title: Effects of resynchronization therapy on sympathetic activity in patients with depressed ejection fraction and intraventricular conduction delay due to ischemic or idiopathic dilated cardiomyopathy.
abstract: This study assesses the effect of biventricular pacing on sympathetic nerve activity (SNA) in patients with depressed ejection fraction and intraventricular conduction delay (IVCD). Biventricular pacing has been shown to result in hemodynamic improvement in patients with depressed ejection fraction and IVCD. The effect of biventricular pacing on SNA, however, remains unclear. A total of 15 men with a mean ejection fraction of 25 +/- 4% were enrolled. Arterial pressure, central venous pressure and SNA were recorded during 3 minutes of right atrial (RA) pacing and RA-biventricular pacing. Pacing was performed at a rate 5 to 10 beats faster than sinus rhythm, with an atrioventricular interval equal to 100 ms during RA-biventricular pacing. RA-biventricular pacing resulted in greater arterial pressures (p <0.05) than RA pacing (146 +/- 15/83 +/- 11 vs 141 +/- 15/80 +/- 10 mm Hg). There were no differences in central venous pressures between the 2 pacing modes (p = 0.76). SNA was significantly less during RA-biventricular pacing (727 +/- 242 U) than during RA pacing (833 +/- 332 U) (p <0.02). Furthermore, there was a positive correlation between baseline QRS duration and the decrease in SNA noted with RA-biventricular pacing (r = 0.58, p = 0.03). Biventricular pacing results in improved hemodynamics and a decrease in SNA compared with intrinsic conduction in patients with left ventricular dysfunction and IVCD. If the current findings are also present with chronic biventricular pacing, then this form of therapy may have a positive impact on mortality.
authors: University of Texas Southwestern Medical Center, and Dallas Veterans Affairs Medical Center, Dallas, Texas 75216, USA. Mohamed.Hamdan@utsouthwestern.edu
authors: Mohamed H
authors: MH
authors: Hamdan
authors: Saverio
authors: S
authors: Barbera
authors: Robert C
authors: RC
authors: Kowal
authors: Richard L
authors: RL
authors: Page
authors: Karthik
authors: K
authors: Ramaswamy
authors: Jose A
authors: JA
authors: Joglar
authors: Valeh
authors: V
authors: Karimkhani
authors: Michael L
authors: ML
authors: Smith
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001158:Arteries; D001794:Blood Pressure; D002304:Cardiac Pacing, Artificial / Q000379:methods; D002311:Cardiomyopathy, Dilated / Q000503:physiopathology* / Q000628:therapy*; D004562:Electrocardiography; D006329:Heart Conduction System / Q000503:physiopathology*; D006352:Heart Ventricles / Q000503:physiopathology*; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D013318:Stroke Volume; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D016896:Treatment Outcome; D014680:Veins