) in the TBA group.

Conclusion

Early impairment of RV systolic function has already occurred in TGA fetuses during the 2nd trimester of pregnancy. PS, VSD, and foramen ovale (FO) were independent risk factors for decreased RV function.

Evaluation of biventricular longitudinal myocardial function in normal fetuses at different gestational ages using ultrasonic velocity vector imaging

Objective

This study aimed to evaluate biventricular myocardial function and biventricular longitudinal global myocardial function of fetuses at different gestational weeks using ultrasonic velocity vector imaging.

Methods

A total of 127 pregnant women were enrolled and divided into five groups according to the gestational age of their fetuses. The velocity, strain, and strain rate of the left and right ventricles were measured, and these biventricular parameters were compared between the groups. The global parameters of the biventricular myocardium were also compared.

Results

A pairwise comparison revealed that the differences in biventricular velocity and strain rate between groups in adjacent gestational weeks were not statistically significant (P > 0.05), but velocity increased with gestational age. A comparison of fetal longitudinal global myocardial parameters revealed that the global velocity, strain, and strain rate of the right ventricle were higher than those of the left ventricle, and the differences were statistically significant (P < 0.05) in all groups.

Conclusion

The peak velocities of the fetal left and right ventricles increased with gestational age, but the global strain and strain rate did not, suggesting that fetal myocardial function is mature and constant in the middle and late stages of pregnancy and can more reliably reflect myocardial deformation. The peak systolic velocity, global strain, and peak strain rate of the right ventricle were higher than those of the left ventricle, suggesting that the right ventricle dominates longitudinal systolic movement from the second trimester of pregnancy.

Fetal myocardial deformation measured with two-dimensional speckle-tracking echocardiography: longitudinal prospective cohort study of 124 healthy fetuses

OBJECTIVES

Two-dimensional speckle-tracking echocardiography (2D-STE) is a promising technique which allows assessment of fetal cardiac function, and can be used in the evaluation of cardiac and non-cardiac diseases in pregnancy. However, reliable fetal reference values for deformation parameters measured using 2D-STE are needed before it can be introduced into clinical practice. This study aimed to obtain reference values for fetal global longitudinal strain (GLS) and GLS rate (GLSR) measured using 2D-STE and compare right and left ventricular values.

METHODS

This was a prospective longitudinal cohort study of uncomplicated pregnancies that underwent echocardiography every 4 weeks from inclusion at 18-21 weeks until delivery to obtain four-chamber loops of the fetal heart. Left and right ventricular GLS and GLSR were measured using 2D-STE at each examination. Using Bayesian mixed-effects models, reference values with lower and upper 5% prediction limits were calculated according to gestational age. Right and left ventricular GLS values according to gestational age were compared using the Wilcoxon signed-rank test.

RESULTS

A total of 592 left ventricular and 566 right ventricular GLS and GLSR measurements were obtained from 124 women with uncomplicated pregnancy and non-anomalous, appropriately grown fetuses. Reference values were obtained for both fetal ventricles according to gestational week. GLS and GLSR values of both ventricles increased (i.e. became less negative) significantly during pregnancy. Right ventricular GLS values were significantly higher (i.e. less negative) than the respective left ventricular values at every gestational week.

CONCLUSIONS

Reference values were obtained for fetal GLS and GLSR measured using 2D-STE. GLS and GLSR values increased significantly for both ventricles from the second trimester until delivery. GLS values were significantly higher for the right ventricle compared with the left ventricle. Future studies are needed to assess whether the obtained reference values are helpful in clinical practice in the assessment of pregnancy complications, such as fetal growth restriction or cardiac anomaly. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Soft-Tissue Material Properties and Mechanogenetics during Cardiovascular Development

During embryonic development, changes in the cardiovascular microstructure and material properties are essential for an integrated biomechanical understanding. This knowledge also enables realistic predictive computational tools, specifically targeting the formation of congenital heart defects. Material characterization of cardiovascular embryonic tissue at consequent embryonic stages is critical to understand growth, remodeling, and hemodynamic functions. Two biomechanical loading modes, which are wall shear stress and blood pressure, are associated with distinct molecular pathways and govern vascular morphology through microstructural remodeling. Dynamic embryonic tissues have complex signaling networks integrated with mechanical factors such as stress, strain, and stiffness. While the multiscale interplay between the mechanical loading modes and microstructural changes has been studied in animal models, mechanical characterization of early embryonic cardiovascular tissue is challenging due to the miniature sample sizes and active/passive vascular components. Accordingly, this comparative review focuses on the embryonic material characterization of developing cardiovascular systems and attempts to classify it for different species and embryonic timepoints. Key cardiovascular components including the great vessels, ventricles, heart valves, and the umbilical cord arteries are covered. A state-of-the-art review of experimental techniques for embryonic material characterization is provided along with the two novel methods developed to measure the residual and von Mises stress distributions in avian embryonic vessels noninvasively, for the first time in the literature. As attempted in this review, the compilation of embryonic mechanical properties will also contribute to our understanding of the mature cardiovascular system and possibly lead to new microstructural and genetic interventions to correct abnormal development.

Ventricular Myocardial Deformation in Fetuses With Tetralogy of Fallot: A Necessary Field of Investigation

Background: Tetralogy of Fallot (TOF) is one of the most common cyanotic congenital heart defects (CHDs). The patterns of fetal myocardial deformations in TOF have not been well-studied. This study aimed to assess biventricular myocardial deformations in fetuses with TOF compared with normal fetuses.

Methods: A retrospective cohort study of fetuses with TOF and gestational age (GA)-matched controls was conducted at a single tertiary referral center from 2014 to 2020. All enrolled fetuses underwent detailed echocardiography, and four-chamber video-clips were recorded and analyzed offline for deformation assessment by using two-dimensional speckle tracking echocardiography (2D-STE). Comparisons for baseline characteristics, cardiac morphological measurements (ventricular, atrial, and great arterial diameters or ratios, global sphericity index), systolic function parameters [ejection fraction (EF), fractional area change (FAC)], and strain parameters [global longitudinal strain (GLS), global longitudinal strain rate in systole and diastole (GLSRs, GLSRd)] were performed between fetuses with TOF and GA-matched controls.

Results: Fifty-two fetuses with TOF and 52 GA-matched controls were enrolled in this study. Fetuses with TOF exhibited similar left ventricular (LV) EF (58.51 ± 5.11% vs. 57.59 ± 5.38%, P = 0.16) and right ventricular (RV) FAC (43.64 ± 2.89% vs. 44.27 ± 3.04%, P = 0.25), compared to normal fetuses. While, in deformational analysis, TOF fetuses demonstrated significantly lower LV and RV GLS values (−22.57 ± 2.91% vs. −27.39 ± 4.38%, P < 0.001 for LV GLS; −24.27 ± 3.18% vs. −28.71 ± 4.48%, P < 0.001 for RV GLS). Both LV GLS (r = −0.518, P < 0.001) and RV GLS (r = −0.534, P < 0.001) were found negatively correlated with the aortic valve-to-pulmonary valve diameter ratio (AV:PV ratio). Z-scores of PV annulus and main pulmonary artery (MPA) also had positive correlation with LV and RV GLS, respectively.

Conclusions: Decreased biventricular myocardial deformations can appear even in fetuses with TOF with normal systolic ventricular function. Both LV and RV GLS values are correlated with the severity of right ventricular outflow tract obstruction. It indicates 2D-STE may be a more sensitive tool to assess fetal cardiac function than the conventional echocardiographic methods.

Prenatal cardiac care: Goals, priorities & gaps in knowledge in fetal cardiovascular disease: Perspectives of the Fetal Heart Society

Perinatal cardiovascular care has evolved considerably to become its own multidisciplinary field of care. Despite advancements, there remain significant gaps in providing optimal care for the fetus, child, mother, and family. Continued advancement in detection and diagnosis, perinatal care and delivery planning, and prediction and improvement of morbidity and mortality for fetuses affected by cardiac conditions such as heart defects or functional or rhythm disturbances requires collaboration between the multiple types of specialists and providers. The Fetal Heart Society was created to formalize and support collaboration between individuals, stakeholders, and institutions. This article summarizes the challenges faced to create the infrastructure for advancement of the field and the measures the FHS is undertaking to overcome the barriers to support progress in the field of perinatal cardiac care.

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Progress in perinatal cardiology is challenged by the rarity of fetal cardiac disease, care variation, and barriers to collaboration.

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The Fetal Heart Society was founded to formalize collaboration between the multiple disciplines in perinatal cardiac care.

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The FHS facilitates interdisciplinary multicenter research, education and advocacy to provide optimal perinatal cardiac care.

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 strain and strain rate during pregnancy measured with speckle tracking echocardiography: A systematic review

Establishment of the maturational patterns of the fetal left and right ventricle strain and strain rate by two-dimensional speckle tracking echocardiography is a prerequisite for its routine clinical adaptation in pregnancy. The aim of this study is to review systematically current literature on the development of left and right ventricle strain and strain rate derived by speckle tracking during gestation. EMBASE, Medline and Central were searched, from inception to October 2019, for observational studies of singletons in uncomplicated, non-anomalous pregnancies, measuring global longitudinal strain and strain rate with 2D speckle tracking echocardiography in the fetal heart during gestation. 23 Studies met the inclusion criteria. The gestational age of the included fetuses varied from 12 to 42 weeks. Four studies used a longitudinal study design, with few consecutive measurements at varying gestational ages. 19 Studies performed either cross sectional or both longitudinal and cross sectional measurements. The ultrasound devices and speckle tracking algorithm software used, varied. Strain and strain rate during gestation increased, decreased or remained stable in the left and right fetal ventricle with increasing gestation. Due to considerable variation in the included gestational ages measured and inconsistency in the direction of strain and strain rate development, a meta-analysis could not be performed. Contradictory results concerning the development of strain and strain rate during gestation were shown, probably due to suboptimal study designs and varying algorithms and ultrasound devices used. A large longitudinal cohort study is needed to obtain reference values for fetal cardiac deformation in the uncomplicated, singleton pregnancy.

Echocardiography vs cardiac magnetic resonance imaging assessment of the systemic right ventricle for patients with d-transposition of the great arteries status post atrial switch

OBJECTIVE

Patients with Dextro-transposition of the great arteries status post atrial switch (dTGA s/p atrial switch) are "at-risk" for systemic right ventricular (RV) dysfunction. Due to complex RV geometry, echocardiography (Echo) does not allow accurate determination of ejection fraction (EF), but cardiac magnetic resonance imaging (CMR) allows quantitative right ventricular assessment. Measures of ventricular deformation may be precursors to global ventricular dysfunction. The primary aim of this study was to characterize imaging and clinical findings for adult patients with dTGA s/p atrial switch.

DESIGN

This was a retrospective cohort study of patients with dTGA s/p atrial switch operation (February 1966 to August 1988) with CMR performed at Children's Hospital of Wisconsin (from September 2005 to May 2015). Eligible patients had clinic visit, Echo, and exercise stress test within 1 year of CMR.

RESULTS

This study enrolled twenty-seven patients (16 males, 11 females) with dTGA s/p atrial switch (18 with Mustard operation and 9 with Senning operation; median age 30 years; 74% New York Heart Association class 1 and 26% class 2). Seventy-four percentage had normal RV systolic function (RV EF >45% by CMR). No correlation was observed between Echo strain data and clinical status (EF, exercise endurance, VO₂ max, or New York Heart Association class). Cardiac magnetic resonance imaging RV global circumferential strain GCS and RV EF had moderate negative correlation (r = -0.65, P < .001). Global circumferential strain was significantly different for those with RV EF above and below 45%, while global peak longitudinal strain (GLS) was not. Patients had reduced CMR myocardial strain values compared with healthy controls.

CONCLUSIONS

Reduced RV CMR GCS (for those with RV EF <45%) suggests that CMR evaluation may enhance early detection of detrimental changes in the systemic RV myocardium.

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.

Early fetal echocardiography

OBJECTIVES

To explore the technical aspects and clinical utility of early fetal echocardiography and screening of the fetal heart in early pregnancy. Also, to document differences in cardiac structure and function which can be demonstrated in the late first/early second trimesters.

METHODS

In addition to summarizing our own experiences of late first/early second trimester fetal echocardiography, we reviewed the literature to explore clinical indications for, technical aspects, safety, accuracy, strengths and weaknesses of early fetal echocardiography.

RESULTS

In the current era, an increasing number of fetuses are identified as being at risk of congenital heart disease from as early as the late first trimester. In experienced hands, early fetal echocardiography can pick up a high proportion of congenital heart disease with good reliability for the majority of lesions. Early fetal echocardiography is relatively poor at assessing pulmonary veins, the atrioventricular valves and lesions that typically occur later or progress during the course of pregnancy. There is increasing interest in widespread implementation of an early obstetric anomaly screen which includes an assessment of the fetal heart for all pregnancies. There are a variety of hemodynamic differences in the late first/early second trimester compared with later in pregnancy.

CONCLUSION

Early fetal echocardiography is has become an established tool for detection of congenital heart disease. It affords opportunities to learn about the true spectrum and progression of congenital heart disease in-utero. Operators should be mindful of safety issues, technical aspects and hemodynamic findings which differ when performing echocardiograms at this stage of pregnancy.