Evaluation Of Left Ventricular Twist In Patients With Complete Left Bundle Branch Block Using Two-dimensional Speckle Tracking Echocardiography

Objective:Left ventricular twist and untwist is one of the important forms of cardiac motion [1],but the effect of complete left bundle branch block(CLBBB)is not yet clear.Our previous study found that left ventricular systolic and diastolic function were reduced in CLBBB patients with normal left ventricular ejection fraction(LVEF)[2],suggesting that CLBBB may affect left ventricular twist and untwist.In our study,speckle tracking imaging(STI)was used to evaluate the effect of CLBBB on left ventricular twist and to discuss the mechanism.Methods:43 cases of CLBBB patients with normal LVEF were selected as the case group(group CLBBB),and 32 healthy people were selected as the control group(group CON).Conventional echocardiography and STI were performed for following parameters: 1.Left ventricular systolic function:Left ventricular end-diastolic dimension(LVEDD)、left ventricular ejection fraction(LVEF),Left ventricle global longitudinal peak stain(LV-GLS).2.Left ventricular diastolic function: Left atrium end-systolic diameter(LAD),Left atrium volume index(LAVI),Mitral flow early and later diastolic velocity(Mitral E and Mitral A),Septal mitral annulus early diastolic velocity(Mitral e′).Calculated Mitral E/A and Mitral E/e′.3.left ventricular twist function: peak twist(Ptw),peak apical rotation(PAR),peak basal rotation(PBR),time to peak twist(Ttw),peak twist velocity(Ptv).4.left ventricular untwist function: untwisting during isovolumetric relaxation(Untw),untwisting rate(Untw-R),and peak untwist velocity(Puv).Results:1.Conventional ultrasonic results(1)Left ventricular systolic function: Compared with group CON,LVEDD in group CLBBB increased(P < 0.001),while LVEF decreased(P < 0.05),but still in normal value,and LV-GLS decreased(P <0.001).(2)Left ventricular diastolic function: Compared with the CON group,the LAD,LAVI,Mitral E/e ’of the CLBBB group increased(P < 0.001),Mitral E/A,Mitral e’ decreased(P < 0.001).2.Left ventricular twist and untwist function(1)left ventricular twist function: Compared with group CON,Ptw,PAR and PBR decreased in group CLBBB(P < 0.001 or 0.05),but there was no significant difference between Ttw and Ptv(P > 0.05).(2)left ventricular untwist function: Compared with group CON,Untw and Untw-R decreased in group CLBBB(P < 0.001 or 0.05),but there was no significant difference between Puv(P > 0.05).3.Left ventricular twist and untwist function of CLBBB in different QRS duration According to QRS duration divided CLBBB patients into narrow QRS group(120 ms = QRS = 150ms)and wide QRS group(QRS > 150 ms),narrow QRS group including 17 cases,wide QRS group including 26 cases.(1)left ventricular twist function: Compared with group CON,Ptw,PAR and PBR in wide QRS group decreased(P < 0.01 or 0.05),while Ptw and PAR in narrow QRS group decreased(P < 0.01),and there was no significant difference between PBR(P > 0.05).Compared with the narrow QRS group,the Ptw in the broad QRS group decreased(P < 0.05),but there was no significant difference in PAR and PBR(P > 0.05).(2)left ventricular untwist function Compared with the CON group,the Untw and Untw-R in the wide QRS group and the narrow QRS group were decreased(P < 0.01 or 0.05),but there was no significant difference in Pu V(P > 0.05).There was no significant difference in the twist parameters between the wide QRS group and the narrow QRS group(P > 0.05).4.Correlation analysis(1)There was a negative correlation between Ptw and QRS in CLBBB patients(r=-0.386,P=0.012)(2)There is a positive correlation between PAR and LV-GLS in CLBBB patients(r=0.342,P=0.035).(3)PBR in CLBBB patients was positively correlated with Untw and Untw-R(r=0.349,P=0.027 and r=0.406,P=0.009),and negatively correlated with Mitral E/e ’(r=-0.347,P=0.026).Conclusion:1.Left ventricular twist and untwist decreases in CLBBB patients with normal LVEF.2.QRS had effects on the left ventricular twist in CLBBB patients,and the left ventricular twist decreased more significantly in the patients with wide QRS.3.Left ventricular apical twist is related to the systolic function,and the base twist is related to the diastolic function..