title: Effects of the volatile anesthetic agents on sinus node function and atrioventricular conduction in dogs: a comparison with chloralose anesthesia.
abstract: The effects of equipotent concentrations (1.5 times minimum alveolar concentration) of the inhalational agents halothane, enflurane, and isoflurane on sinus node function, and atrioventricular (A-V) conduction and refractoriness were compared with chloralose anesthesia in 49 mongrel dogs. Sinus node function was assessed using corrected sinus node recovery time. Atrial-His and His-ventricular conduction times were measured at paced heart rates of 150, 180, and 200 beats/min, and A-V refractoriness was assessed by Wenckebach periodicity. There was no evidence that sinus node function was impaired by any of the inhalational agents. Enflurane anesthesia was associated with a significant prolongation of atrial-His conduction at paced heart rates of 180 and 200 beats/min when compared to chloralose anesthesia and the other two inhalational agents (P < .001). Atrioventricular refractoriness was impaired by enflurane (P < .001) and halothane (P < .05), but not isoflurane, when compared with chloralose anesthesia. Ventricular-His conduction was not altered by any of the agents. The authors conclude that enflurane is associated with a greater impairment of A-V conduction and refractoriness than halothane or isoflurane, and that these changes are related to the anesthetic agent and not the anesthetic state.
authors.affiliation: Department of Anesthesiology, University of Michigan Hospitals, Ann Arbor, MI 48109, USA.
authors.forename: N C
authors.initials: NC
authors.lastname: Wilton
authors.forename: C B
authors.initials: CB
authors.lastname: Hantler
authors.forename: S N
authors.initials: SN
authors.lastname: Landau
authors.forename: L O
authors.initials: LO
authors.lastname: Larson
authors.forename: P R
authors.initials: PR
authors.lastname: Knight
mesh_terms: D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D018686:Anesthetics, Intravenous / Q000494:pharmacology*; D000818:Animals; D001283:Atrioventricular Node / Q000187:drug effects* / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects; D002698:Chloralose / Q000494:pharmacology*; D004285:Dogs; D004562:Electrocardiography / Q000379:methods; D022062:Electrophysiologic Techniques, Cardiac / Q000379:methods; D004737:Enflurane / Q000494:pharmacology; D005260:Female; D006221:Halothane / Q000494:pharmacology; D006329:Heart Conduction System / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D007530:Isoflurane / Q000494:pharmacology; D008297:Male; D012849:Sinoatrial Node / Q000187:drug effects* / Q000502:physiology
chemical_list: D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D002698:Chloralose; D004737:Enflurane; D007530:Isoflurane; D006221:Halothane