What equipment is needed to perform electrocardiography (ECG)?

Updated: Mar 11, 2019
  • Author: Tarek Ajam, MD, MS; Chief Editor: Terrence X O'Brien, MD, MS, FACC  more...
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Answer

Answer

The various components of an electrocardiogram (ECG) (ie, P wave, QRS complex, and T wave) have different and distinct amplitudes and frequencies. Devices that record these signals must make use of various signal filtering and amplification algorithms to produce a clinically useful signal while excluding unwanted signals (such as those resulting from skeletal muscle, respiratory variation, and electromagnetic interference from nearby equipment).

Currently, most ECG recording machines are digital (as opposed to the analog devices used previously). The American College of Cardiology (ACC), in conjunction with the American Heart Association (AHA) and the Heart Rhythm Society (HRS), have published guidelines regarding the technical standards for ECG recording equipment. [16]  These machines can autogenerate preliminary findings based on morphology criteria.

In order to compensate for the effect of low-frequency signals, such as those due to chest wall movement with respiration, while also minimizing the effects of extraneous high frequency on the fidelity of the recordings, various filters must be applied to the raw electrical signal. For the current digital systems in use, these low-frequency and high-frequency cutoff values are 0.5 Hz and 150 Hz, respectively, for adult ECG. In pediatric ECG, the high-frequency filter should be increased to 250 Hz. Additional guidelines are given with respect to signal amplification, compression, and storage; these are beyond the scope of this article.


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