[Anti-arrhythmia effects of magnesium salts. 4 cases].

Known since 1935, the antiarrhythmic effects of magnesium salts are periodically forgotten. They are illustrated here by 4 cases with entirely different clinical and biological features. Of unquestionable therapeutic value was the use of magnesium for the treatment of 2 episodes of severe ventricular extrasystoles with "torsades de pointe". These antiarrhythmic properties are observed whether blood magnesium levels are normal or low and cannot therefore be ascribed to correction of magnesium deficiency. Experimental data are in favour of interferences with transcellular ion flows. Magnesium is thought to ensure normal potassium gradient and also to reactivate the fast sodium channel inhibited by hypokalaemia. Above all, the magnesium ion appears to act as a calcium inhibitor, which would explain its antiarrhythmic properties irrespective of the state of magnesium body stores.