Average Global Strain Research Articles

Diagnostic Accuracy of Strain Imaging of the Left Ventricle in Detection of Obstructive Coronary Artery Disease

Background: Speckle tracking echocardiography using average global strain and strain rate (SR) parameters for early detection of high risk patients with coronary artery disease (CAD) has gained a substantial clinical interest. Objective: Assessment of the diagnostic accuracy of strain imaging of the left ventricle in detection of obstructive coronary artery disease. Methods: One hundred patients were enrolled. They were divided into 3 groups: Group I (n = 40 patients) presented with ST segment elevation myocardial infarction (STEMI), Group II (n = 40 patients) presented with non-ST segment elevation myocardial infarction (NSTEMI) or unstable angina (UA) and Group III (n = 20 patients) with normal coronary angiography served as a control group. All patients were subjected to 2D speckle tracking echocardiography (2D STE) to assess LV longitudinal strain and strain rate (SR). Sensitivity, specificity and diagnostic accuracy of 2D STE in prediction of CAD and its severity using Gensini score were assessed. Results: The mean age for Group I, II and III was 52.20 ± 11.83, 51.97 ± 14.53 and 52.75 ± 10.75 respectively. LV average global systolic strain (AGS) was significantly lower in group I and II when compared to group III. AGS and average global systolic SR showed significant direct correlation with Gensini score. The diagnostic accuracy of 2D STE in prediction of significant LAD stenosis was 92.5%, and it was 89.5% in prediction of 3 vessels CAD. Conclusion: Strain imaging using 2D STE can predict the territory and severity of CAD with high diagnostic accuracy and can be used as a simple noninvasive diagnostic tool to identify high risk CAD patients.

Evalution of left ventricular function before and after coronary artery bypass grafting by speckle tracking imaging

Objective To evaluate regional and global left ventricular systolic function after coronary artery bypass grafting (CABG) by speckle tracking imaging (STI).Methods Transthoracic echocardiography (TTE) was performed in 32 patients with coronary heart disease (CHD) preoperative and 3 months after CABG.The two-dimensional data were obtained in apical 4-chamble,2-chamble and long axis view.Peak systolic longitudinal strain (SLs),global longitudinal systolic strain (GLS) and average global strain(GLS-Avg) were measured using STI.30 healthy volunteers were involved as controls.Results SLs in the control group increased from the basal to the apical ventricular.SLs in the control group and CHD group apical segment were significantly higher than the basal and middle segments.Compared to the control group,SLs,GLS in part of myocardial ischemic segments were lower in CHD group before CABG (P ＜0.05).SLs and GSL in the corresponding segments showed significantly improving 3 months after CABG in CHD group (P ＜ 0.05).There was good relationship between GSL-Avg and left ventricular ejection fraction.Conclusions STI technology can be used to objectively and quantitatively evaluate the change of regional and global left ventricular systolic function.Therefore,it provide a non-invasive means for evaluation of curative effect and prognosis judgement of CHD after CABG. Key words: Echocardiography; Coronary artery bypass; Ventricular function, left; Strain; Speckle tracking imaging

The effect of strain gage size on measurement errors in textile composite materials

The heterogeneous nature of textile composites on the microstructural scale leads to variation in the local strain field within the unit cell. This variation can result in inaccurate measurement of the average global strain when using strain gages of insufficient size. A statistical model for sensor error is presented which leads to expressions for sensor variance. The model includes the effects of unit cell size, gage length, gage width, microstructural defects and irregularities, and instrument error. The proposed model is verified experimentally by using a plain woven-graphite-epoxy composite material and strain gages of various lengths. The experimental results are compared with analytical predictions. A set of guidelines is given for the use of strain gages on textile composites.