Impact of temporary right ventricular pacing from different sites on echocardiographic indices of cardiac function

Aims To assess the impact of pacing from different right ventricular (RV) pacing sites on left ventricular (LV) function. Chronic apical RV pacing may induce heart failure. To reduce this RV, mid-septum and outflow tract are suggested as alternative pacing sites. We therefore assessed cardiac performance during temporary RV pacing from apical vs. mid-septum or outflow tract sites, using echocardiography and electrocardiography. Methods and results Patients scheduled for a permanent pacemaker underwent temporary pacing in dual-chamber mode (DDD) and with atrio-ventricular delay optimized. The ventricular lead was moved to either the RV apex, mid-septum or outflow tract. Comprehensive echocardiography was performed in each position. Twenty-two patients completed the study. The baseline data was collected at atrial pacing mode (AAI). QRS duration lengthened with RV apical pacing (97 +/- 22 ms AAI vs. 154 +/- 18 ms RV apical, P < 0.001) and shortened with mid-septum or outflow tract pacing (147 +/- 14 ms RV mid-septum and 136 +/- 16 ms RV outflow tract, P = 0.001 and P < 0.001, respectively, vs. RV apical). Right ventricular apical pacing was associated with reductions in stroke volume and LV ejection fraction (54 +/- 6% AAI vs. 48 +/- 5% RV apical, P = 0.001). Right ventricular mid-septum (52 +/- 5%) and outflow tract (54 +/- 6%) pacing improved LV ejection fraction in comparison with apical pacing (P < 0.01 for both). Pacing at all sites induced dyssynchrony. In comparison with RV apical pacing dyssynchrony was reduced by mid-septum or outflow tract pacing. Conclusions Right ventricular pacing at the mid-septum or outflow tract results in narrower QRS complexes, less dyssynchrony, and better LV systolic function than RV apical pacing.