UCBM presents the Seminary of Doctor Soumyajyoti MajiSoumyajyoti Maji, Dept. Electronic & Electrical Engineering at Trinity College of Dublin.
It is important to recognize that high fidelity in the reproduction of the ECG waveformIt is important to recognize that high fidelity in the reproduction of the ECG waveformrequires a measurement system that preserves the ECG features and providesamplification selective to the physiological signal while rejecting external interferenceand noise. The most obvious implication is that the presence of a frequency-dependentskin-electrode interface introduces distortion to the signal in its propagation from itssource toInfo the input of the recording amplifier, which may lead to misdiagnosis of seriouscardiac conditions unless the front-end stage is adapted to the source impedance.
Therefore, attention is given to investigating the close relationship between thelow-frequency response of the skin-electrode-amplifier network and the inputimpedance characteristics of electrocardiographs. The transient response of ECGamplifiers is investigated in the light of the IEC 60601 performance standard for ECGrecording equipment. Recent test result on several electrode models suggests that theundershoot limit of 100 ?V and the recovery slope limit of 300 ?V/s in response to a 3mV, 100 ms rectangular pulse are violated when the recommended 10 M? inputimpedance at the input of the recording amplifier is used.
Signal distortions appear in theform of an exaggeration of an S wave and depression in the ST segment, which couldbe misinterpreted clinically as signs of myocardial ischemia or the onset of myocardialinfarction when using a real recorded ECG signal with the recommended 10 M? inputimpedance at the amplifier input. Analysis and test result recommend that an amplifierinput impedance exceeding 3G? and a cut off frequency no higher than 0.05 Hz arenecessary to meet the IEC 60601 performance standard and avoid distortion in the ECGsignal.The need for the revision of theIEC 60601 standards pertainingto electrocardiographyGiovedì.
