The paper presents the results of investigation on the distortions of the fine structure of the heart biopotentials caused by filtering circuits of medical diagnostic equipment. The method of computer simulation is used. Some programs for simulating different types of filters (Bessel, Chebyshev, Butterworth, and elliptic) are developed using LabView software. The artificially generated electrocardiograms (ECG) and high-resolution signals recorded with the equipment based on high-stable low-noise nanoelectrodes in the band from 0 to 150 Hz are used as test signals. Filters used in the ECG equipment may change the amplitude, wavelength, and displacement of (ECG) intervals. When using lowpass filters, small frequency cutoff value makes the low-amplitude potentials of 5-20 mV virtually invisible on the ECG. The higher the order of the filters, the greater is the distortion regardless of the type of filters. The amplitude ripple of filters in the passband and a nonlinear character of phase response contribute to cardiac signal disturbance equal to the informative low-amplitude of the heart biopotential by the order of magnitude. In some cases, application of diagnostic criteria to the filtered signal can produce erroneous results. The data analysis shows that the amplitude of the signal distortion due to time delays and frequency response for different types of filters range from 2 to 15%, which is comparable to the amplitudes of the ventricular late potential which amount to 2% of the amplitude of the cardiac signal.
|Журнал||European Journal of Physical and Health Education|
|Состояние||Опубликовано - 2014|
ASJC Scopus subject areas
- Physical Therapy, Sports Therapy and Rehabilitation
- Orthopedics and Sports Medicine