الفهرس 
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Abstract
Cardiovascular disease is the leading cause of death in the developed and developing countries. Despite considerable advances in prevention, detection and treatment strategies, coronary artery disease remains a significant cause of morbidity and mortality. Coronary revascularization has a recognized role in the acute ischemic setting and also in some patients with chronic coronary artery disease and heart failure. Although conventional echocardiography is considered to be reliable for ventricular wall motion analysis and assessment of regional myocardial function, the visual estimation of wall motion is very subjective and therefore highly operator dependent. It also has high interobserver and intraobserver variability and allows only limited evaluation of radial displacement and deformation, without the possibility of assessing myocardial shortening and twisting. Velocity imaging, displacement imaging and deformation imaging have emerged as valuable tools for more comprehensive and reliable echocardiographic assessment of myocardial function. Strain imaging derived from speckle tracking is a newer echocardiographic technique for obtaining strain and SR measurements. It analyzes motion by tracking speckles in the 2D ultrasonic image that are tracked from frame to frame, the change in speckle position allows determination of its velocity, the motion pattern of myocardial tissue is reflected by the motion pattern of speckles. Echocardiographic strain is a promising tool for the evaluation of myocardial function. The spectrum of clinical applications is very wide due its ability to differentiate between active and passive movement of myocardial segments, to quantify intraventricular dyssynchrony and to evaluate components of myocardial function such as longitudinal myocardial shortening that are not visually assessable. This tool help to detect subclinical myocardial dysfunction which may have significant diagnostic and therapeutic implications. Operators experience and also operators variability affect the global assessment of ventricular function either by m mode or modified simpson method, moreover visual evaluation of WMA and systolic function by eye balling, therefore segmental and global myocardial mechanics assessment of strain and strain rate with relation to original diameter and parameters more accurate than operator dependency method. The study of both mechanics and physiology explained by measure lengthening of fiber in systole with a positive mark, shortening by a negative mark, depend on the extent and rate of deformation extension in myocardial segment in both systole and diastole in cardiac cycle.