Evaluation of the QRS complex on the standard 12-lead electrocardiogram in normal subjects 70 to 79 years of age

T wave amplitudes in normal populations. Variation with ECG lead, sex, and age

Consideration of increased T wave amplitude (tall T waves), either alone or in association with other electrocardiographic (ECG) parameters, may be beneficial for the early detection of acute transmural ischemia, and quantification of the increase might be used in quantifying the ischemic area. The primary purpose of this study was to quantify normal T wave amplitude limits according to ECG lead, sex, and age. One thousand nine hundred thirty-five subjects in two normal populations were analyzed, and the 98th percentile of the positive T wave amplitude for each ECG lead (including -aVR) was considered the upper limit of normal. Normal T wave amplitude was two times greater in the precordial than in the limb leads, and it was approximately 25% greater in men than in women in all leads. There was approximately a 10% decrease in normal T wave amplitude between 18-39- and 40-59-year-old patients and a 15% decrease between 40-59- and 60-79-year-old patients. The upper limit of normal T wave amplitudes identified in this study confirm those developed by Lepeschkin for use as means for each lead when age and sex are not considered. These limits might be incorporated into both normograms and automated ECG analysis systems to determine the presence or absence of tall T waves in patients presenting with symptoms of acute transmural ischemia.

The aging electrocardiogram

With advancing age, widespread histologic changes in the conduction system occur. These changes may alter several features of the aging electrocardiogram, including duration of the PR and QT intervals, orientation of the electrical axis, duration and morphology of the atrial and ventricular complexes, and characteristics of the ventricular repolarization. And although ST segment and T wave abnormalities may be the only clue to acute ischemia, they are nonspecific and associated with a multitude of noncardiac causes. With an awareness of atypical presentations and difficulties in ECG interpretation, emergency physicians may be able to improve the assessment and triage of elderly patients with acute coronary ischemia.