| BackgroundImaging is one of the cornerstones of diagnosis in modern practice, and ultrasonography is among the most mature technologies. Profound understanding of the cardiac function is incomplete without full knowledge of the various forces that are at play during the normal physiology of the living heart. Thus, it is without debate that all major contributors to cardiac function must be accurately measured and fully appreciated in this regard.One of the many measurements that are important for assessing cardiac function is that of left ventricular ejection fraction (LVEF). The widespread utility of the ejection fraction in clinical practice is a result of multiple factors including the conceptual simplicity of its derivation, the ability to determine it easily and reproducibly, using a variety of different imaging techniques, and an extensive documentation of its clinical utility. LVEF is easily acquired, and gives quite important information that can easily and positively help in the evaluation (diagnosis), treatment, and prognostic purposes.Tow-Dimension strain imaging (2D-Strain) technique, a novel echocardiographic technique, is based on two-dimensional gray-scale images and thus angle-independent in principle. 2D-Strain can track speckles frame by frame accurately and thus can be used to assess the function of ischemic myocardium more conveniently and accurately.Since ejection fraction is one important factor in assessing cardiac function, it means that all those factors that influence LVEF can become important windows through which cardiac function can be assessed. In this regard, the various motion patterns exhibited by the heart during systole and diastole can provide information about the functional state of the heart. The motion patterns of interest in this research were, thus, the longitudinal, circumferential and the radial motions, all of which contribute towards LVEF at varying degrees.Thus, the following questions formed the basis for this study: (1) which one of the six patterns including apical 4-chamber, 2-chamber and long-axis views, and the short-axis views (at mitral annulus, papillary muscle and apical levels) is more important than others at global left ventricular level with respect to LVEF ?; (2) which one of the three patterns in short-axis views (at mitral annulus, papillary muscle and apical levels) is more important than others in circumferential and radial directions with respect to LVEF?; (3) which segment of the sixteen segments of left ventricle is more important than the others in circumferential, radial, and longitudinal directions with respect to LVEF?Objectives(1) To find out which one of the three directions including (longitudinal, radial and circumferential) is more important than the others at global left ventricular level with respect to LVEF.(2) To assess which one of the three patterns apical (4-chamber, 2-chamber and long-axis) is more important than the others in longitudinal and radial directions with respect to LVEF.(3) To assess which one of the three pattern short-axis views (at mitral annulus, papillary muscle and apical) is more important than the others in circumferential and radial directions with respect to LVEF. (4)To find out which segment of the sixteen segments of left ventricle is more important than the others in circumferential, radial and longitudinal directions with respect to LVEF.MethodsStudy PopulationWe included 20 subjects (20men, aged 24±2years). The exclusion criteria were based on presence of valvular cardiac disease, Cardiomyopathy, heart failure and arrhythmia. The case history of all subjects was reviewed, and all underwent physical examination, echocardiography, electrocardiography and blood testing for blood cell differential, cardiac troponin inhibitor, levels of total cholesterol, total triglycerides, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, fasting plasma glucose, serum aspatate aminotransferase, alanine aminotransferase, blood urea nitrogen, and creatinine.EchocardiographyEchocardiography was performed in every subject. It was performed using a commercially ultrasound transducer and equipment (M3S probe,Vivid7; GE Medical Systems, Horten, Norway) with subjects at rest in the left lateral decubitus position. Two-dimensional images were acquired of the standard parasternal and apical (4-chamber, 2-chamber and long-axis) views and short-axis views (mitral annulus, papillary muscle and apex) at a frame rate of 60 to 100 frames per second. 3 consecutive cardiac cycles were acquired during breath holding. The images were stored digitally for subsequent offline analysis.Echocardiography AnalysisEchocardiography results were analyzed offline by use of the analysis software (EchoPAC PC SW-Only v.7.0.x; GE-Vingmed, Norway). By a point-and-click approach, we placed some points on the images along the left-ventricular subendocardium at the end of the systolic phase, from the interventricular septum to the lateral wall in the apical 4-chamber view, from the inferior to anterior wall in the apical 2-chamber view, from the posterior wall to the anterior septum in the apical long-axis view and the same was done for the short-axis of LV. The software divided the left ventricular walls into 16 segments automatically. Then strain and strain rate data of the myocardial segments were acquired by the software and were exported to Microsoft Excel for further analysis.The following parameters of the myocardial segments were calculated: the systolic peak strain (Sps), in longitudinal (L), radial (R) and circumferential (C) directions.Statistical AnalysisValues are expressed as mean±standard deviation (SD). Correlation between variables used Bivariate to acquire Pearson Correlation. P < 0.05 was considered statistically significant.Results1. The Pearson Correlation for the three directions (circumferential, radial and longitudinal) at global left ventricular level with respect to LVEF is 0.565, 0.488 and 0.365 respectively.2. The Pearson Correlation for the three patterns (4-chamber, 2-chamber and long-axis) in longitudinal/radial directions with respect to LVEF is 0.864/0.170, 0.504/0.424, 0.457/0.149 respectively.3. The Pearson Correlation of the three patterns short-axis views (at mitral annulus, papillary muscle and apical levels) in circumferential/radial directions with respect to LVEF is 0.733/0.746, 0.154/0.121, 0.565/0.262 respectively.4. The Pearson Correlation of the segment of the sixteen segments of left ventricle in circumferential, radial and longitudinal directions with respect to LVEF is as follow:①basal anterior wall 0.185/0.658/0.613, basal anterior septum 0.492/0.472/0.284, basal inferior wall 0.472/0.758/0.343, basal lateral wall 0.743/0.721/0.705, basal posterior wall 0.743/0.721/0.705, basal inferior septum 0615/0.675/0.247. ②middle anterior wall 0.237/0.158/0.563, middle anterior septum0.411/0.288/0.924, middle inferior wall 0.288/0.323/0.424, middle lateral wall 0.103/0.194/0.314, middle posterior wall 0.165/0.384/0.230, middle inferior septum 0.675/0.148/0.171.③apical anterior wall 0.785/0.131/0.012, apical inferior wall0.105/0.263/0.841, apical lateral wall 0.460/0.139/0.681, apical septum 0.449/0.351/0.662.Conclusions1. Among the three directions (longitudinal, radial and circumferential), circumferential motion is more important than the others at global left ventricular level with respect to LVEF.2. Among the three patterns including the apical (4-chamber, 2-chamber andlong-axis) views, 2-chamber is more important than the others in radial direction and 4-chamber is more important than the others in longitudinal direction at global left ventricular level with respect to LVEF3. Among the three patterns short-axis views (at mitral annulus, papillary muscle and apical levels) mitral annulus is more important than the others in circumferential and radial directions with respect to LVEF.4. Among the sixteen segments of the left ventricle, apical anterior wall in circumferential direction, basal inferior septum in radial direction and middle anterior septum in longitudinal direction are more important than the others with respect to LVEF.
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