High Septal Right Ventricular And Right Ventricular Apical Pacing On Cardiac Structure And Function Of Clinical Research

Objective:To study the effects and mechanism of high right ventricular septal (HRVS) versus right ventricular apical(RVA) pacing on cardiac structure and function. Providing theoretic foundation for the clinical using of HRVS pacing.To study the application of pacemaker stress echocardiography.Method:From June 2007 to June 2008,71 patients implantend pacemaker for sick sinus syndrome or atrioventricular block were divided into two groups according to the pacing site,HRVS pacing group(36 patients) and RVA pacing group(35 patients).The QRS duration,frontal plane QRS axis of all patients were followed up by careful history, physical examination,electrocardiogram.LVESV,LVEDV,LRVPEI,SPWMD,LVEF and the area of mitral regurgitant jet were measured before pacemaker implantation and 1 and 12 months after the implantation by echocardiographic and pacemaker stress echocardiography(after the implantation) The ventricular pacing threshold,lead impedance,R-wave amplitude,paced atrioventricular interval and cumulative percent of ventricular pacing were measured by Medtronic pacemaker programmed device.At last, all the data underwent statistical analysis between the two groups.Results:There was no significant difference in clinical characteristics and all the observed indexes between HRVS pacing group and RVA pacing group before pacemaker implantation.No significant difference in the pacing parameters between the two groups was observed at 1 and 12 months after implantation.At 1 month after implantation,the QRSd,LRVPEI and SPWMD of HRVS pacing group were significantly smaller than those of RVA pacing group(P＜0.05),other indexes were similar between the two groups. By pacemaker stress echocardiography LVEF was higher and the area of mitral regurgitant jet were smaller during HRVS pacing than during RVA pacing(P＜0.05);At 12 months after implantation,the QRSd,LRVPEI,SPWMD and LVESV were smaller and LVEF was higher during HRVS pacing than during RVA pacing(P＜0.05);the LVEDV and the area of mitral regurgitant jet were smaller during HRVS pacing than during RVA pacing,but the difference was insignificant between the two groups(P＞0.05),but by pacemaker stress echocardiography significant difference can be found(P＜ 0.05).There were significant negative correlations between the change in LVEF(△LVEF) and the change in QRSd,LRVPEI,SPWMD(△QRSd,△LRVPEI,△SPWMD) at 12 months after implantation.Moreover,the△QRSd was also correlated with the△LRVPEI and△SPWMD.There was a significant negative correlation between the△LVEF and the cumulative percent of ventricular pacing in RVA pacing group.However,there was no significant correlation between the two parameters in HRVS pacing group.Conclusions:The deleterious long-term,effects on cardiac structure and function was significantly less during HRVS pacing than RVA pacing,but there was no significant difference in short-term effects between the two pacing sites.The main cause of leading to the above effects was that interventricular and intraventricular electrical and mechanical synchrony was better during HRVS pacing than RVA pacing.Furthermore, the difference of the mechanical synchrony between the two pacing sites was more and more clear with the increase of pacing time.Interventricular and intraventricular electrical and mechanical asynchrony was the basic reason for the long-term effects of right ventricular pacing on cardiac structure and function.Moreover,cumulative percent of ventricular pacing played an important role in the process of the effects.Pacemaker stress echocardiography is highly practical value on patients,echocardiographic with permanent pacemaker.