[The value of magnesium in intensive care medicine]

In the management of severely ill patients it has been suggested that magnesium might protect the heart muscle and prevent lift-threatening irregularities of heart rhythm. 1) Cardiac arrhythmias: The mechanism of action of magnesium in monomorphic ventricular tachycardia is not known. Magnesium does not affect the effective refractory period of ventricular structures. It alters the inward rectifying potassium channel in experimental animal models. Though magnesium may exhibit negative inotropic effects in animal studies, an increase of the cardiac index during ventricular tachycardia could be documented in recent investigations. The application of magnesium is usually well tolerated. Magnesium (i.v.) is indicated in Torsade de pointes tachycardia Digitalis-induced cardiac arrhythmias Monomorphic ventricular tachycardia (efficacy ca. 30%) Multifocal atrial tachyarrhythmias. 2) Myocardial infarction: In the past, several trials of intravenous infusions of magnesium have indicated a considerable mortality reduction following myocardial infarction. More recently, the LIMIT-2 (Leicester Intravenous Magnesium Intervention Trial) of a 24-h magnesium infusion in about 2000 patients indicated a benefit of about 25%. Now, the ISIS-4 (International Study of Infarct Survival)-trial has tested magnesium in 58,000 patients. In ISIS-4 there was no evidence of a beneficial effect of magnesium on mortality--neither in all patients nor in any particular type of patient. Overall, there was no beneficial effect on morbidity. According to these data, there seems only a limited role for magnesium in the routine treatment of cardiac infarction patients.

Intravenous magnesium can terminate Torsade de pointes tachycardia and, in selected patients, monomorphic ventricular tachycardia regardless of the serum magnesium concentration.(ABSTRACT TRUNCATED AT 250 WORDS)