The Right Ventricular Function Research In Patients With Righ Ventricular Outflow Tract Septum Pacing

Objective: To compare the hemodynamic changes of right ventricular outflow tract septal pacing with effect of traditional right ventricular apical pacing; to explore the clinical feasibility and safety of the technique that doctors implant screw-in transvenous pacing lead in right ventricularseptum; on the basis of positive results, to discuss the mechanism of hemodynamic improvement of right ventricular outflow tract septal pacing. Methods: 36 patients with indication of pacemaker implantation were divide into two groups randomly. In each patien,t influence of differ-entpacing site to LVEF and pacing parameterwere examined and left ventricular eject fractionswere compared. There were 36 patients who need receive permanent pacing, 28 of them with atrioventricular block, 5 of them with atrialfibr and atrioventricular block and 3 of them with sick sinus syndrome and atrioventricular block, 22 male and 14 female, the mean age was 74.8士4.2 years old; 18 of them were in normal heart function,7 were in NYHA class I,11 was class 1I . The patients were divide into two groups: righ ventricular outflow tract(RVOT) septum pacing group and right ventricular apical (RVA)pacing group. The patients with atrialfibr and atrioventricular block used VVI pacing mode. The patients with atrioventricular block or SSS and atrioventricular block used DDD pacing mode .We examined hemodynamics by ultrasonic cardiogram (UCG) and recorded surface electrocardiogram (ECG) before implantation. To research the hemodynamic difference betweeen right ventricular outflow tract septal pacing and right ventricular apical pacing by auto-control and group-control means.Under X-rayand ECG suggestion, we fixed screw-in pacing leads at righ ventricular outflow tract septum and passive lead at right ventricular apexRVA, about fifteen minutes later we determined pacing threshold and adjusted pacing rates to obtain all captured rhythm,then examined ECG; We examined their UCG and ECG to evaluate the long-term hemodynamic changes. Results: All patients operationwere successful, LVEF of RVOTS group compared with that of RVA showed a difference. Comparing the hemodynamic changes of right ventricular outflow tract septal pacing with right ventricular apical pacing, we found the hemnamic parameters such as LVEF,FS and EV during RVOT pacing were significantly better than parameters during RVA pacing,and there was statitc difference (P<0.05). In contrast to RVA pacing, the QRS duration of RVOT pacing was narrowed but there was no statitc difference (P<0.05), the axis and QRS complex of ECG during RVOT pacingmore get close intrinsic level which had normal ventricular activation sequence andbiventricular contraction synchrony. Investigation for mean time of six months after surgery indicated that RVOT pacing were better than RVA pacing in hemodynamics(P<0.05). Conclusion: The cardiac function are significantly different between right ventricular septum pacing group and rightventricular apex group. The primary study results suggest(:1)It's feasible and safe to use screw-in leads for RVOT pacing.(2)The hemodynamic parameters during RVA pacing were significantly worse than preoperative parameters. And no significant difference existed between RVOT pacing and intrinsic rhythm.(3)The hemodynamic parameters of RVOT pacing were significantly better than that of RVA pacing, so can avoid or relieve deterioration of cardiac function by traditional RVA pacing.(4)RVOT pacing could improve hemodynainic effect through keeping normal ventricular activation sequence and biventricular contraction synchrony.