Discrete Wavelet Transform-based Baseline Wandering ... - ijabme.org

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INTERNATIONAL JOURNAL OF APPLIED BIOMEDICAL ENGINEERING VOL.3, NO.1 2010 29 Fig.5: Result of DWT decomposition and synthesis of the Y lead at level 10. suggested as a noninvasive indicator of an increased risk for VT [8, 9, 10]. Fig.7: The magnified segments in Figures 4c, 5c, and 6c after baseline wandering removal for X, Y, and Z leads, respectively. Fig.8: The vector magnitude of the patient with myocardial infraction. Fig.6: Result of DWT decomposition and synthesis of the Z lead at level 10. One problem of HRECG recordings is baseline wandering which may be caused by large movement of the chest during breathing and it may make analysis of VLPs inaccurate. In order to accurately detect the VLPs, it is necessary to obtain good quality of the HRECG signals. This study has attempted to investigate any possibility of using the DWT decomposition and reconstruction for removal of baseline wandering to detect VLPs. Baseline wandering is a low-frequency activity in the ECG signals. Its frequency component is usu- ally in the range below 1 Hz and it mainly appears in the approximation A10 of the DWT. Thus, the A10 will be subtracted from the original HRECG signal in the reconstruction process. The approximation A10 would be appropriate for removal of baseline wandering. In conclusion, the DWT-based removal of baseline wandering in the ECG signals was shown to be useful in revealing the VLP activity. It may improve the diagnostic performance of the VLPs detection. References [1] M.B. Simson, Use of signals in the terminal QRS complex to identify patients with ventricular tachycardia after myocardial infraction, Circulation, 64(2), pp. 235-242, 1981 [2] PhysioBank Archive Index http://www.physionet.org/physiobank/database/
30 C. Bunluechokchai and T. Leeudomwong: Discrete Wavelet Transform-based Baseline .... (26-31) Fig.9: Normal ECG signals with baseline wandering of X, Y, and Z leads. Fig.12: ECG signals with baseline wandering from the myocardial infraction patient. Fig.10: The synthesized XYZ leads after baseline wandering removal for X, Y, and Z leads, respectively. Fig.13: The synthesized XYZ leads after baseline wandering removal in Figure 12. Fig.11: subject. The vector magnitude of the control healthy Fig.14: The vector magnitude computed from the synthesized XYZ leads in Figure 13.
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