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August 1965

T-P Phenomenon: An Electrocardiographic Clue to Unsuspected Alkalosis

Arch Intern Med. 1965;116(2):220-227. doi:10.1001/archinte.1965.03870020060013

IN THE COURSE of examining the charts of many alcoholic patients, an unusual electrocardiographic pattern was frequently observed which had two main features: (1) sinus tachycardia, and (2) relative prolongation of the QT interval (QTc), which in most cases was actually due to relative prolongation of the ST segment. Thus, the delayed T wave is closely followed by the next P wave, or the P wave may even begin on the downstroke of a T wave (Fig 1), and since this double peak strikes the eye at first glance it has been called T-P approximation or simply T-P. These changes which are illustrated best in leads II, III, AVF, and left precordial leads, have been found to be a reliable indicator of metabolic, respiratory, or mixed alkalosis. Since the electrocardiogram is usually obtained early in the course of a diagnostic survey, it has been helpful in directing attention to