The Significance of a Wide TsÊ Loop

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Abstract
The TsE loops of 130 normal adults were analyzed with reference to their maximal length and width ratio (L/W ratio). Ninety-seven and one-half per cent (97.5%) of the group has a ratio of 2.66:1 or greater. A TsE loop with a L/W ratio of 2.6:1 or less was considered to be abnormally wide. Among 500 consecutive vectorcardio-grams taken in patients known or suspected to have heart disease, 85 (17%) had an abnormally wide TsE loop. Abnormally wide TsE loops are associated with a wide variety of heart diseases and electrocardio-graphic abnormalities. The incidence of abnormally wide TsE loops is comparatively higher in myocardial infarction and ventricular hypertrophy. In 15 patients, 14 of whom have demonstrable organic heart disease, the vectorcardiograms showed abnormally wide TsE loops although there were no apparent abnormalities in the T waves of their electrocardiograms by current standards. Pathophysiology of the wide TsE loop is discussed and an attempt is made to correlate the widening of TsE loop with the changes expected in its scalar counterpart. It is concluded that the vectorcardiogram may reveal an abnormality of the process of repolarization which is not readily apparent in the scalar electrocardiogram. Analysis of the length to width ratio of the TsE loop may offer useful information.