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Alpha-2 adrenergic antagonism enhances risk of ventricular tachycardia during acute ischemia.
Arnar, David O; Xing, Dezhi; Martins, James B.
Afiliación
  • Arnar DO; Department of Internal Medicine, University of Iowa College of Medicine, Iowa City, Iowa 52242, USA.
Scand Cardiovasc J ; 41(6): 378-85, 2007 Dec.
Article en En | MEDLINE | ID: mdl-17852790
OBJECTIVE: In this study we tested the hypothesis that alpha-2 adrenergic antagonism could facilitate induction of previously non-inducible ventricular tachycardia (VT) during acute ischemia. Previous reports suggest that VT during ischemia may be modulated by (alpha-2 adrenergic agonists. DESIGN: The left anterior descending artery was occluded after instrumentation of the ischemic risk zone with 21 multipolar plunge needles, each recording 6 bipolar electrograms. Three dimensional mapping characterized the mechanism of VT induced with extrastimuli. RESULTS: Of 16 non-inducible dogs included, eight which were given the alpha-2 adrenergic antagonist yohimbine all had inducible VT, while all eight in the control group remained non-inducible (p < 0.05). Six of the VTs were of focal Purkinje origin. The cycle length of the VTwas 119 +/- 4 ms. Mean arterial pressure (81+/- 8 to 82 +/- 8 mmHg, p = ns), ventricular effective refractory period (146 +/- 6 to 144 +/- 5 ms, p = ns) and ischemic zone size (55 +/-6% vs. 61 +/- 4%, p = 0.45) were not altered by yohimbine indicating minimal central or pre-junctional effects of the drug. CONCLUSIONS: Yohimbine facilitates induction of VT, especially those with focal Purkinje fiber origin, suggestive of an effect mediated through antagonism of post-junctional alpha-2 adrenoceptors on Purkinje fibers.
Asunto(s)
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Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Yohimbina / Taquicardia Ventricular / Isquemia Miocárdica / Antagonistas Adrenérgicos alfa Tipo de estudio: Etiology_studies / Risk_factors_studies Límite: Animals Idioma: En Revista: Scand Cardiovasc J Asunto de la revista: ANGIOLOGIA / CARDIOLOGIA Año: 2007 Tipo del documento: Article País de afiliación: Estados Unidos Pais de publicación: Reino Unido
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Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Yohimbina / Taquicardia Ventricular / Isquemia Miocárdica / Antagonistas Adrenérgicos alfa Tipo de estudio: Etiology_studies / Risk_factors_studies Límite: Animals Idioma: En Revista: Scand Cardiovasc J Asunto de la revista: ANGIOLOGIA / CARDIOLOGIA Año: 2007 Tipo del documento: Article País de afiliación: Estados Unidos Pais de publicación: Reino Unido