title: Electrical induction of ventricular fibrillation for resuscitation from postcountershock pulseless and asystolic cardiac arrests.
abstract: BACKGROUND
  There is increasing evidence that defibrillation from prolonged ventricular fibrillation (VF) before CPR decreases survival. It remains unclear, however, whether harmful effects are due primarily to initial countershock of ischemic myocardium or to resultant postdefibrillation rhythms (ie, pulseless electrical activity [PEA] or asystole).
  
  
  RESULTS
  We induced 15 dogs into 12 minutes of VF and randomized them to 3 groups. Group 1 was defibrillated at 12 minutes and then administered advanced cardiac life support (ACLS); group 2 was allowed to remain in VF and was subsequently defibrillated after 4 minutes of ACLS; group 3 was defibrillated at 12 minutes, electrically refibrillated, and then defibrillated after 4 minutes of ACLS. All group 1 and 3 animals were defibrillated into PEA/asystole at 12 minutes. After 4 minutes of ACLS, group 2 and 3 animals were effectively defibrillated into sinus rhythm. The extension of VF in group 2 and 3 subjects paradoxically resulted in shorter mean resuscitation times (251+/-15 and 245+/-7 seconds, respectively, versus 459+/-66 seconds for group 1; P<0.05) and improved 1-hour survival (10 of 10 group 2 and 3 dogs versus 1 of 5 group 1 dogs; Fisher's exact, P<0.005) compared with more conservatively managed group 1 subjects.
  
  
  CONCLUSIONS
  Precountershock CPR during VF appears more conducive to resuscitation than CPR during postcountershock PEA or asystole. The intentional induction of VF may prove useful in the management of PEA and asystolic arrests.
authors.affiliation: Division of Cardiology, Department of Medicine, The Johns Hopkins Medical Institutions, The Johns Hopkins University, Baltimore, Md, USA. cleng@mail.jhmi.edu
authors.forename: C T
authors.initials: CT
authors.lastname: Leng
authors.forename: R D
authors.initials: RD
authors.lastname: Berger
authors.forename: H
authors.initials: H
authors.lastname: Calkins
authors.forename: A C
authors.initials: AC
authors.lastname: Lardo
authors.forename: N A
authors.initials: NA
authors.lastname: Paradis
authors.forename: H R
authors.initials: HR
authors.lastname: Halperin
mesh_terms: D000818:Animals; D016887:Cardiopulmonary Resuscitation; D004285:Dogs; D004554:Electric Countershock; D004558:Electric Stimulation; D006323:Heart Arrest / Q000503:physiopathology* / Q000517:prevention & control; D006352:Heart Ventricles / Q000503:physiopathology; D006439:Hemodynamics / Q000502:physiology; D013997:Time Factors; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology; D014693:Ventricular Fibrillation / Q000503:physiopathology* / Q000628:therapy