RVoutflow tract pacing versus RV Apical pathophysiologic Effects and prognostic implications

ABSTRACT

Right ventricular apical pacing has been reported to be associated with adverse haemodynamic effects and alternative sites of pacing have been recommended. On the other hand RV septal pacing was claimed to be more physiological. The present work is intended to compare the classic right ventricular apical DDD pacing to RV outflow tract [RVOT] pacing in both normal and diseased hearts. We studied 30 patients [pts] with complete heart block [CHB]. Fourteen pts [Group I] had no underlying heart disease [8M and 6F with mean age 64.1 +/- 6.4, range 54-76 years] and 16 [Group II] had heart disease [10M, 6F, with mean age 67.5 +/- 8.9, range 58-86 years] including DCM in 12, 1HD in 3 and RHD in Ipt. Right ventricular apical pacing was conducted in 7pts from group I and 8pts from group II. RVA was conducted in 7pts of group I and 8pts of group II. Besides clinical evaluation, all pts were subjected to 2D echo before, and 6 months after pacing. Echo parameters studied included LVEDD, LVESD, EF% and CO with effects expressed in terms of% changes in various parameters. Compared to RVA pacing RVOT pacing in group I [pts with normal heart] induced insignificant% decrease in LVEDD [2.4 +/- 4.8vs 8.6 +/- 9.3, p value =0.146] or LVESD [4.6 +/- 7.8vs 8.3 +/- 6.0,p value =0.113] and insignificant increase in EF [2.4 +/- 4.6vs 0.42.6, p value =0.113] and CO [2.8 +/- 8.0vs 3.3 +/- 3.5, p value =0.08]. However in RVOT pacing in group II [pts with disease heart] induced significantly greater% decrease in LVEDD [3.0 +/- 2.8vs 1.2 +/- 2.3, p=0.005] in LVESD [3.7 +/- 0.9vs 2.5 +/- 2.3, p=0.000], and significantly greater% increase in EF [8.9 +/- 3.3vs I.7 +/- 1.2,p=0.001] and CO [5.8 +/- 9.6vs 10.7 +/- 18.3, p=0.04] in comparison to RVA pacing in group II In the presence of underlying cardiac dysfunction, DDD pacing by RVOT lead is hemodynamically more advantageous to classic RV apical pacing in terms of improving dimensions and enhancing systolic function. We recommend RVOT pacing in the presence of underlying HD to avoid the so called pacing-induced cardiomyopathy.