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.
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.