Impacts of different cumulative percentage of ventricular pacing on heart function

Objective To evaluate ventricular synchrony and cardiac function changes under the different cumulative percentage of ventricular pacing.Methods A total of 60 patients received permanent cardiac pacemaker for atriventricular block(AV block) or sick sinus syndrome(SSS).Two different cardiac pacing modes of VVI(n=16)and DDD(n=44)were performed.According to the final cumulative percentage of ventricular pacing(Cum%VP),the subject were divided into three groups:group A:Cum%VP60%(n=20);group B:Cum%VP≥60%~100%(n=20);group C:Cum%VP=100%(n=20).After 12-month installment of the pacemakers,we investigated patients by 6 min walk,BNP,the change of QRS duration.Tissue Doppler imaging was used to evaluate the time to peak in systolic phase of interventricular septum.The ventricular synchrony was evaluated by QRS duration,PPEI-APEI and Ts.Results There were no differences in threshold parameters and incidence of complications between three groups.The QRS duration and the increment in BNP decreased compared,with preoperative which were all significantly changed after ventricular pacing.The increment in group A is less than that in group B and C.LAD、LVIDs and E/Ea(P0.05)were larger and LVEF(P0.01) was less in group C than in group A and B,LVEF(P0.01) was also less in group A.Compared with group B and C Ts and PPEI-APEI(P0.05) is less in group A.Conclusion At the point of the right ventricular apex pacing,with the increasing in Cum% VP,the increasing deterioration of cardiac function and ventricular desynchronicity are more obvious.