Components of Q-T and Q-U Intervals of the Electrocardiogram In Normals

¹ From the Division of Experimental Medicine, University of Vermont College of Medicine and the DeGoesbriand Memorial Hospital, Burlington, Vermont

Based on the study of 200 normal men and women, a table is presented which shows the dependence of the intervals between the points at the beginning of QRS, at the instant the T wave reaches one-half of its amplitude, at the apex of T, at the end of T and at the apex of U on the sex and the heart rate. In general, all intervals are shorter in men than in women at the same heart rates, but the interval from QRS to the half-way point of T shows the greatest differences. All intervals become longer with falling heart rate, but the descending branch of the T wave and especially the ascending branch of the U wave show the least dependence on the heart rate. Knowledge of these values is important in the differentiation between T and U waves when these are superimposed on each other or have an abnormal voltage or configuration, as well as between the tall T waves occasionally occurring in normal persons and the peaked T waves seen in hyperpotassemia.