These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Biomarkers and endogenous determinants of dofetilide-induced torsades de pointes in α(1) -adrenoceptor-stimulated, anaesthetized rabbits.
    Author: Farkas AS, Rudas L, Makra P, Csík N, Leprán I, Forster T, Csanády M, Papp JG, Varró A, Farkas A.
    Journal: Br J Pharmacol; 2010 Dec; 161(7):1477-95. PubMed ID: 20659107.
    Abstract:
    BACKGROUND AND PURPOSE: Torsades de pointes (TdP) liability is a stochastic event, which indicates that unidentified factors have an important role in facilitating the initiation of TdP by increasing the probability of TdP occurrence. We sought to identify factors that facilitate drug-induced TdP. EXPERIMENTAL APPROACH: We studied dofetilide-induced TdP in pentobarbital-anaesthetized, phenylephrine-sensitized rabbits, seeking biomarkers that discriminated between the animals that experienced TdP ('TdP+' animals) and those that did not ('TdP-' animals). As novel variables, the beat-to-beat variability and instability of ECG intervals were measured at preset times, irrespective of whether or not hearts were in stable sinus rhythm ('absolute' variability and instability). Autonomic activity was also determined. KEY RESULTS: Dofetilide delayed repolarization and induced arrhythmias prior to TdP. The variability of the coupling interval and shape of arrhythmic beats before TdP were significantly greater in the 'TdP+' group than in the 'TdP-' group. Accordingly, the 'absolute' variability and instability of the ECG intervals were significantly elevated in the 'TdP+' group. Phenylephrine increased significantly the up-baroreflex sensitivity in the 'TdP+' group before dofetilide administration. CONCLUSIONS AND IMPLICATIONS: 'Preceding' arrhythmias have characteristics that permit prediction of TdP occurrence: the more chaotic the ventricular rhythm, the greater the probability of TdP initiation. This suggests that complexity of the arrhythmic beats may play an important mechanistic role in TdP genesis. The electrical instability quantified by the novel 'absolute' variability and instability parameters correlates with the probability of TdP occurrence. Baroreflex may contribute to TdP genesis in vivo.
    [Abstract] [Full Text] [Related] [New Search]