| abstract |
The alternans pattern of cycle-to-cycle variability in physiologic waveforms is assessed by applying transducers (28) to a subject (24), recording physiologic signals (32), and analyzing the alternans pattern of variation in waveform morphology (34). Preferred embodiments include method and apparatus for measuring and assessing alternans in the presence of physiologic stress, such as exercise, in order to induce or increase the amplitude of the alternans, improvements in signal processing to improve the sensitivity and specificity of the analysis, improvements to provide real-time analysis and feedback to the operator conducting the recording, reduction in the effect of intercycle variability on waveform variability, reduction in the effects of respiration on the measurement, improved determination of the statistical significance of the measurement, handling normal beats such as atrial and ventricular premature beats, choosing of data epochs over which to perform the alternans measurement and using multiple electrodes to improve accuracy of the measurement. |