The Tp-e interval was determined as the distance from the peak of T wave to the descending part of the T wave and the junction of the isoelectric line
. The Tp-e dispersion was calculated as the difference between the maximum and minimum Tp-e intervals.
The beginning of the P waves was defined as a positive deflection from the isoelectric line
and the end as the point when the positive deflection return to the isoelectric line
The QT interval was defined as between the beginning of QRS complex and the point where T waves descend onto the TP isoelectric line
. When a U wave interrupted the T wave before returning to baseline, the QT interval was measured to the nadir of the curve between the T and U waves (20, 22).
QRS duration was defined as the maximum QRS duration in any lead from the first to the final sharp vector crossing the isoelectric line
. QT interval was measured from the lead II using calipers.
QT interval was measured with the manual technique, as the time in milliseconds (msec) between the first deflection of the QRS complex and the point of return of the T wave to the isoelectric line
. We averaged three consecutive complexes in each lead.
The onset of the P wave was defined as the junction between the isoelectric line
and the beginning of the P wave deflection.