Evaluation Of Left Ventricular Dyssynchrony In Patients With Myocardial Infarction By Real-time Triplane Tissue Doppler Imaging

ObjectiveLeft ventficular myocardial dyssynchrony exists widely in patients with myocardial infarction(MI),so how to evaluate the myocardial dyssynchrony accurately plays an important clinical role in the diagnosis,treatment and judgment of prognosis.it has been a hot topic in cardiac pacing and electrophysiology in recent years throughout the world.Tissue Doppler Imaging(TDI) can evaluate myocardial motion dyssynchrony quickly,no ninvasively,quantitatively and reproducibly.Real-time triplane echocardiography(RT-3PE) is feasible with simple and rapid image acquisition,and accurate time acquisition.This study is to evaluate left ventricular myocardial dyssynchrony in patients with MI by triplane tissue doppler imaging(Triplane-TDI), combining TDI and RT-3PE.The purposes of this study were:1.To evaluate left ventricular myocardial dyssynchrony in patients with MI by Triplane-TDI;2.To study correlation between dyssynchrony index and left ventricular ejection fraction(LVEF);3. To assess relation of electrocardiographic QRS duration and dyssynchrony index.Materials and MethodsGroup normal controls(NC) consisted of 30 healthy volunteers,Group MI consisted of 60 patients with myocardial infarction.Patients in group MI were divided into two subgroups on the basis of QRS width,included normal QRS subgroup(MIⅠ,30) and wide one(MIⅡ,30).The LVEF was derived from Simpon's method,then the Triplane tissue velocity images at apical four-chamber view were obtained.The 6 walls of the left ventricle were divided into basal and middle segments(12 Segments).Time to peak systolic velocities(Ts) and time to peak early diastolic velocities(Te)was measured,then the maximal difference in Ts between any two segments(Ts-maxD),the standard deviation of Ts(Ts-sD),the maximal difference in Te(Te-maxD) and the standard deviation of Te(Te-sD)were calculated.Time to peak displacement(Td) was measured, then the maximal difference in Td(Td-maxD),the standard deviation of Td(Td-sD) were calculated.Results1.There were no significant diference in age,heart rate betweent the two goups(P＞0.05).LVEF of group MI was much lower than that of group NC(P＜0.01).2.The dyssynchrony indexes(Ts-sD,Ts-maxD,Te-maxD,Te-sD,Td-maxD,Td-sD) in the patients with MI were much longer than those in control subjects(p＜0.05).3.Significant negative correlation existed between LVEF and the dyssynchrony indexes Ts-sD,Ts-maxD,Te-maxD,Te-sD,Td-maxD,Td-sD(r=-0.718,-0.668,-0.597, -0.563,-0.671,-0.559,P＜0.05).4.There was significant difference of Ts-sD,Ts-maxD,Te-maxD,Te-sD, Td-maxD and Td-sD between wide QRS subgroup and normal one(p＜0.05).Conclusions1.In control group,there was no significant diference of Ts in LV.which show movement is highly synchronized in LV of normal people.2.LV dyssynchrony is common in patients with MI.3.Triplane-TDI is a rapid,noninvasive,accurate method to detect myocardial dyssynchrony.It affords effective indexs to assess the function of LV,and the degree of LV dyssynchrony is correlated negatively with LVEF.4.The ratio of LV dyssynchrony is higher in MI patients with wide QRS than those with normal QRS.But there is no necessary correlation between QRS width and LV dyssynchrony,so QRS During＞120ms can not be selected as cardiac resynchronization therapy(CRT) reliable evidence.