Interval representative of transmural dispersion of repolarization in children and young adolescents with congenital long QT syndrome.

Background: It has been shown experimentally that the interval from the nadir of the initial negative T wave to the end of the T wave is representative of transmural dispersion of repolarization (TDR) when complex T waves are present. In the clinical setting, however, the interval representative of TDR in patients with long QT syndrome (LQTS) is a controversial subject.

Methods And Results: Five symptomatic patients (3 boys, 2 girls; 3 LQT1, 2 LQT2) were evaluated by a face immersion test before and after treatment to compare the configuration of the T wave. When the notch disappeared after treatment, the single peak of the T wave after treatment coincided with the nadir of the notch before treatment. When the notch remained the same after treatment as before treatment and when the QTc decreased, the corrected interval from the nadir of the notch to the end of the T wave was for the most part shortened.

Conclusions: The present study showed that the interval representative of the TDR in the clinical surface electrocardiogram can be obtained from the nadir of the notch to the end of the T wave in children and adolescents with LQTS, as was shown in the experimental study.