• Journal of Cardiovascular Imaging
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• 제31권3호
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• pp.135-141
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• 2023

BACKGROUND: Global longitudinal strain (GLS) is an accurate and reproducible parameter of left ventricular (LV) systolic function which has shown meaningful prognostic value. Fast, user-friendly, and accurate tools are required for its widespread implementation. We aim to compare a novel web-based tool with two established algorithms for strain analysis and test its reproducibility. METHODS: Thirty echocardiographic datasets with focused LV acquisitions were analyzed using three different semi-automated endocardial GLS algorithms by two readers. Analyses were repeated by one reader for the purpose of intra-observer variability. CAAS Qardia (Pie Medical Imaging) was compared with 2DCPA and AutoLV (TomTec). RESULTS: Mean GLS values were -15.0 ± 3.5% from Qardia, -15.3 ± 4.0% from 2DCPA, and -15.2 ± 3.8% from AutoLV. Mean GLS between Qardia and 2DCPA were not statistically different (p = 0.359), with a bias of -0.3%, limits of agreement (LOA) of 3.7%, and an intraclass correlation coefficient (ICC) of 0.88. Mean GLS between Qardia and AutoLV were not statistically different (p = 0.637), with a bias of -0.2%, LOA of 3.4%, and an ICC of 0.89. The coefficient of variation (CV) for intra-observer variability was 4.4% for Qardia, 8.4% 2DCPA, and 7.7% AutoLV. The CV for inter-observer variability was 4.5%, 8.1%, and 8.0%, respectively. CONCLUSIONS: In echocardiographic datasets of good image quality analyzed at an independent core laboratory using a standardized annotation method, a novel web-based tool for GLS analysis showed consistent results when compared with two algorithms of an established platform. Moreover, inter- and intra-observer reproducibility results were excellent.

• Journal of Cardiovascular Imaging
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• 제31권2호
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• pp.98-104
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• 2023

BACKGROUND: We aimed to investigate left ventricular (LV) global longitudinal strain (GLS) in end-stage renal disease patients and its change after kidney transplantation (KT). METHODS: We retrospectively reviewed patients who underwent KT between 2007 and 2018 at two tertiary centers. We analyzed 488 patients (median age, 53 years; 58% male) who had obtained echocardiography both before and within 3 years after KT. Conventional echocardiography and LV GLS assessed by two-dimensional speckle-tracking echocardiography were comprehensively analyzed. Patients were classified into three groups according to the absolute value of pre-KT LV GLS (|LV GLS|). We compared longitudinal changes of cardiac structure and function according to pre-KT |LV GLS|. RESULTS: Correlation between pre-KT LV EF and |LV GLS| were statistically significant, but the constant was not high (r = 0.292, p < 0.001). |LV GLS| was widely distributed at corresponding LV EF, especially when the LV EF was > 50%. Patients with severely impaired pre-KT |LV GLS| had significantly larger LV dimension, LV mass index, left atrial volume index, and E/e' and lower LV EF, compared to mildly and moderately reduced pre-KT |LV GLS|. After KT, the LV EF, LV mass index, and |LV GLS| were significantly improved in three groups. Patients with severely impaired pre-KT |LV GLS| showed the most prominent improvement of LV EF and |LV GLS| after KT, compared to other groups. CONCLUSIONS: Improvements in LV structure and function after KT were observed in patients throughout the full spectrum of pre-KT |LV GLS|.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.1085-1087
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• 2002

Deformation of soft tissue is known inhomogeneous and non-linear in general. In this study, we propose a measurement methodology of local/global strain during soft tissue elongation precisely using laser extensometer which has high accuracy, resolution and is possible to measure global/local strain. The mechanical tensile test are performed on tibialis cranialis, flexor hallucis longus, extensor digitorum longus of swine hindlimb. In order to measure target displacement, reflective marker is attached to detect elongation on specimen using surgical adhesive. The result of this study is to show that laser extensometer is valid to measure longitudinal elongation which is inhomogeneous and non-linear fur soft tissue.

• Journal of Cardiovascular Imaging
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• 제31권4호
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• pp.191-199
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• 2023

BACKGROUND: Assessment of left ventricular (LV) function plays a pivotal role in the management of patients with valvular heart disease, including those caused by rheumatic heart disease. Noninvasive LV pressure-strain loop analysis is emerging as a new echocardiographic method to evaluate global LV systolic function, integrating longitudinal strain by speckle-tracking analysis and noninvasively measured blood pressure to estimate myocardial work. The aim of this study was to characterize global LV myocardial work efficiency in patients with severe rheumatic mitral stenosis (MS) with preserved ejection fraction (EF). METHODS: We retrospectively included adult patients with severe rheumatic MS with preserved EF (> 50%) and sinus rhythm. Healthy individuals without structural heart disease were included as a control group. Global LV myocardial work efficiency was estimated with a proprietary algorithm from speckle-tracking strain analyses, as well as noninvasive blood pressure measurements. RESULTS: A total of 45 individuals with isolated severe rheumatic MS with sinus rhythm and 45 healthy individuals were included. In healthy individuals without structural heart disease, the mean global LV myocardial work efficiency was 96% (standard deviation [SD], 2), Compared with healthy individuals, median global LV myocardial work efficiency was significantly worse in MS patients (89%; SD, 4; p < 0.001) although the LVEF was similar. CONCLUSIONS: Individuals with isolated severe rheumatic MS and preserved EF, had global LV myocardial work efficiencies lower than normal controls.

• Journal of Cardiovascular Imaging
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• 제31권4호
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• pp.200-206
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• 2023

BACKGROUND: Right ventricular (RV) dysfunction is a significant risk of major adverse cardiac events in patients with acute heart failure (AHF). In this study, we evaluated RV-pulmonary artery (PA) coupling, assessed by tricuspid annular plane systolic excursion (TAPSE)/pulmonary artery systolic pressure (PASP) and assessed its prognostic significance, in AHF patients. METHODS: We measured the TAPSE/PASP ratio and analyzed its correlations with other echocardiographic parameters. Additionally, we assessed its prognostic role in AHF patients. RESULTS: A total of 1147 patients were included in the analysis (575 men, aged 70.81 ± 13.56 years). TAPSE/PASP ratio exhibited significant correlations with left ventricular (LV) ejection fraction(r = 0.243, p < 0.001), left atrial (LA) diameter(r = -0.320, p < 0.001), left atrial global longitudinal strain (LAGLS, r = 0.496, p < 0.001), mitral E/E' ratio(r = -0.337, p < 0.001), and right ventricular fractional area change (RVFAC, r = 0.496, p < 0.001). During the median follow-up duration of 29.0 months, a total of 387 patients (33.7%) died. In the univariate analysis, PASP, TAPSE, and TAPSE/PASP ratio were significant predictors of mortality. After the multivariate analysis, TAPSE/PASP ratio remained a statistically significant parameter for all-cause mortality (hazard ratio [HR], 0.453; p = 0.037) after adjusting for other parameters. In the receiver operating curve analysis, the optimal cut-off level of TAPSE/PASP ratio for predicting mortality was 0.33 (area under the curve = 0.576, p < 0.001), with a sensitivity of 65% and a specificity of 47%. TAPSE/PASP ratio < 0.33 was associated with an increased risk of mortality after adjusting for other variables (HR, 1.306; p = 0.025). CONCLUSIONS: In AHF patients, TAPSE/PASP ratio demonstrated significant associations with RVFAC, LA diameter and LAGLS. Moreover, a decreased TAPSE/PASP ratio < 0.33 was identified as a poor prognostic factor for mortality.

• Journal of Cardiovascular Imaging
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• 제30권3호
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• pp.185-196
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• 2022

BACKGROUND: Two-dimensional (2D) strain provides more predictive power than ejection fraction (EF) in patients with ST-elevation myocardial infarction (STEMI). 3D strain and EF are also expected to have better clinical usefulness and overcome several inherent limitations of 2D strain. We aimed to clarify the prognostic significance of 3D strain analysis in patients with STEMI. METHODS: Patients who underwent successful revascularization for STEMI were retrospectively recruited. In addition to conventional parameters, 3D EF, global longitudinal strain (GLS), global area strain (GAS), as well as 2D GLS were obtained. We constructed a composite outcome consisting of all-cause death or re-hospitalization for acute heart failure or ventricular arrhythmia. RESULTS: Of 632 STEMI patients, 545 patients (86.2%) had a reliable 3D strain analysis. During median follow-up of 49.5 months, 55 (10.1%) patients experienced the adverse outcome. Left ventricle EF, 2D GLS, 3D EF, 3D GLS, and 3D GAS were significantly associated with poor outcomes. (all, p < 0.001) The maximum likelihood-ratio test was performed to evaluate the additional prognostic value of 2D GLS or 3D GLS over the prognostic model consisting of clinical characteristics and EF, and the likelihood ratio was 15.9 for 2D GLS (p < 0.001) and 1.49 for 3D GLS (p = 0.22). CONCLUSIONS: The predictive power of 3D strain was slightly lower than the 2D strain. Although we can obtain 3D strains, volume, and EF simultaneously in same cycle, the clinical implications of 3D strains in STEMI need to be investigated further.

• Journal of Cardiovascular Imaging
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• 제30권4호
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• pp.279-289
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• 2022

BACKGROUND: In many cardiovascular disorders, the contractile performance of the right ventricle (RV) is the primary determinant of prognosis. For evaluating RV volumes and function, 4 dimensional (4D)-echocardiography has become common. This research used 2D and 4D modalities to assess RV contractile performance in hypertensive patients. METHODS: A total of 150 patients with essential hypertension were enrolled in this study, along with 75 age and sex-matched volunteers. Clinical evaluation and echocardiographic examination (including M-mode, tissue Doppler imaging, and 2D speckle tracking) were conducted on all participants. RV volumes, 4D-ejection fraction (EF), 4D-fractional area change (FAC), 4D-tricuspid annular plane systolic excursion (TAPSE), 4D-septal and free wall (FW) strain were all measured using 4D-echocardiography. RESULTS: Hypertensive patients showed 2D-RV systolic and diastolic dysfunction (including TAPSE, 2D-right ventricular global longitudinal strain, RV-myocardial performance index and average E/EaRV) and 4D-RV impairment (including right ventricular EF, FAC, RV strain and TAPSE, right ventricular end-diastolic volume and right ventricular end-systolic volume) compared to the control group. We verified the prevalence of RV systolic dysfunction in hypertension patients using the following parameters: 1) 15% of them had 2D-TAPSE < 17 mm vs. 40% by 4D-TAPSE; 2) 25% of them had 2D-GLS < 19% vs. 42% by 4D-septal strain and 35% by 4D FW strain; 3) 35% of hypertensive patients had 4D-EF < 45%; and finally; 4) 25% of hypertensive patients had 2D-FAC < 35% compared to 45% by 4D-FAC. CONCLUSIONS: The incidence of RV involvement was greater in 4D than in 2D-modality trans-thoracic echocardiography. We speculated that 4D-echocardiography with 4D-strain imaging would be more beneficial for examining RV morphology and function in hypertensive patients than 2D-echocardiography, since 4D-echocardiography could estimate RV volumes and function without making geometric assumptions.

• Earthquakes and Structures
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• 제13권5호
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• pp.485-496
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• 2017

The behavior of 8 steel reinforced high-strength concrete (SRHSC) columns, which comprised of four identical columns with cross-shaped steel and other four identical columns with square steel tube, was investigated experimentally under cyclic uniaxial and biaxial loading independently. The influence of steel configuration and loading path on the global behavior of SRHSC columns in terms of failure process, hysteretic characteristics, stiffness degradation and ductility were investigated and discussed, as well as stress level of the longitudinal and transverse reinforcing bars and steel. The research results indicate that with a same steel ratio deformation capacity of steel reinforced concrete columns with a square steel tube is better than the one with a cross-shaped steel. Loading path affects hysteretic characteristics of the specimens significantly. Under asymmetrical loading path, hysteretic characteristics of the specimens are also asymmetry. Compared with specimens under unidirectional loading, specimens subjected to bidirectional loading have poor carrying capacity, fast stiffness degradation, small yielding displacement, poor ductility and small ultimate failure drift. It also demonstrates that loading paths affect the deformation capacity or deformation performance significantly. Longitudinal reinforcement yielding occurs before the peak load is attained, while steel yielding occurs at the peak load. During later displacement loading, strain of longitudinal and transverse reinforcing bars and steel of specimens under biaxial loading increased faster than those of specimens subjected to unidirectional loading. Therefore, the bidirectional loading path has great influence on the seismic performance such as carrying capacity and deformation performance, which should be paid more attentions in structure design.

• Korean Circulation Journal
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• 제53권12호
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• pp.813-825
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• 2023

Background and Objectives: The prognostic implications of septic cardiomyopathy have not been clearly demonstrated. We evaluated serial changes in left ventricular (LV) and right ventricular (RV) function in patients with septic shock and their prognostic value on 7-day and in-hospital mortality. Methods: Transthoracic echocardiography was performed within 48 hours of the diagnosis of septic shock and 7 days after the initial evaluation. In addition to traditional echocardiographic parameters, LV and RV function was evaluated using global longitudinal strain (GLS), and tricuspid annular plane systolic excursion (TAPSE). Results: A total of 162 patients (men, 83, 51.5%; 70.7±13.4 years; Acute Physiology and Chronic Health Evaluation [APACHE] II, 30.6±9.2) were enrolled. Initial GLS and TAPSE were -14.9±5.2% and 16.9±5.5 mm, and improved in the follow-up evaluation (GLS, -17.6±4.9%; TAPSE, 19.2±5.4 mm). Seven-day and in-hospital mortality were 24 (14.9%) and 64 (39.8%). Seven-day mortality was significantly associated with initial GLS >-16% (odds ratio [OR], 14.066, 95% confidence interval [CI], 1.178-167.969, p=0.037) and APACHE II score (OR, 1.196, 95% CI, 1.047-1.365, p=0.008). The in-hospital mortality of 7-day survivors was associated with follow-up TAPSE <16 mm (OR, 10.109, 95% CI, 1.640-62.322, p=0.013) and Sequential Organ Failure Assessment score (OR, 1.340, 95% CI, 1.078-1.667, p=0.008). GLS was not associated with in-hospital mortality of 7-day survivors. Conclusions: Fluctuation of both ventricular function was common in septic shock. Seven-day mortality of patients with septic shock was related to GLS, whereas in-hospital mortality of 7-day survivors was related to TAPSE, not to GLS.

• 대한기계학회논문집A
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• 제28권10호
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• pp.1435-1450
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• 2004

The investigation, which includes the material homogenization and the calculation of local stress concentration of long-fibrous composites in a microscopic level, has been performed to analyze the behavior of fiber-reinforced composites by using finite element method. In order to carry out this study, the finite element models of composites have been generated by the idealized arrays as square and hexagonal-packed type. In the FE analysis, the boundary conditions of micromechanical finite element method(MFEM) have been defined and verified by comparing with the results from multi-cells, and the effective material properties of composites composed of graphite/epoxy have been also evaluated by rules of mixture. For acquiring the relation between the global and local behaviors of composites, the magnifications of strain, stress, and interfacial stress of composites subjected to a longitudinal and transverse loading respectively have been calculated. And the magnifications have been proposed as the stress concentration in the microscopic level at composite material.