| Differential effects of dofetilide, amiodarone, and class lc drugs on left and right atrial refractoriness and left atrial vulnerability in pigs. | |
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MedLine Citation:
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PMID: 11218069 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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OBJECTIVES: Antiarrhythmic drugs have been shown to prolong right atrial refractoriness while data on the left atrium are not available. In pigs we have observed shorter effective refractory periods (ERP) of the left compared with the right atrium associated with a much higher left atrial vulnerability for tachyarrhythmias. Since this could suggest a different distribution of repolarizing ion channels in left and right atrium, we investigated whether antiarrhythmic drugs blocking different ion channels have a differential effect on left and right atrial ERP and left atrial vulnerability. METHODS: In pentobarbital-anesthetized pigs (n=40) we measured and compared ERPs in both atria before and after different drugs with the S1-S2 extrastimulus method at three basic cycle lengths (BCL) and assessed the inducibility of atrial fibrillation/flutter (AF/AFL) by the premature S2 stimulus. RESULTS: At the three BCL tested (240/300/400 ms) baseline ERPs were shorter in left vs. right atrium (112+/-2/124+/-2/129+/-2 ms vs. 147+/-2/163+/-2/167+/-2 ms, P<0.001). Mostly non-sustained AF/AFL induced by the S2 extrastimulus was very frequent in the left (68%) and nearly absent in the right atrium (3%). Only amiodarone, 5 mg/kg i.v., which showed a balanced increase of left and right atrial ERP (29+/-5/33+/-4/35+/-3% vs. 30+/-5/35+/-5/42+/-7%), decreased the inducibility of AF/AFL significantly (-72%, P<0.01). Dofetilide, 10 microg/kg i.v., had a stronger effect on right than left atrial ERP (36+/-4/39+/-5/46+/-10% vs. 23+/-2/22+/-7/22+/-5%, P<0.05), while flecainide, 1 mg/kg i.v., prolonged left more than right atrial ERP (58+/-15/36+/-7/40+/-7% vs. 26+/-5/24+/-5/21+/-4%, P<0.05) similar to 1 mg/ kg of propafenone (46+/-5/45+/-7/32+/-10% vs. 17+/-4/21+/-5/ 25+/-8%, P<0.05). CONCLUSION: The shorter refractoriness of the left compared with the right atrium observed in pigs was associated with a high left atrial vulnerability for tachyarrhythmias, which was reduced only by amiodarone showing a balanced increase of left and right atrial ERP. Dofetilide was stronger on right atrial ERP, flecainide and propafenone on left atrial ERP. These differences suggest a differential distribution of repolarizing ion channels between left and right atrium with possible relevance for the antiarrhythmic efficacy of drugs. |
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Authors:
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K J Wirth; K Knobloch |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Naunyn-Schmiedeberg's archives of pharmacology Volume: 363 ISSN: 0028-1298 ISO Abbreviation: Naunyn Schmiedebergs Arch. Pharmacol. Publication Date: 2001 Feb |
Date Detail:
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Created Date: 2001-02-19 Completed Date: 2001-05-03 Revised Date: 2003-11-14 |
Medline Journal Info:
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Nlm Unique ID: 0326264 Medline TA: Naunyn Schmiedebergs Arch Pharmacol Country: Germany |
Other Details:
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Languages: eng Pagination: 166-74 Citation Subset: IM |
Affiliation:
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DG Cardiovascular Diseases, Aventis Pharma, Industriepark Höchst, Frankfurt am Main, Germany. klaus.wirth@aventis.com |
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| MeSH Terms | |
Descriptor/Qualifier:
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Amiodarone
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pharmacology*,
therapeutic use Animals Anti-Arrhythmia Agents / pharmacology*, therapeutic use Atrial Fibrillation / drug therapy Atrial Flutter / drug therapy Atrial Function, Left / drug effects*, physiology Atrial Function, Right / drug effects*, physiology Flecainide / pharmacology, therapeutic use Male Phenethylamines / pharmacology*, therapeutic use Propafenone / pharmacology, therapeutic use Sulfonamides / pharmacology*, therapeutic use Swine |
| Chemical | |
Reg. No./Substance:
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0/Anti-Arrhythmia Agents; 0/Phenethylamines; 0/Sulfonamides; 115256-11-6/dofetilide; 1951-25-3/Amiodarone; 54063-53-5/Propafenone; 54143-55-4/Flecainide |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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