British heart journal
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British heart journal · Aug 1985
Case ReportsArtefactual ST segment abnormalities due to electrocardiograph design.
Specifications recommended for electrocardiographs omit any reference to phase characteristics and place undue emphasis on an extended amplitude response. This does not, however, ensure faithful reproduction of the electrocardiogram and may result in less effective attenuation of unwanted noise than can be achieved with modern filters. ⋯ Case reports are presented in which distortion produced by commercial equipment impeded diagnosis. Specifications recommended as standard for electrocardiographs should be modified to include phase response and allow greater attenuation of frequencies below 0.5 Hz.