Temporal stability of the high frequency QRS waveform in normal subjects.
Previous attempts to assess high frequency QRS components relied primarily on counts of QRS notches and slurs. In order to measure high frequency potentials in a more quantitative manner, we adapted a commercially-available microprocessor ECG system equipped with a signal-averaging program to reduce noise and an 80-300 Hz digital band-pass filter. The high frequency QRS output was digitized for measurement of its root-mean-square (RMS) value. Serial high frequency recordings were then obtained in ten normal subjects approximately 100 days apart. Both the morphology and RMS voltage of the high frequency signal were stable over this time period. Furthermore, comparison of inter- and intra- observer variability in making these computer assisted RMS measurements revealed a high degree of reproducibility. This new technique offers a reliable way of quantitatively measuring high frequency QRS potentials and should be useful in assessing serial changes in various pathologic states.
D000200:Action Potentials; D000328:Adult; D003201:Computers; D004562:Electrocardiography / Q000379:methods*; D006321:Heart / Q000502:physiology*; D006801:Humans