title: A combined algorithm for T-wave alternans qualitative detection and quantitative measurement.
abstract: BACKGROUND
  T-wave alternans (TWA) provides a noninvasive and clinically useful marker for the risk of sudden cardiac death (SCD). Current most widely used TWA detection algorithms work in two different domains: time and frequency. The disadvantage of the spectral analytical techniques is that they treat the alternans signal as a stationary wave with a constant amplitude and a phase. They cannot detect non-stationary characteristics of the signal. The temporal domain methods are sensitive to the alignment of the T-waves. In this study, we sought to develop a robust combined algorithm (CA) to assess T-wave alternans, which can qualitatively detect and quantitatively measure TWA in time domain.
  
  
  METHODS
  The T wave sequences were extracted and the total energy of each T wave within the specified time-frequency region was calculated. The rank-sum test was applied to the ranked energy sequences of T waves to detect TWA qualitatively. The ECG containing TWA was quantitatively analyzed with correlation method.
  
  
  RESULTS
  Simulation test result proved a mean sensitivity of 91.2% in detecting TWA, and for the SNR not less than 30 dB, the accuracy rate of detection achieved 100%. The clinical data experiment showed that the results from this method vs. spectral method had the correlation coefficients of 0.96.
  
  
  CONCLUSIONS
  A novel TWA analysis algorithm utilizing the wavelet transform and correlation technique is presented in this paper. TWAs are not only correctly detected qualitatively in frequency domain by energy value of T waves, but the alternans frequency and amplitude in temporal domain are measured quantitatively.
authors: School of Information Engineering, Guangdong University of Technology, Guangzhou, 510006, China. xkwan@gdut.edu.cn
authors: XiangKui
authors: X
authors: Wan
authors: Kanghui
authors: K
authors: Yan
authors: Dehan
authors: D
authors: Luo
authors: Yanjun
authors: Y
authors: Zeng
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D004562:Electrocardiography / Q000379:methods*; D006801:Humans; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D058067:Wavelet Analysis