Document Detail

Acute effects of intravenous magnesium on ventricular refractoriness and monophasic action potential duration in humans.
MedLine Citation:
PMID:  10540920     Owner:  NLM     Status:  MEDLINE    
The objective of this study was to examine the antiarrhythmic mechanisms of magnesium (Mg). The 12 patients who were selected for the study were given 12 mmol Mg sulphate followed by an infusion of 8 mmol/h. Ventricular effective refractory period (VERP). monophasic action potential duration at 50% and 90% repolarization during spontaneous rhythm (MAPD50, MAPD90) and atrial pacing at a cycle length of 600 ms (MAPD(50)600, MAPD(90)600) were measured before and after the intervention. Plasma magnesium concentration rose from 0.83 +/- 0.05 to 1.85 +/- 0.24 mmol/l (p < 0.001). Shortening of MAPD(50) (250 +/- 45 vs 240 +/- 46 ms; p < 0.05), MAPD(90) (294 +/- 42 vs 283 +/- 41 ms; p < 0.05) and shortening of sinus cycle length (SCL) (783 +/- 153 vs 742 +/- 160 ms; p < 0.01) were detected. During controlled cycle length, magnesium decreased MAPD(50)600 (230 +/- 28 vs 221 +/- 28 ms; p < 0.01), MAPD(90)600 (274 +/- 25 vs 261 +/- 29 ms; p < 0.01) and VERP (247 +/- 25 vs 241 +/- 21 ms: p < 0.05). QRS duration, QT interval and blood pressure remained unchanged. The change in SCL correlated with the change in MAPD(50) (r = 0.58; p < 0.05) and MAPD(90) (r = 0.55; p = 0.06 ) but not with MAPD(50)600, MAPD(90)600 or VERP. Magnesium acutely shortens ventricular monophasic action potential duration and refractoriness. This effect is partly mediated by mechanisms that increase heart rate. The reductions might bring salutary effects in arrhythmias evoked by prolonged repolarization.
H J Parikka; L K Toivonen
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Scandinavian cardiovascular journal : SCJ     Volume:  33     ISSN:  1401-7431     ISO Abbreviation:  Scand. Cardiovasc. J.     Publication Date:  1999  
Date Detail:
Created Date:  1999-11-17     Completed Date:  1999-11-17     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9708377     Medline TA:  Scand Cardiovasc J     Country:  NORWAY    
Other Details:
Languages:  eng     Pagination:  300-5     Citation Subset:  IM    
Department of Medicine, Helsinki University Central Hospital, Finland.
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MeSH Terms
Action Potentials / drug effects*,  physiology
Heart Conduction System / drug effects*
Infusions, Intravenous
Magnesium / administration & dosage,  pharmacology*
Middle Aged
Reg. No./Substance:

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