| Electrophysiological effects of high cocaine concentrations on intact canine heart. Evidence for modulation by both heart rate and autonomic nervous system. | |
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MedLine Citation:
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PMID: 8443914 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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BACKGROUND: Previous clinical reports have suggested that cocaine intoxication may produce severe ventricular arrhythmias due to a direct effect on the heart. However, the effects of high plasma levels of cocaine on the electrophysiology of the heart have not been well characterized and remain poorly understood. METHODS AND RESULTS: The purpose of this study was to characterize the electrophysiological effects of high doses of cocaine on the in situ dog heart. In dogs anesthetized with morphine and alpha-chloralose, cocaine (2-11 micrograms/mL) increased both atrial and ventricular refractory periods and produced rate-dependent increases in atrial, atrioventricular, His-Purkinje, and ventricular conduction intervals. The time constant for the onset of cocaine's conduction slowing effect following a reduction in pacing cycle length from 400 to 260 msec was approximately two beats, and the time constant for diastolic recovery from conduction slowing was approximately 200 msec, which are similar to values reported for several class Ib antiarrhythmic drugs. Cocaine produced a rate-dependent increase in QT interval that was greatest at high heart rates yet produced no change in the ST (QT-QRS) interval. This suggests that high plasma levels of cocaine delay repolarization primarily via slowing of conduction. Cocaine's effects on both atrioventricular and intraventricular conduction were significantly larger in autonomically blocked than in autonomically intact animals. CONCLUSIONS: We conclude that high plasma levels of cocaine, similar to those reported in autopsy reports following fatal cocaine overdose in humans, produce significant rate-dependent conduction slowing effects on atrial, atrioventricular, and ventricular conduction in the in situ heart. These rate-dependent effects are intensified following autonomic blockade. |
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Authors:
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C W Clarkson; C Chang; A Stolfi; W J George; S Yamasaki; A S Pickoff |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: Circulation Volume: 87 ISSN: 0009-7322 ISO Abbreviation: Circulation Publication Date: 1993 Mar |
Date Detail:
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Created Date: 1993-04-06 Completed Date: 1993-04-06 Revised Date: 2010-03-24 |
Medline Journal Info:
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Nlm Unique ID: 0147763 Medline TA: Circulation Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 950-62 Citation Subset: AIM; IM |
Affiliation:
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Department of Pharmacology, Tulane University School of Medicine, New Orleans, LA 70112-2699. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Arrhythmias, Cardiac / etiology Autonomic Nervous System / physiology* Bundle of His / physiology Cardiac Pacing, Artificial Cocaine / pharmacology* Coronary Circulation Dogs Dose-Response Relationship, Drug Electrophysiology Female Heart / drug effects*, physiology Heart Conduction System / drug effects Heart Rate / physiology* Hemodynamics Male Osmolar Concentration Refractory Period, Electrophysiological |
| Grant Support | |
ID/Acronym/Agency:
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HL-36096/HL/NHLBI NIH HHS; K04-HL-02520/HL/NHLBI NIH HHS |
| Chemical | |
Reg. No./Substance:
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50-36-2/Cocaine |
| Comments/Corrections | |
Comment In:
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Circulation. 1993 Mar;87(3):1046-7
[PMID:
8443884
]
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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