title: Effect of monopolar radiofrequency energy on pacemaker function.
abstract: BACKGROUND
  This study aimed to quantify the clinical parameters of mono- and bipolar instruments that inhibit pacemaker function. The specific aims were to quantify pacer inhibition resulting from the monopolar instrument by altering the generator power setting, the generator mode, the distance between the active electrode and the pacemaker, and the location of the dispersive electrode.
  
  
  METHODS
  A transvenous ventricular lead pacemaker overdrive paced the native heart rate of an anesthetized pig. The primary outcome variable was pacer inhibition quantified as the number of beats dropped by the pacemaker during 5 s of monopolar active electrode activation.
  
  
  RESULTS
  Lowering the generator power setting from 60 to 30 W decreased the number of dropped paced events (2.3 ± 1.2 vs 1.6 ± 0.8 beats; p = 0.045). At 30 W of power, use of the cut mode decreased the number of dropped paced beats compared with the coagulation mode (0.6 ± 0.5 vs 1.6 ± 0.8; p = 0.015). At 30 W coagulation, firing the active electrode at different distances from the pacemaker generator (3.75, 7.5, 15, and 30 cm) did not change the number of dropped paced beats (p = 0.314, analysis of variance [ANOVA]). The dispersive electrode was placed in four locations (right/left gluteus, right/left shoulder). More paced beats were dropped when the current vector traveled through the pacemaker/leads than when it did not (1.5 ± 1.0 vs 0.2 ± 0.4; p < 0.001).
  
  
  CONCLUSIONS
  Clinical parameters that reduce the inhibition of a pacemaker by monopolar instruments include lowering the generator power setting, using cut (vs coagulation) mode, and locating the dispersive electrode so the current vector does not traverse the pacemaker generator or leads.
authors.affiliation: Department of Surgery, University of Colorado School of Medicine, 12631 East 17th Avenue, MS C313, Aurora, CO 80045, USA.
authors.forename: Henry R
authors.initials: HR
authors.lastname: Govekar
authors.forename: Thomas N
authors.initials: TN
authors.lastname: Robinson
authors.forename: Paul D
authors.initials: PD
authors.lastname: Varosy
authors.forename: Guillaume
authors.initials: G
authors.lastname: Girard
authors.forename: Paul N
authors.initials: PN
authors.lastname: Montero
authors.forename: Christina L
authors.initials: CL
authors.lastname: Dunn
authors.forename: Edward L
authors.initials: EL
authors.lastname: Jones
authors.forename: Greg V
authors.initials: GV
authors.lastname: Stiegmann
mesh_terms: D000818:Animals; D004562:Electrocardiography; D004566:Electrodes; D004867:Equipment Design; D004868:Equipment Failure; D010138:Pacemaker, Artificial; D011846:Radio Waves; D013552:Swine