Quantitatively Evaluating The Longitudinal Left Myocardial Diastolic Function Of Diabetic Nephropathy In Various Stages By Strain Rate Imaging

Objective:To discuss the value of strain rate imaging in quantitatively evaluating longitudinal myocardial function of left ventricle in diabetes nephropathy patients of various stages.Methods:Choose 58 patients with diabetic nephropathy, these diabetes patients were divided into 3 groups based on albuminuria status:Ⅰ(no albuminurian,<30mg/d, n=22),Ⅱ(microalbuminuria,30-300mg/d, n=17),Ⅲ(clinical albuminuria,>300mg/d, n=19),20 healthy controls served as the control group IV which comparable for age and sex. Every object of study didn't got hypertension and in sinus rhythm without signs of left ventricular hypertrophy,bundle-branch block,atrial fibrillation,ischemia,congenital heart disease,valvular disease and pericardium disease through electrocardiogram,Echocardiogram,Coronal Artery Angiography. We got basie clinical data such as age,gender,blood pressure,heart rate,2h Plasma Glucose,Fasting Blood Glucose and 24 hour microalbuminuria. Then all of the subjects underwent conventional echocardiography include following parameters:left Atrium diameter(LA), left ventricle end diastolic diamete(LVDd),interventricular septal thickness(IVSTd),left ventricular postwall thickness(LVPWTd),Peak early mitral inflow (E)velocity, peak atrial filling (A) velocity and E/A were calculated. All subjects had normal left ventricular ejection fraction (LVEF)≥55%, as measured by the Simpson method. Left ventricular mass index(LVMI) were calculated by formula of Devereux. After connected the electrocardiogram, Tissue Doppler images were obtained in the standard echocardiographic views of the LV apical two- chamber (ventricular anterior wall and inferior wall),four-chamber(left ventricular lateral wall and interventricular septum) and long-axis plane views(left ventricular posterior wall and interventricular septum) for three cardiac cycles. All data were acquired at a frame rate equal or greater than 120 frames/s, the tissue doppler myocardial imagine were stored in digital format and used QLAB 5.0 analyzed offline. We got the sampling point at the inner one third myocardium of the basement segments and the middle segments(wipe off the apex segments) among left ventricular myocardium, there are 12 segments we analysed altogether. Wiping off the unsmooth curves and included angle greater than 20 degree between the Doppler beam and direction of longitudinal myocardium movement. Then we got the early diastolic strain rate (SRa) and late diastolic strain rate(SRe) curves. Every subject have there own data(mSRa,mSRe) were averaged of three cardiac cycles; Every group have their averaged data(MSRa,MSRe). All the analyses were performed using SSPS17.0 and quantitative data were compared using t test. The correlations of different data were studied by linear regression analyses. Every subject's mAlb as dependent variable, mSRa,mSRe as independent predictors variable were determined using multiple linear regression analysis. Values were expressed as mean±SD. P<0.01 mean the difference has remarkable statistical signification, P<0.05 mean the difference has statistical significance.Results:①There were no significant differences among the 4 groups in age, heart rate, systolic blood pressure, diastolic blood pressure. The fasting blood glucose,24h albuminuria between groupⅠandⅢwere significantly difference (P<0.05),2h plasma glucose of groupⅢwere higher than groupⅠ, and the difference have obviously statistical signification (P<0.01).②The LVMI between groupⅠandⅢwas significantly difference (P<0.05);③The MSRe,MSRa of diabetes nephropathy patients group (Ⅰ,Ⅱ,Ⅲ) were lower than control groupⅣ, the difference betweenⅢandⅣ,I were obviously statistical signification (P<0.01); MSRe,MSRa betweenⅡand IVwere significantly difference (P<0.05); ④Linear regression analysis showed significant negative correlation of 24-hour urine albumin with mSRe(β1=-0.032)and mSRa((β2=-0.011).Conclusion:The technology of strain rate imaging can be an available quantitatively measure to diagnose the subclinical myocardial disease more effectively and sensitivity; Dividing the left ventricle wall into three layers for study had got the research significance, and the subendocardial function is the most important layer to analysis diabetic nephropathy's diastolic function.