title: High-energy defibrillation increases the dispersion of regional ventricular repolarization.
abstract: OBJECTIVE
  This study evaluated the effects of shock energy on the dispersion of regional ventricular repolarization (DRVR), post-shock rhythm and sinus recovery time (SRT), and the relationship between DRVR and post-shock ventricular arrhythmias.
  
  
  METHODS
  Ten open-chest dogs were anesthetized. Ventricular fibrillation (VF) was electrically induced and recorded from a 6 × 6 unipolar electrode plaque (4 mm spacing) sutured on the left ventricular epicardium. Defibrillation threshold (DFT) was determined after 20 s of VF. DRVR was measured before VF, during the earliest post-shock sinus rhythm, and during sinus rhythm 30 s following shocks. Post-shock rhythm and SRT were evaluated after energies of 100% DFT, 125% DFT, 175% DFT, and 250% DFT.
  
  
  RESULTS
  In the100% DFT group, the DRVR of the earliest sinus rhythm and 30 s after successful defibrillation was not significantly different than that before VF. But the DRVRs were significantly increased in 125% DFT, 175% DFT, and 250% DFT group. DRVR after defibrillation in the 250% DFT group was higher than those in the 100% DFT and 125% DFT groups. SRT in the 250% DFT group was significantly longer than that in the other groups .The incidence of post-shock ventricular tachycardia was increased when a high-shock energy was applied (P = 0.041).
  
  
  CONCLUSIONS
  DRVR was increased by application of high-energy defibrillation associated with SRT prolongation. The increased DRVR may play an important role in the onset of post-shock ventricular tachycardia.
authors.affiliation: Department of Cardiology, Shanghai Rui Jin Hospital, Shanghai Jiao Tong University School of Medicine, No.197, Rui-Jin Er Road, 200025, Shanghai, People's Republic of China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Pang
authors.forename: Qi
authors.initials: Q
authors.lastname: Jin
authors.forename: Ning
authors.initials: N
authors.lastname: Zhang
authors.forename: Shujing
authors.initials: S
authors.lastname: Ren
authors.forename: Tianyou
authors.initials: T
authors.lastname: Ling
authors.forename: Ying
authors.initials: Y
authors.lastname: Chen
authors.forename: Gang
authors.initials: G
authors.lastname: Gu
authors.forename: Yongchu
authors.initials: Y
authors.lastname: Shen
authors.forename: Liqun
authors.initials: L
authors.lastname: Wu
mesh_terms: D000818:Animals; D017147:Defibrillators, Implantable / Q000009:adverse effects*; D004056:Differential Threshold; D004195:Disease Models, Animal; D004285:Dogs; D004554:Electric Countershock / Q000009:adverse effects* / Q000379:methods; D004562:Electrocardiography; D006339:Heart Rate / Q000502:physiology*; D008297:Male; D011897:Random Allocation; D020127:Recovery of Function; D012016:Reference Values; D018570:Risk Assessment; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000628:therapy*; D013997:Time Factors; D014693:Ventricular Fibrillation / Q000175:diagnosis / Q000628:therapy*