Electrocardiographic manifestations of combined hypercalcemia and hypermagnesemia.

Near drowning in the Dead Sea is a potentially lethal accident; the swallowing of the salty water causes acute combined hypercalcemia and hypermagnesemia, and this, rather than aspiration, is considered to be the main pathogenetic fator. The authors reviewed the electrocardiographic data of 37 patients who nearly drowned in the Dead Sea. Common findings in the acute phase included P wave changes, tendency for prolongation of P-R interval, prolongation of QRS complex, infra-His conduction disturbances, tendency for broadening and inversion of T wave, and the appearance of a prominent U wave. Three patients had potentially lethal ventricular tachyarrhythmias. The QaTc interval (beginning of QRS complex to apex of T wave, corrected for heart rate), the expected QaTc calculated from calcium blood level (QaTce), and their difference (DQaTc), were measured or calculated. The QaTc was found within normal limits and did not change during recovery from the Dead Sea water poisoning. The DQaTc correlated significantly with serum magnesium level (p less than 0.001). This correlation signifies that hypermagnesemia normalizes the QaTc interval, which is usually shortened by isolated hypercalcemia. Combined hypercalcemia and hypermagnesemia can be caused by swallowing excessively salty water. The potential cardiac complications require strict monitoring and electrocardiographic follow up study.