Evaluation Of Short-term Changes Of Cardiac Structure And Function After Left Bundle Branch Pacing By Three-dimensional Speckle-tracking Imaging

Objective:To explore the short-term changes in cardiac structure and function in patients with left bundle branch pacing(LBBP)using a combination of conventional two-dimensional echocardiography,real-time three-dimensional echocardiography,and three-dimensional speckle-tracking imaging.Methods:From January 2020 to February 2021,30 patients(aged 65.4 ± 12.4 years,16 males and 14 females)with sinus node dysfunction(SND),atrioventricular block(AVB)and Atrial fibrillation accompanied by slow ventricular rate(AF-SVR)who underwent successful left bundle branch pacing were finally included after screening according to the inclusion and exclusion criteria.Echocardiography was performed before implantation and 7 days after implantation,and the measured parameters included:(1)conventional two-dimensional ultrasound and Doppler ultrasound parameters: twodimensional left ventricular fraction(2D-LVEF),two-dimensional left ventricular stroke volume(2D-LVSV),left ventricular end-diastolic diameter(LVEDD),left ventricular end-systolic diameter(LVESD),left ventricular pre-ejection period(LVPEP),right ventricular pre-ejection period(RVPEP),the time difference between left ventricular preejection period and right ventricular pre-ejection period as interventricular mechanical delay(IVMD);(2)Three-dimensional speckle-tracking imaging(3D-STI): global longitudinal strain(GLS),global circumferential strain(GCS),global radial strain(GRS),and global area strain(GAS);(3)Real-time three-dimensional echocardiography(RT-3DE): three-dimensional left ventricular mass(3D-LVM),three-dimensional left ventricular end-diastolic volume(3D-LVEDV),three-dimensional left ventricular end-systolic volume(3D-LVESV),three-dimensional left ventricular ejection fraction(3D-LVEF),threedimensional left ventricular stroke volume(3D-LVSV);The standard deviation of time from the QRS starting point to the minimum systolic volume of 16 LV segments(Tmsv-16-SD),The standard deviation of time from the QRS starting point to the minimum systolic volume of 12 LV segments(Tmsv-12-SD)and systolic dyssynchrony index(SDI).Compare the difference of each parameter before and after implantation.For the convenience of description and statistical research in this study,the strain data are expressed in absolute values.All data were statistically analyzed using SPSS 26.0.Results:(1)Compared with ventricular synchrony index,Tmsv-16-SD,Tmsv-12-SD,SDI,IVMD and RR intervals decreased 7 days after implantation,and the differences were statistically significant(P<0.05).LVPEP and RVPEP increased at 7 days after implantation,and the difference had statistical significance(P < 0.01);(2)Compared with left ventricular strain parameters,GLS,GCS,GAS and GRS increased at 7 days after implantation,and the difference had statistical significance(P < 0.05);(3)Compared with left ventricular function changes,2D-LVEF and 3D-LVEF increased at 7 days after implantation,and the difference had statistical significance(P < 0.05);compared with 7days after implantation,LVEDD,LVESD,3D-LVEDV,3D-LVEDV and 3D-LVM decreased,and the difference had statistical significance(P < 0.05);compared with 7 days after implantation,3D-LVSV and 2D-LVSV increased at 7 days after implantation,but the difference had no statistical significance(P > 0.05);(4)Analyzed the correlation between parameters,There was a positive correlation between GLS,GCS,GAS,GRS and 3D-LVEF at 7 days after implantation,with a correlation coefficient of r 0.747-0.892,P < 0.05;there was a negative correlation between SDI and 3D-LVEF at 7 days after implantation,with a correlation coefficient r of-0.399 and-0.535,respectively,P <0.05;the correlation coefficient r between Tmsv-16-SD and 3D-LVEF before implantation was-0.337,P > 0.069(P > 0.05);and the correlation coefficient r between Tmsv-16-SD and 3D-LVEF at 7 days after implantation was-0.419,P < 0.05.Conclusion:Left ventricular synchrony and hemodynamics are improved in patients after left bundle branch pacing in the short term.Real-time three-dimensional echocardiography and three-dimensional speckle-tracking imaging can more accurately and timely evaluate changes in cardiac structure and function after left bundle branch pacing.