Evaluation Of Ventricular Function And Synchronization In Patients With Isolated Complete Right Bundle Branch Block-Compared With Isolated Complete Left Bundle Branch Block By Echocardiography

Objective: Complete bundle branch block is a relatively common cardiac conduction system disease,which can be divided into two types: complete left bundle branch block(CLBBB)and complete right bundle branch block(CRBBB).Due to delayed activation of the left ventricle or right ventricle,the ventricular activation sequence changes,resulting in asynchrony of myocardial electro-mechanical movement.The results of our previous study showed that patients with isolated CLBBB with normal left ventricular ejection fraction(LVEF)had reduced left ventricular systolic,diastolic function,and synchrony.However,studies on isolated CRBBB are rare.Therefore,this study aims to compares the left and right ventricular systolic,diastolic and synchronic changes in patients with isolated CLBBB with normal LVEF and patients with isolated CRBBB by echocardiography,to provide important information for clinical judgment.Methods1.Patients selection: 44 CRBBB patients(CRBBB group)and 44 CLBBB patients with normal LVEF(CLBBB group),and 42 healthy adults(control group)were selected.2.Ultrasound detection:Left ventricular systolic function: conventional echocardiography is used to measure the left ventricular end-diastolic diameter(LVEDD),left ventricular end-diastolic and endsystolic volume,LVEDV and LVESV),LVEF,using 2D-speckle tracking echocardiography(2D-STE)to detect left ventricular systolic longitudinal strain(LVGLS);Left ventricular diastolic function: left atrium volume index(Left atrium volume index,LAVI),mitral valve(MV)early and late diastolic blood flow velocity(E and A),MV interval and early diastolic velocity of sidewall annulus(MV-e′-Sep and MV-e′-lat),and calculate E/A and E/e′,tricuspid regurgitation peak flow rate(Tricuspid regurgitation,TR)detected by conventional echocardiography,and performing diastolic function classification;Overall right ventricular function: tricuspid valve isovolumetric contraction time(IVCT),ejection time(ET),isovolumetric relaxation time(IVRT)detected by tissue Doppler method,and calculating Tei-Index;Right ventricular systolic function: Measure of the maximum end-diastolic area and the minimum end-systolic area of the right ventricle,and calculating the right ventricular fractional area change(RV-FAC)and tricuspid annular plane systolic excursion,TAPSE),right ventricular basal diameter(RV-base),TV annulus systolic velocity of septal side(TV-s’);Right ventricular diastolic function: tricuspid valve(TV)early and late diastolic blood flow velocity(E and A),TV lateral valve annulus early diastolic velocity(TV-e’)and tricuspid valve E wave deceleration time(TV-EDT);Heart synchronization detection:(1)Atrioventricular synchronization: left ventricular diastolic filling time ratio(the ratio of left ventricular diastolic filling time to RR interval,LVDFT/RR);(2)Interventricular synchronization: Doppler method is used to detect left ventricular outflow tract blood flow spectrum before ejection and right ventricular outflow tract blood flow spectrum ejection Interventricular mechanical delay(IVMD);(3)Left ventricular systolic synchronization: 2D-STE is used to detect the standard deviation of left ventricular 18 segments peak longitudinal strain(Standard deviation of left ventricular18 segments peak strain time),SDt-LV18);(4)Right ventricular synchronization: 2DSTE was used to detect the standard deviation of right ventricular 6 segments peak strain time(SDt-RV6)Results1.Comparison of general clinical data: compared with the control group,the QRS duration of the CRBBB group was increased(all P<0.001);compared with the CLBBB group,the SBP of the CRBBB group was lower.There is no significant difference in clinical data.2.Comparison of left ventricular systolic function between groups: compared with the control group,LVEDD,LVESV of CRBBB group increased,and LVEF and LV-GLS of in CRBBB group was reduced,suggesting that left ventricular systolic function of CRBBB group had reduced(P<0.001);compared with CLBBB group,CRBBB group had lower LVEDD,suggesting that left ventricular systolic function of CRBBB group was higher than the former.3.Comparison of left ventricular diastolic function between groups: compared with the control group,the MV-e’-sep,MV-e’-lat,MV-E/A and left ventricular diastolic function evaluation of the CRBBB group were reduced.MV-E/e’ and LAVI were significantly increased,suggesting that the CRBBB group had decreased left ventricular diastolic function;compared with CLBBB group,MV-e’-sep,MV-e’-lat,MV-E/A were higher,MV-E/e’ and LAVI were lower.The degree of left ventricular diastolic function decrease was also lower in CRBBB group(P<0.001),suggesting that the CRBBB group had higher left ventricular diastolic function than the former.4.Comparison of the overall function of the right ventricle between the groups: compared with the control group,the Tei-Index of the CRBBB group were increased,indicating that the overall right ventricular function of the CLBBB group and the CRBBB group were reduced;and compared with the CLBBB group,the Tei-Index of the CRBBB group was higher,indicating that the overall right ventricular function of the CRBBB group was lower than the former.5.Comparison of right ventricular systolic function between groups: compared with control group,RV-FAC,TAPSE,RV-GLS,TV-s’ in CRBBB group decreased,and RVbase increased(P<0.001),suggesting that the right ventricular contraction function of CRBBB group was reduced;compared with CLBBB group,RV-FAC,TAPSE,RV-GLS in CRBBB group were significantly reduced,and RV-base was significantly increased(all P<0.001),suggesting that the right ventricular contraction function of CRBBB group was significantly lower than the CLBBB group.6.Comparison of right ventricular diastolic function between groups: compared with the control group,the RV-E/A,TV-E/e’ and TV-EDT of the CRBBB group were increased,suggesting that the right ventricular diastolic function of the CRBBB group were reduced;compared with the CLBBB group,TV-E/e’ of the CRBBB group was significantly increased(P<0.001),suggesting that the right ventricular diastolic function of the CRBBB group was significantly lower than the CLBBB group.7.Comparison of synchronization between groups: compared with the control group,LVDFT/RR of CRBBB group was significantly lower,IVMD、SDt-LV18、SDt-RV6 were higher,suggesting that atrioventricular synchronization,ventricular synchronization,left ventricular synchrony,and right ventricular synchrony of the CRBBB group decreased;compared with CLBBB group,LVDFT/RR was higher,IVMD、SDt-LV18 of the CRBBB group were lower,while SDt-RV6 was higher(all P<0.001),suggesting that compared with CLBBB group,except for the right ventricular synchrony of CRBBB group decreased,other synchronicity functions were better than the former.Conclusion1.Patients with isolated CLBBB and isolated CRBBB with normal LVEF had reduced left and right ventricular systolic and diastolic functions and synchronization.2.The left ventricular systolic,diastolic function,atrioventricular synchronism,interventricular synchronism,and left ventricular synchrony of patients with isolated CLBBB with normal LVEF were significantly lower than those of patients with isolated CRBBB.3.The systolic and diastolic functions of the right ventricle and the synchrony of the right ventricle of patients with isolated CRBBB were significantly lower than those of patients with isolated CLBBB.