Use Of Longitudinal Strain Research Articles

Usefulness of Longitudinal Strain to Assess Cancer Therapy-Related Cardiac Dysfunction and Immune Checkpoint Inhibitor-Induced Myocarditis.

Longitudinal strain (LS) measured by echocardiography has been reported to be useful not only for the diagnosis and risk stratification of various cardiac diseases, but also in cardio-oncology. Most previous studies have been conducted on patients undergoing treatment with anthracyclines and human epidermal growth factor receptor 2-targeted therapies. Existing guidelines recommend that global LS (GLS) should be measured before and after the administration of cancer drugs. This recommendation is based on many reports showing that a decline in GLS is indicative of early or mild cancer therapy-related cardiac dysfunction. The main purpose of this article is to provide insight into the importance of LS in patients undergoing cancer treatment and highlight the role of LS evaluation in patients undergoing immune checkpoint inhibitor (ICI) treatment, which is being used with increasing frequency. Among cancer drug therapies, immune checkpoint inhibitors (ICIs) have an important place in cancer treatment and are used for the treatment of many types of cancer. Although the efficacy of ICIs in cancer treatment has been reported, immune-related adverse events (irAEs) have also been reported. Among these irAEs, cardiovascular complications, although rare, are recognized as important adverse events that may result in ICI treatment discontinuation. Myocarditis is one severe adverse event associated with ICIs, and it is important to standardize diagnostic and therapeutic approaches to it. Several studies have reported a relationship between LS and cardiac complications associated with ICIs which may contribute to the early diagnosis of ICI-induced cardiac complications.

Usefulness of Longitudinal Strain Adjusted to Regional Thickness in Hypertrophic Cardiomyopathy.

Background. We assessed the usefulness of a longitudinal strain adjusted to regional thickness in hypertrophic cardiomyopathy (HCM). Indeed, with conventional software, the width of the region of interest (ROI) is the same over the entire myocardial wall, wherein the software analyzes only partially the left ventricular (LV) hypertrophic segments. Methods. We included 110 patients: 55 patients with HCM (HCM group) and 55 healthy subjects (age- and sex-matched control group). The global longitudinal strain (GLS) and regional strain for each of the 17 segments was calculated with standard software (for two groups) and with software adjusted to the myocardial wall thickness (for the HCM group). Results. GLS was significantly decreased in the HCM group compared to the control group (−15.1 ± 4.8% versus −20.5 ± 4.3%, p < 0.0001). In the HCM group, GLS (standard method versus adjusted to thickness) measurements were not significantly different (p = 0.34). Interestingly, the regional strain adjusted to thickness was significantly lower than the standard strain in the hypertrophic segments, especially in the basal inferoseptal segment (p = 0.0002), median inferoseptal segment (p < 0.001) and median anteroseptal segment (p = 0.02). The strain adjusted to thickness was still significantly lower in the most hypertrophic segments (≥20 mm) (−3.7 ± 3%, versus −5.9 ± 4.4%, p = 0.049 in the basal inferoseptal segment and −5.7 ± 3.5% versus −8.3 ± 4.5%, p = 0.0007 in the median inferoseptal segment). In the segments with significant myocardial fibrosis, the longitudinal strain adjusted to thickness was significantly lower than the conventional strain (−8.3 ± 3.3% versus −11.4 ± 4.5%, p = 0.002). The analysis of the strain adjusted to thickness had a better feasibility (97.5% versus 99%, p = 0.01). Conclusions. The analysis of a longitudinal strain adjusted to regional thickness is feasible in HCM and allows a better evaluation of myocardial deformation, especially in the most LV hypertrophic segments.

A Method of Monitoring the Cross-Section Deformation of Tunnels Using the Strain Data from the Fully Distributed Optical Fibre Sensors

Fully distributed optical fiber sensing technology allows the high-density strain to measure the overall curvature and cross-section deformation of tunnels. However, there are few studies on the use of longitudinal strain along the tunnel to measure the cross-section convergence deformation, and the method of obtaining the strain along the tunnel loop is costly. To address this issue, a method of monitoring the cross-section deformation of tunnels using the strain data is proposed. First, a model of the relationship between strain and deformation in tunnels is constructed to obtain the overall settlement using the longitudinal strain. Second, based on the finite element method (FEM), the deformation law about the strain measured points and non-measured points on the cross-section of the tunnel is proposed, and on this basis, the correlation coefficient is presented. Using the product of overall settlement and correlation coefficient, the cross-section deformation at non-measured points is obtained. The results of numerical examples shown that the proposed method can effectively expand the monitoring scale and realize high-density cross-section deformation measurement of tunnels.

Fully automated global longitudinal strain assessment using artificial intelligence developed and validated by a UK-wide echocardiography expert collaborative

Abstract Background Left ventricular longitudinal strain has been reported to deliver reproducibility, sensitivity and prognostic value over and above ejection fraction. However, it currently relies on uninspectable proprietary algorithms and suffers from a lack of widespread clinical use. Uptake may be improved by increasing user trust through greater transparency. Purpose We therefore developed a machine-learning based method, trained, and validated with accredited experts from our AI Echocardiography Collaborative. We make the dataset, code, and trained network freely available under an open-source license. Methods AI enables strain to be calculated without relying on speckle tracking by directly locating key points and borders across frames. Strain can then be calculated as the fractional shortening of the left ventricular perimeter. We first curated a dataset of 7523 images, including 2587 apical four chamber, each labelled by a single expert from our collaboration of 17 hospitals, using our online platform (Figure 1). Using both this dataset and a semi-supervised approach, we trained a 3d convolutional neural network to identify the annulus, apex, and the endocardial border throughout the cardiac cycle. Separately, we constructed an external validation dataset of 100 apical 4 chamber video-loops. The systolic and diastolic frame were identified, and each image was separately labelled by 11 experts. From these labels we then derived the expert consensus strain for each of the 100 video loops. These experts also ordered all 100 echocardiograms by their visual grading of left ventricular longitudinal function. Finally, a single expert calculated strain using two different proprietary commercial packages (A and B). Results Consensus strain measurements (obtained by averaging individual assessments by the 11 experts) across the 100 cases ranged from −4% to −27%, with strong correlations with the individual experts and machine methods (Figure 2). Using each cases' consensus across experts as the gold standard, median error from consensus was 3.1% for individual experts, 3.4% for Propriety A, 2.6% for Proprietary B, 2.6% for our AI. Using the visual grading of longitudinal strain as the reference, the 11 individual experts and 4 machine methods each showed significant correlation: coefficients ranged from 0.55 to 0.69 for experts, and for Proprietary A was 0.68, Proprietary B 0.69, and our AI 0.69. Conclusions Our open-source, vendor-independent AI-based strain measure automatically produces values that agree with expert consensus, as strongly as the individual experts do. It also agrees with the subjective visual ranking by longitudinal function. Our open-source AI strain performs at least as well as closed-source speckle-based approaches, and may enable increased clinical and research use of longitudinal strain. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): NIHR Imperial BRC ITMAT.Dr Howard was additionally funded by Wellcome. Figure 1. Collaborative online platformFigure 2. Correlations between strain methods

Usefulness of Longitudinal Strain to Assess Remodeling of Right and Left Cardiac Chambers Following Transcatheter Aortic Valve Implantation

Remodeling after transcatheter aortic valve implantation (TAVI) has been well characterized for the left ventricle (LV) but not for the other cardiac chambers. We aimed to describe conventional indices of cardiac remodeling and novel longitudinal strain (LS) in all 4 cardiac chambers post-TAVI and to explore gender remodeling disparities. Consecutive patients with significant aortic stenosis who underwent TAVI were included if echocardiograms in sinus rhythm before and 1-year postprocedure were available. Speckle tracking analysis was performed retrospectively to evaluate size and function of the 4 cardiac chambers. Baseline and 1-year data were compared. From a total of 612 patients who underwent TAVI, 213 were included in this study (82 ± 9 years old, 42% men). Although no significant size or function changes were seen for right cardiac chambers at follow-up, significant improvements were seen for ejection fraction (EF) and LS in both the LV and left atrium (LA) (p < 0.05 for both). The absolute percentage of LV and LA function improvement was higher for LS than for EF (p < 0.05). Women had smaller LV and right ventricular (RV) size, whereas parameters of LV and RV function were higher. All 1-year remodeling parameters were similar for men and women. Conventional LV remodeling parameters (LV mass) failed to improve 1 year after TAVI. However, novel strain-derived parameters of size and function showed remodeling of left chambers but not of RV or right atrium. The degree of LV and LA remodeling by LS is almost twice that of EF. Remodeling was similar for both genders.

Usefulness of longitudinal strain adjusted to regional thickness in hypertrophic cardiomyopathy

In hypertrophic cardiomyopathy (HCM), longitudinal strain analysis allows to early detect left ventricular (LV) contraction abnormalities despite preserved LV ejection fraction. In current software, the width of the region of interest (ROI) is the same over the entire myocardial wall and might analyze partially LV hypertrophic segments. The aim of this study is to evaluate a novel software for strain analysis with an adjustable ROI according to each segment thickness. We included 110 patients: 55 patients with HCM (HCM group) and 55 healthy subjects (age- and sex-matched control group). All pts underwent echocardiography using a Vivid 9 GE system and measurements were performed using EchoPAC software. Global longitudinal strain (GLS) and regional strain for each of the 17 segments were calculated with standard software (for 2 groups) and with software adjusted to the myocardial wall thickness (for HCM group). GLS was significantly decreased in the HCM group as compared to the control group (−15.1 ± 4.8% versus–20.5 ± 4.3%, P < 0.0001). In HCM group, GLS (standard method versus adjusted to thickness) was not significantly different ( P = 0.34). Interestingly, regional strain adjusted to thickness was significantly lower than standard strain in hypertrophic segments, especially in basal inferoseptal segment ( P = 0.0002), median inferoseptal segment ( P < 0.001) and median anteroseptal segment ( P = 0.02). Strain adjusted to thickness was still significantly lower in the most hypertrophic segments (≥ 20 mm) (−3.7 ± 3%, versus −5.9 ± 4.4%, P < 0.049 in the basal inferoseptal segment and −5.7 ± 3.5% versus −8.3 ± 4.5%, P < 0.0007 in the median inferoseptal segment). Analysis of strain adjusted to thickness had a better feasibility (97.5% versus 99%, P = 0.01). Analysis of longitudinal strain adjusted to regional thickness is feasible in HCM and allows a better evaluation of myocardial deformation, especially in the most LV hypertrophic segments.

15 - Usefulness of longitudinal strain adjusted to regional thickness in hypertrophic cardiomyopathy

Background In hypertrophic cardiomyopathy (HCM), longitudinal strain analysis allows to early detect left ventricular (LV) contraction abnormalities despite preserved LV ejection fraction. In current software, the width of the region of interest (ROI) is the same over the entire myocardial wall and might analyze partially LV hypertrophic segments. Purpose The aim of this study is to evaluate a novel software for strain analysis with an adjustable ROI according to each segment thickness. Methods We included 110 patients: 55 patients with HCM (HCM group) and 55 healthy subjects (age- and sex-matched control group). All pts underwent echocardiography using a Vivid 9 GE system and measurements were performed using EchoPAC software. Global longitudinal strain (GLS) and regional strain for each of the 17 segments were calculated with standard software (for 2 groups) and with software adjusted to the myocardial wall thickness (for HCM group). Results GLS was significantly decreased in the HCM group as compared to the control group (−15.1 ± 4.8% versus–20.5 ± 4.3%, P Conclusion Analysis of longitudinal strain adjusted to regional thickness is feasible in HCM and allows a better evaluation of myocardial deformation, especially in the most LV hypertrophic segments.

Relationship between Longitudinal Strain and Symptomatic Status in Aortic Stenosis

Global longitudinal strain (GLS) and basal longitudinal strain (BLS) assessed using two-dimensional speckle-tracking imaging have been proposed as subtle markers of left ventricular (LV) systolic dysfunction with potential prognostic value in patients with aortic stenosis (AS). The aim of this study was to evaluate the relationship between longitudinal strain and symptomatic status in patients with AS. GLS and BLS were measured in 171 patients with pure, isolated, at least mild AS prospectively enrolled at two institutions. The population was divided into four groups: asymptomatic nonsevere AS (n=55), asymptomatic severe AS with preserved LV ejection fraction (LVEF; ≥50%) (n= 37), symptomatic severe AS with preserved LVEF (n= 60), and severe AS with reduced LVEF (<50%) (n= 19). GLS was significantly different among the four groups (P < .0001), but the difference was due mainly to patients with reduced LVEFs. In addition, there was an important overlap among the groups, and in multivariate analysis, after adjustment for age, gender, AS severity, and LVEF, GLS was not an independent predictor of symptomatic status (P= .07). BLS was also significantly different among the four groups (P < .0001) but in contrast was independently associated with symptomatic status (P < .0001). However, as for GLS, there was an important overlap between groups and differences were close to intraobserver or interobserver variability (1.3 ± 1.1% and 2.0 ± 1.6%, respectively). In this prospective multicenter cohort of patients with wide ranges of AS severity, symptoms, andLVEFs, BLS but not GLS was independently associated with symptomatic status. However, there was an important overlap among groups, and differences were close to measurements' reproducibility, raising caution regarding the use of longitudinal strain, at least as a single criterion, in the decision-making process for patients with severe asymptomatic AS.

Use of longitudinal strain in identifying driving and resisting elements of landslides : Baum, R L; Fleming, R W Bull Geol Soc AmV103, N8, Aug 1991, P1121–1132

Use of longitudinal strain in identifying driving and resisting elements of landslides : Baum, R L; Fleming, R W Bull Geol Soc AmV103, N8, Aug 1991, P1121–1132

Use of longitudinal strain in identifying driving and resisting elements of landslides

Observations of deformation at the surfaces of landslides in Utah and Hawaii indicate that the upslope parts of the land-slides have stretched and the downslope parts have shortened parallel with the direction of movement. The maximum displacement of each landslide occurs in a relatively undeformed zone between the zones of shortening and stretching. The pattern of deformation at the surface of these landslides may be useful in analyzing their mechanics by helping to constrain the longitudinal forces in limit-equilibrium stability analysis. We used earth-pressure calculations to determine the range of possible longitudinal forces (per unit width) for active failure in the zone of stretching and for passive failure in the zone of shortening of one of the Hawaiian landslides. Longitudinal forces computed by stability analysis, assuming homogeneous strength, exceeded the possible forces in much of the upslope half of the landslide. Consequently, we assumed inhomogeneous strength and adjusted shear-strength parameters at each segment of the slip surface until the longitudinal forces computed by stability analysis agreed with those computed by earth-pressure theory, and the factor of safety approached unity. The distribution of longitudinal forces computed for inhomogeneous strength indicated that the boundary between driving and resisting elements of the landslide is near the thickest part of the slide, in agreement with a simple formula for the location of the boundary.