Abnormal QT intervals associated with negative T waves induced by antiarrhythmic drugs are rapidly reduced using magnesium sulfate as an antidote.
Clin Cardiol
; 16(1): 35-8, 1993 Jan.
Article
em En
| MEDLINE
| ID: mdl-8416758
This study was undertaken to determine whether prolonged QTc interval as a consequence of abnormal repolarization induced by coronary disease or antiarrhythmic drugs could be shortened by intravenous administration of magnesium sulfate. A total of 21 patients with basal prolonged QTc intervals (QTc > 500 ms) were divided in two groups: 7 with ischemic coronary disease and negative T waves (Group A), and 14 treated with antiarrhythmic drugs (Group B). Nine of the latter had negative T waves (Subgroup B-1) and five had positive T waves (Subgroup B-2) recorded in precordial leads. Nine patients were taking amiodarone and six quinidine. Magnesium sulfate was given intravenously in a bolus of 3.75 g (25% solution) over 3 min. Patients had normal electrolyte serum levels. The prolonged QTc and JTc intervals were shortened after magnesium sulfate in patients of Subgroup B-1 from the basal values [QTc 20.7% and JTc 25.4%, (p = < 0.0001 and 0.02, respectively)]. None of the patients in Group A or Subgroup B-2 experienced altered QTc or JTc intervals. While some antiarrhythmic drugs are capable of altering the refractoriness of ventricular cells, probably by causing changes in the intracellular metabolic pathways, in patients with coronary disease gaps in the membrane induced by ischemic injury let calcium enter the cells parallel with dispersion of ventricular repolarization. When secondary negative T waves are present, magnesium sulfate as an antidote probably acts as a blocking agent at the sarcoplasmic reticulum, thus reducing both QTc and JTc intervals.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Doença das Coronárias
/
Eletrocardiografia
/
Sulfato de Magnésio
/
Antiarrítmicos
Tipo de estudo:
Risk_factors_studies
Limite:
Female
/
Humans
/
Male
/
Middle aged
Idioma:
En
Revista:
Clin Cardiol
Ano de publicação:
1993
Tipo de documento:
Article
País de afiliação:
Argentina
País de publicação:
Estados Unidos