Assessment of Global Longitudinal and Circumferential Strain Using Computed Tomography Feature Tracking: Intra-Individual Comparison with CMR Feature Tracking and Myocardial Tagging in Patients with Severe Aortic Stenosis

In this study, we used a single commercially available software solution to assess global longitudinal (GLS) and global circumferential strain (GCS) using cardiac computed tomography (CT) and cardiac magnetic resonance (CMR) feature tracking (FT). We compared agreement and reproducibility between these two methods and the reference standard, CMR tagging (TAG). Twenty-seven patients with severe aortic stenosis underwent CMR and cardiac CT examinations. FT analysis was performed using Medis suite version 3.0 (Leiden, The Netherlands) software. Segment (Medviso) software was used for GCS assessment from tagged images. There was a trend towards the underestimation of GLS by CT-FT when compared to CMR-FT (19.4 ± 5.04 vs. 22.40 ± 5.69, respectively; p = 0.065). GCS values between TAG, CT-FT, and CMR-FT were similar (p = 0.233). CMR-FT and CT-FT correlated closely for GLS (r = 0.686, p < 0.001) and GCS (r = 0.707, p < 0.001), while both of these methods correlated moderately with TAG for GCS (r = 0.479, p < 0.001 for CMR-FT vs. TAG; r = 0.548 for CT-FT vs. TAG). Intraobserver and interobserver agreement was excellent in all techniques. Our findings show that, in elderly patients with severe aortic stenosis (AS), the FT algorithm performs equally well in CMR and cardiac CT datasets for the assessment of GLS and GCS, both in terms of reproducibility and agreement with the gold standard, TAG.

Practical tips and tricks in measuring strain, strain rate and twist for the left and right ventricles

Strain imaging provides an accessible, feasible and non-invasive technique to assess cardiac mechanics. Speckle tracking echocardiography (STE) is the primary modality with the utility for detection of subclinical ventricular dysfunction. Investigation and adoption of this technique has increased significantly in both the research and clinical environment. It is therefore important to provide information to guide the sonographer on the production of valid and reproducible data. The focus of this review is to (1) describe cardiac physiology and mechanics relevant to strain imaging, (2) discuss the concepts of strain imaging and STE and (3) provide a practical guide for the investigation and interpretation of cardiac mechanics using STE.

Variability of longitudinal strain measurements: levelling the playing field

Speckle tracking echocardiography offers a unique opportunity to evaluate myocardial function, and global longitudinal strain (GLS) is currently recommended as a measurement of global left ventricular function. To facilitate clinical applicability of the method, collective efforts have been made to standardise strain measurements and to raise awareness of the potential sources of variability. The purpose of this review is to familiarise the reader with the most common sources of variability of longitudinal strain measurements and detail the possible measures to increase the accuracy and reproducibility of strain parameters.

The Association of a classical left bundle Branch Block Contraction Pattern by vendor-independent strain echocardiography and outcome after cardiac resynchronization therapy

Background

The association of a Classical left bundle branch block (LBBB) contraction pattern and better outcome after cardiac resynchronization therapy (CRT) has only been studied using vendor-specific software for echocardiographic speckle-tracked longitudinal strain analysis. The purpose of this study was to assess whether a Classical LBBB contraction pattern on longitudinal strain analysis using vendor-independent software is associated with clinical outcome in CRT recipients with LBBB.

Methods

This was a retrospective cohort study including CRT recipients with LBBB, heart failure, and left ventricular (LV) ejection fraction ≤35%. Speckle-tracked echocardiographic longitudinal strain analysis was performed retrospectively on echocardiograms using vendor-independent software. The presence of a Classical LBBB contraction pattern was determined by consensus of two readers. The primary end point was a composite of time to death, heart transplantation or LV assist device implantation. Secondary outcome was ≥15% reduction in LV end-systolic volume. Intra- and inter-reader agreement of the longitudinal strain contraction pattern was assessed by calculating Cohen’s κ.

Results

Of 283 included patients, 113 (40%) were women, mean age was 66 ± 11 years, and 136 (48%) had ischemic heart disease. A Classical LBBB contraction pattern was present in 196 (69%). The unadjusted hazard ratio for reaching the primary end point was 1.93 (95% confidence interval, 1.36–2.76, p < 0.001) when comparing patients without to patients with a Classical LBBB contraction pattern. Adjusted for ischemic heart disease and QRS duration < 150 milliseconds the hazard ratio was 1.65 (95% confidence interval, 1.12–2.43, p = 0.01). Of the 123 (43%) patients with a follow-up echocardiogram, 64 of 85 (75%) of patients with a Classical LBBB contraction pattern compared to 13 of 38 (34%) without, had ≥15% reduction in LV end-systolic volume (p < 0.001). Cohen’s κ were 0.86 (95% confidence interval, 0.71–1.00) and 0.42 (95% confidence interval, 0.30–0.54) for intra- and inter-reader agreement, respectively.

Conclusion

Using vendor-independent strain software, a Classical LBBB contraction pattern is associated with better outcome in CRT recipients with LBBB, but inter-reader agreement for the classification of contraction pattern is only moderate.

Age-specific diastolic dysfunction improves prediction of symptomatic heart failure by Stage B heart failure

Aims

We investigated whether addition of diastolic dysfunction (DD) and longitudinal strain (LS) to Stage B heart failure (SBHF) criteria (structural or systolic abnormality) improves prediction of symptomatic HF in participants of the SCReening Evaluation of the Evolution of New Heart Failure study, a self‐selected population at increased cardiovascular disease risk recruited from members of a health insurance fund in Melbourne and Shepparton, Australia. Both American Society of Echocardiography and European Association of Cardiovascular Imaging (ASE/EACVI) criteria and age‐specific Atherosclerosis Risk in Communities (ARIC) study criteria, for SBHF and DD, and ARIC criteria for abnormal LS, were examined.

Methods and results

Inclusion criteria were age ≥60 years with one or more of self‐reported ischaemic or other heart disease, irregular or rapid heart rhythm, cerebrovascular disease, renal impairment, or treatment for hypertension or diabetes for ≥2 years. Exclusion criteria were known HF, or ejection fraction <50% or >mild valve abnormality detected on previous echocardiography or other imaging. Echocardiography was performed in 3190 participants who were followed for a median of 3.9 (interquartile range: 3.4, 4.5) years after echocardiography. Symptomatic HF was diagnosed in 139 participants at a median of 3.1 (interquartile range: 2.1, 3.9) years after echocardiography. ARIC structural, systolic, and diastolic abnormalities predicted HF in univariate and multivariable proportional hazards analyses, whereas ASE/EACVI structural and systolic, but not diastolic, abnormalities predicted HF. ARIC and ASE/EACVI SBHF criteria predicted HF with sensitivities of 81% and 55%, specificities of 39% and 76%, and C statistics of 0.60 (95% confidence interval: 0.57, 0.64) and 0.66 (0.61, 0.71), respectively. Adding ARIC DD to SBHF increased sensitivity to 94% with specificity of 24% and C statistic of 0.59 (0.57, 0.61), whereas addition of ASE/EACVI DD to SBHF increased sensitivity to 97% but reduced specificity to 9% and the C statistic to 0.52 (0.50, 0.54, P < 0.0001). Addition of LS to ARIC or ASE/EACVI SBHF criteria had minimal impact on prediction of HF.

Conclusions

Age‐specific ARIC DD criteria, but not ASE/EACVI DD criteria, predicted symptomatic HF, and addition of age‐specific ARIC DD criteria to ARIC SBHF criteria improved prediction of symptomatic HF in asymptomatic individuals with cardiovascular disease risk factors. Addition of LS to ASE/EACVI or ARIC SBHF criteria did not improve prediction of symptomatic HF.

Wall motion tracking in fetal echocardiography-Application of low and high frame rates for strain analysis

OBJECTIVE

Compared to adults, fetal heart rates (HR) are elevated necessitating higher frame rates (FR) for strain analysis by speckle tracking echocardiography. The aim of this study was to investigate the influence of high FR compared to low FR on strain analysis in 2D speckle tracking.

METHODS

Fetal echocardiography was prospectively performed and acquired from the apical or basal four-chamber views of the heart. Images were optimized for clear delineation of myocardial walls and stored in either raw Digital Imaging and Communications in Medicine (DICOM) cine-loop format for offline analysis with a low FR of 60 frames per second (fps) or in the original FR (acoustic FR = AFR). For each loop, right (RV) and left (LV) ventricular fetal longitudinal peak systolic strain (LPSS) values were assessed by 2D Wall Motion tracking.

RESULTS

One hundred and three healthy fetuses were included with a mean gestational age of 26.3 ± 5.5 weeks. Mean AFR was 127 ± 26 fps. A mean FR/HR ratio was assessed of 0.42 and 0.90 between the low FR and AFR group, respectively. Relating to LPSS values, there was a significant difference between low FR and AFR for both ventricles (LV: -16.5% ± 3.9% (low FR) vs -13.6% ± 3.5% (AFR); and RV: -15.1% ± 3.6% (low FR) vs -12.6% ± 3.7% (AFR), both P < 0.001).

CONCLUSIONS

Fetal LV and RV LPSS values derived with high AFR were significantly lower than corresponding LPSS values analyzed with low FR of 60 fps. Future studies are needed to clarify the clinical importance of this relationship.

In-depth echocardiographic analysis of left atrial function in healthy adults using speckle tracking echocardiography and volumetric analysis

Purpose

Left atrial (LA) dilatation is predictive for complications in a multitude of cardiac diseases; therefore, adequate assessment is essential. Technological advances have made it possible to quantify LA function with Speckle Tracking Echocardiography (STE); however, there are currently no recommendations for normal values with regard to LA function. We aimed to assess LA myocardial and volumetric function in a healthy cohort and investigate correlations with baseline characteristics.

Methods

This prospective cohort study included 147 (aged 20–72) healthy individuals and assessed LA volumetric function using maximum, minimum and pre‐a‐wave volumes and myocardial function using reservoir function using peak strain in LA relaxation (LA‐strain), conduit function using peak strain rate in early LA contraction (LA‐SRe) and pump function using peak strain rate in late LA contraction (LA‐SRa).

Results

Mean LA‐strain was 39.7 ± 6.2%, LA‐SRe −2.78 ± 0.62 s⁻¹ and LA‐SRa −2.56 ± 0.62 s⁻¹. Subjects were divided into 5 age decades (each 50% female). LA‐strain and LA‐SRe were lower in the oldest groups, whereas LA‐SRa was higher. LA‐SRa was higher in males(−2.69 ± 0.68 s⁻¹ vs −2.42 ± 0.52 s⁻¹). Age‐specific values are provided. Age proved to be an independent predictor for LA‐SRa after correction for blood pressure and heart rate. LA expansion index and passive emptying fraction decreased with age, while active emptying fraction increased with age. LA maximum volume did not increase with age.

Conclusion

This study provides normal values for the three phasic functions of the LA, assessed with STE and volumetric function. Our results suggest the need for age‐specific reference ranges, and normal values for this cohort have been calculated.

Quantitative Assessment of the Effect of the Out-of-Plane Movement of the Homogenous Ellipsoidal Model of the Left Ventricle on the Deformation Measures Estimated Using 2-D Speckle Tracking-An In-Silico Study

Effect of the out-of-plane (OOP) movement amplitude on estimates of global displacements (radial, circumferential) and strains (radial , circumferential ) was studied in an ellipsoidal model of the left ventricle using finite-element modeling (FEM), synthetic ultrasonic data, and short-axis view. This effect was assessed using median of the absolute relative error (RE) of the global parameters. FEM provided node displacements for synthetic ultrasonic data and reference data generation. Displacements were estimated using block-matching (BM) and B-spline (BS) methods. FEM-derived data analysis, free from errors resulting from speckle tracking, indicated that the tissue motion introduced REs of global strain estimates below 4.5%. The effect of the OOP motion amplitude on strain estimates was strain specific and depended on the displacement estimation method. In the case of , the increase of the OOP amplitude resulted in quasi-linear increase of the RE from approximately 10% to 15%. The modulus of the end-systolic (ES) errors of the estimates almost linearly increased with increasing OOP amplitude approximately from 10% to 16%. REs of the estimate were close to 80% and 40%, respectively, in the case of the BM and BS methods, and increased with increasing OOP amplitude. The modulus of the ES errors of the estimates in the case of the BS method was about -40% and showed low sensitivity to the OOP amplitude; in the BM case, these errors varied approximately from -70% to -58% for OOP amplitude from 0 to 15 mm.

An introduction to left ventricular strain

PURPOSE OF REVIEW

The assessment of left ventricular function by two-dimensional (2D) transthoracic echocardiography (TTE) is conventionally performed by measuring the ejection fraction, which has been shown to have important prognostic implications. However, left ventricular ejection fraction (LVEF) has notable shortcomings, including limited reproducibility, suboptimal inter/intraobserver variability and dependence on load/volume. Furthermore, subclinical left ventricular dysfunction cannot be measured with LVEF. With the advent of left ventricular deformation (strain) analysis, a new and robust means for assessing left ventricular function has emerged.

RECENT FINDINGS

Contemporary research and guidelines have attempted to standardize the definition, acquisition and measurement of left ventricular strain. In addition, multiple studies have sought to establish normal values for left ventricular strain in addition to evaluating the benefits and prognostic value of strain assessment.

SUMMARY

This article reviews the definition of left ventricular strain, outlines the types of strain and reviews how strain is acquired and measured. In addition, the advantages of strain analysis over LVEF as well as the incremental prognostic value of strain are examined. We further review the challenges associated with strain imaging as well as outline the future of strain imaging.

Speckle tracking stress echocardiography in children: interobserver and intraobserver reproducibility and the impact of echocardiographic image quality

Speckle tracking echocardiography (STE) is increasingly used during functional assessments. However, reproducibility and dependence on echocardiographic image quality for speckle tracking stress echocardiography in pediatric patients have not been studied to date. 127 consecutive normotensive children without structural heart disease (mean age 13.4 ± 3.0 years, 50.4% female) underwent a stepwise semisupine cycle ergometric protocol. Left ventricular (LV) myocardial peak strain and strain rate were assessed at rest and during exercise. Interobserver and intraobserver assessments were performed and analyzed regarding echocardiographic image quality. LV peak global strain and strain rate were well reproducible with narrow limits of agreement without any significant bias both at rest and during all stages of exercise testing. Moreover, strain rate reproducibility slightly deteriorated in values between -1.5 and -3 s^-1. Surprisingly, there was no significant difference in reproducibility between optimal, intermediate and poor quality of echocardiographic images. STE derived strain and strain rate measurements in children are feasible and highly reproducible during semisupine cycle ergometric stress echocardiography. Echocardiographic image quality does not seem to influence strain (rate) reproducibility. Myocardial deformation measurements in images with suboptimal visualization quality must be interpreted with caution.

Multimodality imaging for evaluation of chest pain using strain analysis at rest and peak exercise

BACKGROUND

Exercise stress echocardiography (SE) is commonly used for diagnosing coronary artery disease (CAD). The use of quantitative echocardiographic measures such as strain imaging is expected to improve the sensitivity of conventional SE which relies on the visual diagnosis of wall-motion abnormalities (WMAs). This study is set to demonstrate the added value of resting and exercise strain analysis to detect underlying microangiopathy and inducible myocardial ischemia during a resting and SE in comparison with the results of coronary computed tomographic angiogram (CCTA).

METHODS

A total of 103 consecutive outpatients from the executive screening program were identified and underwent resting and SE. Global longitudinal strain (GLS) and wall-motion changes at rest and peak exercise were analyzed and compared. Baseline demographics, heart rate, and blood pressure measurements were retrospectively extracted for analysis. CCTA was chosen as an alternative test to match with wall motion and strain imaging.

RESULTS

Patients who had abnormal CCTA had lower resting GLS (14.85% ± 3.05 vs 17.99% ± 2.88, P-value = .001) when compared to patients with normal CCTA. All patients who had abnormal CCTA had higher wall-motion score index (1.35 ± 0.2 vs 1.00, P-value < .0001) and lower and abnormal peak stress GLS (pGLS) as compared to patients with normal CCTA (14.89% ± 3.35 vs 18.44% ± 4.27, P-value = .007). However, all patients with pGLS ≥ 20% had normal/nonobstructive CCTA. Patients with multiple comorbidities showed reduced and lower values of resting and pGLS (P-value < .0001), suggesting associated subclinical left ventricular dysfunction.

CONCLUSIONS

Global longitudinal strain offers quantitative interpretation of the resting and SE study, detects underlying subclinical left ventricular dysfunction and a peak stress value more than 20% excludes obstructive CAD on CCTA.

Accuracy of speckle tracking in the context of stress echocardiography in short axis view: An in vitro validation study

Aim

This study aimed to test the accuracy of a speckle tracking algorithm to assess myocardial deformation in a large range of heart rates and strain magnitudes compared to sonomicrometry.

Methods and results

Using a tissue-mimicking phantom with cyclic radial deformation, radial strain derived from speckle tracking (RS-SpT) of the upper segment was assessed in short axis view by conventional echocardiography (Vivid q, GE) and post-processed with clinical software (EchoPAC, GE). RS-SpT was compared with radial strain measured simultaneously by sonomicrometers (RS-SN). Radial strain was assessed with increasing deformation rates (60 to 160 beats/min) and increasing pulsed volumes (50 to 100 ml/beat) to simulate physiological changes occurring during stress echocardiography. There was a significant correlation (R² = 0.978, P <0.001) and a close agreement (bias ± 2SD, 0.39 ± 1.5%) between RS-SpT and RS-SN. For low strain values (<15%), speckle tracking showed a small but significant overestimation of radial strain compared to sonomicrometers. Two-way analysis of variance did not show any significant effect of the deformation rate. For RS-SpT, the feasibility was excellent and the intra- and inter-observer variability were low (the intraclass correlation coefficients were 0.96 and 0.97, respectively).

Conclusions

Speckle tracking demonstrated a good correlation with sonomicrometry for the assessment of radial strain independently of the heart rate and strain magnitude in a physiological range of values. Though speckle tracking seems to be a reliable and reproducible technique to assess myocardial deformation variations during stress echocardiography, further studies are mandated to analyze the impact of angulated and artefactual out-of-plane motions and inter-vendor variability.

Ultrasound functional imaging in an ex vivo beating porcine heart platform

In recent years, novel ultrasound functional imaging (UFI) techniques have been introduced to assess cardiac function by measuring, e.g. cardiac output (CO) and/or myocardial strain. Verification and reproducibility assessment in a realistic setting remain major issues. Simulations and phantoms are often unrealistic, whereas in vivo measurements often lack crucial hemodynamic parameters or ground truth data, or suffer from the large physiological and clinical variation between patients when attempting clinical validation. Controlled validation in certain pathologies is cumbersome and often requires the use of lab animals. In this study, an isolated beating pig heart setup was adapted and used for performance assessment of UFI techniques such as volume assessment and ultrasound strain imaging. The potential of performing verification and reproducibility studies was demonstrated. For proof-of-principle, validation of UFI in pathological hearts was examined. Ex vivo porcine hearts (n  =  6, slaughterhouse waste) were resuscitated and attached to a mock circulatory system. Radio frequency ultrasound data of the left ventricle were acquired in five short axis views and one long axis view. Based on these slices, the CO was measured, where verification was performed using flow sensor measurements in the aorta. Strain imaging was performed providing radial, circumferential and longitudinal strain to assess reproducibility and inter-subject variability under steady conditions. Finally, strains in healthy hearts were compared to a heart with an implanted left ventricular assist device, simulating a failing, supported heart. Good agreement between ultrasound and flow sensor based CO measurements was found. Strains were highly reproducible (intraclass correlation coefficients  >0.8). Differences were found due to biological variation and condition of the hearts. Strain magnitude and patterns in the assisted heart were available for different pump action, revealing large changes compared to the normal condition. The setup provides a valuable benchmarking platform for UFI techniques. Future studies will include work on different pathologies and other means of measurement verification.

Comparison of strain imaging techniques in CRT candidates: CMR tagging, CMR feature tracking and speckle tracking echocardiography

Parameters using myocardial strain analysis may predict response to cardiac resynchronization therapy (CRT). As the agreement between currently available strain imaging modalities is unknown, three different modalities were compared. Twenty-seven CRT-candidates, prospectively included in the MARC study, underwent cardiac magnetic resonance (CMR) imaging and echocardiographic examination. Left ventricular (LV) circumferential strain was analysed with CMR tagging (CMR-TAG), CMR feature tracking (CMR-FT), and speckle tracking echocardiography (STE). Basic strain values and parameters of dyssynchrony and discoordination obtained with CMR-FT and STE were compared to CMR-TAG. Agreement of CMR-FT and CMR-TAG was overall fair, while agreement between STE and CMR-TAG was often poor. For both comparisons, agreement on discoordination parameters was highest, followed by dyssynchrony and basic strain parameters. For discoordination parameters, agreement on systolic stretch index was highest, with fair intra-class correlation coefficients (ICC) (CMR-FT: 0.58, STE: 0.55). ICC of septal systolic rebound stretch (SRS_sept) was poor (CMR-FT: 0.41, STE: 0.30). Internal stretch factor of septal and lateral wall (ISF_sep-lat) showed fair ICC values (CMR-FT: 0.53, STE: 0.46), while the ICC of the total LV (ISF_LV) was fair for CMR-FT (0.55) and poor for STE (ICC: 0.32). The CURE index had a fair ICC for both comparisons (CMR-FT: 0.49, STE 0.41). Although comparison of STE to CMR-TAG was limited by methodological differences, agreement between CMR-FT and CMR-TAG was overall higher compared to STE and CMR-TAG. CMR-FT is a potential clinical alternative for CMR-TAG and STE, especially in the detection of discoordination in CRT-candidates.

The years 2015-2016 in the European Heart Journal-Cardiovascular Imaging. Part I

The multimodality cardiovascular imaging journal, European Heart Journal-Cardiovascular Imaging, was launched in 2012. It has gained an impressive impact factor of 5.99 during its 5 first years and is now established as the most important cardiovascular imaging journal in Europe. The most important studies from the journal's forth and fifth years will be highlighted in two reports. Part I of the review will focus on studies about myocardial function and risk prediction, myocardial ischaemia, and emerging techniques in cardiovascular imaging, while Part II will focus on valvular heart disease, heart failure, cardiomyopathies, and congenital heart disease.

Fast Simulation of Dynamic Ultrasound Images Using the GPU

Simulated ultrasound data is a valuable tool for development and validation of quantitative image analysis methods in echocardiography. Unfortunately, simulation time can become prohibitive for phantoms consisting of a large number of point scatterers. The COLE algorithm by Gao et al. is a fast convolution-based simulator that trades simulation accuracy for improved speed. We present highly efficient parallelized CPU and GPU implementations of the COLE algorithm with an emphasis on dynamic simulations involving moving point scatterers. We argue that it is crucial to minimize the amount of data transfers from the CPU to achieve good performance on the GPU. We achieve this by storing the complete trajectories of the dynamic point scatterers as spline curves in the GPU memory. This leads to good efficiency when simulating sequences consisting of a large number of frames, such as B-mode and tissue Doppler data for a full cardiac cycle. In addition, we propose a phase-based subsample delay technique that efficiently eliminates flickering artifacts seen in B-mode sequences when COLE is used without enough temporal oversampling. To assess the performance, we used a laptop computer and a desktop computer, each equipped with a multicore Intel CPU and an NVIDIA GPU. Running the simulator on a high-end TITAN X GPU, we observed two orders of magnitude speedup compared to the parallel CPU version, three orders of magnitude speedup compared to simulation times reported by Gao et al. in their paper on COLE, and a speedup of 27000 times compared to the multithreaded version of Field II, using numbers reported in a paper by Jensen. We hope that by releasing the simulator as an open-source project we will encourage its use and further development.

Speckle Tracking Stress Echocardiography Uncovers Early Subclinical Cardiac Involvement in Pediatric Patients with Inflammatory Bowel Diseases

Inflammatory bowel disease (IBD) is an established risk factor for cardiovascular disease (CVD). However, whether cardiac consequences present early in IBD is unknown. This is the first study in children aiming to unmask altered myocardial mechanics in IBD. We enrolled 50 consecutive normotensive children with Crohn’s disease (CD) (n = 28) or ulcerative colitis (UC) (n = 22). The study groups consisted of 18 patients with active inflammatory disease (mean age 14.6 ± 2.5 years) and 32 children with IBD in remission (14.3 ± 2.3 years). 60 age- and gender-matched children served as healthy controls. Speckle tracking stress echocardiography (STE) was used to assess left ventricular (LV) myocardial strain and strain rate. Circumferential strain rate was significantly decreased in children with active IBD (−1.55 ± 0.26 s⁻¹) and IBD in remission (−1.49 ± 0.26 s⁻¹) versus healthy controls (1.8 ± 0.4 s⁻¹) both at rest (p < 0.001) and during exercise (p = 0.021). Moreover, longitudinal strain rate, circumferential strain and E/E′ ratio were significantly impaired in IBD. Pediatric patients with IBD feature subclinical signs of LV systolic and diastolic myocardial impairment early in the course of CD and UC. This may not be reversible even when IBD is clinically controlled. Patients with IBD should be regularly screened for signs of CVD.

Feasibility and Reproducibility of Two-Dimensional Wall Motion Tracking (WMT) in Fetal Echocardiography

Objective The primary objective of this study was to determine the feasibility and reproducibility of 2-dimensional speckle tracking imaging based on the wall motion tracking (WMT) technique in fetal echocardiography. The secondary objective was to compare left and right ventricular global and segmental longitudinal peak strain values. Methods A prospective cross-sectional study was performed. Global and segmental longitudinal peak strain values of the left ventricle (LV) and right ventricle (RV) were assessed prospectively. Based on apical 4-chamber views, cine loops were acquired and digitally stored. Strain analysis was performed offline. Intra- and interobserver variabilities were analyzed. Results A total of 29 healthy fetuses with an echocardiogram performed between 19 and 37 weeks of gestation were included. Analysis was performed with a temporal resolution of 60 frames per second (fps). For both examiners, in all cases Cronbach's alpha was>0.7. The interobserver variability showed a strong agreement in 50% of the segments (ICC 0.71-0.90). The global strain values for LV and RV were -16.34 and -14.65%, respectively. Segmental strain analysis revealed a basis to apex gradient with the lowest strain values in basal segments and the highest strain values in apical segments. Conclusion The assessment of fetal myocardial deformation parameters by 2D WMT is technically feasible with good reproducibility.

In-vivo validation of a new clinical tool to quantify three-dimensional myocardial strain using ultrasound

Three-dimensional (3D) strain analysis based on real-time 3-D echocardiography (RT3DE) has emerged as a novel technique to quantify regional myocardial function. The goal of this study was to evaluate accuracy of a novel model-based 3D tracking tool (eSie Volume Mechanics, Siemens Ultrasound, Mountain View, CA, USA) using sonomicrometry as an independent measure of cardiac deformation. Thirteen sheep were instrumented with microcrystals sutured to the epi- and endocardium of the inferolateral left ventricular wall to trace myocardial deformation along its three directional axes of motion. Paired acquisitions of RT3DE and sonomicrometry were made at baseline, during inotropic modulation and during myocardial ischemia. Accuracy of 3D strain measurements was quantified and expressed as level of agreement with sonomicrometry using linear regression and Bland-Altman analysis. Correlations between 3D strain analysis and sonomicrometry were good for longitudinal and circumferential strain components (r = 0.78 and r = 0.71) but poor for radial strain (r = 0.30). Accordingly, agreement (bias ± 2SD) was -5 ± 6 % for longitudinal, -5 ± 7 % for circumferential, and 15 ± 19 % for radial strain. Intra-observer variability was low for all components (intra-class correlation coefficients (ICC) of respectively 0.89, 0.88 and 0.95) while inter-observer variability was higher, in particular for radial strain (ICC = 0.41). The present study shows that 3D strain analysis provided good estimates of circumferential and longitudinal strain, while estimates of radial strain were less accurate between observers.

Optimal Acquisition Settings for Speckle Tracking Echocardiography-Derived Strains in Infants: An In Vitro Study

The purpose of this study was to investigate the effect of frame rate and probe frequency on the accuracy of speckle tracking echocardiography-derived strain measurements in infants. An infant-sized left ventricle phantom with sonomicrometer crystals was made from polyvinyl alcohol. The examined stroke rates were 60, 120 and 180 strokes per min (SPM). Longitudinal strain and circumferential strain measurements were analyzed from a total of 1860 cine loops. These cine loops were acquired using two pediatric probes of different frequencies at both fundamental and harmonic imaging modes. Both probes were examined at different settings (in total, 30 different frame rate-frequency combinations). At optimal settings, both longitudinal and circumferential strain displayed high accuracy. Frequency settings did not have a consistent effect on accuracy, while low frame rates led to less accurate measurements. We recommend a frame rate/heart ratio >1 frame per second/beats per min, especially for circumferential strain.

Frame rate required for speckle tracking echocardiography: A quantitative clinical study with open-source, vendor-independent software

OBJECTIVES

To determine the optimal frame rate at which reliable heart walls velocities can be assessed by speckle tracking.

BACKGROUND

Assessing left ventricular function with speckle tracking is useful in patient diagnosis but requires a temporal resolution that can follow myocardial motion. In this study we investigated the effect of different frame rates on the accuracy of speckle tracking results, highlighting the temporal resolution where reliable results can be obtained.

MATERIAL AND METHODS

27 patients were scanned at two different frame rates at their resting heart rate. From all acquired loops, lower temporal resolution image sequences were generated by dropping frames, decreasing the frame rate by up to 10-fold.

RESULTS

Tissue velocities were estimated by automated speckle tracking. Above 40 frames/s the peak velocity was reliably measured. When frame rate was lower, the inter-frame interval containing the instant of highest velocity also contained lower velocities, and therefore the average velocity in that interval was an underestimate of the clinically desired instantaneous maximum velocity.

CONCLUSIONS

The higher the frame rate, the more accurately maximum velocities are identified by speckle tracking, until the frame rate drops below 40 frames/s, beyond which there is little increase in peak velocity. We provide in an online supplement the vendor-independent software we used for automatic speckle-tracked velocity assessment to help others working in this field.

The influence of acute unloading on left ventricular strain and strain rate by speckle tracking echocardiography in a porcine model

Noninvasive measurements of myocardial strain and strain rate by speckle tracking echocardiography correlate to cardiac contractile state but also to load, which may weaken their value as indices of inotropy. In a porcine model, we investigated the influence of acute dynamic preload reductions on left ventricular strain and strain rate and their relation to the pressure-conductance catheter-derived preload recruitable stroke work (PRSW) and peak positive first derivative of left ventricular pressure (LV-dP/dtmax). Speckle tracking strain and strain rate in the longitudinal, circumferential, and radial directions were measured during acute dynamic reductions of end-diastolic volume during three different myocardial inotropic states. Both strain and strain rate were sensitive to unloading of the left ventricle (P < 0.001), but the load dependency for strain rate was modest compared with strain. Changes in longitudinal and circumferential strain correlated more strongly to changes in end-diastolic volume (r = -0.86 and r = -0.72) than did radial strain (r = 0.35). Longitudinal, circumferential, and radial strain significantly correlated with LV-dP/dtmax (r = -0.53, r = -0.46, and r = 0.86), whereas only radial strain correlated with PRSW (r = 0.55). Strain rate in the longitudinal, circumferential and radial direction significantly correlated with both PRSW (r = -0.64, r = -0.58, and r = 0.74) and LV-dP/dtmax (r = -0.95, r = -0.70, and r = 0.85). In conclusion, the speckle tracking echocardiography-derived strain rate is more robust to dynamic ventricular unloading than strain. Longitudinal and circumferential strain could not predict load-independent contractility. Strain rates, and especially in the radial direction, are good predictors of preload-independent inotropic markers derived from conductance catheter.

Subclinical Alterations of Cardiac Mechanics Present Early in the Course of Pediatric Type 1 Diabetes Mellitus: A Prospective Blinded Speckle Tracking Stress Echocardiography Study

Diabetic cardiomyopathy substantially accounts for mortality in diabetes mellitus. The pathophysiological mechanism underlying diabetes-associated nonischemic heart failure is poorly understood and clinical data on myocardial mechanics in early stages of diabetes are lacking. In this study we utilize speckle tracking echocardiography combined with physical stress testing in order to evaluate whether left ventricular (LV) myocardial performance is altered early in the course of uncomplicated type 1 diabetes mellitus (T1DM). 40 consecutive asymptomatic normotensive children and adolescents with T1DM (mean age 11.5 ± 3.1 years and mean disease duration 4.3 ± 3.5 years) and 44 age- and gender-matched healthy controls were assessed using conventional and quantitative echocardiography (strain and strain rate) during bicycle ergometer stress testing. Strikingly, T1DM patients had increased LV longitudinal (p = 0.019) and circumferential (p = 0.016) strain rate both at rest and during exercise (p = 0.021). This was more pronounced in T1DM patients with a longer disease duration (p = 0.038). T1DM patients with serum HbA1c > 9% showed impaired longitudinal (p = 0.008) and circumferential strain (p = 0.005) and a reduced E/A-ratio (p = 0.018). In conclusion, asymptomatic T1DM patients have signs of hyperdynamic LV contractility early in the course of the disease. Moreover, poor glycemic control is associated with early subclinical LV systolic and diastolic impairment.