The importance of right atrial pacing electrode position and pacing configuration for intra-atrial and inter-atrial conduction times

Pace prevention of atrial tachyarrhythmias is based in part on the reductio n of intra-atrial (IAA) and/or inter-atrial (IEA) conduction. We previously introduced a novel pacing mode using floating atrial ring electrodes on a VDD-lead (BIdirectional MO nophasic impulSe: BIMOS). The effects of BIMOS p acing on IAA and IEA conduction times has not been studied. In nine Merino sheep electrode catheters were placed at the His-Bundle (HBE), high right a trium (HRA), coronary sinus ostium (Cs-Os), and left lateral atrium (LLA). A VDD-lead was introduced with floating electrodes in the high and mid righ t atrium (Floating). IAA (S/P-HRA, S/P-Cs-Os, S/P-HBE, S/P-Floating), IEA c onduction times (S/P-LLA), and P-wave duration (PD) were measured during si nus rhythm (S), during bipolar cathodal pacing (P) in the HRA, in the Cs-Os position, as well as during BIMOS floating pacing. The mean PD during S wa s significantly shorter than during HRA- (66.6 +/- 12.8 ms; vs. 116.2 +/- 1 1.1 ms; p < 0.05) and Cs-Os-P (66.6 +/- 12.8 ms vs. 94.4 +/- 9.0 ms; p < 0. 05). In comparison to HRA-P, BIMOS configuration lead to a significant redu ction of the P-wave duration (116.2 +/- 11.1 ms vs. 85.4 +/- 8.8 ms; p < 0. 05). During BIMOS pacing, the global atrial conduction time was significant ly shorter than during pacing in the HRA and Cs-Os position. The results of this study demonstrate a clear reduction of IAA and IEA conduction times u sing BIMOS configurations compared to conventional HRA-P. Furthermore, BIMO S pacing produced a more homogeneous atrial activation when compared with c onventional HRA- and Cs-Os-P.