Artefacts and Heart Rhythm Disturbances in HRV

How Can Artefacts Be Distinguished from Rhythm Disturbances? “How to Identify Artefacts and Rhythm Disturbances?”

We frequently receive emails and calls at our office enquiring about why certain measurements show such high error rates. Are these artefacts or cardiac arrhythmias? Therefore, we at Autonom Health would like to clarify the difference in this blog post.

Initial Steps

The measurement has been successfully uploaded to the Autonom Health analysis portal and is ready for analysis. However, at first glance, we notice that the measurement’s error rate is too high.

What now? What does the error rate actually indicate? The error rate represents the portion of the measurement that is unusable. This could be due to artefacts, signal loss, or cardiac arrhythmias.

How do I determine what’s causing the issue? What else needs attention?

First tip: Several example measurements related to this topic can be found in the example account.

Artefacts and How to Identify Them:

What Are Artefacts?

Artefacts are incorrect measurement data that do not originate from the heart but are caused by disruptions during signal recording and/or transmission.

How Can Artefacts Be Identified?

Life Fire Image / Spectrogram: Unphysiologically excessive intensity, density, and height; highly heterogeneous pattern; frequent detections above 0.4 Hz (image above)
Filter Bar: Multiple filtered areas (image above)
Pulse Curve: Highly irregular progression with ‘peaks’ and an unphysiologically large range, potentially displaying a 5-minute range from 40-190 BpM and beyond (image above)
Scatter Plot: In addition to torpedo or comet shapes, linear patterns extending from the lower left edge, corresponding to unphysiologically rapid heart rates exceeding 200 BpM (image bottom left)
Histogram: Often beginning at the x-y axis intersection and extending outwards, generally too broad overall (image bottom centre)
Tachogram: Unphysiological heart rates – particularly too rapid – up to 230 BpM and beyond, with unphysiological variations, e.g., sudden jumps from 80 BpM to over 200 BpM (image bottom right) BpM

How Can Artefacts Be Prevented?

Disruptions primarily stem from signal transmission issues:
The gel in the electrode centres has dried out due to age or improper storage.

Electrodes were carelessly applied, are loose or poorly positioned.
Electrodes adhere poorly due to excessive body hair (Note: chest hair in men! Either shave the skin area or place electrodes several centimetres away).
Body lotion interferes with signal transmission – skin areas should be free from oils (particularly important for women).

Wrinkled, sweaty or displaced electrodes prevent clean signal transmission – change electrodes frequently! Mechanical interference from pulling or jerking of cables or electrodes causes artefacts.

The recorder and cables are not properly connected or may even be inserted incorrectly. The electrodes were placed too far apart, causing excessive cable tension. The device might be faulty. Tip: performing a self-measurement can provide clarity! The fundamental principle is: The more care taken during measurement, the lower the probability of artefacts!

Frequently changing electrodes can often prevent the occurrence of artefacts – particularly in overweight individuals or those who perspire heavily.

Rhythm Disorders and How to Identify Them

What Are Rhythm Disorders?

Rhythm disorders are disturbances in either cardiac impulse formation (e.g., supraventricular or ventricular extrasystoles) or cardiac conduction (e.g., atrioventricular block). Clinically dangerous conditions include very rapid disturbances, which can lead to ventricular flutter and ultimately ventricular fibrillation, and particularly slow ones that can result in cerebral hypoperfusion – ultimately indicating a need for cardiac pacemakers. A special form is known as atrial fibrillation, where impulse formation originates not from the sinus node but from other atrial regions.

How Can Rhythm Disorders Be Identified?

Life Fire / Spectrogram: Excessively intense, dense, and elevated life fire pattern. More homogeneous and ‘aesthetically pleasing’ compared to artefacts (image above)
Filter Bar: Corresponding filtering of the affected areas (image above)
Pulse Curve: Age and activity-appropriate broader aura, without extreme ‘peaks’ as seen in artefacts (image above)
Scatter Plot: Excessive dispersion or ‘archipelagos’ indicating regularly occurring deviations (image bottom left)
Histogram: Overly broad distribution along the x-axis (image bottom centre)
Tachogram: ‘Aesthetic pattern’; regularly recurring deviations within physiological limits, for example, starting from an average HR of 48 BPM, interrupted by an extra beat at 75 BPM, followed by 36 BPM, representing a ‘compensatory pause’ (image bottom right)

What Should Be Done About Rhythm Disorders?

Consultation with an internist/cardiologist is warranted when rhythm disturbances occur frequently, are accompanied by ‘heart flutter’ or other symptoms, when unexplained performance decreases are reported, dizziness or fainting spells occur, or when particularly rapid, salvo-like disturbances or notably slow ones around 30 BPM appear.

The pattern of transient or permanent atrial fibrillation (see example account) should be clear. If the measured individual is unaware of this condition, refer them promptly to a physician for stroke prevention.

For additional queries regarding artefacts and cardiac rhythm disorders, our Professionals and Partners are available both for coaching and directly in the Community.