Evaluation Of Left Ventricular Diastolic Function Using Velocity Vector Imaging And Its Reference Value Range

[BACKGROUND]With the medical progress and development, living standards, the pace of life changes and aging of the population, diastolic heart failure (diastolic heart failure, DHF) cases of all heart failure patients roars up from 38% to 54% the past 20 years, with the prognosis of DHF and systolic heart failure as the same serious, and thus becomes the hot spot of basic and clinical research in recent years. Therefore early and accurate assessment of left ventricular diastolic function has an important clinical value for the diagnosis of DHF, and it needed to include a new standard for the diagnosis and treatment of DHF.At present, the methods of evaluation the left ventricular diastolic function are: (1) The determination of left ventricular end diastolic pressure (hemodynamic test) is recognized as the golden standard for the evaluation of left ventricular diastolic function, but as its invasive nature leads to a difficulty in clinical applications; (2) imaging inspection such as MRI, with better image quality, easy to operate, short check time, measurement accuracy, without contrast injection, no radiation damage, no assumption on the ventricular morphology, can be more accurate evaluate left ventricular diastolic function, and has become an ideal inspection method,but due to its radioactive, respiratory effects,high cost limits its clinical applications; (3) Two-dimensional ultrasound such as E/A:E/A is Conventional Doppler echocardiography to measure the mitral flow spectrum. Widely used in the evaluation of left ventricular diastolic function. However, when there is increased left atrial pressure, left ventricular compliance becomes further retreat, it may appear mitral flow spectrum of the "pseudo-normalization". Although simple, but the accuracy is poor, therefore, the technical deficiencies; (4) NT-proBNP (N terminal pro-brain natriuretic peptide)in heart failure clinical studies have shown that NT-proBNP levels elevated, and consistent with the severity of heart failure in systolic dysfunction. In systolic dysfunction and diastolic dysfunction all have this change, along with improved heart function, NT-proBNP levels decreased. NT-proBNP level elevation by the progress and prognosis of heart failure has good predictive value, is relatively independent predictors of DHF. However, NT-proBNP levels affected by many factors, including kidney function, atrial fibrillation, myocardial ischemia, pulmonary embolism, chronic obstructive pulmonary disease, tumors, other factors such as age, sex, diuretics andβ-receptor blockers also have some influence on the results. Thus, NT-proBNP concentration alone diagnosis of heart failure has some limitations. (5) tissue Doppler (tissue Doppler imaging, TDI) With extracted directly from myocardial Doppler frequency shift signals, quantitative determination of wall motion speed, accurate analysis of visual wall and valve annulus, noninvasive and easy to operate, TDI can be a more accurate assessment of left ventricular diastolic function. However, because of similarities with the limitations of Doppler flow imaging, angle exists between Doppler ultrasound beam and the direction of myocardial movement, heart during a cardiac cycle the overall movement, breathing movement, instruments such as gain adjustment can affect the measurement, the results shown in checking the operation of differences, lacking of quantitative, so poor reproducibility and angle dependence of the inevitable existence, subject to certain restrictions on its accuracy. With the development of echocardiography, tissue Doppler imaging provides a new tool for the evaluation of left ventricular diastolic function. TDI is a display myocardial motion by Doppler effect of ultrasound imaging characteristics of new technologies to extract it directly from myocardial Doppler frequency shift signals, quantitative determination of wall motion speed, accurate analysis of visual wall and valve annulus.Domestic and foreign literature has reported the average Mitral ring velocity quickly, prospective evaluation of left ventricular systolic and diastolic function. However, because of similarities with the limitations of Doppler flow imaging, poor reproducibility and angle dependence of the inevitable existence, its accuracy is subject to certain restrictions, limiting the TDI evaluation of left ventricular diastolic function in the application and development.Velocity vector imaging (VVI) is based on two-dimensional speckle-tracking principle to establish a new study of myocardial structural mechanics, analysis of regional cardiac function acoustic diagnostic techniques, the accurate ultrasonic speckle-tracking in the organization and determine spots mutual relationship between the location of the establishment of a Non-angle-dependent myocardial function evaluation methods, and more easily capture images, which significantly improve the measurement accuracy. In recent years, VVI evaluation of diastolic function has become the hot domestic and international clinical research, causing cardiovascular disease research attention. The VVI using acoustic collection, no angle dependence, smaller noise than traditional Doppler noise, intuitive display mode, In cardiac long axis, short axis and the circumferential direction at any point on the quantitative structure of the mechanical parameters, accurate quantification of ventricular volume and ejection fraction, can be used to evaluate congestive heart failure, myocardial dysfunction and other cardiac synchronization dysfunction in patients with mechanical cardiac function and anatomical changes in clinical and scientific research has opened a new road, in the non-invasive evaluation of left ventricular diastolic function in greater advantage.Zhang Chuan and others'studies with acute myocardial ischemia in dogs VVI evaluation of left ventricular diastolic function in the state that use of different hemodynamic and quantitative tissue velocity imaging (QTVI).VVI technology mitral ring were measured in the long axis of the diastolic heart speed, the results show that the QTVI and VVI mode E'(early TD lengthening velocity), the average of E'for the two technologies and LVEDP had a good negative correlation of the two techniques in measured left ventricular diastolic function. Em, along with the different left ventricular diastolic function decline, it corresponded to decline. The use of these two technologies can be measured Em is noninvasive assessment of left ventricular diastolic function in a good way. Em of VVI mode is more correlation with LVEDP than QTVI. VVI evaluation of left ventricular diastolic function with non-invasive, easy to operate, the advantages of good reproducibility, is more worthy of the recommended evaluation of left ventricular diastolic function of the technical methods, with a wider range of applications.However, up to now no study in normal population of diastolic function to evaluate and give reference to define by VVI, much less by VVI on diastolic heart failure patients to evaluate and define. Therefore the clinical application of VVI still has some limitations.The purpose of this study and main contents are:1. normal population distribution of left ventricular diastolic function in VVI; 2. to determine VVI defined left ventricular function reference values in normal population. [Objective] To study the velocity vector imaging (VVI) Assessment of normal left ventricular diastolic function and determine its normal reference range.[Methods] Combination of ultrasound, NT-proBNP, clinical symptoms and other indicators of 97 healthy people screened, using Siemens Acuson Sequoia C512 echocardiography instrument, under VVI measured resting left ventricular mitral annulus level of the six wall:septal, lateral wall, anterior wall, inferior wall, anterior septum, posterior wall myocardial early diastolic velocity (E), the offline workstation interface entered VVI blind method using image analysis and calculator the mean Em, measured E/Em.[Results]E/Em of 97 normal patients in the reference range (unilateral boundaries to take 95% limit) to (0,22.935); E/Em of male in the reference range (0,22.300), female E/Em values of the reference range was (0,24.766); E/Em of male under 50 years old in the reference range 22.300; female under 50 years old E/Em values of the reference range was(0,24.766); E/Em of male over the age of 50 years old in the reference range (0,22.300); female over the age of 50 years old E/Em values of the reference range was (0,24.766);by Mann-Whitney test non-parametric test, male, female E/Em was no significant difference, P= 0.296.[Conclusions] VVI,as a new ultrasound technology, is a good method for non-invasive evaluation of left ventricular diastolic function, and as an accurate clinical assessment of left ventricular diastolic function provides a reliable means.