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G. E. Burch, M.D.
AMA Arch Intern Med. 1954;94(4):509-512. doi:10.1001/archinte.1954.00250040001001.
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EXCELLENT studies * have resulted in one of the most important recent diagnostic developments in electrocardiography, that is, identification of the electrocardiographic pattern of disturbances in electrolyte equilibrium and metabolism. It has been known for many years that ill health of many types can change the T waves, but interest in disturbances in electrolytes has been limited primarily to calcium. The duration of the Q-T interval is known to vary inversely with the ionic concentration of calcium in the plasma, whereas the configuration of the T wave remains unchanged except for duration.9 Changes in duration of the S-T segment and T wave are primarily responsible for changes in duration of the Q-T interval.10 Until recently, the U wave was considered to possess no clinical significance and was purely of physiologic interest. However, studies in animals and in man by Winkler and his associates 1; Nadler, Bellet, and co-workers,2


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