title: The roles of pacing interval and pacing strength in ventricular fibrillation induced by rapid pacing with 1 : 1 capture.
abstract: BACKGROUND
  The roles of pacing interval (PI) and pacing strength (PS) in ventricular fibrillation (VF) induced by rapid pacing with 1 : 1 capture remain unclear.
  
  
  METHODS
  Epicardial unipolar electrograms (UEs) were simultaneously recorded using contact mapping in 11 swine. Activation-recovery interval (ARI) restitution was constructed at 4 sites, i.e. the apex and base of the left and right ventricles, respectively. A steady state pacing (SSP) protocol was performed to induce VF. The longest PI and the lowest PS for inducing VF were recorded. Statistical correlation analysis was performed to determine the relationship between local ARI restitution properties and PI and PS for VF induction.
  
  
  RESULTS
  Forty restitution curves were constructed from 11 SSP procedures. The maximal slope (Smax) of the ARI restitution curve of the right ventricular apex was positively correlated with the PI for VF induction (r = 0.761, p < 0.05). Spatial dispersions of ARI and Smax were negatively correlated with the PS for VF induction (r = -0.626 and r = -0.722, respectively, both p < 0.05).
  
  
  CONCLUSIONS
  Ventricular fibrillation can be induced by rapid ventricular pacing with 1 : 1 capture. The PI for VF induction was related to the Smax of the ARI restitution curve of the right ventricular apex, while PS for VF induction was associated with the spatial dispersions of ARI and its restitution property.
authors.affiliation: Department of Cardiology, the Tenth People's Hospital of Tongji University, Shanghai, China.
authors.forename: Dongdong
authors.initials: D
authors.lastname: Zhao
authors.affiliation: Department of Cardiology, the Tenth People's Hospital of Tongji University, Shanghai, China.
authors.forename: Ban
authors.initials: B
authors.lastname: Liu
authors.affiliation: Department of Cardiology, the Tenth People's Hospital of Tongji University, Shanghai, China.
authors.forename: Yidong
authors.initials: Y
authors.lastname: Wei
authors.affiliation: Department of Cardiology, the Tenth People's Hospital of Tongji University, Shanghai, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Tang
authors.affiliation: Department of Cardiology, the Tenth People's Hospital of Tongji University, Shanghai, China.
authors.forename: Xuejing
authors.initials: X
authors.lastname: Yu
authors.affiliation: Department of Cardiology, the Tenth People's Hospital of Tongji University, Shanghai, China.
authors.forename: Yawei
authors.initials: Y
authors.lastname: Xu
keywords: activation-recovery interval; electrical restitution; rapid ventricular pacing; ventricular fibrillation induction