The Clinical Investigation Of The Influence Of RVA Pacing And RVOT Pacing To Ventricular Synchronism And Cardiac Function

Objective To explore the effects of right ventricular apical(RVA) pacing and right ventricular outflow tract(RVOT) pacing on ventricular synchrony and cardiac performance via using tissue doppler imaging technique to evaulate the synchronization of cardiac mechanical activity.Methods RVA pacing was conducted in 20 patients(12 males and 8 females), with a mean age of (68.30±9.49) years, of whom 15 had atriventricular block(AV block) and 5 had sick sinus syndrome(SSS).And RVOT pacing was also conducted in 20 patients (10 males and 10females), with a mean age of (66.65±10.72)years, of whom 13 had AV block and 7 had SSS. All patients were implanted DDD or VVI pacemaker. Six months after installment of the pacemakers, the ventricular threshold and pacing impedance changes trend and complications associated with pacing procedure were collected to evaluate the feasibility of RVOT pacing; To compare the change of QRS duration; Tissue Doppler imaging was used to evaluated the time to peak in systolic phase of interventricular septum and left ventricular .PPEI,APEI, LAD, IVSD, LVIDd, LVIDs and LVEF were also measured by conventional 2-Dimensional echocardiography;The ventricular synchrony and cardiac performance were assessed by QRS duration,P PEI-APEI , Ts, and Tei index.Results There were no diferences in threshold parameters between RVOT and RVA pacing.;Compared with pre-implantation, the QRS duration were significantly changed after ventricular pacing both in RVA pacing and RVOT pacing (p<0.01).But the increment in RVOT pacing is less than RVA pacing(32.45±27.34 VS 52.45±26.93,P=0.025);LAD and LVIDs (P<0.05)were larger and LVEF (P<0.01) was less in RVA pacing than in RVOT pacing, LVEF(P<0.01) was also less in RVOT pacing; Compared with RVA pacing, RVOT pacing is better in E/Ea(8.31±2.52 VS 11.49±3.67,P<0.01),Tei index (0.55±0.15 VS 0.76±0.24,P<0.01),Ts(P<0.05) and PPEI-APEI(P<0.05) ; The QRS duration,absolute value of PPEI-APEI and Ts-SD had a positive relationship with the Tei index. So, compared with RVA pacing, RVOT pacing has less impact on cardiac electric-mechnical activation, and it is a better pacing site.Conclusion 1. Using the active fixation endocardial lead in RVOT pacing is safe and feasible. 2. Compared with RVA pacing , RVOT pacing can provide smaller variation in the duration and morphology of QRS complex, more physiological depolarization vector. 3. Compared with RVA pacing, RVOT pacing can provide better ventricular synchronization and cardiac electric-mechnical synchrony from the comparison of PPEI-APEI ,Ts-SD and Tei index. RVOT pacing can also slow down the deterioration of cardiac function. 4. Tissue doppler imaging techinque can provide a better option for pacing location on clinical pacing therapy via evaluating the coordination of myocardial exercise.