High-Bandpass Filters in Electrocardiography: Source of Error in the Interpretation of the ST Segment
F Buendía-Fuentes1, M A Arnau-Vives, A Arnau-Vives
1La Fe Research Institute, Avenue Campanar 22, 46009 Valencia, Spain.
Abstract:
Introduction. Artifactual variations in the ST segment may lead to confusion with acute coronary syndromes. Objective. To evaluate how the technical characteristics of the recording mode may distort the ST segment. Material and Method. We made a series of electrocardiograms using different filter configurations in 45 asymptomatic patients. A spectral analysis of the electrocardiograms was made by discrete Fourier transforms, and an accurate recomposition of the ECG signal was obtained from the addition of successive harmonics. Digital high-pass filters of 0.05 and 0.5 Hz were used, and the resulting shapes were compared with the originals. Results. In 42 patients (93%) clinically significant alterations in ST segment level were detected. These changes were only seen in "real time mode" with high-pass filter of 0.5 Hz. Conclusions. Interpretation of the ST segment in "real time mode" should only be carried out using high-pass filters of 0.05 Hz.
Related Concept Videos
Instrumentation Amplifier
To overcome this challenge, an ECG machine utilizes an instrumentation amplifier. This specialized amplifier is...
Bode Plots Construction
Bandpass Sampling
A bandpass signal has a spectrum with a lower frequency limit, denoted as ω1, and an upper frequency limit, denoted as ω2. The spectrum...
Electrocardiogram
Three major waveforms are present in a typical ECG recording: the P wave, the QRS complex, and the T...
Electrocardiogram Fundamentals
An electrocardiogram (ECG) is a diagnostic tool for identifying cardiac conditions such as arrhythmias, conduction abnormalities, and myocardial ischemia.
Definition
An electrocardiogram (ECG) visualizes the heart's electrical activity by tracing the electrical movement associated with each heartbeat on a graph or monitor. As the heart beats, an electrical wave passes through it, correlating with the cardiac cycle events.
Parts of an ECG
An ECG utilizes electrodes on the skin to...
Passive Filters
Low-Pass Filters
Low-pass filters are designed to transmit signals with frequencies lower than the cutoff frequency, ωc, and attenuate those above it. The cutoff frequency...


