Document Detail

Dofetilide Promotes Repolarization Abnormalities in Perfused Guinea-pig Heart.
MedLine Citation:
PMID:  22918600     Owner:  NLM     Status:  Publisher    
PURPOSE: Dofetilide is class III antiarrhythmic agent which prolongs cardiac action potential duration because of selective inhibition of I (Kr), the rapid component of the delayed rectifier K(+) current. Although clinical studies reported on proarrhythmic risk associated with dofetilide treatment, the contributing electrophysiological mechanisms remain poorly understood. This study was designed to determine if dofetilide-induced proarrhythmia may be attributed to abnormalities in ventricular repolarization and refractoriness. METHODS: The monophasic action potential duration and effective refractory periods (ERP) were assessed at distinct epicardial and endocardial sites along with volume-conducted ECG recordings in isolated, perfused guinea-pig heart preparations. RESULTS: Dofetilide was found to produce the reverse rate-dependent prolongation of ventricular repolarization, increased the steepness of action potential duration rate adaptation, and amplified transepicardial variability in electrical restitution kinetics. Dofetilide also prolonged the T peak-to-end interval on ECG, and elicited a greater prolongation of endocardial than epicardial ERP, thereby increasing transmural dispersion of refractoriness. At epicardium, dofetilide prolonged action potential duration to a greater extent than ERP, thus extending the critical interval for ventricular re-excitation. This change was associated with triangulation of epicardial action potential because of greater dofetilide-induced prolonging effect at 90 % than 30 % repolarization. Premature ectopic beats and spontaneous short-lasting episodes of monomorphic ventricular tachycardia were observed in 44 % of dofetilide-treated heart preparations. CONCLUSIONS: Proarrhythmic potential of dofetilide in guinea-pig heart is attributed to steepened electrical restitution, increased transepicardial variability in electrical restitution kinetics, amplified transmural dispersion of refractoriness, increased critical interval for ventricular re-excitation, and triangulation of epicardial action potential.
Oleg E Osadchii
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-8-24
Journal Detail:
Title:  Cardiovascular drugs and therapy / sponsored by the International Society of Cardiovascular Pharmacotherapy     Volume:  -     ISSN:  1573-7241     ISO Abbreviation:  Cardiovasc Drugs Ther     Publication Date:  2012 Aug 
Date Detail:
Created Date:  2012-8-24     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8712220     Medline TA:  Cardiovasc Drugs Ther     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen N, Denmark,
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