文献抄读20180129

Left ventricular ejection fraction(LVEF)
The LV ejection fraction (EF) has important implications in diagnosis, management, and prognosis of many pathological conditions, especially in heart failure, ischemic, and valvular diseases. LVEF could be easily calculated through endocardial border delineation, or alternatively, it can be “eyeball” estimated,It is one of the most used parameters to evaluate the LV systolic function.The most commonly used and recommended echocardiographic 2-D measurement for volume measurements is the modified Simpson’s rule with biplane planimetry,According to the European and American Society of Echocardiography, its normal value is above 55 %, while a value ranging from 45 to 54 %, 30 to 44 %, and ＜30 % represents a mild, moderate, and severe systolic dysfunction, respectively.
INTRODUCTION
The human heart has a complex structure of muscular fibers, organized in layers. Left ventricular (LV) sub-endocardial and sub-epicardial fibers have a longitudinal disposition, from the apex to the base, drawing a spiral around the ventricle (subepicardial are clockwise oriented,sub-endocardial are counter clockwise, seen from apex to the base), while the mid-wall fibers are circumferential.Contraction and release of all these fibers generates a complex deformation and movement of the LV walls both in systole and diastole. The final global result is systolic blood ejection into the aorta and diastolic ventricular filling.
Measurement of LV ejection fraction and stroke volume
Limitations of ejection fraction measurement
Tቤተ መጻሕፍቲ ባይዱe principal technical limitations are the difficulty to obtain true two- and four-chamber apical views in some patients.
Longitudinal function can be evaluated in many ways, such as M-mode echocardiography, tissue Doppler imaging, and speckle tracking echocardiography.This latter is a relatively new tool to assess LV function through measurement of myocardial strain, with a high temporal and spatial resolution and a better inter- and intraobserver reproducibility compared to Doppler strain. It is angle independent, not affected by translation cardiac movements, and can assess simultaneously the entire myocardium along all the three-dimensional geometrical(longitudinal, circumferential, and radial) axes. Speckle tracking echocardiography also allows the analysis of LV torsion. The aim of this paper was to review the main echocardiographic parameters of LV systolic function and to describe its pros and cons.
Echocardiographic assessment of left ventricular systolic function: from ejection fraction to torsion
超声心动图评价左室收缩功能：从射血 分数到扭转
ABSTRACT
Assessment of left ventricular (LV) systolic function is the cornerstone of the echocardiographic examination. There are many echocardiographic parameters that can be used for clinical and research purposes,each one with its pros and cons. The LV ejection fraction is the most used one due to its feasibility and predictability,but it also has many limits.LV longitudinal function is expression of subendocardial fibers contraction. Because the subendocardium is often involved early in many pathological processes, its analysis has been a fertile field for the development of sensitive parameters.
The invasive LV dP/dt max, that is, the change in maximum rate of systolic pressure rise, is a sensitive parameter of myocardial performance that closely approximates changes of contractility; however, its utility has been limited because it needs an intraventricular catheter for its assessment.Doppler echocardiography can estimate the rate of pressure gradient changes by using the continuous wave Doppler signal of mitral regurgitation;This beatby-beat and repeatable estimation should be very useful in patients with heart failure and mitral regurgitation; in this settings this parameter is highly feasible because a mitral regurgitation is a common finding in patients with congestive heart failure.
It is not affected by wall motion abnormalities.Sometimes mitral regurgitant jet velocities can be difficult to record in case of eccentric regurgitant jets.
The myocardial performance index (the Tei index)
Tei et al. devised and published an index of myocardial performance (the Tei index) that combines the evaluation of the LV systolic and diastolic function. In last decades, the Tei index has proved to be a reliable method for the evaluation of LV myocardial performance, with clear advantages over older established indices and prognostic value in many kinds of heart disease. The Tei Index was assessed in dilated cardiomyopathy and heart failure and showed a good correlation with the LVEF and NYHA class as well a prognostic value for short- and longterm outcome. Patients with acute myocardial infarction had Tei Index values higher than healthy controls, and higher values have been observed in patients with more severe coronary disease and with more complicated course.
ventricular aneurysms, asymmetrical ventricles, wall motion abnormalities
Conventional Doppler indices of global left ventricular function
The Doppler dP/dt