P763Analysis of the optimal pacing position by 2D strain echocardiography, a comparison among right ventricular outflow-tract, mid-ventricular septum and apical pacing.


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Abstract

Purpose: In recent years right ventricular septal (RVS) pacing has been performed instead of right ventricular apical (RVA) pacing because of the detrimental effects on the ventricular function associated with the latter type of pacing. We previously reported that right ventricular outflow tract (RVOT) pacing resulted in a significantly greater cardiac output as compared to mid-septum (RVMS) and RVA pacing regardless of the paced QRS duration. However the mechanism of the predominance of RVOT pacing is unknown. In this study, we investigated the differences in the synchronity of left ventricular (LV) wall motion among those pacing positions in individual patients in whom a permanent pacemaker was implanted.Methods: In 71 patients, we temporarily positioned a pacing lead for RVA, RVMS and RVOT in sequence, the paced QRS duration was measured, and the LV wall motion in each pacing position was visualized by 2D strain echocardiography. In each pacing position, we calculated the SD in time to peak systolic strain in the 18 left ventricular segments. Results: The RVMS pacing was associated with a shorter QRS duration in comparison to the RVOT pacing (159.5±2.9 vs. 178.0±3.1 ms, p<0.0001) and the RVA pacing (159.5±2.9 vs. 191.2±3.0 ms, p<0.0001), and the RVOT pacing was associated with a shorter QRS duration in comparison to the RVA pacing (178.0±3.1 vs. 191.2±3.0 ms, p<0.0001). The SD in time to peak systolic strain in the 18 left ventricular segments was significantly greater in the RVA than the RVOT pacing (77.6±2.6 vs. 68.2±2.4 ms, p=0.0005), but there was no remarkable difference as compared to the RVMS pacing (77.6±2.6 vs. 77.6±2.9 ms, p=0.9938). Moreover, the RVMS pacing showed the significantly greater SD than the RVOT pacing (77.6±2.9 vs. 68.2±2.4 ms, p=0.0007).Conclusions: The RVOT pacing was suggested to reveal the better synchronity in the LV wall motion in comparison to the RVMS and RVA pacing. To calculate the SD in time to peak systolic strain in the 18 left ventricular segments is useful for predicting beneficial effect of the RVOT pacing and superiority to the RVMS and RVA pacing in patients in which high incidence of the ventricular pacing would be manifested.

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