title: Proarrhythmic effects of ibutilide in a canine model of pacing induced cardiomyopathy.
abstract: The authors developed a canine model of pacing induced cardiomyopathy to study the possible mechanisms of ibutilide induced torsades de pointes (TP) in heart failure. Thirteen dogs received intravenous ibutilide after acute AV block for 60 minutes, and after implantation of a VVI pacemaker, with a rate of 270 beats/min for 2-3 weeks. Twelve-lead ECG and right and left ventricle monophasic action potentials were recorded at different right ventricle pacing cycle lengths from 600 ms to 1200 ms during the study. The results showed ibutilide could significantly prolong ventricular repolarization and increase the dispersion in a dose dependent and reverse use dependent manner. Furthermore, after ibutilide administration, cardiomyopathic dogs had a greater dispersion of ventricular repolarization, and also had higher incidences of early afterdepolarizations and spontaneous or pacing induced TP than acute AV block dogs.
authors.affiliation: Department of Medicine, National Yang-Ming University, School of Medicine, Taipei, Taiwan.
authors.forename: M H
authors.initials: MH
authors.lastname: Hsieh
authors.forename: Y J
authors.initials: YJ
authors.lastname: Chen
authors.forename: S H
authors.initials: SH
authors.lastname: Lee
authors.forename: Y A
authors.initials: YA
authors.lastname: Ding
authors.forename: M S
authors.initials: MS
authors.lastname: Chang
authors.forename: S A
authors.initials: SA
authors.lastname: Chen
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology*; D001145:Arrhythmias, Cardiac / Q000209:etiology / Q000503:physiopathology*; D002304:Cardiac Pacing, Artificial / Q000379:methods; D009202:Cardiomyopathies / Q000209:etiology / Q000503:physiopathology*; D004195:Disease Models, Animal; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D006339:Heart Rate / Q000187:drug effects; D006352:Heart Ventricles / Q000187:drug effects / Q000503:physiopathology; D006439:Hemodynamics / Q000187:drug effects; D008297:Male; D013449:Sulfonamides / Q000494:pharmacology*; D016171:Torsades de Pointes / Q000139:chemically induced / Q000503:physiopathology
chemical_list: D000889:Anti-Arrhythmia Agents; D013449:Sulfonamides; C067192:ibutilide