Abstract
Background : Right ventricular apex (RVA) pacing has been thought to be an published effect for the heart function in some studies. Instead, the pacing site of right ventricular outflow tract (RVOT) is known as the alternative pacing site. Previous studies have reported the differences between RVA and RVOT pacing in the early short-term. Therefore the aim of this study is to describe the advantages of RVOT pacing in the chronic phase. Methods : We compared QRS duration, threshold, sense, lead impedance, BNP, left ventricular ejection fraction (EF), left ventricular diastolic/systolic diameter, septal to posterior wall motion delay (SPWMD) and incident rate of atrial fibrillation in the RVA group (20pts) and in the RVOT group (20pts) for two years among patients who don' t have cardiac dysfunction (EF>40%). Results : The QRS intervals was significantly shorter in the RVOT group than the RVA group (142 ± 22 vs176 ± 18 msec. p<0.001), but the QRS duration has not been changed in the RVA group. The threshold (0.5 ± 0.1 vs 0.7 ± 0.3mv/0.4msec), sense (17 ± 8 vs13 ± 8) and impedance (615 ± 123 vs 660 ± 231) were not significantly different. The BNP (70.6 ± 56 vs 192 ± 189), EF and LV Dd/Ds were not significant different between both groups. SPWMD measurement tended to be better in the RVOT group (112 ± 65Vs152 ± 36). Incidence of atrial fibrillation after the pacemaker implantation RVOT grop was less than that of the RVA group (18% Vs 50%). The total duration time of the atrial fibrillation in the RVOT group did not increase compared to the RVA group. Conclusion : The RVOT group avoids the risk of disynchronization of the left ventricle, and atrial fibrillation does not worsen. We considered that the RVOT pacing is safe and has more clinical merits compared to the RVA pacing in the chronic phase.
