Objective To compare and analyze the synchrony of cardiac contraction when left bundle branch area pacing ( LBBP ) using tissue Doppler imaging ( TDI ) . Methods T wenty‐four patients with LBBP and 20 patients with right ventricular pacing ( RVP ) were enrolled in the study . Among them , 35 cases were diagnosed as sick sinus syndrome ( SSS ) and 9 cases were diagnosed as Ⅱ or Ⅲ degree atrioventricular block ( AVB) before operation . Echocardiographic images were collected with ventricular pacemaker‐on ,and patients with SSS in LBBP group under the condition of pacemaker program control also collected the image of self‐conduction . TDI was used to measure time of the peak velocity ( T s ) of myocardial contraction in the left ventricular 12 segments ,right ventricle 2 segments ,and atrial 3 walls .The difference between the basal segment of left ventricular lateral wall and right ventricular free wall ( T s‐LV‐RV ) ,the mean value of the right ventricular 2 segments ( T s‐2‐RV ) ,the average( T s‐12‐LV ) and standard deviation ( T sd‐12‐LV ) of the left ventricular 12 segments ,and the difference in peak systolic time among 3 walls T AL‐R ,T AI‐R ,T AL‐I were calculated . Results Compared with the RVP pacing state ,the parameters of left ventricular systolic synchrony in LBBP pacing were shortened ,and the difference was statistically significant ( P ＜ 0 .05 ) . T here was no significant difference in parameters of left ventricular/right ventricular systolic synchrony and cardiac function between the LBBP group and the self‐conduction status ( P＞0 .05) . Conclusions Left ventricular systolic synchrony is superior to RVP in LBBP pacing ,and left/right ventricular systolic synchrony and cardiac function are not different from self‐conduction . LBBP is a new physiological pacing . TDI is able to quantitatively assess cardiac systolic synchrony .

Objective:To assess the changes of left ventricular systolic function and global synchronization and myocardial work in patients with left bundle branch pacing (LBBP) by two-dimensional multi-layered speckle tracking imaging.Methods:Forty-two patients with Ⅱ degree Ⅱ type or Ⅲ degree atrioventricular block (AVB) in the Cardiovascular Hospital of Xiamen University from April to December 2019 were selected as pacing group, which were further divided into two groups according to different pacemaker modes: twenty patients with right ventricular septal pacing (RVSP), twenty-two patients with LBBP, and twenty patients with normal ECG and cardiac structure were enrolled as control group. Echocardiography of pacing group and control group was performed and analyzed. The left ventricular subendocardial longitudinal strain peak(LSendo), the middle layer myocardial longitudinal strain peak(LSmid), subepicardial longitudinal strain peak(LSepi), global myocardial longitudinal strain peak(GLS), peak strain dispersion (PSD), global work index (GWI), global constructive work (GCW), global wasted work (GWW) and global work efficiency (GWE) were acquired. The differences among the three groups were analyzed and the high difference indexes were screened by statistical modeling.Results:LSendo in three groups had no difference ( P>0.05). LSmid, LSepi, GLS in the control group, LBBP group and RVSP groups were decreased gradually ( P<0.05). GLS in LBBP group was higher than in RVSP group ( P<0.05). Compared with the control group, the increases of QRS and PSD in LBBP group were not statistically significant ( P>0.05), while the decreases of QRS and PSD in LBBP group were statistically significant compared with the RVSP group ( P<0.05). The values of GCW among three groups had no statistical significance ( P>0.05). Compared with the control group, the decrease of GWI in LBBP group was not statistically significant ( P>0.05), while the increase of GWW and the decrease of GWE were statistically significant ( P<0.05). Compared with the RVSP group, the increases of GWI and GWE and the decrease of GWW in LBBP group were statistically significant ( P<0.05). QRS, LSendo, GLS, LSmid, left ventricular apex rotation to basal rotation peak time(ApexBase period) were the indexes with significant difference among LBBP and RVSP groups and all index characteristics showed better in LBBP than RVSP group. Conclusions:Two-dimensional multi-layered speckle tracking imaging can be used to evaluate the effect of LBBP on left ventricular systolic function and global synchronization and myocardial work. LBBP longitudinal mechanical synchronization is better than right ventricular septal pacing by improving the peak global myocardial longitudinal strain and myocardial work after pacemaker.