Could we really determine the duration of the T-wave? An answer comes from T-wave triggered signal averaged ECG

We introduced a new, computer-interactive method for determination of the beginning and the end of the T-wave, which is based on T-wave triggered signal-averaged ECG. This method assumes that critical points could be recognized as nadir of the curve, representing time-related changes of the ratio of 23.5-121.6/0-23.5 Hz frequency contents over scanned on-set and off-set regions. The new method was tested in 10 healthy subjects and 20 patients after myocardial infarction. This method allows one to measure the duration of QT and T-wave. For comparisons manual measurements were also obtained. T-wave duration and dispersion assessed semiautomatically on SAECG was longer or similar (respectively) than manually determined ones and weak or no correlations existed between both these methods. Simultaneously, there were good correlations between both methods for QT duration and dispersion, which confirm the accuracy of the T-wave off-set determination.