ECG Blog #422 — Was Clubbing an ECG Hint?

I was sent the ECG in Figure-1 — with the following history:

• The patient is a young man in his early 20s — who presents to the ED (Emergency Department) because of SOB (Shortness Of Breath) that had been ongoing for several hours. No chest pain.
• He reports a number of similar previous episodes over the past few years (although apparently has not been formerly evaluated for this).
• Physical exam remarkable for tachypnea (respiratory rate ~30/minute) and cyanosis, with clubbing of extremities.

QUESTIONS:

• In view of the above history — How would YOU interpret the ECG in Figure-1?
• Is the rhythm likely to be VT (Ventricular Tachycardia)?

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

MY Initial Thoughts on Figure-1:

Although technically there is some folding and distortion of this 12-lead tracing — the recording speed is the standard 25 mm/second — and quality of the tracing clearly is sufficient for evaluation.

• There is a regular WCT (Wide-Complex Tachycardia) in Figure-1 — at a rate of ~190/minute, but without clear sign of sinus P waves.
• I thought that some kind of atrial activity might be present — but I was not certain of this. Despite the presence of a slender upright deflection before each P wave in lead I — there was no such upright deflection in lead II (as is needed for the rhythm to be sinus).
• I considered the possibility of 1:1 retrograde P waves (VA conduction) — but I did not know if the slender negative “dip” in the middle of the inferior lead ST-T waves represented a retrograde P wave vs simply being the ST segment alone.
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• PEARL #1: Even if this negative “dip” in the inferior lead ST segments did represent retrograde P waves — this would not be of any assistance for distinguishing between some form of  SVT (SupraVentricular Tachycardia) vs VT — because reentry SVT rhythms and VT may both manifest 1:1 VA retrograde conduction.
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• MY Conclusion Thus Far: The rhythm in Figure-1 represents a regular WCT rhythm at ~190/minute, without clear sign of sinus P waves. This leaves us with the usual differential diagnosis for this rhythm presentation (as per ECG Blog #361) ==> We need to consider i) VT until proven otherwise: ii) SVT with either preexisting BBB or aberrant conduction; — or, iii) Something else (ie, WPW, hyperkalemia, some other toxicity, etc.).

PEARL #2: How Might the History Help?

Statistically — When an older adult with known underlying heart disease presents to the ED in a regular WCT rhythm, but without clear sign of sinus P waves — the odds that the rhythm will turn out to be VT are ~90% even before you look at the ECG. But this is not the situation in today's case — since today's patient is a man in his early 20s.

• Although this young adult age range places today's patient in the group most susceptible to some form of idiopathic VT (See ECG Blog 197) — Strongly against a diagnosis of idiopathic VT are the physical findings of cyanosis and clubbing of the extremities, since these findings strongly suggest some form of underlying cardiopulmonary disease.

PEARL #3: What about QRS Morphology?

As discussed in detail in many of my blog posts that break down the assessment of regular WCT rhythms — QRS morphology may provide invaluable assistance for working through the differential diagnosis (See ECG Blog #42, among many others).

• Although no morphologic criterion is perfect for distinguishing between supraventricular conduction vs VT — the more QRS morphology of a regular WCT rhythm resembles some known form of conduction defect, the greater the chance that the rhythm is of supraventricular etiology. 
• Conversely — the more abnormal-looking QRS morphology during a regular WCT rhythm is (ie, the less it resembles some known form of conduction block) — the greater the chance that the rhythm represents an ischemic form of VT.

Today's case therefore presents the paradox that despite this patient's young age — QRS morphology of his ECG manifests many atypical features. These include: i) Significant fragmentation (ie, multiple leads in Figure-1 showing multiple "extra notching" of the QRS complex); and, ii) Bizarre shape of the QRS complex in lead V1, with a rounded R' deflection instead of a more defined triphasic rsR' configuration (as is most often seen with RBBB-conduction in a younger adult).

• PEARL #4: The combination of longstanding dyspnea episodes in this young adult with cyanosis and extremity clubbing + the above described atypical QRS morphology during his WCT — should suggest some form of significant underlying cardiopulmonary disease. High on my list of possibilities was an expression of CHD (Congenital Heart Disease) in an adult.
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• This still leaves us with the differential diagnosis for the regular WCT rhythm in today’s case between a fascicular VT (given some resemblance to rbbb conduction in the chest leads — with marked right axis deviation in the limb leads) — vs some form of an SVT rhythm, in which the patient’s baseline tracing was rendered markedly abnormal from longstanding CHD.
• MY Hunch: Awareness of the longstanding nature of today’s patient’s symptoms from some presumed form of established CHD — made me suspect that a supraventricular etiology would be more likely, rather than sudden development of fascicular VT. That said, I could not rule out the possibility of fascicular VT on the basis of this single tracing.
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• PEARL #5: Finding a copy of a prior ECG on today's patient could be the most time-efficient way to determine IF the regular WCT rhythm in Figure-1 was of a supraventricular etiology, as I suspected. If this were the case — the patient's baseline ECG during sinus rhythm would most likely manifest a very abnormal QRS morphology (similar to that seen in Figure-1) — as the result of longterm hypoxemia.  

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Today’s CASE Continues:

Medical treatment of the WCT rhythm shown in Figure-1 — was not successful. As a result, synchronized cardioversion was performed — after which the post-cardioversion rhythm shown at the bottom of Figure-2 was obtained.

QUESTIONS:

• How would you interpret this post-cardioversion tracing?
• Why does QRS morphology in ECG #2 change every-other-beat? How does this changing QRS morphology in ECG #2 confirm that the rhythm in ECG #1 is not VT?

Figure-2: Comparison between today’s initial ECG — with the repeat ECG obtained following synchronized cardioversion (See text).

The Post-Conversion Tracing in Figure-2:

Sinus rhythm has been restored in the post-cardioversion tracing, at a rate of ~100/minute — as determined by the presence of huge, upright and pointed P waves with a constant and normal PR interval in front of each of the 17 beats in the long lead II rhythm strip.

• PEARL #6: The fact that sinus P waves with the identical PR interval are seen in front of each beat in ECG #2 — confirms that the post-cardioversion rhythm is of sinus origin. This means that the changing QRS morphology every-other-beat must be the result of some alternating form of conduction defect.
• NOTE: This changing QRS morphology in ECG #2 is more evident in some leads than in others (ie, While not so evident in lateral chest leads V4,5,6 of ECG #2 — the alternating QRS morphology is obvious in leads such as I, III, aVL, V1 and V3).

PEARL #7: As unusual as QRS morphology is during the regular WCT rhythm in today's initial ECG — Compare this QRS morphology (within the dark BLUE rectangles in Figure-3) — to QRS morphology of odd-numbered beats in each of the 12-leads of the post-cardioversion tracing (within the light BLUE rectangles in Figure-3).

• With the exception of minor differences — Isn't QRS morphology during the WCT — and, for odd-numbered beats after conversion to sinus rhythm, virtually the same?
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• KEY Point: This virtually-the-same QRS morphology during and after confirms that the regular WCT in today's initial tracing was not VT. Instead, it tells us that today's patient has an extremely abnormal "baseline" ECG.

Figure-3: Comparison of QRS morphology during the WCT — and for odd-numbered beats after conversion to sinus rhythm (See text).

What Kind of Conduction Defect?

As is often emphasized on this ECG Blog (ie, See ECG Blog #204) — Rapid determination of the type of conduction defect is most easily (and most time-efficiently) determined by assessment of QRS morphology in 3 KEY leads ( = right-sided lead V1 — and left-sided leads I and V6).

• PEARL #8: QRS morphology of odd-numbered beats in the post-cardioversion tracing (ie, within the light BLUE rectangles of ECG #2 in Figure-4) — is consistent with RBBB/LPHB conduction because: i) There is an rSR' complex with taller right rabbit ear in lead V1 — with wide terminal S waves in lateral leads I and V6; and, ii) The S wave in lead I is predominantly negative, with an extremely deep straight component to this S wave (See ECG Blog #203 for review on the rapid ECG diagnosis of the hemiblocks).
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• KEY Point: In contrast to the RBBB/LPHB conduction of odd-numbered beats in ECG #2 — even-numbered beats in Figure-4 show neither RBBB nor LPHB conduction! 

Figure-4: I've labeled KEY findings in today's case.

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Putting It All Together:

We finally have enough information to explain today's fascinating case:

• This young man in his early 20s presented with an episode of acute dyspnea in a regular WCT rhythm at ~190/minute, without clear sign of sinus P waves.
• Definitive ECG diagnosis was not possible on the basis of the single tracing shown in ECG #1. That said — physical exam findings of cyanosis and clubbing, together with the history of longstanding dyspnea episodes suggested more of a chronic problem (presmably the expression of Congenital Heart Disease in an adult) — rather than an isolated episode of VT in a young man.
• In any event — the rhythm in ECG #1 mandated treatment before a definite ECG diagnosis was known. When a trial of medical therapy was unsuccessful — synchronized cardioversion was performed — with resultant conversion to sinus rhythm (as shown in ECG #2).
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• Proof that the unusual QRS morphology during the WCT rhythm was supraventricular — was forthcoming from the finding of nearly identical QRS morphology during the WCT rhythm — with QRS morphology of each odd-numbered beat after conversion to sinus rhythm.
• This suggests that the reason for QRS widening during the initial ECG — was rate-related aberrant conduction (with a pattern of RBBB/LPHB conduction). After conversion to sinus rhythm in ECG #2 — the slower ventricular rate allowed for normal conduction with each even-numbered beat.
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• PEARL #9: That today's patient almost certainly has some form of severe CHD as the cause of his longstanding dyspnea episodes, cyanosis and clubbing — is evident from the exceedingly tall, peaked and pointed P waves (nearly 1 large box tall in lead II — as well as being markedly peaked in many of the chest leads — as seen within the RED ovals in ECG #2). In the context of today's case — these P waves are diagnostic of RAE = P Pulmonale (See ECG Blog #75) and almost certain associated pulmonary hypertension.
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• PEARL #10: Taking another LOOK at the initial ECG in today's case — atrial activity was evident during ECG #1 (in the form of retrograde P waves with a relatively long RP' interval — as highighted by YELLOW arrows in Figure-4). It is because of the marked RAE (Right Atrial Enlargement) that when conducted retrograde, these huge P waves simulated inferior lead T wave inversion during the WCT rhythm. Retrospectively — I interpret this 1:1 retrograde conduction as diagnostic of a reentry SVT rhythm as the etiology of the initial tachycardia. Given the relatively long RP' interval — there is a good chance that this patient has an AP (Accessory Pathway) — and that the type of SVT reentry is AVRT (See ECG Blog #240 — for complete review on distinction between AVNRT vs AVRT depending on retrograde conduction features).

FINAL Thought: The underlying etiology of today's tachyarrhythmia, and this patient's principal problem — appears to be the expression of CHD in an adult.

• As noted by Moodie in his manuscript on Adult Congenital Heart Disease (Tex Heart Inst J: 38(6):705, 2011) — there are now more people over the age of 20 with CHD than under that age!
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• Hopefully today's patient receives full evaluation for his CHD. 

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Acknowledgment: My appreciation to Abdullah Al Mamum (from Dhaka, Bangladesh) for the case and this tracing.

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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 — and ECG Blog #361 — Review of the approach to the regular WCT ( = Wide-Complex Tachycardia).
• ECG Blog #196 — Reviews another Case with a regular WCT rhythm.
• ECG Blog #263 and Blog #283 — 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 #361 — A regular WCT in a middle-aged man.
• ECG Blog #35 — Review of RVOT VT. 
• ECG Blog #42 — Review of criteria for distinguishing VT vs aberrant conduction.
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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.