Palpitations while awaiting CABG

Written by Willy Frick

A 57 year old man with was admitted to the hospital with chest pain. He underwent coronary angiography which showed severe multivessel disease, and he agreed to proceed with workup for CABG. Overnight, his cardiac telemetry showed the following:

Telemetry Sample 1

What do you think?

The rhythm terminated before it could be captured on 12-lead. Upon questioning, the patient reported palpitations. The team immediately paged cardiology, concerned for polymorphic ventricular tachycardia. Further review of telemetry showed the following just a few seconds before the above.

Telemetry Sample 2

Does this change how you feel?

Close inspection of telemetry sample 2 shows regularly spaced QRS complexes marching through the entire strip.

Since sinus conducted QRS complexes cannot co-exist together with ventricular tachycardia, this must all be artifact. Returning to telemetry sample 1, we can use the same calipers to identify the underlying QRS amid all the artifact.

Here is another example which also prompted cardiology consultation. The red coloring is because the telemetry software incorrectly identified the artifact as VT. See if you can identify the underlying QRS complexes.

Answer shown below:

What about when the underlying rhythm is not regular? Such as atrial fibrillation or sinus rhythm with extrasystoles. Here is an example of that. Again, see if you can find the underlying QRS complexes, including the extrasystoles.

Answer shown below:

This can be even more challenging with atrial fibrillation where the only thing you can rely on is careful morphologic inspection.

Learning points:

• Artifact can be challenging to tell apart from VT, especially on telemetry. If you've ever inspected the application of telemetry electrodes, you can see they often end up in totally bizarre configurations (for example multiple electrodes all closely spaced in one area of the thorax.

• VT cannot co-exist with sinus conducted QRS complexes. If you can identify the latter, the "VT" is artifact.

• Sometimes this type of artifact happens in atrial fibrillation and it can be very challenging. Your only clue might be that the VT just seems a little "off."

• Take advantage of all the telemetry leads. The native QRS may be more obvious in one lead or another.

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MY Comment, by KEN GRAUER, MD (6/15/2024):

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I was not taught about artifact in medical school. Like most clinicians — I learned about artifact "the hard way" = by seeing clinical cases that initially fooled me. But artifact is "alive and well" — and learning to recognize it will amaze many of your colleagues (and may serve to avoid an unnecessary defibrillation or two).

In today's case — I fully acknowledge that I was not certain about the etiology of Tele Sample #1 when I first saw this tracing.

• I immediately thought this tracing looked bizarre!
• The deflections were clearly irregularly irregular — but very fast — yet seemingly "geometric" (straight) and not nearly as wide as I would expect for PMVT (PolyMorphic VT). 
• Obvious artifact was present in the last part of the tracing for the 2 lower leads — yet not so much in the upper lead.
• There seemed to be no ST-T wave.
• AND — This rhythm occurred on overnight telemetry, yet the patient was not dead the next morning.
• 
  
• BOTTOM Line: Although I was not certain — the above impressions strongly suggested to me that this rhythm was not "real". I suspected the answer might be found in additional monitor tracings — and sure enough (as per Dr. Frick) — Tele Sample #2 confirmed the artifact.

KEY Point: As per Dr. Frick: i) Artifact is "alive and well" in 2024. We need to maintain a high index of suspicion when "something doesn't look right"; and, ii) The BEST clue to artifact is being able to find the underlying rhythm undisturbed by the unusual deflections (as is masterfully demonstrated by Dr. Frick in today's case!).

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Links to Examples of ARTIFACT:

What follows below is an expanding list of technical "misadventures" — most from Dr. Smith's ECG Blog — some from other sources (NOTE: As I did not previously keep track of these — there are additional examples of artifact sprinkled through Dr. Smith's ECG Blog that I have not yet included here ... ).

• The June 15, 2024 post ( = Today's case by Dr. Frick) — re Telemetry artifact that simulates PMVT. 
• The May 18, 2024 post — re the effect of baseline artifact.
• The January 15, 2024 post — for an OMI despite lots of artifact!
• The September 15, 2023 post — for PTA (Pulse-Tap Artifact).
• The April 6, 2023 post — excessive baseline artifact misdiagnosed as AFib (instead of sinus rhythm with AV Wenckebach — as in Figure-4 in this post).
• The March 17, 2023 post — for PTA.
• The January 17, 2023 post — for PTA.
• The October 21, 2022 post — for "artifactual VT".
• The November 10, 2020 post — for PTA.
• The October 17, 2020 post — for a 70-year old woman with "Artifactual VT".
• The September 27, 2019 post — for the Rowlands & Moore article with the above-noted formulas for recognizing the “culprit” extremity.
• The September 22, 2019 post — intermittent ST-T wave artifact.
• The August 26, 2019 post — baseline artifact.
• The January 30, 2018 post — for PTA. 
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• Brief review by Tom Bouthillet on some common causes of artifact.
• Additional review of ECG artifacts by Pérez-Riera et al (Ann Noninvasic Electrocardiol 23:e12494, 2018)
• VT Artifact — by Knight et al: NEJM 341:1270-1274, 1999.
• Artifact simulating VFib — CLICK HERE.
• More VT-VFib artifact — CLICK HERE.
• Artifact simulating AFlutter — CLICK HERE.
• Parkinsonian Tremor vs AFlutter — CLICK HERE.
• Left Leg artifact — CLICK HERE.
• Should the cath lab be activated? — CLICK HERE.