How trustworthy are ECG monitors? The filter selection dilemma

Abstract

Introduction:

Electrocardiographic monitoring has long been established as a standard for basic anesthetic monitoring by international societies, also being routine in intensive care settings. However, there are some caveats to this technology, and overreliance on the monitors’ results may lead to misdiagnosis. In this article we analyze the influence of filter selection on the final electrocardiographic (ECG) tracing. Though not a new subject, the precise mechanisms involved are usually more familiar to technicians and basic scientists than to physicians, mainly because of a lack of focus on the technical peculiarities of equipment function during medical education.

Materials and Methods:

We performed a Pubmed search for the expressions “ECG filters” and “ECG artifacts”, complementing it with references from the articles deemed most relevant.

Results:

The present article presents the basics of frequency representation of ECG signals, as well as examples of artifacts that can be removed or distortions that can be artificially introduced. Real world examples are used to exemplify these concepts.

Discussion and Conclusions:

Correct filter selection has the potential to provide a neater, clearer tracing, whereas lack of knowledge as to the settings being used may either provoque or mask important changes, namely repolarization abnormalities.