Global Strain Measurements Research Articles

Detection of the Strains Induced in Murine Tibias by Ex Vivo Uniaxial Loading with Different Sensors.

In this paper, the characterization of the main techniques and transducers employed to measure local and global strains induced by uniaxial loading of murine tibiae is presented. Micro strain gauges and digital image correlation (DIC) were tested to measure local strains, while a moving coil motor-based length transducer was employed to measure relative global shortening. Local strain is the crucial parameter to be measured when dealing with bone cell mechanotransduction, so we characterized these techniques in the experimental conditions known to activate cell mechanosensing in vivo. The experimental tests were performed using tibia samples excised from twenty-two C57BL/6 mice. To evaluate measurement repeatability we computed the standard deviation of ten repetitive compressions to the mean value. This value was lower than 3% for micro strain gauges, and in the range of 7%–10% for DIC and the length transducer. The coefficient of variation, i.e., the standard deviation to the mean value, was about 35% for strain gauges and the length transducer, and about 40% for DIC. These results provided a comprehensive characterization of three methodologies for local and global bone strain measurement, suggesting a possible field of application on the basis of their advantages and limitations.

The effect of local rebar geometry on global strain measurements in pull out tests

AbstractStrain gauges are the common means to measure local strains in structural elements. It is well known that the strain at a given coordinate on the boundary of a structural element depends on the geometry, boundary conditions, loading system, and material properties. The precise location of the strain gauge along a line is not considered critical to obtaining a quality strain measurement at a specific location, wherever a continuous variation of strain along this line is expected, and a slight deviation of the gauge location will yield similar measurements. In a recent study, precise measurement of the circumferential strains on the outer face of cylindrical concrete specimens was carried out during pullout of a central rebar. Analyzing the measured data indicated that a slight shift in the strain gauge location on the order of millimeters only may considerably affect the measured strain. These controlled pullout tests highlighted the pronounced effect of the relative distance between the rebar rib and the strain gauge location on the strain magnitude and its variation with the increasing slip. This effect has not been reported before. It means that a slight difference in the strain gauge location yields different strain–slip relationships. This new finding may affect the interpretation of the measured strains. Attention should be given to the exact strain gauges' locations and detailed rebar ribs locations to properly interpret the measured data.

Validation of Finite Element Image Registration‐based Cardiac Strain Estimation from Magnetic Resonance Images

AbstractAccurate assessment of regional and global function of the heart is an important readout for the diagnosis and routine evaluation of cardiac patients. Indeed, recent clinical and experimental studies suggest that compared to global metrics, regional measures of function could allow for more accurate diagnosis and early intervention for many cardiac diseases. Although global strain measures derived from tagged magnetic resonance (MR) imaging have been shown to be reproducible for the majority of image registration techniques, the measurement of regional heterogeneity of strain is less robust. Moreover, radial strain is underestimated with the current techniques even globally. Finite element (FE)‐based techniques offer a mechanistic approach for the regularization of the ill‐posed registration problem. This paper presents the validation of a recently proposed FE‐based image registration method with mechanical regularization named equilibrated warping. For this purpose, synthetic 3D‐tagged MR images are generated from a reference biomechanical model of the left ventricle (LV). The performance of the registration algorithm is consequently tested on the images with different signal‐to‐noise ratios (SNRs), revealing the robustness of the method.

Normal Ranges of Left Ventricular Strain by Three-Dimensional Speckle-Tracking Echocardiography in Adults: A Systematic Review and Meta-Analysis

Establishing normal values and associated variations of three-dimensional speckle-tracking echocardiography- (3DSTE-) derived left ventricular (LV) strain is necessary for accurate interpretation and comparison of measurements. We aimed to perform a meta-analysis of normal ranges of LV global longitudinal strain (GLS), global circumferential strain (GCS), global radial strain (GRS), and global area strain (GAS) measurements derived by 3DSTE and to identify confounding factors that may contribute to variance in reported measures. The authors searched four databases, PubMed, Scopus, Embase, and Cochrane Library, through January 2019 using the key terms "left ventricular/left ventricle/left ventricles", "strain/deformation/speckle tracking", and "three dimensional/three-dimensional/three-dimension/three dimension/3D". Studies were included if the articles reported LV strain using 3DSTE in healthy normal subjects, either in the control group or comprising the entire study cohort. The weighted mean was estimated by using the random effects model with a 95% CI. Heterogeneity across studies was assessed using the I2 test. Effects of demographic (age), clinical, and vendor variables were assessed in a metaregression. The National Institutes of Health tools were used to assess the quality of included articles. Publication bias was examined by Begg's funnel plot and Egger's regression test. The search yielded 895 articles. After abstract and full-text screening we included 33 data sets with 2,346 patients for meta-analysis. The reported normal mean values of GLS among the studies varied from -15.80% to -23.40% (mean, -19.05%; 95% CI, -18.18% to -19.93%; I2=99.0%), GCS varied from -15.50% to -39.50% (mean, -22.42%; 95% CI, -20.96% to -23.89%, I2=99.7%), GRS varied from 19.81% to 86.61% (mean, 47.48%; 95% CI, 41.50%-53.46%; I2=99.8%), and GAS varied from -27.40% to -50.80% (mean, -35.03%; 95% CI, -33.19% to -36.87%; I2=99.3%). Software for strain analysis was consistently associated with variations in normal strain values (GLS: P=.016; GCS: P<.001; GRS: P<.001; GAS: P<.001). Variations in the normal ranges across studies were significantly associated with the software used for strain analysis, emphasizing that this factor must be considered in the interpretation of strain data.

How Does Regional Hypertrophy Affect Strain Measurements With Different Speckle-Tracking Methods?

In this study, we evaluate the impact of abnormal myocardial shapes, such as regional hypertrophy, on longitudinal strain measurements with different tracking approaches. We selected 40 patients with normal ejection fraction and prominent septal bulge. We assessed longitudinal strain with full wall (FW) tracking, (GE EchoPAC) as well as endo-, mid-, and epicardial (EME) tracking (Tomtec ImageArena), on the same image acquired with a GE machine (using raw data and full frame rate DICOM data, respectively). We used a region of interest (ROI) which follows precisely the endo- and epicardial contours (true contour ROI) and one where the bulging region was excluded (straight ROI). In segments with bulge, absolute segmental longitudinal strain values were in all myocardial layers significantly higher with a straight ROI compared to a true contour ROI, both with FW tracking and EME tracking. The highest difference was found in the endocardial layer (3.4 ± 2.5% and 7.7 ± 7.1%, respectively, both P < 0.001). In the bulged segments, the effect of ROI shape was more pronounced in EME tracking software compared to FW tracking software. Bulged segments also influenced global longitudinal strain measurements, mostly in the endocardial layer (P < 0.001). Global longitudinal strain values obtained with the straight ROI correlated better with longitudinal fractional shortening of the LV. Regional bulging has a significant effect on both global and segmental strain measurements. Endocardial strain values obtained with EME tracking and a true contour ROI were most sensitive to bulging. Midwall strain values derived from FW tracking using a straight ROI were most robust.

Regional Versus Global Measurements of Right Ventricular Strain Performed in the Operating Room With Transesophageal Echocardiography

To compare regional and global measures of right ventricular (RV) strain in patients undergoing intraoperative transesophageal echocardiography (TEE). Prospective, nonrandomized, observational study. Single tertiary-level, university hospital. The study comprised 48 patients undergoing intraoperative TEE. None. A global RV strain measurement (termed RV 5-wall strain [RV 5WS]) was calculated by averaging the longitudinal strain calculated from multiple TEE views. This global strain measurement was compared with the more standard regional strain measurements obtained in a single 4-chamber view (RV free-wall strain [RV FWS] and RV global longitudinal strain [RV GLS]) and with traditional measures of RV function. Regional and global strain measurements were feasible in the operating room. RV FWS and RV GLS strongly correlated with RV 5WS (r = 0.86 and 0.87, respectively) with no significant bias and limits of agreement of approximately -5% to 5%. RV FWS and RV GLS were even more closely correlated with each other (r = 0.99) with no significant bias and limits of agreement less than -2% to 2%. Both regional and global RV strain measurements showed a high sensitivity (RV FWS 94%; RV GLS 94%; RV 5WS 89%) and moderate specificity (RV FWS 70%; RV GLS 67%; RV 5WS 63%) for RV dysfunction based on a reference standard of 3-dimensional RV ejection fraction. Both regional and global RV strain measurements are feasible in the operating room with TEE. Regional and global measures of RV function correlate well and are sensitive indicators of RV dysfunction.

Low-to-high cycle fatigue properties of a NiTi shape memory alloy

Low-to-high cycle fatigue behavior of a pseudoelastic NiTi SMA was analyzed. The evolution of both global and local strain were captured during fatigue tests. Local strains were measured in-situ by the digital image correlation (DIC) technique. Significant differences were observed at the two scales, due to the localized nature of stress-induced transformations. Strain-life fatigue curves obtained from global and local strain measurements were compared. It was demonstrated that local phenomena play a very important role on the fatigue properties of pseudoelastic SMAs.

Assessment of global and regional strain left ventricular in patients with preserved ejection fraction after Fontan operation using a tissue tracking technique

To evaluate the use of the tissue tracking (TT) technique to measure myocardial strain left ventricular in post-Fontan children with preserved ejection fraction (pEF). Nineteen (male/female, 10/9) patients with univentricular hearts after completion of the Fontan circulation (post-Fontan group) and 19 age- and gender-matched healthy children (control group) were retrospectively enrolled. Cardiovascular magnetic resonance (CMR) imaging was conducted on a 1.5-T MRI scanner. Global and regional strains of the left ventricle in post-Fontan patients (EF > 55%) and controls were obtained using CMR-TT software. The Mann-Whitney U test was used to compare parameters between the two groups. Correlation between EF and strain was investigated using Pearson correlation coefficients. The Bland-Altman method was used to identify the inter- and intra-observer agreement in measurement of global strain. Global longitudinal strain was lower in post-Fontan patients than in healthy controls (- 18.87 ± 4.61 vs. -19.72 ± 1.58; P = 0.54), though the difference was not statistically significant. Global circumferential strain and global radial strain were significantly lower in post-Fontan patients than in healthy controls (- 14.55 ± 3.79 vs. -19.91 ± 1.97; P < 0.001; and 29.62 ± 8.41 vs. 36.85 ± 5.95; P = 0.01; respectively). The regional circumferential strain (RCS) decrease was marked in regional segments compare with post-Fontan patients and controls (basal, - 11.81 ± 2.98 vs. - 16.21 ± 2.72, P < 0.001; mid, - 15.05 ± 3.31 vs. - 20.17 ± 2.28, P = 0.005; apical, - 16.86 ± 3.09 vs. - 23.37 ± 2.62, P < 0.001). All circumferential and longitudinal parameters had an inter-observer ICC of ≥ 0.85, but this coefficient was lower for radial parameters. CMR-TT appears to be a feasible technique for identification of early myocardial dysfunction in post-Fontan with pEF.

Myocardial strain imaging by cardiac magnetic resonance for detection of subclinical myocardial dysfunction in breast cancer patients receiving trastuzumab and chemotherapy

BackgroundOur objectives were to evaluate the temporal changes in CMR-based strain imaging, and examine their relationship with left ventricular ejection fraction (LVEF), in patients treated with trastuzumab. Patients and methodsIn this prospective longitudinal observational study, 41 women with HER2+ breast cancer treated with chemotherapy underwent serial CMR (baseline, 6, 12, and 18 months) after initiation of trastuzumab (treatment duration 12 months). LVEF and LV strain (global longitudinal[GLS] and circumferential[GCS]) measurements were independently measured by 2 blinded readers. ResultsOf the 41 patients, 56% received anthracycline-based chemotherapy. Compared to baseline (60.4%, 95%CI 59.2–61.7%), there was a small but significant reduction in LVEF at 6 months (58.4%, 95%CI 56.7–60.0%, p = 0.034) and 12 months (57.9%, 95%CI 56.4–59.7%, p = 0.012), but not at 18 months (60.2%, 95%CI 58.2–62.2%, p = 0.93). Similarly, compared to baseline, GLS and GCS decreased significantly at 6 months (p = 0.024 and < 0.001, respectively) and 12 months (p = 0.002 and < 0.001, respectively) with an increase in LV end-diastolic volume, but not at 18 months. There were significant correlations between the temporal (6 month-baseline) changes in LVEF, and all global strain measurements (Pearson's r = −0.60 and r = −0.75 for GLS and GCS, respectively, all p < 0.001). ConclusionThere was a significant reduction in LV strain during trastuzumab treatment, which correlated with a concurrent subtle decline in LVEF and was associated with an increase in LV end-diastolic volume. LV strain assessment by CMR may be a promising method to monitor for subclinical myocardial dysfunction in breast cancer patients receiving chemotherapy. Future studies are needed to determine its prognostic and therapeutic implications.

Evaluation of the left venticular systolic function with the measurement of global longitudinal strain by Speckle tracking echocardiography in anaphylaxis

BackgroundIt is not known how cardiac functions are affected during anaphylaxis.ObjectiveOur aim was to measure the cardiac functions shortly after an anaphylaxis attack using a new technique that detects subclinical left ventricular dysfunction.MethodsPatients in our hospital who experienced anaphylaxis and urticaria (control group) due to any cause were included in the study. Tryptase levels were measured on the third hour of the reaction and 6 weeks later. Left ventricular systolic functions were evaluated with global strain measurement using echocardiography, approximately 4 hours and 6-week post reaction.ResultsTwelve patients were included in the anaphylaxis group (83.3% female; mean age, 43.25 ± 9.9 years). The causes of anaphylaxis were drug ingestion (n = 11) and venom immunotherapy. Eight of the anaphylactic reactions (66.7%) were severe and in 9 reactions (75%) tryptase levels increased. In the anaphylaxis group, strain values measured shortly after anaphylaxis were significantly lower than those calculated 6 weeks later (p < 0.001) and tryptase levels significantly increased (p = 0.002). The strain values measured both shortly after anaphylaxis and 6 weeks later did not differ according to severity of anaphylaxis. In severe anaphylaxis, tryptase levels during anaphylaxis and 6 weeks later were significantly higher (p = 0.019, p = 0.035). The control group evidenced no differences regarding strain and tryptase levels measured at reaction and 6 weeks later. At reaction, in the anaphylaxis group, the tryptase levels were higher and the strain values were lower than those in the urticaria group (p = 0.007, p = 0.003).ConclusionCardiac dysfunction may develop during an anaphylaxis independent of severity of reaction.

A novel approach to simulate the stiffness behaviour of spot welded vehicle structures under multi axial variable amplitude loading

Under cyclic loading in combination with high local stress levels a change in stiffness of connection points, e.g. spot welds, self-piercing rivets or flow drill screws can be observed. This paper introduces a numerical approach for the simulation of stiffness changes in vehicle structures under multiaxial cyclic loading as a result of the stiffness degradation of individual spot welds. The basic approach is based on a conventional damage accumulation combined with a power law representing the change in the spot weld’s stiffness. Instead of an accumulated damage value D a residual stiffness is set as failure criterion. Extensions to the approach are presented for its application to multiaxial loading with variable amplitudes. A conventional multiaxial fatigue test of a complete vehicle, focusing on its rear end including global stiffness and local strain measurements at the beginning, median and at the end of the test are presented and compared to the simulated results. This computation approach allows a more reliable fatigue assessment in comparison to a fatigue analysis which does not consider stiffness changes. The damage propagation after the crack initiation at an individual spot weld is represented more accurately as subsequent changes in the load paths are considered.

Multi-layered sensor yarns for in situ monitoring of textile reinforced composites

In this contribution, the characteristic of yarns that have intrinsically conductivity as well as such with coaxial conductive coatings acting as in situ strain sensors are described. The objective of the based research projects is the real-time in situ sensing of both global stresses acting on fibre reinforced plastic (FRP) components and the detection of resulted local microscopic damages due to creep, delamination and micro-cracks in the fibre-matrix interphase of glass fibre (GFRP) and carbon fibre (CFRP) composites. Sensor materials similar to the particular FRP and its mechanical behaviour have been chosen. In the first approach, GF- and aramid-based sensor yarns have been developed with multiple tailored silver layer coating system capable to distinguish multiple scaled damage mechanism due to these effects globally and locally. The second approach bases on the piezoresistive effect of CF rovings for their usage as in situ strain sensors. In the next step, suitable fibre and polymer film-based cleading have been tested and evaluated, granting sufficient electrical isolation to avoid shortcircuits between the conductive sensor layers itself or between the sensor and intrinsically conductive CFRP respectively. Initially, the sensor performance of global strain measurement, means the accumulated strain along the integration length of the sensor yarn, has been evaluated during tensile stressing of FRP with integrated suchlike functionalised sensor yarns.

Full-field, high-spatial-resolution detection of local structural damage from low-resolution random strain field measurements

Structural damage is typically a local phenomenon that initiates and propagates within a limited area. As such high spatial resolution measurement and monitoring is often needed for accurate damage detection. This requires either significantly increased costs from denser sensor deployment in the case of global simultaneous/parallel measurements, or increased measurement time and labor in the case of global sequential measurements. This study explores the feasibility of an alternative approach to this problem: a computational solution in which a limited set of randomly positioned, low-resolution global strain measurements are used to reconstruct the full-field, high-spatial-resolution, two-dimensional (2D) strain field and rapidly detect local damage. The proposed approach exploits the implicit low-rank and sparse data structure of the 2D strain field: it is highly correlated without many edges and hence has a low-rank structure, unless damage—manifesting itself as sparse local irregularity—is present and alters such a low-rank structure slightly. Therefore, reconstruction of the full-field, high-spatial-resolution strain field from a limited set of randomly positioned low-resolution global measurements is modeled as a low-rank matrix completion framework and damage detection as a sparse decomposition formulation, enabled by emerging convex optimization techniques. Numerical simulations on a plate structure are conducted for validation. The results are discussed and a practical iterative global/local procedure is recommended. This new computational approach should enable the efficient detection of local damage using limited sets of strain measurements.

Comparison of Displacement Encoding With Stimulated Echoes to Magnetic Resonance Feature Tracking for the Assessment of Myocardial Strain in Patients With Acute Myocardial Infarction

The aim of this study was to compare myocardial strain by cardiovascular magnetic resonance feature tracking (CMR-FT) to those derived from displacement encoding with stimulated echoes (DENSE) in patients with acute myocardial infarction (AMI). Twenty patients (65 pa13years) with AMI underwent cine, DENSE, black-blood T2-weighted and late gadolinium enhancement CMR at 1.5T. Global and segmental strain was determined by CMR-FT analysis and DENSE on matched 3 short-axis planes. Global circumferential strain by CMR-FT showed a good agreement with that by DENSE (r= 0.85, p <0.001; bias 0.02, limits of agreement-0.03 to 0.06). For segmental circumferential strain, r coefficient between CMR-FT and DENSE was 0.61 (p <0.001) with bias of 0.02, limits of agreement of-0.07 to 0.11. Regional circumferential strain determined by CMR-FT in infarct segments (-0.08 ± 0.05) was significantly altered compared with that in remote normal segments (-0.15 ± 0.05, p <0.001). CMR-FT measurement of regional and global circumferential strain showed good agreement with DENSE in patients with AMI.

Crack monitoring using multiple smart materials; fiber-optic sensors & piezo sensors

ABSTRACTThis article focuses on health monitoring of structures using multiple smart materials. In this research, two fiber-optic sensors, namely fiber Bragg grating (FBG) and fiber-optic polarimetric sensor (FOPS), are investigated for damage detection in the beam specimen. FBG is used for local strain measurement while FOPS is used for global strain measurement. Both FBG and FOPS show significant changes in the strain due to damages in the specimen. Also, at the center of the specimen, piezoelectric wafer active sensor (PWAS) is attached. The electromechanical admittance (EMA) signature of the specimen beam is recorded by PWAS. The changes in the amplitudes of the peaks obtained at various frequencies in this EMA signature are analyzed, and it is shown that the peak amplitudes respond differently to damages and to change in loading. Thus, multiple smart materials (FBG, FOPS, and PWAS) are used to get improved information on the health of the beam.

Measurement of strains experienced by viscerofugal nerve cell bodies during mechanosensitive firing using digital image correlation.

Mechanosensory neurons detect physical events in the local environments of the tissues that they innervate. Studies of mechanosensitivity of neurons or nerve endings in the gut have related their firing to strain, wall tension, or pressure. Digital image correlation (DIC) is a technique from materials engineering that can be adapted to measure the local physical environments of afferent neurons at high resolution. Flat-sheet preparations of guinea pig distal colon were set up with arrays of tissue markers in vitro. Firing of single viscerofugal neurons was identified in extracellular colonic nerve recordings. The locations of viscerofugal nerve cell bodies were inferred by mapping firing responses to focal application of the nicotinic receptor agonist 1,1-dimethyl-4-phenylpiperazinium iodide. Mechanosensory firing was recorded during load-evoked uniaxial or biaxial distensions. Distension caused movement of surface markers which was captured by video imaging. DIC tracked the markers, interpolating the mechanical state of the gut at the location of the viscerofugal nerve cell body. This technique revealed heterogeneous load-evoked strain within preparations. Local strains at viscerofugal nerve cell bodies were usually smaller than global strain measurements and correlated more closely with mechanosensitive firing. Both circumferential and longitudinal strain activated viscerofugal neurons. Simultaneous loading in circumferential and longitudinal axes caused the highest levels of viscerofugal neuron firing. Multiaxial strains, reflecting tissue shearing and changing area, linearly correlated with mechanosensory firing of viscerofugal neurons. Viscerofugal neurons were mechanically sensitive to both local circumferential and local longitudinal gut strain, and appear to lack directionality in their stretch sensitivity.

Comparison of heart deformation analysis and cine DENSE in volunteers and heart failure patients

Background Post-processing methods have been developed to quantify myocardial strain from steady-state free-precession (SSFP) cine images. In the left ventricle (LV), global strain measurements from SSFP in healthy volunteers and in some types of heart disease compare favorably with myocardial tagging as a reference. We compared heart deformation analysis (HDA) of SSFP images and cine Displacement Encoding with Stimulated Echoes (DENSE) for the assessment of global and segmental circumferential strain (Ecc) and derivative indices in healthy volunteers and heart failure (HF) patients with left bundle branch block (LBBB).

Reference Ranges of Left Ventricular Strain Measures by Two-Dimensional Speckle-Tracking Echocardiography in Children: A Systematic Review and Meta-Analysis

Establishment of the range of reference values and associated variations of two-dimensional speckle-tracking echocardiography (2DSTE)-derived left ventricular (LV) strain is a prerequisite for its routine clinical adoption in pediatrics. The aims of this study were to perform a meta-analysis of normal ranges of LV global longitudinal strain (GLS), global circumferential strain (GCS), and global radial strain (GRS) measurements derived by 2DSTE in children and to identify confounding factors that may contribute to variance in reported measures. A systematic review was launched in MEDLINE, Embase, Scopus, the Cumulative Index to Nursing and Allied Health Literature, and the Cochrane Library. Search hedges were created to cover the concepts of pediatrics, STE, and left-heart ventricle. Two investigators independently identified and included studies if they reported 2DSTE-derived LV GLS, GCS, or GRS. The weighted mean was estimated by using random effects models with 95% CIs, heterogeneity was assessed using the Cochran Q statistic and the inconsistency index (I(2)), and publication bias was evaluated using the Egger test. Effects of demographic (age), clinical, and vendor variables were assessed in a metaregression. The search identified 2,325 children from 43 data sets. The reported normal mean values of GLSamong the studies varied from -16.7% to -23.6% (mean, -20.2%; 95% CI, -19.5% to -20.8%), GCS varied from -12.9% to -31.4% (mean, -22.3%; 95% CI, -19.9% to -24.6%), and GRS varied from 33.9% to 54.5% (mean, 45.2%; 95% CI, 38.3% to 51.7%). Twenty-six studies reported longitudinal strain only from the apical four-chamber view, with a mean of -20.4% (95% CI, -19.8% to -21.7%). Twenty-three studies reported circumferential strain (mean, -20.3%; 95% CI, -19.4% to -21.2%) and radial strain (mean, 46.7%; 95% CI, 42.3% to 51.1%) from the short-axis view at the midventricular level. A significant apex-to-base segmental longitudinal strain gradient (P<.01) was observed in the LV free wall. There was significant between-study heterogeneity and inconsistency (I(2)>94% and P<.001 for each strain measure), which was not explained by age, gender, body surface area, blood pressure, heart rate, frame rate, frame rate/heart rate ratio, tissue-tracking methodology, location of reported strain value along the strain curve, ultrasound equipment, or software. The metaregression showed that these effects were not significant determinants of variations among normal ranges of strain values. There was no evidence of publication bias (P=.40). This study defines reference values of 2DSTE-derived LV strain in children on the basis of a meta-analysis. In healthy children, mean LV GLS was -20.2% (95% CI, -19.5% to -20.8%), mean GCS was -22.3% (95% CI, -19.9% to -24.6%), and mean GRS was 45.2% (95% CI, 38.3% to 51.7%). LV segmental longitudinal strain has a stable apex-to-base gradient that is preserved throughout maturation. Although variations among different reference ranges in this meta-analysis were not dependent on differences in demographic, clinical, or vendor parameters, age- and vendor-specific referenced ranges were established as well.

Regional cardiac dysfunction and outcome in patients with left ventricular dysfunction, heart failure, or both after myocardial infarction.

Global measures of left ventricular (LV) function, in particular LV ejection fraction (LVEF) and global myocardial strain measures, are powerful predictors of outcomes in patients with LV dysfunction, heart failure, or both. However, less is known about the relationship between regional myocardial function, especially that assessed by strain echocardiography and clinical prognosis. We studied 248 patients with LV dysfunction, heart failure, or both 5 days after first myocardial infarction (MI) from the VALIANT study. We assessed peak longitudinal strain (LS) via B-mode speckle tracking in 12 segments from the apical 4- and 2-chamber views and visually assessed LV wall motion score (WMS). We related these measures of regional myocardial function to each other and to clinical outcomes over 20-month follow-up. Normal reference values for segmental LS were derived from 50 healthy controls. Regional LS (-7.7%, Q1: -11.2%, Q3: -4.9%) was worse in segments with abnormal WMS, although was significantly impaired even in segments scored as normokinetic compared with normal controls (-10.4 ± 5.2% vs. -20.0 ± 7.6%, P < 0.001). In multivariable Cox proportional hazards models, each additional abnormal LS segment was associated with an increased risk of all-cause mortality (hazard ratio: 1.42, 95% confidence interval: 1.06-1.90, P = 0.02) even after adjustment for clinical covariates, including LVEF, LV end-systolic volume, and number of abnormal segments by WMS. In patients with LV dysfunction, heart failure, or both after MI, regional LS is significantly depressed even in segments with normal WMS, and this measure was related to adverse outcome.

Evaluation of torsion and twist mechanics of the left ventricle in patients with systemic lupus erythematosus.

Objective:Myocardial involvement in systemic lupus erythematosus (SLE) has great importance. The aim of this study is to evaluate the rotation and twisting mechanics of the left ventricle (LV) in patients with SLE.Methods:Forty-three patients fulfilled at least four of the American College of Rheumatology criteria for SLE and 30 individuals as controls were included in the study. SLE disease activity was assessed using the SELENA–SLEDAI score. Echocardiography was performed for all subjects. The patients fulfilled at least four of the American College of Rheumatology criteria for SLE were enrolled in the study. SLE disease activity was assessed using the SELENA-SLEDAI score. Echocardiography was performed for all individuals. Comparisons between groups were made using independent samples t-test with the standard statistical software (SPSS, version 15.0; SPSS Inc., Chicago, IL, USA). Each image was digitally stored for offline analysis. Measurement of global strain assessed by 17-segment model and rotational parameters were performed. LV ejection fraction was calculated by the biplane Simpson's method. Comparisons between groups were made using the independent samples t-test with the standard statistical software. A p value of 0.05 was considered statistically significant.Results:The values of mean global longitudinal strain, basal global circumferential strain (GCS), mean basal radial strain, and apical GCS were significantly lower in SLE patients. The difference between basal rotation, apical rotation, twist of the LV, and torsion of the LV in the SLE patients and controls were not significant (8.8±5.5 vs. 10.6±5.8, p=0.183;-4.7±3.0 vs. -4.8±3.2, p=0.947; 11.7±6.4 vs. 13.2±6.4, p=0.366; and 1.8±0.8 vs. 1.9±2.3, p=0.725, respectively). Although there was not any significant relationship between SELENA–SLEDAI score and myocardial strain analyses of the LV, the basal rotation and the torsion of the LV were lower in patients with SLE having a SLEDAI score of ≥17 (p=0.024 for basal rotation and p=0.032 for torsion).Conclusion:The number of segmental and global strain analyses were decreased in SLE patients with globally normal LVEF. The twist and torsion mechanics of the LV were preserved according to the control group, and the left ventricular torsion and basal rotation were found to be significantly decreased in those with an activity score of ≥17.