[Magnesium in cardiology]

Magnesium acts as a cofactor of numerous enzymes and is important for the maintenance of a high intracellular potassium concentration and the transmembrane action potential. Of the total magnesium content of about 1000 mmol, only 0.3% are located in plasma. Hypomagnesemia and probable magnesium deficiency are found in 7 to 11% of hospitalized patients but are only rarely accompanied by relevant clinical symptoms. Prolonged diuretic therapy and secondary aldosteronism are frequent causes of hypomagnesemia in cardiology. Intravenous magnesium is a vasodilatator and prolongs the AH interval. In animal studies magnesium has been shown to have cardioprotective and platelet-inhibiting properties. The only verified indication for intravenous magnesium is the initial treatment of torsade de pointes. Magnesium may suppress digitalis-induced tachyarrhythmias and convert paroxysmal supraventricular tachycardia and monomorphic ventricular tachycardia to sinus rhythm. Its role in the treatment of acute myocardial infarction and of ventricular arrhythmias in congestive heart failure is unclear.