title: [The effects of cardiac pacing with multisite combination on myocardial mechanics and cardiac work in dogs].
abstract: OBJECTIVE
  To approach the effects of multi-site synchronous ventricular pacing on myocardial mechanics and cardiac work.
  
  
  METHODS
  Five modes of multi-site synchronous ventricular pacing were randomly performed in 12 dogs with anesthetized, opened chest and artificial-ventilation. Some parameters were measured simultaneously including: the peak of left ventricular pressure rise and fall (+/- dp/ dt(max)), the time constant of left ventricular relaxation(tau), the muscle tensile force in left/right ventricular wall (V-tensile force, V-TF), SV, LVSW and RVSW.
  
  
  RESULTS
  The myocardial systolic mechanical parameters: +dp/dt(max) and LV-TF of cHisB-LVPL and RVA-LVPL pacing by biventricular pacing modes were increased than that of cHisB-RVA pacing in right ventricular bifocal pacing mode. +dp/dt(max) in above two groups of biventricular pacing was increased than that in cHisB-RVA pacing. Tau value of cHisB-LVPL and RVA-LVPL pacing modes were shorted than that of cHisB-RVA pacing. The above parameters of cHisB-RVA-LVPL and cHisB-RVA-LVA biventricular trifocal pacing were superior to that of cHisB-LVPL and RVA-LVPL biventricular pacing. The +dp/dt(max), LV-TF and RV-TF of cHisB-RVA-LVPL pacing were increased as compared with that of cHisB-RVA-LVA pacing (P > 0.05). The -dp/dt(max) in cHisB-RVA-LVPL pacing were increased by 6.0% and tau value was shorted by 3.7% compared with those in cHisB-RVA-LVA pacing (P > 0.05). SV, LVSW and RVSW of cHisB-LVPL and RVA-LVPL biventricular pacing were increased than those of cHisB-RVA bifocal pacing. The above parameters of cHisB-RVA-LVPL pacing were increased than that of cHisB-RVA-LVA and cHisB-LVPL pacing.
  
  
  CONCLUSIONS
  It was explained that the cHisB-RVA-LVPL biventricular trifocal sites synchronous pacing mode would increase the velocity of ejection and filling during myocardial contraction and relaxation and enhance cardiac work by maintaining normal VSS.
authors.affiliation: 2nd Affiliated Hospital of Hebei Medical University, Shijiazhuang 050000, China.
authors.forename: Ning
authors.initials: N
authors.lastname: Ma
authors.forename: Xiang-Hua
authors.initials: XH
authors.lastname: Fu
authors.forename: Shi-Qiang
authors.initials: SQ
authors.lastname: Lu
authors.forename: Wei-Li
authors.initials: WL
authors.lastname: Wu
authors.forename: Xin-Shun
authors.initials: XS
authors.lastname: Gu
authors.forename: Yun-Fa
authors.initials: YF
authors.lastname: Jiang
mesh_terms: D000818:Animals; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D004285:Dogs; D005260:Female; D006321:Heart / Q000502:physiology*; D006352:Heart Ventricles; D008297:Male; D009206:Myocardium