EXTRA COPY- ECG Blog #52i7 — What’s Going On? — EXTRA COPY

The ECG in Figure-1 — was obtained from an older man with CP (Chest Pain).

QUESTION: 

• Should the cath lab be activated?

Figure-1: The initial ECG in today's case.

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Figure-2: I've labeled today's initial ECG.

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Figure-3: Comparison of today's 2 tracings.

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Figure-4: ECG from My Comment in the September 15, 2023 post in Dr. Smith's ECG Blog.

KEY: Why 2 artifacts for each beat with PTA!

An arterial pulse tapping artifact can appear to have 2 separate deflections per heartbeat because the mechanical motion of the artery impacts the ECG electrode twice during the cardiac cycle — typically during systole (contraction) and diastole (relaxation) — or as a result of a sharp movement that creates an oscillatory, biphasic signal. (The artery, when hitting a nearby electrode can create a sharp movement when it expands (systole) — and another artifact when it relaxes (diastole).

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ECG Blog #201 — Reviews the "Culprit Lead" - Roland article!

https://ecg-interpretation.blogspot.com/2021/03/ecg-blog-201-ecg-mp-18-should-cath-lab.html

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PEARL #2: The distribution of the bizarre ST-T wave deflections precisely follows the location and relative amount of amplitude distortion predicted by Einthoven’s Triangle.

• The bizarre ST elevation is approximately equal in 2 of the limb leads (ie, in leads I and II) — and, not seen at all in the 3rd limb lead (ie, no artifact at all is seen in lead III). By Einthoven’s Triangle (See the picture below for today’s ECG Media Pearl — which shows Einthoven’s Triangle in the righthand corner) — the finding of equal ST segment amplitude artifact in Lead I and Lead II, localizes the "culprit" extremity to the RA ( = Right Arm) electrode.
• The absence of any artifact at all in lead III is consistent with this — because, derivation of the standard bipolar limb lead III is determined by the electrical difference between the LL ( = Left Leg) and LA ( = Left Arm) electrodes, which will not be affected if the source of the artifact is the right arm.
• As I discuss in detail in my MP-18 Audio Pearl below — the finding of maximal amplitude artifact in unipolar lead aVR confirms that the right arm is the “culprit” extremity. 

  

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ECG Media PEARL #18 (7:45 minutes Audio) — On recognizing Artifact — and — using Einthoven’s Triangle to determine within seconds the “culprit” extremity causing the Artifact on your ECG.

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NOTE: I reproduce below in Figures 4, 5 and 6 — the 3-page article by Rowlands and Moore (J. Electrocardiology 40: 475-477, 2007) — which is the BEST review I’ve seen on the physiology explaining the relative size of artifact amplitude deflections when the cause of the artifact is a single extremity. These principles are illustrated by the colored deflections in Figure-3:

• As noted by the equations on page 477 in the Rowlands and Moore article: i) The amplitude of the artifact is maximal in the unipolar augmented electrode of the “culprit” extremity — which is lead aVR in Figure-3 (RED outline of the inverted T wave in this lead); and, ii) The amplitude of the artifact in the other 2 augmented leads (ie, leads aVL and aVF) is about 1/2 the amplitude of the artifact in lead aVR (GREEN outline of the sharply angled ST-T waves in leads aVL and aVF).
• Similarly — the amplitude of the artifact deflections in the 6 unipolar chest leads in Figure-3 is also significantly reduced from the maximal amplitude seen in leads I, II and aVR (GREEN outline of the sharply angled ST-T waves in each of the 6 chest leads).

 

PEARL #3: A final important clue to artifact as the cause of the bizarre ST-T wave deflections we see in ECG #1 — is provided in the long lead II rhythm strip at the bottom of the tracing!

• Did YOU notice how the artifact comes and goes in this long lead II rhythm strip? Thus, we see maximal artifact in beats #2, 3, 9, 10 and 15 in this long lead II rhythm strip (including that baseline elevation distortion that begins just before the QRS complex of these beats — and which gives false impression of a spiked Helmet Sign).
• In contrast — there is no artifactual ST elevation at all in beats #5, 6, 12, 13 and 17 — and an intermediate amount of artifact distortion in the remaining beats. This changing amount of artifact from one-beat-to-the-next would be consistent with the RA electrode making only intermittent contact with the pulsating artery. I can not think of a physiologic reason other than artifact to explain this beat-to-beat variation in ST-T wave appearance.

 

BOTTOM LINE: You will see artifact frequently in real-life practice. With a little practice, you can immediately KNOW with 100% certainty that the bizarre deflections on a tracing like this one are the result of artifact, and are related to arterial pulsations in one of the extremities. 

• Nothing else shows fixed relation to the QRS complex in the mathematical relationships described above, in which there is equal maximal artifact deflection in 2 of the 3 limb leads (with no artifact at all in the 3rd limb lead) — in which maximal artifact in the unipolar augmented lead will be seen in the extremity electrode that shares the 2 limb leads that show maximal artifact (as according to Einthoven’s Triangle).

 

Figure-4: Page 475 from the Rowlands and Moore article referenced above (See text).

 

Figure-5: Page 476 from the Rowlands and Moore article referenced above (See text).

 

Figure-6: Page 477 from the Rowlands and Moore article referenced above (See text).

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From the 1/17/2023 post in SSmith Blog

https://drsmithsecgblog.com/a-60-year-old-with-chest-pain-2/

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KEY Point: As emphasized by Samaniego et al (Emerg Med J 20: 356-357, 2003) — there are 2 main sources of artifact — which are “physiologic” vs “non-physiologic” sources:

• Non-Physiologic Artifact Sources — include 60 hertz cycle interference (from AC current devices in the area) — and/or cable or electrode malfunction (ie, loose or broken wire, loose electrode lead connection, etc.).
• Physiologic Artifact Sources — include patient movement and/or voluntary or involuntary muscular activity (ie, tremor, shivering, scratching, coughing, hiccups, distressed breathing, etc.).

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From the 9/15/2023 post in SSmith Blog

https://drsmithsecgblog.com/a-60-year-old-diabetic-with-chest-pain/

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The 1st time that I saw APTA (Arterial Pulse Tap Artifact) — I did not know what it was. Since then (as we have shown on already many cases of Dr. Smith’s ECG Blog) — this is actually a surprisingly common phenomenon that all-too-often goes unrecognized (as per the unnecessary cardiac catheterization that was done in today’s case).

• As per Dr. Smith — I review in detail the mathematical relationships seen when there is APTA in one of the extremities in My Comment in the January 17, 2023 post of Dr. Smith’s ECG Blog.
• Awareness of the mathematical relationships discussed in this Jan. 17, 2023 post — allows you within seconds to recognize with certainty that the unusual deflections in the ECG in front of you is the result of APTA. This is wonderfully illustrated in today’s case.

Take another LOOK at today’s ECG (which I’ve reproduced and labeled in Figure-1):

Figure-4: ECG from My Comment in the September 15, 2023 post in Dr. Smith's ECG Blog.

How to Recognize APTA within SECONDS!

As per Dr. Smith — You should suspect APTA in today’s ECG immediately on seeing that despite unusual (if not frankly bizarre) deflections in multiple leads — one of the 3 standard limb leads (ie, leads I,II,III) looks normal — as lead I does in Figure-1 (within the RED rectangle).

• As per my discussion in the January 17, 2023 post, when there is APTA — maximal artifact will be seen in the other 2 standard limb leads ( = leads II and III) — as well as in that augmented lead that is common to both of these maximal artifactual limb leads (in this case lead aVF — with these 3 leads showing maximal artifact being within the BLUE rectangles).
• NOTE: It is that augmented lead that shows maximal artifact — that identifies the “culprit“ extremity (ie, the Left Foot in today’s case).
• The other 2 augmented leads ( = leads aVR and aVL — within the GREEN rectangles) — show approximately half the amount of artifact, compared to maximal artifact leads II,III,aVF.
• Final confirmation that the only thing that can produce these mathematical relationships is APTA — is forthcoming from seeing approximately 1/3 the amount of artifact in each of the chest leads (within the YELLOW rectangles).
• In Conclusion: It literally took me no more than seconds to recognize APTA in today’s tracing because: i) I saw a normal-looking lead I — despite bizarre deflections elsewhere; — ii) With maximal artifact in leads II,III,aVF — and about half that artifact amount in aVR,aVL; — and, iii) A lesser amount of artifact in each of the chest leads. 

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Dear sir, please forgive me for sending two EKG at the same time. Ist EKG ( Top one) is of a 60 years old diabetic gentleman with chest pain. Some of my colleagues thought about " Spike Helmet " sign involving inferior leads. But because the Lead 1 was normal, the thought of artifacts came to my mind. So i repeated the EKG. Repeat EKG is the 2nd EKG here ( Bottom one). It's within normal limit. So 1st EKG had artifacts. Can you please tell me the clues to dete ct artifacts (vs Spike Helmet) from 1st EKG.

MY REPLY:

Hi. This is PTA = "Pulse-Tap Artifact". YOU correctly told me how it is detected — because despite marked deflections, there is a NORMAL lead = lead I !!!

You can see LOTS of examples of artifact (and many PTA cases). Simply click on this tab in the top menu on ANY page in my ECG Blog! See my ECG Blog #201 for full details! 

With your permission — I'd like to use this case for an ECG Blog. I'll be glad to acknowledge you — and I will let you know when the case is  published. It will be a while, as I have a bunch of others to go before, but I'll let you know. Let me know if you still have questions after reviewing ECG Blog #201 ! — :)

P.S.: GOOD question! As I take another look — I see 2 artifact deflections for each R-R interval — and that is confusing, because typically there should only be 1 artifact deflection that occurs with a fixed relation to the QRS ... I am not sure why there is the 2nd deflection ... But as per the attached Einthoven Triangle diagram — it should be the LL electrode that is producing the artifact (because leads II and III both use the LL electrode — but lead I does is not affected). I'll have to look up to see if there might be a reason for why we are getting 2 artifact deflections! But we KNOW this is artifact because lead I is normal — and because it all went away with the repat ECG — :)

NOTE: Look what I found! So the arterial pulse can have 2 deflections for each R-R interval! I've seen a good 20 or so cases of this — and NONE of the others had 2 deflections for each R-R interval. So we all learn something new each day !!! — :)

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Acknowledgment: My appreciation to Bashiruddin Sayeem (from Chittagong, Bangladesh) for the case and this tracing.

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Related ECG Blog Posts to Today’s Case:

• ECG Blog #205 — Reviews my Systematic Approach to 12-lead ECG Interpretation.
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ADDENDUM (4/XXX/2026):

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