The lead II rhythm strip shown below in Figure-1 was obtained from an older man who was on multiple medications — and, who presented to the hospital with shortness of breath.
QUESTION:
- The concern regarding this rhythm strip was whether this patient was having intermittent episodes of Torsades de Pointes or of PMVT (PolyMorphic Ventricular Tachycardia)?
-USE.png) |
Figure-1: Long lead II rhythm strip — obtained from an older man with acute dyspnea. |
MY Thoughts on the Rhythm in Figure-1:
As emphasized in
ECG Blog #231 — the ECG appearance
during an episode of Torsades and PMVT
looks the same! The difference diagnostically between these 2 arrhythmias — depends on whether or not the QTc is prolonged
prior to the onset of the ventricular tachyarrhythmia.
- The above said — neither Torsades nor PMVT is present in Figure-1.
What Do the RED Arrows Show?
The KEY for interpreting today’s rhythm is highlighted by the RED arrows that I have added in Figure-2.
- QUESTION: What do YOU see in Figure-2?
-USE.png) |
Figure-2: What do the RED arrows represent? |
ANSWER:
The RED arrows in Figure-2 — represent normally conducted (ie, narrow) supraventricular complexes. This is easiest to appreciate when we clearly see 2 narrow QRS complexes in a row (ie, for the narrow QRS complexes highlighted by RED arrows #4,5; 7,8; 10,11; 13,14; 16,17;) — and especially toward the end of this rhythm strip, where we see 3 narrow QRS complexes in a row (ie, for the QRS complexes highlighted by RED arrows #19,20,21 and #22,23,24).
- Now look at RED arrow #2 near the beginning of the tracing. Note that the narrow QRS complex highlighted by this arrow #2 — is immediately preceded by the 1st of a series of very tall, very wide bizarre complexes (A) — and then followed by 5 consecutive bizarre wide complexes (B,C,D,E,F).
- The space between each of these 6 wide, bizarre complexes is no more than 1 large box — which means that the rate of these bizarre complexes (A-thru-F) is ~300/minute!
- Note that the 1st of these wide bizarre complexes occurs immediately before the QRS highlighted by arrow #2 — and that the 2nd of these bizarre complexes occurs immediately after this QRS. This cannot be! If these wide, bizarre complexes were "real" — then A would have prevented this QRS from occurring. Similarly, B could not have occurred, because it is too close to the QRS during the ARP (Absolute Refractory Period). As a result — these wide, bizarre complexes in Figure-2 can not be "real", and must therefore represent Artifact!
PEARL #1: The BEST way to identify artifact — is when you can see the underlying cardiac rhythm continue unaffected through the artifact! This is precisely the situation in Figure-2.
- Although some QRS complexes are easier to identify than others — each of the RED arrows in Figure-2 clearly corresponds to an on-time narrow QRS complex.
- Note that there are 2 PINK arrows in Figure-2. ( = arrows #3 and #12) These correspond to the 2 places where we would expect 2 on-time QRS complexes to occur (ie, It would be extremely unusual for the 22 on-time QRS complexes that we do see in Figure-2 — to suddenly drop 2 beats without altering the underlying regularity of this rhythm).
- Thus, the underlying rhythm in Figure-2 — appears to represent some type of supraventricular rhythm at a rate of ~140/minute, albeit without clear evidence of atrial activity. (Then again, there appears to be too much disturbance of the baseline by artifact to tell if atrial activity might be present, but hidden).
- BOTTOM Line: The presence of an apparent regular supraventricular rhythm throughout the lead II rhythm strip in Figure-2 (albeit with the exception of the 2 PINK arrows) — tells us that these wide, bizarre complexes which manifest an unpredictable variation in morphology, are almost certain to represent artifact.
=============================
The CASE Continues:
In Figure-3 — we see the 12 lead ECG that was recorded simultaneousy with the long lead II rhythm strip seen in Figure-2.
QUESTION:
- Does this 12-lead ECG in Figure-3 clarify our impression of the long lead II rhythm strip?
-USE.png) |
Figure-3: The 12-lead ECG recorded simultaneously with today’s long lead II rhythm strip. (To improve visualization — I've digitized the original ECG using PMcardio). |
ANSWER:
The simultaneously recorded 12-lead ECG in Figure-3 — confirms our impression that the very rapid and wide irregular deflections in the long lead II rhythm strip are artifact.
- Note that some artifact is seen in all leads of this 12-lead tracing. That said — Isn't the relative amount of artifact decidedly less for the 4 leads that appear below the horizontal RED line in Figure-4?
- By PEARL #1 — Isn't it now easier to confirm the regular occurrence of an underlying supraventricular rhythm in leads III, aVF, V3 and V6?
-USE.png) |
Figure-4: Which leads manifest the least artifact? |
Return for a moment to Figure-3.
- Among the 3 standard limb leads (ie, leads I,II,III ) — Isn't the relative amplitude of artifact deflections greatest in leads I and II, compared to lead III?
- And among the 3 augmented limb leads (ie, leads aVR, aVL, aVF) — Isn't the relative amplitude of artifact deflections greatest in lead aVR?
- PEARL #2: As discussed in ECG Blog #428 — the quick way to identify which exremity is most responsible for producing artifact when 2 of the standard limb leads manifest similar artifact amplitude (as we see for leads I and II in Figure-3) — is to see which of the augmented leads manifests greatest artifact amplitude. Since this is lead aVR — there is likely to be excessive patient movement of the RA (Right Arm) — which can easily be verified by a quick look at the patient!
PEARL #3: Regarding suspected artifact:
Look at the patient — and he/she will usually tell you the cause. In today’s case — We are told that the patient presented with
shortness of breath.
- A quick look at the patient will probably tell you IF the artifact in Figure-4 is resulting from; i) Shortness of breath — with in addition, excessive movement of the right upper extremity; and/or ii) Some other artifact-producing movement (such as tremor, shivering, seizure activity — and/or loose electrode leads).
- Hopefully the amount of artifact can at least be reduced once the source of this artifact is found and addressed. At that point — Repeat the ECG in the hope of determining if the rapid supraventricular rhythm (about 140/minute in Figure-4) is sinus tachycardia (that should slow down as the patient’s condition improves) — or some other SVT rhythm (such as AVNRT or atrial tachycardia).
=============================
Beyond-the-Core:
Take a final look at today's artifact from another perspective.
- Step Back for a moment — and Look from afar at the long lead II rhythm strip. In Figure-5 — Doesn't it seem like there is a pattern to the baseline variation?
- MY Thought: It would be interesting to look at the patient and validate whether the repetitive upward slanting BLUE lines in Figure-5 correspond to a respiratory rate of ~50/minute (ie, each breath occurring in a bit more than 1 second).
-USE.png) |
Figure-5: Stepping back and looking from afar at the pattern of baseline variation. |
==================================
ADDENDUM — Links to Examples of ARTIFACT
More technical "misadventures" are referenced here — some from this ECG Blog; some from Dr. Smith's ECG Blog — some from other sources.
- The January 15, 2024 post — All about ARTIFACT!
- The February 18, 2024 post — About Filters; PTA.
- The May 18, 2024 post — Filters; RA Artifact.
- The June 10, 2024 post — Bizarre = Artifact?
- The September 15, 2023 post — for PTA (Pulse-Tap Artifact).
- 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.
- 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.
- ECG Blog #148 — Artifact simulating VFib.
- ECG Blog #132 — More VT-VFib artifact.
- ECG Blog #139 — Artifact simulating AFlutter.
- ECG Blog #44 — Parkinsonian Tremor vs AFlutter.
- ECG Blog #255 — Left Leg artifact.
- ECG Blog #201 — Should the cath lab be activated?
- ECG Blog #432 — Not PMVT — but ARTIFACT!
- ECG Blog #478 — Artifact simulates Torsades ...