The influence of pacing site to left ventricular myocardial contraction patterns and function

Abstract

Objective To evaluate left ventricular(LV)myocardial contraction patterns and function when pacing in different right ventricular(RV)sites and discuss echocardiogarphic method to evaluate physiologcal pacing mode.Methods This study included 26 patients with paroxysmal supraventricular tachycardia without organic heart disease.Four pacing modes including right atrium pacing(AAI),RV apex pacing(VVI-RVA),RV septal pacing(VVI-IVS)and RV outflow tract pacing(VVI-RVOT)were performed on the patients in a random order after succussful radiofrequency ablation.The parameters measured in each pacing mode included(1)LV systolic function parameters:LV twist angle(Twist),aortic systolic velocity-time integral(VTIAo)and LV global strain(Ge)；(2)LV contracting pattern:segmental peak systolic strain(Se),the time to peak value(TPe),and the distribution of segmental Se,TPe in each layer or wall.The relationship between Se,TPe of each wall was analyzed.[Results]Pacing from RV sites showed lower Twist,VTIAO and Ge than AAI mode.Ge demonstrated significant difference in three RV sites pacing mode(VVI-RVOT＞VVI-IVS＞VVI-RVA,P＜0.05).Compared with the AAI mode,the distribution of segmental Se,TPe in the each layer or wall alerted significantly in three RV sites pacing mode,especially in VV1-RVA.The distribution pattern was similar in VVI-RVOT and VVI-IVS.Furthermore,the wall Se collated negtively with wall TPe(r =-0.51,P＜0.001).[Conclusions]Compared with AAI mode,RV pacing,especially the VVI-RVA induced the alternation of LV contraction patterns and reduction of systolic function.Longitudinal strain parameters can be used to assess the myocardial contraction patterns and function in different pacing mode. Key words: Echocardiography; Cardiac pacing,artificial; Ventricular function,left; Speckle tracking imaging