title: Effect of right ventricular versus biventricular pacing on electrical remodeling in the normal heart.
abstract: BACKGROUND
  Biventricular (BIV) pacing can improve cardiac function in heart failure by altering the mechanical and electric substrates. We investigated the effect of BIV versus right ventricular (RV) pacing on the normal heart.
  
  
  RESULTS
  Male New Zealand White rabbits (n=33) were divided into 3 groups: sham-operated (control), RV pacing, and BIV pacing groups. Four weeks after surgery, the native QT (P=0.004) interval was significantly shorter in the BIV group compared with the RV or sham-operated groups. Also, compared with rabbits in the RV group, rabbits in the BIV group had shorter RV effective refractory period at all cycle lengths and shorter LV paced QT interval during the drive train of stimuli and close to refractoriness (P<0.001 for all comparisons). Protein expression of the KVLQT1 was significantly increased in the BIV group compared with the RV and control groups, whereas protein expression of SCN5A and connexin43 was significantly decreased in the RV compared with the other study groups. Erg protein expression was significantly increased in both pacing groups compared with the controls.
  
  
  CONCLUSIONS
  In this rabbit model, we demonstrate a direct effect of BIV but not RV pacing on shortening the native QT interval as well as the paced QT interval during burst pacing and close to the ventricular effective refractory period. These findings underscore the fact that the effect of BIV pacing is partially mediated through direct electric remodeling and may have implications as to the effect of BIV pacing on arrhythmia incidence and burden.
authors.affiliation: Cardiovascular Institute, University of Pittsburgh, Pittsburgh, Pa., USA. sabas@upmc.edu
authors.forename: Samir
authors.initials: S
authors.lastname: Saba
authors.forename: Haider
authors.initials: H
authors.lastname: Mehdi
authors.forename: Michael A
authors.initials: MA
authors.lastname: Mathier
authors.forename: M Zahadul
authors.initials: MZ
authors.lastname: Islam
authors.forename: Guy
authors.initials: G
authors.lastname: Salama
authors.forename: Barry
authors.initials: B
authors.lastname: London
mesh_terms: D000200:Action Potentials; D000818:Animals; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D018031:Connexin 43 / Q000378:metabolism; D004452:Echocardiography; D004562:Electrocardiography; D051638:Ether-A-Go-Go Potassium Channels / Q000378:metabolism; D006329:Heart Conduction System / Q000502:physiology; D051657:KCNQ1 Potassium Channel / Q000378:metabolism; D008297:Male; D009206:Myocardium / Q000378:metabolism; D062554:NAV1.5 Voltage-Gated Sodium Channel; D010138:Pacemaker, Artificial; D011817:Rabbits; D015222:Sodium Channels / Q000378:metabolism; D020257:Ventricular Remodeling
chemical_list: D018031:Connexin 43; D051638:Ether-A-Go-Go Potassium Channels; D051657:KCNQ1 Potassium Channel; D062554:NAV1.5 Voltage-Gated Sodium Channel; D015222:Sodium Channels