Study On Real-time Three-dimensional Echocardiography Combined With Tissue Doppler Technique For Synchrony Of Cardiac Motion In Patients With Sick Sinus Syndrome After Left Bundle Branch Pacing

Objectives To study the patients with sick sinus syndrome(SSS)by combining real-time three-dimensional echocardiography(RT-3DE)and tissue Doppler imaging(TDI)for synchrony of cardiac motion atfer left bundle branch area pacing(LBBP).Methods A observational study of 20 patients with LBBP and 20 patients with right ventricular pacing(RVP)was performed and divided into LBBP group and RVP group.The pacemakers were respectively programmed for atrial pacing and ventricular pacing mode.The QRS width were recorded by 12-lead electrocardiogram(ECG)before acquiring ultrasound images.The time from QRS starting point to the point with minimal systolic volume(Tmsv)in each segment obtained by RT-3DE was taken to derive the following indexes of systolic asynchrony: the Standard deviation(SD)of all 16 segments(Tmsv-16-SD),the SD of Tmsv of 6 basal and 6 mid segments(Tmsv-12-SD),the SD of Tmsv of 6 basal segments(Tmsv-6-SD),the maximal difference of Tmsv among all 16 segments(Tmsv-16-Dif),the maximal difference of Tmsv among 6 basal and 6 mid segments(Tmsv-12-Dif),the maximal difference of Tmsv among 6 basal segments(Tmsv-6-Dif),systolic dyssynchrony index(SDI).The standard deviation(Tsd-12-LV)and the mean value(Ts-12-LV)of the left ventricular 12-segment contraction velocity peak time(Ts)were measured by TDI.The mean value of right ventricular 2 segments(Ts-2-RV)and the difference of Ts between basal segment of the left ventricular lateral wall and the right ventricular free wall(Ts-LV-RV)were calculated.Results Tsd-12-LV in the LBBP group was lower than the RVP group in the ventricular pacing state measured by TDI.The Tmsv-16-SD and SDI in LBBP group were significantly lower than those in the RVP group analyzed by RT-3DE in the ventricular pacing state.The above differences were statistically significant(P < 0.05).The synchrony parameters measured in the ventricular pacing state of the RVP group were greater than those in the atrial pacing state(P<0.05).The synchrony parameters and cardiac function measured in the ventricular pacing state of the LBBP group were not statistically different compared with the atrial pacing state(P>0.05).Conclusions Cardiac synchrony of LBBP is better than RVP in ventricular pacing state,and there is no difference between self-conduction and ventricular pacing state in LBBP.LBBP is a physiological pacing method.TDI and RT-3DE are both useful tools to evaluate cardiac synchrony.