title: Comparison of a novel rectilinear biphasic waveform with a damped sine wave monophasic waveform for transthoracic ventricular defibrillation. ZOLL Investigators.
abstract: OBJECTIVE
  We compared the efficacy of a novel rectilinear biphasic waveform, consisting of a constant current first phase, with a damped sine wave monophasic waveform during transthoracic defibrillation.
  
  
  BACKGROUND
  Multiple studies have shown that for endocardial defibrillation, biphasic waveforms have a greater efficacy than monophasic waveforms. More recently, a 130-J truncated exponential biphasic waveform was shown to have equivalent efficacy to a 200-J damped sine wave monophasic waveform for transthoracic ventricular defibrillation. However, the optimal type of biphasic waveform is unknown.
  
  
  METHODS
  In this prospective, randomized, multicenter trial, 184 patients who underwent ventricular defibrillation were randomized to receive a 200-J damped sine wave monophasic or 120-J rectilinear biphasic shock.
  
  
  RESULTS
  First-shock efficacy of the biphasic waveform was significantly greater than that of the monophasic waveform (99% vs. 93%, p = 0.05) and was achieved with nearly 60% less delivered current (14 +/- 1 vs. 33 +/- 7 A, p < 0.0001). Although the efficacy of the biphasic and monophasic waveforms was comparable in patients with an impedance < 70 ohms (100% [biphasic] vs. 95% [monophasic], p = NS), the biphasic waveform was significantly more effective in patients with an impedance > or = 70 ohms (99% [biphasic] vs. 86% [monophasic], p = 0.02).
  
  
  CONCLUSIONS
  This study demonstrates a superior efficacy of rectilinear biphasic shocks as compared with monophasic shocks for transthoracic ventricular defibrillation, particularly in patients with a high transthoracic impedance. More important, biphasic shocks defibrillated with nearly 60% less current. The combination of increased efficacy and decreased current requirements suggests that biphasic shocks as compared with monophasic shocks are advantageous for transthoracic ventricular defibrillation.
authors.affiliation: New York Hospital-Cornell Medical Center, New York, USA.
authors.forename: S
authors.initials: S
authors.lastname: Mittal
authors.forename: S
authors.initials: S
authors.lastname: Ayati
authors.forename: K M
authors.initials: KM
authors.lastname: Stein
authors.forename: B P
authors.initials: BP
authors.lastname: Knight
authors.forename: F
authors.initials: F
authors.lastname: Morady
authors.forename: D
authors.initials: D
authors.lastname: Schwartzman
authors.forename: D
authors.initials: D
authors.lastname: Cavlovich
authors.forename: E V
authors.initials: EV
authors.lastname: Platia
authors.forename: H
authors.initials: H
authors.lastname: Calkins
authors.forename: P J
authors.initials: PJ
authors.lastname: Tchou
authors.forename: J M
authors.initials: JM
authors.lastname: Miller
authors.forename: J M
authors.initials: JM
authors.lastname: Wharton
authors.forename: R J
authors.initials: RJ
authors.lastname: Sung
authors.forename: D J
authors.initials: DJ
authors.lastname: Slotwiner
authors.forename: S M
authors.initials: SM
authors.lastname: Markowitz
authors.forename: B B
authors.initials: BB
authors.lastname: Lerman
mesh_terms: D000368:Aged; D001145:Arrhythmias, Cardiac / Q000628:therapy*; D004554:Electric Countershock / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D016896:Treatment Outcome