Saturday, April 17, 2021

Blog #215 (ECG-MP-32) — At Least 4 Notable Findings


The ECG shown in Figure-1 was obtained from a 60-ish year old man who presented with new-onset chest pain.

  • HOW would you interpret this ECG?
  • HINT: There are at least 4 remarkable findings that should be noted ...

 

Figure-1: ECG obtained from a 60-ish year old man with new-onset chest pain (See text).


 

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NOTE #2: Some readers may prefer at this point to listen to the 7:30 minute ECG Audio PEARL before reading My Thoughts regarding the ECG in Figure-1. Feel free at any time to review to My Thoughts on this tracing (that appear below ECG MP-29).

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Today’s ECG Media PEARL #32 (7:30 minutes Audio) — reviews the Cabrera ECG Format — and doing ECGs at a recording speed of 50 mm/second.

 

 

The First 2 Findings that should be Noted:

Depending on where you live and work — the ECG in Figure-1 may have appeared unusual. The first 2 findings that should be noted relate to technical aspects of the ECG format used.

  • The recording speed for each of the leads in the 12-lead tracing was 50 mm/second — or twice as fast as the standard (25 mm/second) recording speed used in the United States, and throughout much of the world. Germany, Sweden, and some other countries favor the faster 50 mm/second speed. 
  • DID YOU NOTICE the notation of “50 mm/sec” that appeared in the upper left of the 12-lead tracing in Figure-1(enclosed within the RED rectangle in Figure-2).
  • The other technical finding that should be noted in Figure-1 — is the difference in limb lead sequencing (compared to the standard lead sequencing format used in the United States, and throughout much of the world). The ECG in Figure-1 was recorded in Germany — and it was recorded using the Cabrera Lead Format (Figure-2).

 

Figure-2: I’ve labeled the technical findings from Figure-1 that should be noted. These are: i) A recording speed of 50 mm/second for leads in the 12-lead tracing (within the RED rectangle in the upper left corner); and, ii) The Cabrera Format for limb lead sequencing (See text).


 



Editorial NOTE:

As an American-trained physician who practiced exclusively in the United States — I had not been exposed to ECG formats other than the standard format used in the United States. This changed for me in 2010 — at which time I began active participation in multiple ECG internet forums, many with a huge international audience. 

  • Even for those clinicians not participating in internet ECG forums — the internet has changed the world. Because of international travel — the chances are that all clinicians at one time or another will encounter in medical records or elsewhere, different ECG formats from countries other than their own.
  • Two of these differences are seen in today’s case: i) Use of the Cabrera Format for limb lead sequencing; andii) Use of a 50 mm/second recording speed.

 

 

The Cabrera Format:

Figure-2 highlights the difference in limb lead sequencing with the Cabrera Format:

  • Instead of beginning the limb lead display with standard lead I — the Cabrera format begins with the highest lateral lead ( = lead aVLcorresponding to an electrical viewpoint perspective obtained from -30 degrees).
  • The right augmented lead is displayed using reversed polarity ( = -aVRcorresponding to an electrical viewpoint perspective obtained from +30 degrees).
  • As suggested by the Axis Insert in Figure-2 — the Cabrera Format offers a more logical display of limb lead sequencing, in that there is a gradual progression of equally spaced (at increments of 30 degrees) limb leads, beginning with lead aVL (at -30 degrees) — and continuing until the most rightward frontal plane lead = lead III (at +120 degrees).
  • In contrast, the standard U.S. format is not sequential — it views the right augmented lead from the remote perspective of the right shoulder — and it uses unequal spacing between neighboring leads.
  • NOTE: The chest leads are unchanged with the Cabrera format.

 

 

Potential Advantages of the Cabrera Format:

The more logical limb lead sequencing used in the Cabrera Format offers a number of potential advantages:

  • It simplifies calculation of the frontal plane axis. One can tell at a glance which of the 6 limb leads manifests the greatest net QRS deflection.
  • The addition of lead -aVR provides a transition lead between lateral and inferior frontal plane location. Having 6 equally spaced frontal plane viewpoints facilitates appreciation of the location and relative amounts of ST segment elevation and reciprocal ST depression in the 6 limb leads, making it easier to assess acute ischemia and/or infarction in these infero-lateral leads.
  • Availability of 6 equally-spaced, sequential limb leads renders comparison of serial tracings easier and more accurate.

 

 

Correcting for the 5mm/second Recording Speed:

The format used in recording the ECG shown in Figure-2 provides a single complex in each of the 12 leads(recorded at 5mm/second) — and a long lead II rhythm strip at the bottom of the tracing (recorded at 25 mm/second).

  • Confession — My brain is “programmed” to interpreting 12-lead ECGs and rhythm strips at the 25 mm/second speed that is standard in the United States. After 4+ decades of interpreting tens of thousands of tracings — there is an instant (automatic) process of “pattern recognition” that I find takes place in my brain, even before I begin systematic interpretation of any given tracing. This process is invalidated by the unfamiliar appearance of wider-than-expected complexes that are produced when a 50 mm/second recording speed is used.


PEARL #1: For readers like me who find themselves “visually challenged” by the sight of an ECG recorded at 50 mm/second speed — I will offer the quick and easy way I’ve developed for “visually correcting” the wider appearance produced by a doubling of recording speed to 50 mm/second.

  • To compensate for a 50 mm/second recording speed — I upload the ECG to Power Point and perform these 2 Steps: i) Reduce the width of the ECG by 50% (ie, from 10 inches to 5 inches); andii) Make SURE that I uncheck the “Keep Proportions” ( = “Lock aspect ratio” box) in the Format Pane under Size options in Power Point before reducing the tracing’s width. Carrying out these 2 Steps narrows the width of the ECG by 50% without affecting the height. 
  • NOTE: When you perform these 2 Steps — each R-R interval on ECG paper will contain twice as many little boxes (which must be considered when assessing rates and interval duration) — but QRS complexes and ST-T waves will now "look normal" to my eye.

 

 

Figure-3 shows the result of applying the procedure I describe in Pearl #1 — with end result of reducing the width of QRST complexes by 50% (but not affecting the height of QRST complexes) for the 12-lead ECG shown in Figure-2.

  • For clarity — I have added an insert of Cabrera limb lead sequencing to the upper left part of Figure-3.
  • Visually — QRST complexes in Figure-3 now “look normal” to my eye (although you’ll note the reduced width of little boxes, compared to the wider small boxes in the long lead II rhythm strip that was recorded at 25 mm/second).

 

Figure-3: Application of the procedure described in Pearl #1 results in a 50% reduction in QRST complex width — with end result that QRST complexes in the 12-lead ECG now “look normal” to my eye (See text).


 

 

Interpreting the 12-Lead ECG in Figure-3:

I now found it much easier to interpret the ECG in today’s case. Assessment of QRST complexes in the 12-lead tracing shown in Figure-3 suggests acute RCA (Right Coronary Artery) Occlusion. I noted the following findings:

  • There is marked ST segment elevation with hyperacute T waves in each of the inferior leads.
  • Inferior lead Q waves are seen. Although small in size — given dramatic ST-T wave changes in each of these leads with Q waves — it is likely that these Q waves reflect ongoing infarction.
  • There is terminal QRS distortion (T-QRS-D) in each of the leads that manifest acute ST-T wave changes. By this, I mean that none of the 4 inferior leads with ST elevation have either J-point notching or an S wave. Although usually reported as a finding supportive of acute infarction when seen in anterior leads — the impressive T-QRS-D seen in Figure-3 is clearly an additional manifestation of ongoing acute RCA occlusion.
  • High lateral leads I and aVL show marked reciprocal ST depression.
  • PEARL #2: Note how nicely the Cabrera limb lead sequencing seen in Figure-3 displays gradual progression of ST elevation that begins with transitional lead -aVR (at +30 degrees) — and then maximizes in leads IIaVF and III. As expected from the Cabrera limb lead insert in this Figure — maximal ST elevation in leads II, aVF and III is countered by maximal reciprocal ST depression in lead aVL (much more so than the modest ST depression seen in lead I)Cabrera sequencing localizes the vector of maximal ST elevation “rightward” (ie, to about +90 degrees) — which supports our suspicion of the RCA (rather than the Left Circumflex) as the “culprit” artery.
  • In addition to acute inferior infarction — maximal ST depression in leads V2V3 and V4 strongly suggests associated acute posterior MI. Presumption of posterior MI is supported by the finding of taller-than-expected anterior R waves (with a dominant R wave already seen by lead V3).
  • NOTE: ST depression extends across the entire precordium. How much of this ST depression that extends to leads V5 and V6 is a result of extensive posterior MI — vs lateral ischemia — vs LV “strain” is uncertain from this single tracing (NOTEAlthough subtle due to overlap of QRS complexes — R wave amplitude in lead V5 is very large, therefore consistent with LVH).
  • In Addition — there is terminal T wave positivity in leads V2-thru-V5. This is one more finding consistent with acute ongoing/evolving infarction.
  • Finally — there are small and narrow q waves in leads V5 and V6. These are of uncertain significance.

 

 

Interpreting the Long Lead II Rhythm Strip:

For facility of discussion — I intentionally deferred assessment of the rhythm in today’s case until last (Figure-4).

  • Unfortunately — the tracing in today’s case is curved, and therefore somewhat distorted. That said — accurate interpretation of the rhythm in Figure-4 is clearly possible.
  • Note that the recording speed for the long lead II rhythm strip is 25 mm/second — so no adjustment in tracing width was made.
  • The QRS complex is narrow — therefore the rhythm originates within the conduction system.
  • Although curvature of the long lead II rhythm strip makes precise measurement and comparison of intervals problematic — I believe the ventricular rhythm is regular (or at least, almost regular) — with an R-R interval of ~6 large boxes, corresponding to a ventricular rate of ~50/minute.
  • RED arrows in the long lead II rhythm strip highlight sinus P waves that we know are present.
  • I strongly suspect additional P waves are present under the YELLOW arrows because: i) Given how regular the RED arrows seem to be — we would logically expect P waves to also be present under the YELLOW arrows (ie, there would have to be a highly unusual form of SA block if you didn’t postulate regular sinus P waves continuing throughout the tracing); andii) I believe there is a slight deformity under each of the YELLOW arrows, corresponding to partially hidden P waves.
  • Note that none of the PR intervals repeat in this 9-beat rhythm strip. This suggests there is complete AV dissociation. But despite the slow ventricular rate (ie, of ~50/minute) — and despite P waves having more than adequate opportunity to conduct, yet failing to do so (ie, P waves occur at virtually all points in the cardiac cycle) — there is no indication that any of the P waves conduct. Therefore — there is complete AV block.

 

Figure-4: I’ve labeled P waves in today’s case with colored arrows (See text).


 


 

Putting It All Together:

In summary — the notable findings for the ECG in today’s case include the following:

  • Use of the Cabrera Format.
  • A recording speed of 50 mm/second for the 12-lead ECG.
  • Strong suggestion of acute RCA occlusion in this 60-ish year old man with new-onset chest pain — with an ongoing, acute infero-postero STEMI.
  • Complete AV Block — with an AV nodal escape rhythm at ~50/minute.
  • LVH and strain and/or ischemia.

 

 

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Acknowledgment: My appreciation to Tim Hellmann (from W├Ârth am Rhein, Germany) for the case and this tracing.

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REFERENCES: 

  • ECG Blog #114 — Reviews another case using the Cabrera format (from Romania) — and explores a bit more potential advantages of this more logical anatomical sequencing.
  • The September 26, 2018 post in Dr. Smith’s ECG Blog (Please scroll down to the BOTTOM of the page for My Comment regarding this interesting ECG submitted from Sweden).
  • The October 26, 2020 post by Dr. Pendell Meyers, in Dr. Smith’s ECG Blog (Please scroll down to the BOTTOM of the page for My Comment regarding this fascinating ECG case of dynamic shark fin” morphology, submitted from Norway).
  • The November 14, 2019 post in Dr. Smith’s ECG Blog (Please scroll down to the BOTTOM of the page for My Comment and illustration of the phenomenon of T-QRS-D = Terminal QRS Distortion).






Wednesday, April 14, 2021

ECG Blog #214 (ECG MP-31) — 12 Leads are Better than One


The rhythm strips in Figure-1 were obtained from 2 different patients. Both patients were hemodynamically stable at the time these rhythm strips were recorded.

 

WHICH statements are true? (There may be more than 1 correct answer!)

  • A) Tracing A — The rhythm is Mobitz I.
  • B) Tracing A — The rhythm is sinus with PACs (atrial trigeminy).
  • C) Tracing B — This is an SVT (SupraVentricular Tachycardia).
  • D) Tracing B — This might be VT (Ventricular Tachycardia).
  • E) We need more information ... IF so — WHY?

 

Figure-1: Rhythm strips obtained from 2 different patients. WHAT do they show?


 

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NOTE #1: Some readers may prefer at this point to listen to the 5:30 minute ECG Audio PEARL beforereading My Thoughts regarding the ECG in Figure-1. Feel free at any time to review to My Thoughts on this tracing (that appear below ECG MP-31).

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Today’s ECG Media PEARL #31 (5:30 minutes Audio) — WHY do I emphasize the phrase, "12 Leads are Better than One?"

 


 

Looking First at Rhythm A:

The underlying rhythm in Tracing A is sinus — as determined by the presence of upright P waves with fixed PR interval preceding beats #1,2; 4,5; 7,8; 10,11; and 13, in this lead II monitoring lead. The QRS complex of sinus beats is narrow.

  • Every-third-beat occurs earlier-than-expected and looks slightly different. That is — the QRS complex of beats #369 and 12 each have a smaller r wave, and a less deep S wave than do sinus beats. The QRS complex for each of these early beats looks to be narrow and preceded by a premature P wave (BLUE arrows in Figure-2 — compared to the RED arrows that highlight sinus P waves).

 

Figure-2: To Figure-1 — I’ve added RED arrows that show sinus-conducting P waves — and BLUE arrows over what looks to be PACs occurring every-third-beat (See text).




QUESTION: Is there another possible explanation for what we are seeing in Figure-2?

  • HINT #1: Do we really have enough information from Figure-2 to determine IF the QRS complex of each early beat is truly narrow?
  • HINT #2: Look at Figure-3 — in which we have added a simultaneously-recorded lead I rhythm strip. Does the QRS of each early beat still look narrow?


Figure-3: I’ve added a simultaneously-recorded lead I rhythm strip to Figure-2 (See text).




ANSWER: Look at the vertical RED timeline that I’ve added to Figure-3.

  • The QRS complex of every-third-beat in Lead I is actually wide! (ie, beats #3,6,9 and 12).
  • The vertical RED timeline that begins with the onset of the wide QRS complex in lead I shows that the notch in lead II (which looked to be a premature P wave in Figure-2) — is actually the initial part of the QRS complex in simultaneously-recorded lead I. 


12 Leads are BETTER than ONE:

intentionally used Figure-1 as a “trick tracing” to emphasize a number of important points brought about by this case:

  • POINT #1: 12 Leads are Better than One. It is EASY to get fooled when you are not provided with complete information. That said — it is our responsibility as clinicians to reserve making a definitive diagnosis until we have enough information to confidently do so. This often requires more than a single monitoring lead tracing. IF your patient is hemodynamically stable — then by definition, you do have time to obtain additionalmonitoring leads (and ideally, a 12-lead ECG).
  • POINT #2Part of the QRS complex may lie on the baseline. When this happens — the QRS complex may look narrow in one lead — whereas in reality, it is actually quite wide. At other times (as in Figure-3) — what looks like a preceding “P wave”, may actually be the initial part of the QRS complex.
  • POINT #3: Assume that a premature beat is “guilty” (ie, a PVC) until you prove otherwise! Statistically, when the underlying rhythm is sinus — most early-occurring beats that look different and are not clearly preceded by a premature P wave — will be ventricular in etiology. The “onus of proof” always rests with the interpreter to establish that the abnormal-looking beat(s) is(are) aberrantly conducted (and not the other way around). Figure-2 illustrates how you can not “prove” aberrant conduction for beats #3,6,9,12 with the incomplete information provided from a single monitoring lead. 
  • BOTTOM LINE: The rhythm in Tracing A is sinus with ventricular trigeminy (ie, every-third-beat is a PVC). It would be best not to monitor this patient solely in lead II — because doing so would suggest the false impression of atrial trigeminy.

 





Looking Next at Rhythm B:

Take another look at Tracing B (Figure-4) — and at the Questions we posed earlier at the beginning of this case. Keeping in mind the insights gained in our discussion of Tracing A — HOW would you now respond?

 

WHICH statements are true about Tracing B? (There may be more than 1 correct answer!)

  • C) Tracing B — This is an SVT (SupraVentricular Tachycardia).
  • D) Tracing B — This might be VT (Ventricular Tachycardia).
  • E) We need more information ... IF so — WHY?

 

Figure-4: Tracing B was obtained from a patient who was hemodynamically stable. HOW would you interpret this rhythm?


 


 

ANSWER:

  • A single V1 monitoring lead is shown in Figure-4. At first glance — this tracing suggests there is a regularSVT (ie, narrow-complex) rhythm, at a rate just over 150/minute, but without clear sign of sinus P waves.
  • That said — it is impossible to be certain where the QRS complex ends from the single monitoring lead shown in Figure-4 (and it looks as if there may be an extra “shoulder” attached to the end of the QRS complex in lead V1).
  • More monitoring leads are needed. Since this patient is hemodynamically stable — a 12-lead ECG is indicated (Figure-5).

 

Figure-5: The 12-lead ECG from which the lead V1 rhythm strip in Figure-4 was taken.


 

 

Interpretation of Figure-5:

It should be obvious that the rhythm in Figure-5 is VT. The QRS complex is wide — and several ECG findings that are virtually diagnostic of VT are present. These findings include: i) QRS morphology in Figure-5 does not resemble any known form of conduction defect; ii) The QRS complex in a number of leads shows delay in the initial deflection of the QRS (ie, a slow downsloping S wave in leads I, aVL, and V2-thru-V6); iii) There is global negativity of the QRS in all 6 of the limb leads; andiv) There is extreme axis deviation (ie, the QRS in lead I is all negative).

  • In Figure-5 — the QRS complex looks narrow in 2 of the 12 leads (ie, in leads aVR and V1). The QRS looks wide in each of the remaining 10 leads!
  • BOTTOM LINE: Part of the QRS may sometimes lie on the baseline (as it does in leads aVR and V1). When this happens — it could be easy to be misled IF the single lead you are monitoring happens to be the lead in which part of the QRS lies on the baseline (as we saw in Figure-4). Therefore, whenever your patient is hemodynamically stable — 12 Leads will be BETTER than ONE!





Sunday, April 11, 2021

ECG Blog #213 (ECG MP-30) — Aberrant Conduction with AFib?


The lead II rhythm strip shown in Figure-1 was obtained from a hemodynamically stable patient.

  • WHAT is the rhythm? 

 

Figure-1: ECG obtained from a hemodynamically stable patient (See text).


 

 

MY Approach to the Rhythm in Figure-1:

There is a LOT going on in Figure-1. My approach to this rhythm was as follows:

  • I find it easiest whenever there are a number of things “going on” — to look first for an underlying rhythm. To do this — I return to the “Ps, Qs & 3R Approach” that I favor (Reviewed in ECG Blog #185).
  • The most commonly-occurring QRS complex in Figure-1 is an upright narrow R wave — so the beats I focused on to determine the underlying rhythm were beats #1, 2; 5; 10-thru-21; and 23. It is EASIEST to defer assessment of the different-looking beats (ie, beats #3,4 — 6,7,8,9 — and — #22) until after we determine the underlying rhythm!

 

Focusing my attention on beats #1, 2; 5; 10-thru-21; and 23:

  • As alluded to a moment ago — the QRS complex for this most-commonly occurring QRS morphology is narrow (ie, clearly not more than HALF a large box = ≤0.10 second in duration). 
  • NOTE #1: Ideally — we would have a complete 12-lead tracing to assist in assessing QRS duration and morphology. That said — given hemodynamic stability of the patient, and what appears to be a narrow and normal-looking QRS morphology in this lead II, I thought it safe to proceed for the moment on the assumption that the QRS complex of the underlying rhythm was narrow.
  • Normal sinus P waves are absent (ie, there is NO sign of upright P waves in this lead II monitoring lead).
  • There are therefore no sinus P waves that might be Related to neighboring QRS complexes.
  • The rhythm is Rapid — and clearly not Regular. The average R-R interval between the run of 12 consecutivebeats of this most commonly-occurring QRS morphology (that is, looking at beats #10-thru-21) — is no more than 2 large boxes in duration — or corresponding to a ventricular rate that is close to 150/minute.

 

Therefore — the underlying rhythm in Figure-1 appears to be AFib with a rapid ventricular response (ie, narrow QRS — no P waves — fast rate close to 150/minute — irregularly irregular for the run of consecutive beats from #10-thru-#21).

  • This leaves us with having to determine the etiology of beats #3, 4 and 22 — and — beats #6-thru-9.

 

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NOTE #2: Some readers may prefer at this point to listen to the 7:40 minute ECG Audio PEARL before reading My Thoughts regarding other aspects of the rhythm in Figure-1. Feel free at any time to review my final thoughts on this rhythm (that appear below ECG MP-30).

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Today’s ECG Media PEARL #30 (7:40 minutes Audio) — HOW to distinguish between Aberrant Conduction vs Ventricular Ectopy — when the underlying rhythm is AFib?

  • NOTE #3: For review of the Ashman Phenomenon which is mentioned in this Audio Pearl — Please See ECG Blog #70. Use of the Ashman phenomenon with AFib is reviewed in ECG Blog #71.

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BACK to the Rhythm in Today’s Case:

We’ve established that the underlying rhythm is rapid AFib. This leaves us with other QRS morphologies that we need to assess (Figure-2).

  • Morphology #1 = the 3 wide QS (negative) complexes ( = beats #3, 4 and 22).
  • Morphology #2 = the 4 consecutive RS complexes ( = beats #6,7,8,9).


Figure-2: I’ve labeled Figure-1 to facilitate assessment (See text).


MORPHOLOGY #1: I strongly suspect that beats #3, 4 and 22 are PVCs (Premature Ventricular Contractions):

  • The QRS complex for these 3 negative beats looks extremely wide (especially for beats #3 and 22)  and, QRS morphology of these QS complexes is very different compared to the all-positive (R wave) morphology of QRS complexes during the underlying AFib rhythm.
  • PEARL #1: Since the majority of ventricular beats originate from a site in the ventricles that lies outside of the conduction system — these ventricular beats not only manifest a different QRS morphology — but also often manifest a slowing in the slope of the initial QRS deflection. This is because initial conduction arising from ventricular myocardium is slower than conduction of supraventricular impulses, that when the ventricular conduction system is intact, are accelerated after exiting the AV node. We especially see this reduced slope for the initial QRS downstroke deflection of beats #3 and 22 (RED arrows in Figure-2).
  • PEARL #2: As a result of retrograde conduction from ventricular beats — PVCs are often followed by a brief post-ectopic pause, even when the underlying rhythm is AFib. This differs from the usual situation seen with aberrant conduction in AFib — in which the irregular irregularity of the AFib rhythm continues throughout, completely uninfluenced by whether or not there is aberrant conduction. Although no post-ectopic pause is seen after beat #4 in Figure-2 — a post-ectopic pause is clearly seen after beat #22 (PURPLE lines in Figure-2). Note that this brief pause seen between beats #22-23 is the longest pause in this tracing — and that it clearly changes the pattern of the underlying AFib rhythm.



MORPHOLOGY #2: In contrast to beats #3,4,22 — I strongly suspect that beats #67, 8 and 9 represent a run of supraventricular beats with aberrant conduction.

  • The QRS complex for these 4 consecutive beats (with biphasic RS morphology) does not look overly wide (if widened at all, in this single monitoring lead).
  • The underlying irregular irregularity of the AFib rhythm in Figure-2 is not altered at all by the change in morphology of these 4 beats. 
  • There is no post-ectopic pause after beat #9.
  • The initial direction and slope of the R wave upstroke for beats #6-thru-9 is virtually the same as the rapidly rising R wave upstroke for the 16 normally conducted beats in the underlying AFib rhythm (both light and dark BLUE arrows in Figure-2 showing a rapidly-rising R wave of similar slope).
  • There is a reason to explain WHY beats #6-thru-9 might conduct with aberrancy — namely, that the shortestcoupling interval in this tracing is seen before the first different-looking beat (ie, the shortest coupling interval is seen between beats #5-6).


BOTTOM LINE: The underlying rhythm in today’s case is rapid AFib. Three different QRS morphologies are seen in this lead II rhythm strip. Even without additional monitoring leads — this single lead II rhythm strip suggests that beats # 3,4,22 are PVCs — and beats #6,7,8,9 are AFib impulses conducted with aberration

  • Because AFib is the underlying rhythm in this case — this means we have lost the diagnostic feature of identifying a premature P wave (there are no P waves with AFib). As a result — I can not be 100% certain from this single lead rhythm strip of the etiology of the different-looking beats.
  • Use of additional monitoring leads (or obtaining a 12-lead ECG during tachycardia) — could greatly assist in further assessment of this rhythm.
  • Clinically — it probably does not matter if beats #6-thru-9 represent a run of NSVT (Non-Sustained Ventricular Tachycardia) or AFib with aberrant conduction. Regardless, the “theme” of the rhythm in Figure-2 is rapid AFib, with at least some ventricular ectopy. As long as the patient remains stable — management with goal of controlling the rapid rate of this AFib plus correcting potential precipitating factors, may be all that is needed to improve the clinical situation.


 

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Relevant ECG Blog Posts to Today’s Case:

  • ECG Blog #185 — Systematic Approach to Rhythm Interpretation
  • ECG Blog #70 — Reviews the basics of the Ashman phenomenon
  • ECG Blog #71 — Is the Ashman phenomenon accurate in AFib?
  • ECG Blog #211 — Reviews in detail WHY aberrant conduction occurs (and why RBBB aberration is the most common form).
  • ECG Blog #212 — Shows application of the Ashman phenomenon — and of assessment of QRS widening in the setting of underlying fast AFib.