title: Coupled pacing improves left ventricular function during simulated atrial fibrillation without mechanical dyssynchrony.
abstract: OBJECTIVE
  Electrical stimulation [coupled pacing (CP)] applied near the end of the T-wave is able to create a retrograde activation of the atrioventricular (AV) node in turn to prevent rapid ventricular conduction during atrial fibrillation (AF). The impact of this pacing modality associated with cardiac resynchronization therapy (CRT) has been evaluated in the present experimental study.
  
  
  RESULTS
  After inducing AF by rapid pacing in six dogs, we applied the following pacing modalities: rapid right ventricular (RV) pacing, rapid CRT, CRT with an additional RV paced beat (CP) at a specific delay (CRT + CP), and CRT with vagal stimulation (CRT-VS). Left ventricular (LV) pressure recordings and echocardiography for 2D strain analysis were performed. CRT + CP reduced the ventricular response rate and increased the LV systolic pressure and cardiac output compared with CRT alone (136 +/- 6 vs. 86 +/- 13 mmHg, P < 0.05 and 2.0 +/- 0.4 vs.1.2 +/- 0.1, P < 0.05 L/m, respectively). Compared with CRT-VS, CRT + CP increased the LV ejection fraction (LVEF = 51 +/- 10 vs. 28 +/- 4%, P < 0.05), peak global circumferential strain (-17 +/- 2 vs. -11 +/- 3%), and diastolic filling time (49 +/- 6 vs. 28 +/- 3%, P < 0.02) suggesting beneficial effects of CP beyond rate control. CRT + CP did not result in increased dyssynchrony [CRT (8.3 +/- 2%) vs. CRTCP (8.4 +/- 3%, P = NS)].
  
  
  CONCLUSIONS
  CRT + CP effectively reduces ventricular contractile rate and leads to an increase in systolic and diastolic performance without inducing mechanical dyssynchrony.
authors.affiliation: Department of Cardiovascular Medicine, APHP, Henri Mondor University Hospital, 51 Av. de Lattre de Tassigny, Creteil 94 010, France. pascal.lim@hmn.aphp.fr
authors.forename: Pascal
authors.initials: P
authors.lastname: Lim
authors.forename: George E
authors.initials: GE
authors.lastname: Yanulis
authors.forename: David
authors.initials: D
authors.lastname: Verhaert
authors.forename: Neil L
authors.initials: NL
authors.lastname: Greenberg
authors.forename: Richard A
authors.initials: RA
authors.lastname: Grimm
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Tchou
authors.forename: Nicolas
authors.initials: N
authors.lastname: Lellouche
authors.forename: Don W
authors.initials: DW
authors.lastname: Wallick
mesh_terms: D000818:Animals; D001281:Atrial Fibrillation / Q000503:physiopathology / Q000628:therapy*; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D003971:Diastole / Q000502:physiology; D004195:Disease Models, Animal; D004285:Dogs; D004562:Electrocardiography; D006339:Heart Rate / Q000502:physiology; D013599:Systole / Q000502:physiology; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology / Q000628:therapy*; D016277:Ventricular Function, Left