Echocardiography To Predict Cardiac Resynchronization Treatment Efficacy Of The Best Parameters Of Experimental Research

Objective Tissue Doppler imaging(TDI),real-time three-dimensional echocardiography(RT3DE) and speckle tracking strain imaging(STSI) are methods to assess left ventricular(LV) dyssynchrony.In this study we used dogs with heart failure to investigate which parameter is the best to predict the effect of cardiac resynchronization therapy(CRT).Methods Twelve adult beagle dogs were divided into three groups.Eight of them received right ventricular pacing(Group A＆B).When their LVEF decreased below 35%,dogs in Group A treated with CRT and dogs in Group B were terminated rapid ventricular pacing.The other 4 dogs were used without connection to the pacemakers (Group C).We placed epicardial leads on the left ventricles.Endocardial pacing leads were implanted in the right atria and right ventricles in all the 12 beagle dogs.Right ventricle was paced at 230 beats/min in Group A＆B.TDI,RT3DE and STSI were performed at baseline,2 weeks after pacing,4 weeks after CRT.TDI dyssynchrony parameters included the standard deviation of time to maximum systolic velocity of the 12 LV segments(Ts-12SD).We also used the standard deviation of time to minimum volume of the 16 LV segments(Tmsv-16SD) as well.STSI dyssynchrony parameters included standard deviation of time from onset of QRS to peak radial strain(Trs-6SD),peak radial strain rate(Trsr-6SD) and peak circumferential strain (Tcs-6SD) of the 6 middle LV segments.LV ejection fraction(LVEF),end diastolic volume(LVEDV) and end-systolic volume(LVESV) were measured by RT3DE.Results In Group A＆B,rapid RV pacing decreased LVEF,enlarged LVESV and dyssynchronized LV segments.Although in Group B LVEF and LVESV returned dramatically,LVEDV remained enlarged to a 4-week period.After 4 weeks of CRT, LVEDV reduced from 37.35±9.53ml to 28.95±3.98ml.Ts-12SD,Tmsv-16SD, Trs-6SD and Tcs-6SD correlated well with LVEF and LVEDV.Tmsv-16SD showed the strongest correlation with LVEF,and Trs-6SD with LVEDV by multiple regression analysis. Conclusions RT3DE and STSI can effectively detect left ventricular dyssynchrony in heart failure canines.Tmsv-16SD and Trs-6SD showed the strongest correlation with LVEF and LVESV.Standard deviation of time to minimum volume and peak radial strain may be the best to predict the effect of cardiac resynchronization therapy.