title: Biventricular pacing decreases sympathetic activity compared with right ventricular pacing in patients with depressed ejection fraction.
abstract: BACKGROUND
  Although there have been few studies in which the hemodynamic effects of right ventricular (RV) and left ventricular (LV) pacing were compared with those of biventricular (BV) pacing, the autonomic changes during these different pacing modes remain unknown. We hypothesized that BV pacing results in improved hemodynamics and a decrease in sympathetic nerve activity (SNA) compared with single-site pacing.
  
  
  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. BP was greater during LV (151+/-7/85+/-3 mm Hg) and BV (151+/-6/85+/-3 mm Hg) pacing than during RV pacing (146+/-7/82+/-3 mm Hg) (P:<0.05). There were no differences in CVP among all pacing modes (P:=0.27). SNA was significantly less (P:<0.02) during both LV (606+/-35 U) and BV (582+/-41 U) pacing compared with RV pacing (685+/-32 U) (P:<0.02). Although not statistically significant (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 pacing (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.
authors.affiliation: University of Texas Southwestern Medical Center and Dallas Veterans Affairs Medical Center, Dallas, TX 75216, USA. Hamdan@ryburn.swmed.edu
authors.forename: M H
authors.initials: MH
authors.lastname: Hamdan
authors.forename: J D
authors.initials: JD
authors.lastname: Zagrodzky
authors.forename: J A
authors.initials: JA
authors.lastname: Joglar
authors.forename: C J
authors.initials: CJ
authors.lastname: Sheehan
authors.forename: K
authors.initials: K
authors.lastname: Ramaswamy
authors.forename: J F
authors.initials: JF
authors.lastname: Erdner
authors.forename: R L
authors.initials: RL
authors.lastname: Page
authors.forename: M L
authors.initials: ML
authors.lastname: Smith
mesh_terms: D000368:Aged; D002304:Cardiac Pacing, Artificial; D004562:Electrocardiography; D006333:Heart Failure / Q000503:physiopathology; D006439:Hemodynamics; D006801:Humans; D008297:Male; D012044:Regression Analysis; D013564:Sympathetic Nervous System / Q000503:physiopathology; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology / Q000628:therapy*; D018497:Ventricular Dysfunction, Right / Q000503:physiopathology / Q000628:therapy*