Magnesium and the heart.

Magnesium is a most important cation in the body mostly distributed in the skeleton, muscles and liver. The most important causes of magnesium deficiency in the body include wide range of gastrointestinal disorders, diuretic therapy, endocrine disorders, renal diseases, alcoholism, etc. The demonstration of hypomagnesemia in patients of digitalis toxicity is of great clinical significance since magnesium can be replaced among these patients and toxicity and mortality due to this drug can be minimised. In patients with low serum magnesium, the cellular content of this ion may be normal. Therefore, it is of great interest to study the myocardial level of this ion in cardiovascular diseases. The clinical features of magnesium deficit are related to neuromuscular disorders. However, ST and T waves changes are quite commonly seen in the electrocardiogram and cardiac arrhythmias rarely have also been described. Magnesium administration on the other hand causes hypotention, bradycardia, and conduction defects. Magnesium depresses central nervous system, neuromuscular transmission and conductivity of the heart. Magnesium therapy is indicated when clinical features of magnesium deficiency are present in association with low serum or tissue levels.