Dynamic changes of the TU complex in the electrocardiogram

The dynamicity of the repolarization process is reflected in the beat-to-beat variation of the TU complex. In short term (≤5 minutes) recordings this variability is measured on a beat by beat basis. The recordings were obtained from 86 healthy subjects and 13 patients with the long QT syndrome. No effect of preceding RR on T or U amplitude could be demonstrated, although these amplitudes show a substantial intraindividual variation. Peak T and U do show a (weak) correlation. Patients with the long QT syndrome have an instability of the repolarization process which is expressed in substantial variation in QT duration and the appearance of TU wavelets well beyond the classical end of T wave.