Dimensional Strain Research Articles

Two-dimensional Echocardiographic Assessment of Myocardial Strain: Important Echocardiographic Parameter Readily Useful in Clinical Field.

Echocardiography is the first and is the most-available imaging modality for many cardiovascular diseases, and echocardiographic parameters can give much important information for diagnosis, treatment, and prognostic evaluations. Left ventricular ejection fraction (LVEF) is the most commonly used echocardiographic parameter for left ventricular (LV) systolic function. Although LVEF is used routinely in daily practice, it is calculated from volumetric change without representing true myocardial properties. Recently, strain echocardiography has been used to objectively measure myocardial deformation. Myocardial strain can give accurate information about intrinsic myocardial function, and it can be used to detect early-stage cardiovascular diseases, monitor myocardial changes with specific therapies, differentiate cardiomyopathies, and predict the prognosis of several cardiovascular diseases. Although strain echocardiography has been applied to measure the right ventricle and left atrium, in addition to analyzing the LV, many cardiologists who are not imaging specialists are unaware of its clinical use and importance. Therefore, this review describes the measurement and clinical utility of 2-dimensional strain analysis in various cardiovascular diseases.

Use of myocardial strain imaging by echocardiography for the early detection of radiotherapy-induced cardiotoxicity in breast cancer patients (BACCARAT Study)

Radiotherapy (RT) is a major component of breast cancer treatment. However, breast RT is associated with long-term cardiac toxicity with clinical detection only relevant 10 to 15 years after RT. Early surrogate end-points, predictive for the development of later cardiac events, would be useful. To evaluate echocardiographic strain imaging for the detection of sub clinical myocardial dysfunction arising after breast cancer RT. BACCARAT is a monocentric prospective cohort study of unilateral breast cancer patients treated with RT but without chemotherapy. They are followed for 2 years with repeated cardiac imaging examinations, including 2-dimensional speckle strain imaging for the detection of sub clinical left ventricular abnormalities. Between October 2015 and December 2017, this study prospectively included 114 women (95 left-sided and 19 right-sided) aged 58 ± 8 years. Cardiac evaluations with strain imaging are performed before RT, 6 months and 24 months after RT. At this stage of the study, strain imaging measurements before RT and RT + 6 months are available for 65 patients. Mean heart and left ventricle doses were 2.9 ± 1.3 Gy and 6.1 ± 2.9 Gy for the left-sided patients, 0.4 ± 0.1 Gy and 0.1 ± 0.04 Gy, respectively, for the right-sided patients. A decrease in global longitudinal strain was observed at 6 months post-RT for left-sided patients (−14.1% ± 3.6% at 6 months after RT vs. −15.4% ± 3.2% before RT, percentage of change 9.2%, P = 0.02) but not for right-sided patients. No significant change was observed with conventional echocardiography left ventricular ejection fraction measurement. These preliminary results demonstrate a statistically significant reduction of global longitudinal strain 6 months after RT. Further investigation of BACCARAT study could illustrate strain imaging may have a potential role for screening and identification of patients at risk to develop cardiac complications.

Role of electrocardiographic and echocardiographic types of left bundle branch block in prediction of response to cardiac resynchronization therapy.

To assess the value of the complex analysis of electrocardiographic (ECG) variants and echocardiographic (echo) manifestation of left bundle branch block (LBBB) in predicting the success of cardiac resynchronization therapy (CRT). The study included 39 patients (mean age 61.49±9.0 years) on sinus rhythm with LBBB, QRS duration ≥130 ms, left ventricular ejection fraction (LVEF) ≤35%, heart failure (HF) NYHA II-IV despite optimal pharmacological therapy during 3 month. All patients had undergone CRT-D implantation. Depending on presence or absence of ECG-criteria, proposed by D.G. Strauss et al., patients were divided into 2 groups: 1 group - strict LBBB, proposed by D.G. Strauss et al. (n=29) and 2 group - other patients (n=10). In addition to standard echocardiography, global longitudinal 2-dimensional strain (GLS) and LBBB contraction pattern have been performed initially and in 6 months after implantation. Response to CRT was defined as decrease in LV end-systolic volume by >15% after 6 months of follow-up. Typical LBBB echo contraction pattern was detected in 25 patients (64% of all included). These patients had more pronounced longitudinal dissynchrony and a more expressed global longitudinal strain before CPT-D implantation (p<0.05). 27 patients (69% of all included) were included in the "response" group, the remaining 12 patients (31% of all included) - the "non-response" group. In the "response" group the morphology of the QRS complex was significantly more likely to meet the criteria, proposed by D.G. Strauss et al., than other variants (23 vs. 6, respectively, p=0.02), and the echo contraction pattern of this patients more often corresponded to "typical" LBBB (24 vs. 1, p=0.001). All patients, who had the ECG criteria, proposed by D.G. Strauss et al., and echo "typical" LBBB contraction pattern, responded on CPT. Moreover, the proportion of these patients in the "response" group was rather high - 81.5% (22 of 27 patients). ECG criteria LBBB, proposed by D.G. Strauss et al., identify patients with delayed transseptal interventricular conduction due to complete LBBB, what is a good target for CPT. Evaluation of the echo contraction pattern based on the definition of longitudinal myocardial deformation by means of a two-dimensional strand technology allows predicting the success of CPT in patients with LBBB. Patients with «typical» LBBB contraction pattern show more pronounced global longitudinal strain and larger longitudinal dissynchrony compared with other patients, and it explains their better response to CPT. Complex analysis of strict LBBB ECG criteria and echo contraction pattern are promising parameters in predicting beneficial response to CRT in patients with HF.

3D deformation and strain measurement of an intact eardrum using digital image correlation

In the field of hearing research, strain measurements are scarce. Such measurements can however provide valuable data on several middle ear pathologies. They could also help to gain a better understanding of the properties of the eardrum and further validate middle ear finite element models. We built a digital image correlation setup in order to assess three dimensional deformation and strain measurements of an intact eardrum. Different types of speckle pattern were evaluated. We then measured the deformation and strain of an eardrum subjected to large static pressures. The results illustrate that the application of digital image correlation to measure deformation and strain in intact eardrums is feasible. In the future, the setup will be further developed and eardrum strain measurements will be performed for different pathologies.

Quantitative finite strain analysis of the quartz mylonites within the Three Pagodas shear zone, western Thailand

Abstract The NW–trending Three Pagodas shear zone exposes a high–grade metamorphic complex named Thabsila gneiss in the Kanchanaburi region, western Thailand. The quartz mylonites within this strike–slip zone were selected for strain analysis. 2–dimensional strain analysis indicates that the averaged strain ratio (Rs) for the lower greenschist facies increment of XZ– plane is Rs = 1.60–1.97 by using the Fry’s method. Kinematic vorticity analysis of the quartz mylonites in the shear zone showed that the mean kinematic vorticity number of this increment is Wk = 0.75–0.99 with an average at 0.90 ±0.07. The results implied that the quartz mylonites within the Three Pagodas shear zone have a dominant simple shear component of about 72% with a small pure shear component. A sinistral shear sense is indicated by kinematic indicators from macro– to micro–scale. We conclude that the Three Pagodas shear zone deformed in the process of sinstral shear–dominated transpression, which is similar to the Mae Ping shear zone in the north.

Assessment of the Left Ventricular Deformable Indices (Strain Components) in Different Echocardiography Systems

This Article provides simplified, easy-to-understand descriptions of the echocardiographic software used in conjunction with different echocardiography machines, such as those from Toshiba, Philips, GE, and Siemens, and explains how these sophisticated systems can best be used to exploit fully their ability to deliver more precise diagnoses and assist in treatment choice and follow-up. A variety of applications are covered, with presentation of algorithms and highlighting of tips and tricks. It will be of value for cardiologists, other interested clinicians, those pursuing fellowships in echocardiography, and sonographers; it will also be highly relevant for biomedical engineers, bio-mathematicians, computer scientists, and researchers in medical physics. There would be enormous clinical benefits of any non-invasive technique to estimate the true level of wall abnormal motions. Strain and strain rate are deformation measures. If different components of an object have different velocities, the object shape may be changed. In this article, we mentioned the left ventricular 2- dimensional strain in normal hearts for each different type of strain methods from 5 echocardiography machines and we have also introduced MATLAB software as an echocardiography desk.

Preclinical cardiovascular changes in children with obesity: A real-time 3-dimensional speckle tracking imaging study.

The aims of this study were (1) to quantify changes in 3-dimensional (3D) strain in obese children using real-time 3D echocardiography (RT3DE) and 3D speckle tracking echocardiography (3DSTE), and (2) to investigate the utility of left ventricular (LV) strain variables in measuring early cardiovascular changes in children with obesity. A total of 181 obese children (study group) aged 4–18 years old were prospectively enrolled and compared with 229 healthy subjects (control group). We acquired demographic, clinical, biochemical, and 2D echocardiography/Doppler data. Also, RT3DE and 3DSTE were performed to measure LV volume, left ventricular ejection fraction (LVEF), LV mass (LVM), LV peak systolic global longitudinal strain (GLS), radial strain (GRS), circumferential strain (GCS), and global strain (GS). There were significant differences in anthropometric measurements, blood pressures, Cholesterol, C-reactive protein (CRP), Intima-media thickness (IMT), left atrium end-systolic dimension (LASD), interventricular septal end-diastolic dimension (IVSD), LV posterior wall end-diastolic dimension (LVPWD), LV end-diastolic dimension (LVEDD), LV end-systolic dimension (LVESD), LV end-diastolic volumes (LVEDV), and LV end-systolic volumes (LVESV), E and A velocities, E/A,e’, e’/a’, E/e’, LVM, LV mass index (LVMI), GLS, GRS, GCS, and GS between the study and control groups. The receiver operating characteristic curves (ROC) for the statistically significant echocardiographic variables showed that the range of areas of ROC curves varied from 0.76 (GLS), 0.74 (GRS), 0.72 (LASD), to 0.58 (LVESD), respectively. In conclusion, LV 3D strain variables by RT3DE and 3DSTE decrease in obese children. LV 3D strain is more sensitive than other echocardiographic and vascular ultrasound variables in detecting cardiovascular changes in children with obesity.

Incremental Prognostic Value of Right Ventricular Strain in Patients With Acute Decompensated Heart Failure.

Although 2-dimensional strain analyses based on speckle tracking echocardiography have been used to detect myocardial deformation, the prognostic impact of 2-dimensional strain is unclear in patients with acute decompensated heart failure (HF). We investigated whether left ventricular and right ventricular (RV) strain parameters assessed by speckle tracking echocardiography provide incremental prognostic information in hospitalized patients because of acute decompensated HF. Six hundred eighteen patients (age, 72±13 years; 38% women; ejection fraction, 46±16%) hospitalized for acute decompensated HF underwent clinical and echocardiographic evaluation just before discharge. We performed strain analyses of left ventricular global longitudinal strain and left ventricular global circumferential strain. We also analyzed RV longitudinal strain only from the free wall (RV-fwLS) and from all segments of the RV global longitudinal strain wall by using Tomtec software. The primary composite end point was cardiovascular death and readmission for HF. There were 34.8% cardiac events during a median follow-up of 427 days. In multivariate Cox models, among echocardiographic parameters, only impaired RV-fwLS (≥-13.1%; hazard ratio, 1.51; 95% CI, 1.12-2.04; P=0.01) was independently associated with cardiac events. Adding RV-fwLS to clinical risk evaluation (age, New York Heart Association class III/IV, blood urea nitrogen, and brain natriuretic peptide) markedly improved prognostic utility and consequently increased net reclassification improvement by 0.30 ( P=0.01). RV-fwLS is an independent predictor of cardiac events in acute decompensated HF and provides greater prognostic power than standard echocardiographic parameters.

Seismic ground motion induced lateral earth pressures on basement walls

Research on the dynamic lateral earth pressures acting on basement walls induced by seismic ground motions has appeared in the literature in the last few years to examine the apparent inconsistency between the theoretical pressures and the pressures suggested by basement wall good performance of during large earthquakes. This inconsistency suggested that the current methods would yield excessive lateral earth pressures. In this paper, a two dimensional plane strain finite element model of a 2-story concrete basement wall was used to examine the dynamic lateral earth pressures. The seismic ground motion was the N-S component of the 1992 Erzincan earthquake motion record. The assumed soil profile was a sands deposit overlying a reflecting bedrock layer. The observed time history outputs were the wall acceleration in horizontal direction, the lateral earth pressures, and the associated lateral thrust. The outputs were examined further to evaluate the amplification of wall acceleration, the different time history pattern of wall acceleration and lateral thrust, the influence of limiting soil tensile strength, the time difference for peak wall acceleration and peak lateral thrust, and a discussion on phase difference. The results suggested that the complex interaction could not be represented by typical simple peak input acceleration – soil pressure relationships.

The role of patch-parent configurations on the tensile response of patch repaired carbon/epoxy laminates

This work investigated the individual and associated effects of parent laminate and patch orientations with stacking sequence on the tensile response of adhesively bonded external patch repaired carbon/epoxy laminates. Four kinds of parent laminates ([0]4, [45]4, [0/45]s, [45/0]s) were repaired with double sided external patches of four different configurations ([0]2, [45]2, [45/0], [0/45]), having two laminae on each side. Real time Digital Image Correlation (DIC) was employed to capture the two dimensional strain field, damage onset and damage growth of the repaired specimens during the tests. The results reveal that the angle of orientation of plies of both the patch and the parent laminate is a key design parameter which affects the performance after the repair. The results reveal that the repair of main load bearing plies (0°) of parent laminate with [45]2 patches presented the most favourable residual tensile behaviour by effectively releasing the stress concentration in the damaged area. The maximum residual strength after repair with [45]2 patch for [0]4, [45]4, [0/45]s, [45/0]s laminates was approximately 70%, 115%, 90% and 80% respectively.

Study on the influence of elastic modulus heterogeneity on in-situ stress and its damage to gas shale reservoirs

Shale heterogeneity has a significant effect on drilling and completions, hydraulic fracturing, as well as hydrocarbon development performance. However, it lacks representation of rock damage/failure caused by the mechanical heterogeneity and “stress shadow” effect during the hydraulic fracturing process. In this paper, the Galerkin finite element method was adopted to numerically simulate the hydro-mechanical coupled interaction based on the solver in the COMSOL Multiphysics software and Matlab scripting development. The Weibull probability density function was used to represent the mechanical heterogeneity of gas shale. Under the condition of fully fluid-solid coupling during the fracking process, the effect of mechanical heterogeneity on von – Mises stress, strain energy density, damage factor, and fluid pressure was numerically simulated in the gas shale wells. The curves of von – Mises stress, strain energy density, and damage factor along a certain straight line showed the obvious decreasing distribution in a completely homogeneous formation. As the strata are heterogeneously enhanced, their distribution curves showed fluctuations. Moreover, von – Mises stress and strain energy density had a good relationship with damage factors. Accordingly, the method of rock damage/fracture and "stress shadow" effect caused by mechanic heterogeneity was put forward under the circumstance of two–dimensional plane strain. That was to use, the von – Mises stress or strain energy density at the single point or line to characterize the degree of local rupture or the shadow effect of stress, and the average strain energy density per unit area to characterize the degree of rupture of the rock or the intensity of the shadow effect. The study is of great significance to further improve the SRV(Stimulated Reservoir Volume) fracturing design and the productivity of gas shale wells.

Cardiac Iron Overload: Correlation between MRI T2* & Two Dimensional Strain Echocardiography in Children with b-Thalassemia Major

AbstractBackground: b-thalassemia is a group of inherited blood disorders that causes iron overload in the heart. Development of overt heart failure is delayed till the second decade of life. Early detection of cardiac iron overload is necessary before development of heart failure.Aim of the Study: Was to evaluate cardiac function in children with b-thalassemia major having iron overload and to Compare MRI T2* and doppler echocardiography in dem-onstration of iron deposition in cardiac muscles in those patients.Patients and Methods: Fifty children with thalassemia major were subjected to history taking, clinical assessment, laboratory assessment, Doppler echocardiography and MRI for cardiac iron load assessment.Results: There is a negative correlation between cardiac MRI T2* with age, ferritin and serum iron level. As regard correltion between MRI and doppler echocardiography there is a positive correlation between MRI T2* and diastolic echocardiographic parameters Tei index in patients with thalassemia Major.Conclusion: There is a significant correlation between MRI T2* and Doppler echocardiography in patients with b thalassemia major.

TCTAP A-080 Strain Analysis Using Speckle Tracking Echocardiography for Detection of Coronary Artery Disease in Patients of Chronic Stable Angina with No Regional Wall Motion Abnormality at Rest

Speckle-tracking imaging is a novel method for assessing left ventricular function and ischemic changes. The aim of this study was to predict the presence of coronary artery disease by longitudinal 2-dimensional strain analysis using speckle tracking echocardiography in patients with stable or

Early Cardiac Involvement Affects Left Ventricular Longitudinal Function in Females Carrying α-Galactosidase A Mutation: Role of Hybrid Positron Emission Tomography and Magnetic Resonance Imaging and Speckle-Tracking Echocardiography.

Hybrid 18F-fluorodeoxyglucose (FDG) positron emission tomography and magnetic resonance imaging may differentiate mature fibrosis or scar from fibrosis associated to active inflammation in patients with Anderson-Fabry disease, even in nonhypertrophic stage. This study was designed to compare the results of positron emission tomography and magnetic resonance cardiac imaging with those of speckle-tracking echocardiography in heterozygous Anderson-Fabry disease females. Twenty-four heterozygous females carrying α-galactosidase A mutation and without left ventricular hypertrophy underwent cardiac positron emission tomography and magnetic resonance using 18F-FDG for glucose uptake and 2-dimensional strain echocardiography. 18F-FDG myocardial uptake was quantified by measuring the coefficient of variation (COV) of the standardized uptake value using a 17-segment model. Focal 18F-FDG uptake with COV >0.17 was detected in 13 patients, including 2 patients with late gadolinium enhancement at magnetic resonance. COV was 0.30±0.14 in patients with focal 18F-FDG uptake and 0.12±0.03 in those without (P<0.001). Strain echocardiography revealed worse global longitudinal systolic strain in patients with COV >0.17 compared with those with COV ≤0.17 (-18.5±2.7% versus -22.2±1.8%; P=0.024). For predicting COV >0.17, a global longitudinal strain >-19.8% had 77% sensitivity and 91% specificity and a value >2 dysfunctional segments 92% sensitivity and 100% specificity. In females carrying α-galactosidase A mutation, focal 18F-FDG uptake represents an early sign of disease-related myocardial damage and is associated with impaired left ventricular longitudinal function. These findings support the hypothesis that inflammation plays an important role in glycosphingolipids storage disorders.

Variations in Hardness with Position In One Dimensionally Recovered Shock Loaded Metals

The microstructural and mechanical response of materials to shock loading is of the utmost importance in the development of constitutive models for high strain-rate applications. However, unlike a purely mechanical response, to ensure that the microstructure has been generated under conditions of pure one dimensional strain, the target assembly requires both a complex array of momentum traps to prevent lateral releases entering the specimen location from the edges and spall plates to prevent tensile interactions (spall) affecting the microstructure. In this paper, we examine these effects by performing microhardness profiles of shock loaded copper and tantalum samples. In general, variations in hardness both parallel and perpendicular to the shock direction were small indicating successful momentum trapping. Variations in hardness at different locations relative to the impact face are discussed in terms of the initial degree of cold work and the ability to generate and move dislocations in the samples.

3-dimensional strain evaluation of compression tights using digital image correlation method

3-dimensional strain evaluation of compression tights using digital image correlation method

A new approach to estimating temperature fields around a group of vertical ground heat exchangers in two-dimensional analyses

Abstract Vertical ground heat exchangers (VHEs), in the form of either Borehole Heat Exchanger (BHE) or thermo-active piles, are increasingly being deployed to provide low cost and sustainable heating and cooling to buildings. These are often installed within densely built urban environments, where adjacent foundation systems and underground structures can be affected by soil temperature changes induced by the heat exchangers. Therefore, they need to be considered in the geotechnical design of such structures, which typically involves carrying out two dimensional finite element plane strain analyses in order to assess their stability and performance. In such a scenario, it is common to model a line of heat exchangers as a planar source with one infinite dimension and a heat flux rate calculated by dividing the design extraction rate of a single heat exchanger by their spacing in the out-of-plane direction. This study shows that this approach largely overestimates the generated temperature field and proposes a simplified but accurate procedure to estimate the required heat flux to be applied to the planar heat sources in a 2D analysis. For this purpose, a correction factor, T ∗ , is introduced which is shown to depend on geometric parameters and thermal ground properties.

An Anisotropic Model for Granular Material Based on Experiments

Soil is a heterogeneous material and most natural soil deposits show a definite stratification. The mechanical behaviour of such material is generally different in different directions, especially in the direction parallel and perpendicular to the stratification. A series of isotropic compression tests were carried out to study the behavior of granular material produced under controlled stratification in the laboratory. These tests were conducted both on cylindrical and square prismatic tri-axial specimens. It was observed that for hydrostatic loading, the strain response was different in different directions, especially in directions parallel and perpendicular to the direction of soil deposition. A definite trend of anisotropy was observed in the deformation pattern. The observed anisotropy is modeled in this paper by treating soil-dilatancy as a variable quantity. The equation of the plastic potential surface of the model which obeys a non-associated flow rule, is assumed to be dependent on three main variables confining pressure ( $$\sigma_{3}$$ ), void ratio (e) and the angle of bedding plane orientation (δ) during deposition. The angle of bedding plane orientation (δ) was measured with respect to the direction of the major principal stress. The model has a cap yield surface in the isotropic stress direction, which is supplemented by a shear hardening Mohr–Coulomb surface in the deviator direction. This paper focuses on predicting the anisotropic strain response of stratified soil deposits subjected to isotropic compression. The proposed anisotropic model incorporates within an existing strain-hardening sand model, a modified cap yield surface and a modified plastic potential function related to the cap surface, to account for the anistropic response observed in isotropic compression tests. The two dimensional stress–strain model was extended to three dimensional Cartesian space. The strain anisotropy observed in the isotropic compression tests was predicted by the three dimensional anisotropic model proposed for granular materials.

Finite element limit analysis of ultimate lateral pressure of XCC pile in undrained clay

X-section Cast in place Concrete (XCC) pile is a non-cylindrical pile that the cross section not obeying plane rotationally symmetric. In this case, the geometry of cross section as well as the lateral load direction may have influence on the ultimate lateral pressure of XCC pile. This paper presents rigorous upper and lower bound solutions for the ultimate lateral pressure of X-section Cast in place Concrete (XCC) pile in clay through two dimensional plane strain finite element limit analysis (FELA). The geometric effect, lateral load direction and the adhesion factor at the pile-soil interface are selected for parametric study. Subsequently, an empirical closed-form equation of the ultimate lateral pressure factor is proposed for predicting the lateral force acting on a XCC pile in undrained clay. It is found that the XCC pile with relatively small ratio of b/a has larger ultimate lateral pressure than the conventional circular pile under the condition of the same area of cross section.

Myocardial Deformation Measured by 3-Dimensional Speckle Tracking in Children and Adolescents With Systemic Arterial Hypertension

Systemic arterial hypertension predisposes children to cardiovascular risk in childhood and adult life. Despite extensive study of left ventricular (LV) hypertrophy, detailed 3-dimensional strain analysis of cardiac function in hypertensive children has not been reported. The aim of this study was to evaluate LV mechanics (strain, twist, and torsion) in young patients with hypertension compared with a healthy control group and assess factors associated with functional measurements. Sixty-three patients (26 hypertension and 37 normotensive) were enrolled (mean age, 14.3 and 11.4 years; 54% men and 41% men, respectively). All children underwent clinical evaluation and echocardiographic examination, including 3-dimensional strain. There was no difference in LV volumes and ejection fraction between the groups. Myocardial deformation was significantly reduced in those with hypertension compared with controls. For hypertensive and normotensive groups, respectively, global longitudinal strain was -15.1±2.3 versus -18.5±1.9 (P<0.0001), global circumferential strain -15.2±3 versus -19.9±3.1 (<0.0001), global radial strain +44.0±11.3 versus 63.4±10.5 (P<0.0001), and global 3-dimensional strain -26.1±3.8 versus -31.5±3.8 (P<0.0001). Basal clockwise rotation, apical counterclockwise rotation, twist, and torsion were not significantly different. After multivariate regression analyses blood pressure, body mass index and LV mass maintained a significant relationship with measures of LV strain. Similar ventricular volumes and ejection fraction were observed in hypertensive and normotensive children, but children with hypertension had significantly lower strain indices. Whether reduced strain might predict future cardiovascular risk merits further longitudinal study.