title: Coupling interval from slow to tachycardiac pacing decides sustained alternans pattern.
abstract: We discovered that the coupling beat interval from a slow to a tachycardiac pacing period considerably affected the pattern of the beat-to-beat alternation of the tachycardia-induced sustained contractile alternans. We analyzed the relationship between the coupling interval and the pattern and amplitude of the alternans in the isovolumic left ventricle of canine blood-perfused hearts. The alternans pattern and amplitude varied transiently over the first 30-50 beats and became gradually stable over the first minute in all 12 hearts. We discovered that stable alternans, even under the same tachycardiac pacing, had three different strong-weak beat patterns depending on the coupling interval. A relatively short coupling interval produced a representative sustained alternans of the strong and weak beats. A relatively long coupling interval produced a similar sustained alternans but in a reversed order of even- and odd-numbered beats counted from the coupling interval. However, sustained alternans disappeared after 1-3 specific coupling intervals. We conclude that ventricular pacing rate does not solely determine the pattern and amplitude of sustained contractile alternans induced by tachycardia.
authors.affiliation: Department of Physiology II, Okayama University Medical School, Okayama 700-8558, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Suzuki
authors.forename: J
authors.initials: J
authors.lastname: Araki
authors.forename: Y
authors.initials: Y
authors.lastname: Doi
authors.forename: W
authors.initials: W
authors.lastname: Fujinaka
authors.forename: H
authors.initials: H
authors.lastname: Minami
authors.forename: G
authors.initials: G
authors.lastname: Iribe
authors.forename: S
authors.initials: S
authors.lastname: Mohri
authors.forename: J
authors.initials: J
authors.lastname: Shimizu
authors.forename: M
authors.initials: M
authors.lastname: Hirakawa
authors.forename: H
authors.initials: H
authors.lastname: Suga
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002304:Cardiac Pacing, Artificial; D002306:Cardiac Volume / Q000502:physiology; D004285:Dogs; D006321:Heart / Q000502:physiology*; D009200:Myocardial Contraction / Q000502:physiology*; D009206:Myocardium / Q000378:metabolism; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D013610:Tachycardia / Q000503:physiopathology*; D017725:Ventricular Pressure / Q000502:physiology
chemical_list: D002118:Calcium