The Clinical Research Of Assessment Of Left Ventricular Diastolic Function In Type-2 Diabetes Mellitus By Tissue Doppler Imaging Measuring Mitral Annular Motion

Background Ventricular walls motion plays an important role in the clinical practice. Two-dimentional echocardiography is used to be the most popular technique used for noninvasive assessment of ventricular walls motion based on visual interpretation of endocardial excursion and wall thickening. Acoustic quantification (AQ) and Color kinesis (CK) can distinguish automatically and in real time tissue-blood interface and show subendocardial layers motion more clearly. However, all of these techniques suffer from limitations related to poor echogenicity and operator dependence. Doppler tissue imaging (DTI) that preserves the low doppler shift frequencies of high energy generated by the walls motion with a high-frequency transducer, a low wall filter, and low gain setting contains potential information for the assessment of myocardial properties. Pulsed wave DTI (PW-DTI) offering a high temporal resolution and accurate myocardium velocity is of primary importance in evaluating left ventricular function. Quantitation of the ventricular systolic and diastolic functions in the longitudinal axis is clinically relevant since the contraction of the ventricle in this direction is mainly due to subendocardial fibers. Motion of mitral annular longitudinal dynamics shows the motion of the cardiac base and is easy to be detected. So, longitudinal motion velocity of mitral annular measured for the assessment of left ventricular diastolic dysfunction (LVDD) by PW-DTI had been reaearched and reported successfully.Objective The aim of this study was to discuss invasive indexes to evaluate diabetic cardiomyopathy by selecting type-2 diabetic mellitus (DM) patients. Left ventricular diastolic function was regarded specially by PW-DTI comprised with mitral pulsed wave Doppler inflow (MPWD) in order to differentiate LVDD more early and exactly. Changes of PW-DTI indexes were also observed during diastole after applyingnitroglycerin (TNG) sublingually in order to validate the view that Doppler tissue velocity during early left ventricular filling is preload indepent.Methods 77 normotensive asymptomatic patients with well-controlled type-2 DM, 43 health volunteers and 18 obesity (OB) patients were studied by PW-DTI and MPWD during left ventricular filling and constriction respectively. Six position of mitral annular were measured by PW-DTI including systolic velocity Sm, early diastolic velocity Em and end diastolic velocity Am. Early mitral inflow velocity E , end mitral inflow velocity and left ventricular isovolumetric relaxation (IVRT) were measured by MPWD. Left ventricular mass index (LVMI), heart rate (HR), ejection fraction (EF), fraction shortening (FS) and stroke volume (SV) were measured by M-mode echocardiography. All indexes were measured during 3-5 heart beats. Their average value, Em/Am ratio and E/A ratio were calculated. And after taking nitroglycerin sublingually, forgoing processes and measurement were repeated.Results Em, Em/Am and E/A ratio were significantly decreased in DM than in control. Sm decreased in DM but still holding normal. Compared with group control, Am and A was increased; IVRT was prolonged; and early mitral inflow E was not changed in DM. There was no change in EF, FS and SV between the two groups and LVMI was higher in DM. The two methods showed a significant correlation in Em/Am vs. E/A (r=0.68 in DM and r=0.79 in control). There was an obvious difference in PW-DTI and MPWD in distinguishing LVDD of type-2 DM patients from the normal. The LVDD diffentiated rate in group DM was 94.81% by PW-DTI and 79.22% by MPWD. After taking 5.0mg TNG sublingually, HR increased and IVRT prolonged in all groups. ?In group DM: Em, Em/Am ratio, E and E/A ratio decreased. Sm, EF and FS increased. ?In group OB: Em, E and E/A decreased. EF and FS increased. ?In group control: Em/Am ratio, E and E/A ratio decreased. Am and Sm increased .Conclusions The mode of mitral annular velocities measured by PW-DTI was similar to that of MPWD during diastole which were both characterized by the mode of LVDD. And the two methods showed a significant correlation in assessing filling function. Howere, PW-DTI could analysize diastolic function more sensitively and roundly due to its potent differentiation of pseunormalization. And the prevalence of LVDD in type-2 DM patients was higher than that of previous investigation reported. The LVDD diffentiated rate in DM by PW-DTI was higher than that of MPWD. Finally, Doppler tissue velocities during left ventricular diastole was preload dependent in assessment of left ventricular filling in similar to MPWD.