title: Multicenter study of principles-based waveforms for external defibrillation.
abstract: OBJECTIVE
  The efficacy of a shock waveform for external defibrillation depends on the waveform characteristics. Recently, design principles based on cardiac electrophysiology have been developed to determine optimal waveform characteristics. The objective of this clinical trial was to evaluate the efficacy of principles-based monophasic and biphasic waveforms for external defibrillation.
  
  
  METHODS
  A prospective, randomized, blinded, multicenter study of 118 patients undergoing electrophysiologic testing or receiving an implantable defibrillator was conducted. Ventricular fibrillation was induced, and defibrillation was attempted in each patient with a biphasic and a monophasic waveform. Patients were randomly placed into 2 groups: group 1 received shocks of escalating energy, and group 2 received only high-energy shocks.
  
  
  RESULTS
  The biphasic waveform achieved a first-shock success rate of 100% in group 1 (95% confidence interval [CI] 95.1% to 100%) and group 2 (95% CI 94.6% to 100%), with average delivered energies of 201+/-17 J and 295+/-28 J, respectively. The monophasic waveform demonstrated a 96.7% (95% CI 89.1% to 100%) first-shock success rate and average delivered energy of 215+/-12 J for group 1 and a 98.2% (95% CI 91.7% to 100%) first-shock success rate and average delivered energy of 352+/-13 J for group 2.
  
  
  CONCLUSIONS
  Using principles of electrophysiology, it is possible to design both biphasic and monophasic waveforms for external defibrillation that achieve a high first-shock efficacy.
authors.affiliation: Survivalink Corporation, Minneapolis, MN, USA. a.bain@raymedica.com
authors.forename: A C
authors.initials: AC
authors.lastname: Bain
authors.forename: C D
authors.initials: CD
authors.lastname: Swerdlow
authors.forename: C J
authors.initials: CJ
authors.lastname: Love
authors.forename: K A
authors.initials: KA
authors.lastname: Ellenbogen
authors.forename: T F
authors.initials: TF
authors.lastname: Deering
authors.forename: J E
authors.initials: JE
authors.lastname: Brewer
authors.forename: R S
authors.initials: RS
authors.lastname: Augostini
authors.forename: P J
authors.initials: PJ
authors.lastname: Tchou
mesh_terms: D000368:Aged; D016001:Confidence Intervals; D017147:Defibrillators, Implantable; D004554:Electric Countershock / Q000379:methods*; D005260:Female; D006801:Humans; D007432:Intraoperative Period; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D016896:Treatment Outcome; D014481:United States; D014693:Ventricular Fibrillation / Q000628:therapy*