title: Effect of pulse width on transesophageal atrial pacing in dogs.
abstract: OBJECTIVE
  To determine the impact of stimulus pulse width (PW) on pacing threshold (PT), zone of capture (ZOC) and extraneous muscular stimulation (EMS).
  
  
  METHODS
  Experimental trial in client-owned dogs.
  
  
  METHODS
  Seventeen dogs, median weight 16.1 kg (interquartile range: 11.4-21.5).
  
  
  METHODS
  Transesophageal atrial pacing (TAP) involved a 6 Fr pacing catheter inserted trans-orally into the esophagus to a position aboral to the heart in anesthetized dogs. The catheter was slowly withdrawn until atrial pacing was noted on an electrocardiogram. The catheter was withdrawn in 1 cm increments until TAP could not be achieved. PTs were recorded at each pacing site using PWs of 10.0, 5.0, 2.0 and 1.8 ms, always in that order.
  
  
  RESULTS
  The overall lowest mean PTs for all dogs were 6 ± 3 mA, 9 ± 4 mA, 11 ± 5 mA and 13 ± 5 mA at PWs of 10.0, 5.0, 2.0 and 1.8 ms, respectively. A significant decrease in overall minimum PT was noted using a PW of 10.0 ms compared with either 2.0 or 1.8 ms (p = 0.043 and p = 0.001, respectively) and pacing using 5.0 ms compared with 1.8 ms (p = 0.028). A significant increase in ZOC was noted using a PW of 10.0 ms compared with PWs of 5.0, 2.0 and 1.8 ms (p = 0.0047, p = 0.0006 and p = 0.0003, respectively), using a PW of 5.0 ms compared with PWs of 2.0 and 1.8 ms (p = 0.0011 and p = 0.0003, respectively) and using a PW of 2.0 compared with one of 1.8 ms (p = 0.0084).
  
  
  CONCLUSIONS
  Use of 10.0 or 5.0 ms PW to perform TAP minimized the power required to pace the atria, while a PW of 10.0 ms maximized the size of the ZOC.
authors.affiliation: Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Sanders
authors.affiliation: Department of Veterinary Clinical Sciences, Veterinary Medical Center, The Ohio State University, Columbus, OH, USA.
authors.forename: Emily H
authors.initials: EH
authors.lastname: Chapel
mesh_terms: D000758:Anesthesia / Q000662:veterinary*; D000818:Animals; D001919:Bradycardia / Q000517:prevention & control / Q000662:veterinary*; D002304:Cardiac Pacing, Artificial / Q000379:methods / Q000662:veterinary*; D004285:Dogs; D008297:Male; D019990:Perioperative Care / Q000662:veterinary
keywords: cardiac; heart rate support; pacing; temporary