ECG Blog #445 — VT or LBBB?

The ECG in Figure-1 was obtained from an 80-year old woman — who presented to the ED (Emergency Department) — with a several hour history of "palpitations" and CP (Chest Pain). She was hemodynamically stable at the time ECG #1 was recorded.

QUESTIONS:

The ECG in Figure-1 was seen by a number of physicians — the majority of whom thought the rhythm was some form of SVT (SupraVentricular Tachycardia) with LBBB (Left Bundle Branch Block) aberration.

• Do YOU Agree with the interpretation of the majority of physicians who said that the rhythm in ECG #1 was SVT with LBBB aberration?
• How certain are you of your answer?
• How would you treat this patient?

Figure-1: The initial ECG in today's case. (To improve visualization — I've digitized the original ECG using PMcardio).

MY Thoughts on Today's CASE:

The ECG in Figure-1 — shows a regular WCT (Wide-Complex Tachycardia) rhythm at a rate just under 150/minute, with no clear sign of sinus P waves.

• Although QRS morphology — is consistent with LBBB conduction in the limb leads of Figure-1 (ie, monophasic, all-upright R wave in lateral leads I and aVL) — QRS morphology is not as expected in the chest leads, because we never see a predominant R wave in lateral lead V6. Instead — a similar rS morphology is seen in all 6 chest leads, in which the initial upright deflection (r wave) is surprisingly wide already by lead V4. 
• NOTE: The deep S waves in leads V1,V2 in ECG #1 suggest the likelihood of underlying LVH. One reason why LBBB conduction in a patient with marked LVH may not evolve to a predominant (if not all positive) R wave by lead V6 — is that leftward and posterior forces of marked LVH with LBBB may delay transition to predominant positivity in the chest leads until more posteriorly oriented chest leads, such as V7 or V8.

MY Impression of ECG #1: As emphasized often in this ECG Blog (See today's ADDENDUM below) — statistical odds that a regular WCT rhythm without clear sign of sinus P waves will turn out to be VT begin at 80% likelihood. 

• The older age of today's patient and somewhat atypical QRS morphology for LBBB conduction — move this statistical likelihood up to ~90%.
• While 90% is not equal to 100% — the message regarding the ECG in Figure-1 is clear: Assume VT until proven otherwise! Treat the patient accordingly.
• PEARL #1: Stated a different way — Rather than having to prove that ECG #1 is VT — We need to prove that this rhythm is not VT. Until we do — Assume VT until proven otherwise (and treat the patient accordingly).

Additional Points regarding ECG #1: 

Is there truly no sign of atrial activity in this initial tracing?

• Although there are small-amplitude undulations in the baseline in today's initial tracing — these undulations are present in all 6 limb leads, whereas "true" atrial activity will generally appear more prominently in some leads compared to others (and true atrial activity should not persist throughout the entire baseline — as we see in leads I, aVR and aVL).
• The undulations that we see in the limb leads of Figure-1 — are not consistent in shape, as I would expect them to be if this truly represented atrial activity.
• Finally — although the rate of almost 150/minute in ECG #1 should suggest the possibility of underlying AFlutter with 2:1 AV conduction — 2:1 atrial activity does not work out! (See Figure-2):

Figure-2: I've added RED lines to Figure-1 to show that 2:1 atrial activity does not work out! (See text).

PEARL #2: The way in which I look for flutter waves is to carefully set my calipers at precisely HALF the R-R interval of the tachycardia (since IF the rhythm is AFlutter — then the atrial rate should be twice the ventricular rate if there is 2:1 AV conduction). 

• My "GO TO" leads that I favor for identifying less obvious atrial activity are leads II, III, aVF; aVR; and V1. IF none of these 5 leads suggest atrial activity — then I’ll survey the remaining 7 leads. That said, AFlutter will almost always provide ready evidence of atrial activity in one or more of my “Go To” leads.
• In Figure-2 — I've placed RED lines above those points in leads II, III and aVR that I thought might possibly indicate underlying atrial activity. But notice that the distance between these RED lines is not constant, as it would need to be IF there was underlying flutter with a precisely regular P-P interval. Therefore — the rhythm in ECG #1 is not AFlutter! (See ECG Blog #287 — if interested in more on ECG recognition of AFlutter).

How Would You Treat this Patient?

As is often emphasized in this ECG Blog — "Sometimes ya just gotta be there!" That said — I'll offer the following thoughts:

• The rhythm in ECG #1 is a regular WCT rhythm at ~150/minute, without clear sign of sinus P waves. As noted above, given the older age of this patient and the somewhat atypical QRS morphology for lbbb conduction — I would estimate statistical likelihood that the rhythm is VT at ~90%. Therefore — Assume VT, and treat accordingly!
• We are told that this patient was "hemodynamically stable" — but, given that this older woman is complaining of chest pain — I would not want to leave this patient in this rhythm (that is probably VT) for an extended period of time before moving to synchronized cardioversion.
• I would not try Adenosine — because the rhythm is most likely ischemic VT, and: i) Although Adenosine may convert some forms of idiopathic VT (ie, in which the patient is a younger adult without underlying heart disease) — Adenosine is unlikely to convert ischemic VT; and, ii) Adenosine is not completely benign (For more on the pros and cons of Adenosine — See the ADDENDUM in ECG Blog #393).
• Depending on your level of comfort in this particular case (ie, "Sometimes ya just gotta be there!" ) — IV Amiodarone might be tried, with the provider being ready to cardiovert at the 1st sign of decompensation.

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The CASE Continues:

The patient spontaneously converted to the repeat ECG that is shown below in Figure-3. This spontaneous conversion occurred before any antiarrhythmic medication was given.

• The patient was placed on a "Rule-Out MI" protocol — but the CP she was having disappeared almost immediately after she spontaneously converted to the rhythm shown in ECG #2.
• IV Amiodarone was started in the hope of preventing recurrence of the WCT that the patient presented with.

QUESTIONS:

• How would YOU interpret the repeat ECG shown in Figure-3?
• Is the rhythm in ECG #2 now sinus?
• Does the ECG in Figure-3 alter your opinion in any way as to what the initial rhythm in Figure-1 was?
• Is the patient having an acute MI?

Figure-3: I have put together the initial ECG — with the repeat ECG obtained after spontaneous conversion. (To improve visualization — I've digitized the original ECG using PMcardio).

ANSWERS:

Looking at ECG #2 — the rate of the rhythm has slowed and the QRS complex has narrowed compared to what it was in ECG #1. That said — Did YOU Notice that no upright P wave is present in lead II of ECG #2? (BLUE arrow in lead II of Figure-4).

• PEARL #3: The lack of a clearly upright P wave in lead II in the presence of upright P waves in leads I and aVL (RED arrow in Figure-4) — is most often due to 1 of 2 causes: i) A low atrial rhythm; — or, ii) A "technical misadventure". 
• The most common type of lead reversal is mixup of the LA (Left Arm) and RA (Right Arm) electrodes. This is not present in ECG #2 because the P wave and QRS complex are both positive in lead I, and the QRS is negative in lead aVR (See ECG Blog #264 — for more on LA-RA reversal).
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• The 2nd most common type of lead reversal in my experience, is mixup of the LA-LL (Left Arm - Left Leg) electrodes (See ECG Blog #375 — for more on LA-LL reversal).
• The "good news" — is that regardless of whether there is a low atrial rhythm in ECG #2 — or, whether the rhythm is sinus, but with LA-LL lead reversal — the patient is no longer in a WCT. Instead — the patient has spontaneously converted to a supraventricular rhythm at a much more controlled heart rate (and without suggestion of acute ST-T wave changes in this repeat ECG).

Figure-4: I've added colored arrows to ECG #4 to highlight the lack of an upright P wave in lead II of the post-conversion tracing.

IF there was LA-LL Reversal — What would ECG #2 Look Like?

Lead placement was not checked after recording the post-conversion tracing — and I was not provided with any more tracings from this case. As a result — We'll never know if the post-conversion tracing represents a low atrial rhythm or sinus rhythm with LA-LL reversal.

• As discussed and illustrated in ECG Blog #375 — LA-LL lead reversal will result in the ECG changes shown in Figure-5.

Figure-5: The effect of LA-LL reversal on an ECG.

Correcting for LA-LL Reversal:

We can correct for the predicted changes of LA-LL lead reversal. Doing so allows us to predict what the post-conversion ECG would have looked like if the reason for the lack of an upright P wave in lead II of ECG #2 was LA-LL reversal.

• I show in ECG #2a (Bottom tracing in Figure-5) — what the post-conversion ECG would have looked like if the reason for lack of an upright P wave in lead II was LA-LL reversal.
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• Note in ECG #2a — that an upright sinus P wave is now seen in lead II (as would be expected if the post-conversion rhythm is sinus).

So — Assuming that there was LA-LL lead reversal in ECG #2 — that we have now "corrected for" in ECG #2a — I show in Figure-6 what comparison of today's initial tracing ( = ECG #1, in which there was the regular WCT rhythm) would look like — compared to the post-conversion tracing corrected for presumed LA-LL lead reversal.

Figure-6: What ECG #2 would have looked like if the reason for the lack of an upright P wave in lead II was LA-LL reversal.

PEARL #4: The reason for me highlighting the likelihood of LA-LL reversal in the post-conversion tracing of today's case — is that we will often not be certain as to the etiology of a regular WCT at the time that we need to begin treatment.

• In such cases — it may only be after return to sinus rhythm, that by comparison of the WCT with the post-conversion tracing, can we retrospectively determine whether the WCT was VT (See ECG Blog #422 and ECG Blog #263).
• In today's case — the corrected post-conversion tracing ( = ECG #2a) shows sinus rhythm and no preexisting bundle branch block. While this does not rule out the possibility of rate-related aberrant conduction — the unusual QRS morphology that I described above still suggests (in my opinion) — a ~90% probability that the regular WCT in ECG #1 was VT.

CASE Conclusion:

Given the rapid rate of the regular WCT rhythm in today's case in this symptomatic older woman — additional evaluation to assist in optimal management was indicated.

• Echo was done — and was found to be unremarkable (with normal LV function). 
• Troponin — was negative for acute infarction. 
• Cardiac cath — showed no significant coronary disease.
• The patient was offered EP (ElectroPhysiologic) study — but she refused, since she "was feeling well". She was discharged from the hospital on Amiodarone.

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Acknowledgment: My appreciation to Jean Max Figueiredo (from Nova Iguaçu, Brazil) for the case and this tracing.

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ADDENDUM (8/29/2024):

• I've reproduced below from ECG Blog #196 — a number of helpful figures and my Audio Pearl on assessment of the regular WCT rhythm.

Figure-7 : My LIST #1 = Causes of a Regular WCT (Wide-Complex Tachycardia) of uncertain Etiology (ie, when there is no clear sign of sinus P waves).

Figure-8: Use of the "3-Simple Rules" for distinction between SVT vs VT.

Figure-9: Use of Lead V1 for assessing QRS morphology during a WCT rhythm.

—  —

ECG Media PEARL #13a (12:20 minutes Audio) — reviews “My Take” on assessing the regular WCT (Wide-Complex Tachycardia), when sinus P waves are absent — with tips for distinguishing between VT vs SVT with either preexisting BBB or aberrant conduction.

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Additional Relevant ECG Blog Posts to Today’s Case:

• ECG Blog #185 — Reviews my System for Rhythm Interpretation, using the Ps, Qs & 3R Approach.
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• ECG Blog #210 — Reviews the Every-Other-Beat (or Every-Third-Beat) Method for estimation of fast heart rates — and discusses another case of a regular WCT rhythm. 
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• ECG Blog #220 — Review of the approach to the regular WCT ( = Wide-Complex Tachycardia).
• e Regular WCT (Wide-Complex Tachycardia).
• ECG Blog #196 — Reviews another Case with a regular WCT rhythm.
• ECG Blog #263 and Blog #283 — Blog #361 — and Blog #384 — More WCT Rhythms ...
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• ECG Blog #197 — Reviews the concept of Idiopathic VT, of which Fascicular VT is one of the 2 most common types. 
• ECG Blog #346 — Reviews a case of LVOT VT (a less common idiopathic form of VT).
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• ECG Blog #204 — Reviews the ECG diagnosis of the Bundle Branch Blocks (RBBB/LBBB/IVCD). 
• ECG Blog #203 — Reviews ECG diagnosis of Axis and the Hemiblocks. For review of QRS morphology with the Bifascicular Blocks (RBBB/LAHB; RBBB/LPHB) — See the Video Pearl in this blog post.
• ECG Blog #211 — WHY does Aberrant Conduction occur?
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• ECG Blog #301 — Reviews a WCT that is SupraVentricular! (with LOTS on Aberrant Conduction).
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• ECG Blog #323 — Review of Fascicular VT.
• ECG Blog #38 and Blog #85 — Review of Fascicular VT.
• ECG Blog #278 — Another case of a regular WCT rhythm in a younger adult.
• ECG Blog #35 — Review of RVOT VT. 
• ECG Blog #42 — Criteria to distinguish VT vs Aberration.
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• ECG Blog #133 and ECG Blog #151— for examples in which AV dissociation confirmed the diagnosis of VT.

• Working through a case of a regular WCT Rhythm in this 80-something woman — See My Comment in the May 5, 2020 post on Dr. Smith’s ECG Blog. 
• Another case of a regular WCT Rhythm in a 60-something woman — See My Comment at the bottom of the page in the April 15, 2020 post on Dr. Smith’s ECG Blog. 
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• Review of the Idiopathic VTs (ie, Fascicular VT; RVOT and LVOT VT) — See My Comment at the bottom of the page in the September 7, 2020 post on Dr. Smith’s ECG Blog.
• Review of a different kind of VT (Pleomorphic VT) — See My Comment in the June 1, 2020 post on Dr. Smith’s ECG Blog.