Quantitative analysis of the electrocardiographic pattern of hypopotassemia.

LLECTROCARDIOGRAMS of patients with low concentrations of extracellular potassium frequently show characteristic abnormalities that disappear after administration of potassium salts.1' 2 Regression of the electrocardiographic pattern of hypopotassemia during administration of potassium is characterized by a gradual increase of T-wave amplitude, decrease of U-wave amplitude, and diminution of S-T segment depression in the standard limb and precordial leads without any change in Q-T or other components of the Q-U interval.' This sequence of regression suggests that the converse, the evolution of the hypopotassemia pattern, consists of a progressive decrease of T-wave amplitude, increase of U-wave amplitude, and S-T segment depression in the standard limb and precordial leads. Accordingly, a schematic construction of 5 patterns, representing 5 stages in the evolution of the electrocardiogram in hypopotassemia, has been made.' At that time no attempt was made to analyze the electrocardiographic signs of hypopotassemia in a quantitative manner or to correlate these signs with the concentrations of extracellular potassium.