Background-Although there have been few studies in which the hemodynamic ef
fects of right ventricular (RV) and left ventricular (LV) pacing were compa
red with those of biventricular (BV) pacing, the autonomic changes during t
hese different pacing modes remain unknown. We hypothesized that BV pacing
results in improved hemodynamics and a decrease in sympathetic nerve activi
ty (SNA) compared with single-site pacing.
Methods and Results-Thirteen men with a mean ejection fraction of 0.28+/-0.
7 were enrolled in the study. Arterial blood pressure (BP), central venous
pressure (CVP), and SNA were recorded during 3 minutes of right atrial (RA)
-RV, RA-LV, and RA-BV pacing at a rate 10 beats faster than sinus rhythm. B
P was greater during LV (151+/-7/ 85+/-3 mm Hg) and BV (151+/-6/85+/-3 mm H
g) pacing than during RV pacing (146+/-7/82+/-3 nm Hg) (P<0.05). There were
no differences in CVP among all pacing modes (P=0.27). SNA was significant
ly less (P<0.02) during both LV (606+/-35 U) and BV (582+/-41 U) pacing com
pared with RV pacing (585+/-32 U) (P<0.02). Although not statistically sign
ificant (P=0.08 to 0.14), there was a trend for patients with a narrow QRS
to have a lower mean BP and higher SNA during LV pacing than during BV paci
ng (r=0.42 to 0.49).
Conclusions-LV-based pacing results in improved hemodynamics and a decrease
in SNA compared with RV pacing in patients with LV dysfunction regardless
of the QRS duration.