The Influence Of Right Ventricular Septal And Apex Pacing On Ventricular Synchrony

Objective:The objective of the present study was to compare the influence of the right ventricular septal pacing(RVSP) and right ventricular apex pacing (RVAP) on the intraventricular synchrony and the interventricular synchrony of the short-time with medium term and to demonstrate the effectiveness and physiology.Methods:A total of37Patients from March2010to June2011in Tianjin Chest Hospital with an indication for a permanent pacemaker because of atrioventricular block were randomly divided into2subgroups:RVAP group and RVSP group. The RVS group and RVA group were analysed1month, nine months after the implantation in terms of echocardiogram feature and12-lead electrocardiogram. Recording threshold, perception, impedance parameters when programming pacemaker. The RVSP group received X-ray perspective imaging during the operation and received chest CT examination after the implantation. Taking ventricular electrode top plane of the mediastinal window image, we measured the accurate distance from electrode top to pulmonary valve and from the top to the centerline of the sternum distance. The following parameters were obtained:Left ventricular end-diastolic dimension(LVEDD), left ventricular ejection fraction(LVEF) and velocity time integral of aortic(AVTI) were to asses left ventricular contractive function; mitral E-wave velocity (E), the ration of E/A(mitral A-wave velocity) and the ration of E/E’(peak early diastolic velocity at the lateral mitral annulus) were to assess left ventricular diastolic function; measuring the time from the beginning of the E to the termination of A, ration of E+A/RR were to asses atrioventricular synchrony; aorta pre-ejection interval(APEI) and pulmonary arter pre-ejection(PPEI), interventricular mechanical delay (IVMD) defined as the difference between the APEI and PPEI; The apical four-chamber, three-chamber, and two-chamber tissue doppler imaging was conducted for off-line analysis. To assess intraventricular synchrony, tissue velocity profile signals were analysed in each LV segment using twelve-segmental mode, using the time-to-peak myocardial velocity(Ts) and calculating the standard deviation of the12LV segments(Ts-SD).Results:1. The QRS duration was significantly prolonged in the RVAP group than in the RVSP group [(160.98±10.64) ms vs (177.78±10.05) ms,P<0.01]. Complex wave were in the lead I of the RVSP group, the sensitivity and specificity of using the index to predict the ventricular electrode top in the right ventricular septal was73.3%and20.0%, respectively; the sensitivity and specificity of small negative wave in the lead I of the RVSP group was46.7%and80.0%, respectively. Negative wave were in the aVL lead, R wave in the II, III, aVF lead, the lead V4were the transitional zone frequently.2. In the RVSP group,when the ventricular electrode top below the pulmonary valve in15to25mm and horizontal distance from the sternum20-40mm range, the QRS duration was (151.37±12.76) ms, comparing QRS duration beyond the range, the difference was statistically significant [(151.37±12.76) ms vs (164.12±15.07) ms, P <0.05].3. Capture threshold, lead impedance, and R-wave sensing were measured during implantation and at each follow-up visit, there is no significant differences in pacing parameters.4. LVEDD, LVEF, AVTI, E/E’ and E+A/RR were not statistically different in either group during baseline and9-month follow up.5. There were signicant difference in IVMD, Ts of maximum difference and Ts-SD at9-month follow between RVSP group and RVAP group.6. There were correlations of Ts of maximum difference and Ts-SD with QRS duration(r=0.487, P=0.002; r=0.491,P=0.002).Conclusion:1. The RVSP is feasible and safe with the active screw lead.2. RVS pacing site is approximate to the normal conduction system, so the paced QRS duration was significantly shorter in patients in the RVSP group [(160.98±10.64) ms vs (177.78±10.05) ms, P<0.05]3. According to the CT image and QRS complex relationship can determine the electrode position in X-ray perspective of features.4. The two groups keep better atrioventricular synchrony1month, nine months after the implantation, but none in left ventricular function, intraventricular synchrony and interventricular synchrony1month after the implantation; The RVSP is superior to RVAP in terms of intraventricular synchrony and interventricular synchrony, but none in LVEDD, LVEF, AVTI, E/E’and E+A/RR9months after the implantation to the patients with normal heart function.