ECG Blog #343 — GI Bleed and a "Funky" ECG

The 12-lead ECG with long lead II rhythm strip in Figure-1 — was obtained from a patient who was admitted for GI bleeding. She had a prior history of AFib and coronary disease. The patient had no cardiac symptoms — and, she was hemodynamically stable at the time this ECG was obtained. 

• How would YOU interpret the ECG in Figure-1?
• What is the rhythm?

Figure-1: 12-lead ECG and long lead II rhythm strip from a woman with a GI bleed. (To improve visualization — I've digitized the original ECG using PMcardio).

MY Initial Thoughts on the ECG in Figure-1:

As always — I favor starting with the long lead rhythm strip before turning my attention to the 12-lead ECG. This approach is especially relevant for today's tracing — since determining the cardiac rhythm is essential for interpreting this tracing!

• A bigeminal rhythm is consistently seen throughout the long lead II rhythm strip shown in Figure-1. That is — we see "group" beating, in which QRS morphology alternates for the 2 beats in each pair.
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• PEARL #1: I've presented a variety of bigeminal rhythms in my ECG Blog (links to many of which I list at the bottom of this page). The etiology of some of these bigeminal rhythms can be deceptive — which is why awareness of the common differential diagnosis may be extremely helpful (Figure-3).

Figure-2: Common causes of a bigeminal rhythm.

A Closer Look at the Rhythm in ECG #1:

I've emphasized my use of the Ps, Qs, 3R Approach to rhythm interpretation (ECG Blog #185). Today's rhythm is one in which the KEY step after recognizing the group beating of a bigeminal rhythm — is to identify P waves.

• RED arrows in Figure-3 highlight P waves that are rapid and regular (at ~135/minute) throughout the entire tracing.

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NOTE: If you had trouble finding the P waves highlighted by RED arrows in Figure-3 — then you probably did not use calipers. The clinical realities are: 

• i) If you do not regularly use calipers for complex rhythms — then you will often miss the diagnosis! 
• ii) Once you get used to using calipers — You will find that it SAVES you a LOT of time (because you can instantly confirm or refute P-to-QRS relationships).

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QUESTIONS:

• Are any of these RED arrow P waves conducting to the ventricles?
• IF so — Which P waves are conducting?

Figure-3: I've highlighted sinus P waves with RED arrows.

Which P Waves are Conducting?

Interpretation of today's tracing is complicated by the fact — that the underlying rhythm is ATach (Atrial Tachycardia) at the rapid rate of ~135/minute.

• Note that the PR interval is constant and normal (ie, ~0.16 second) in front of all odd-numbered beats in Figure-3. As a result — it appears that the P waves in front of beats #1,3,5,7,9,11,13,15,17,19 and 21 are all being conducted to the ventricles.
• In contrast — the PR interval for all P waves in front of even-numbered beats are all too short to be normally conducted. While possible that there is some degree of fusion between supraventricular and ventricular impulses — the fact that the P waves in front of beats #2,4,6,8,10,12,14,16,18,20 and 22 occur so close to the QRS complex of these beats means that these beats have to be originating from below the AV node!
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• PEARL #2: It's impossible to tell from Figure-3 if even-numbered beats do (or do not) manifest some degree of fusion. This is because we never see an even-numbered beat that is not preceded by a P wave. As a result — we can not tell if QRS morphology for even-numbered beats in Figure-3 is the same as the QRS morphology would be for a pure ventricular beat.
• That said — Clinically, it does not matter if there is (or is not) fusion of even-numbered beats — because the fact that the PR interval in front of these beats is so short tells us that these beats have to be at least in part arising from the ventricles! (For more on the ECG diagnosis of Fusion Beats — Please check out ECG Blog #128).

QUESTION:

• Is the QRS complex wide or narrow for conducted beats in today's tracing?
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• HINT: How does Figure-4 help to answer this question?

Figure-4: To facilitate identifying which beats are wide and which are narrow — I've enclosed within RED-YELLOW rectangles simultaneously-recorded beats from each 3-lead grouping.

Is the QRS Wide or Narrow?

The "tricky" part of today's tracing — is that the QRS complex does not look very wide for any of the 22 beats in the long lead II rhythm strip. Fortunately — We can use the simultaneously-recorded leads in the 12-lead ECG (within the RED-YELLOW rectangles in Figure-4) — to facilitate assessment of which beats are wide, and which are narrow.

• Start by looking at simultaneously-recorded leads I,II,III for beat #4. The QRS complex of beat #4 looks to be obviously widened in leads I and III — but not so in lead II, because part of the QRS lies on the baseline in this lead.
• The QRS looks wide in leads aVR,aVL,aVF for beat #10.
• The QRS looks wide in leads V1,V2,V3 for beat #16
• But the QRS does not look wide in leads V4,V5,V6 for beat #20!

Putting It All Together: 

When assessing interval duration (of the PR, QRS or QTc intervals) — one uses the longest interval that can clearly be seen in any of the 12 leads. Therefore, despite the narrow appearance of even-numbered beats in the long lead II rhythm strip — simultaneously-recorded leads confirm that the QRS is wide for all even-numbered beats!

• Note that each of the even-numbered beats in Figure-4 are "premature" (ie, they occur slightly earlier-than-expected).
• QRS morphology for even-numbered beats in the chest leads — is potentially consistent with RBBB-conduction. That said — the qR configuration in lead V1 (ie, with taller left "rabbit ear" in this lead) is atypical. QRS morphology is even more atypical for supraventricular conduction in the limb leads, because the predominantly negative QRS in both leads I and II — with qR pattern in lead III — resembles neither LAHB nor LPHB conduction.
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• BOTTOM Line: I interpreted the rhythm in today's ECG as showing ATach at ~135/minute with ventricular bigeminy (ie, every-other beat a PVC). Note in Figure-2 — that ventricular bigeminy is one of the causes of a bigeminal rhythm.

CASE Conclusion: 

Now that we've interpreted the rhythm in today's case — We need to focus our attention on QRST morphology of the conducted beats in each of the 12 leads (ie, on odd-numbered beats #1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21).

• There is LAD (Left Axis Deviation) — with an all positive QRS in lead I for conducted beats — and predominant negativity in lead aVF for conducted beats. But there is not enough LAD to qualify as LAHB (Left Anterior HemiBlock) — because the QRS of beats #1,3,5 in lead II is more positive than negative (ie, the frontal plane axis is about -15 degrees).
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• There is LVH (ie, the R wave in lead aVL >12 mm — with ST-T wave changes of LV "strain" in high-lateral leads I and aVL).
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• Lead V2 may be malpositioned — as it does not make physiologic sense for the R wave of conducted beats in lead V2 to be taller than the R wave in both leads V1 and V3 — and it does not make physiologic sense for the T wave in V2 to be inverted when it is not inverted in either neighboring lead.
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• Transition (ie, where the R wave becomes taller than the S wave is deep) — is slightly delayed in this ECG (ie, it only occurs between leads V5-to-V6).
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• Finally — There is symmetric T wave inversion in the odd-numbered beats of most chest leads. This may be ischemic (and/or it may be related to the frequent ventricular ectopy).
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• FOLLOW-UP: Unfortunately, I do not know the hospital course of this patient. That said — there does not appear to be any sign of an acute cardiac event on ECG — nor any symptoms of pulmonary embolus. Highest priority for management would therefore entail control of this patient's GI bleed — with optimization of oxygenation, fluid status, and ensuring normal electrolytes. Hopefully — addressing these priorities will control the atrial rate, reduce the ventricular ectopy, and result in improvement of the chest lead T wave inversion. Close follow-up will clearly be needed.

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ADDENDUM (November 8, 2022):

• The Audio PEARL (5:45 minutes) below reviews the concept of Bigeminy.

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Acknowledgment: My appreciation to Abdullah Alhasan @EcgOxford (from Kuwait) for the case and this tracing.

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Related ECG Blog Posts to Today’s Case: 

ECG Blog #185 — Reviews the Ps, Qs and 3R Approach to Systematic Rhythm Interpretation.

ECG Blog #232 — Reviews an example of a bigeminal rhythm.

ECG Blog #312 — Another example of a bigeminal rhythm.

ECG Blog #163 — Reviews a case of "escape-capture" bigeminy, in which SA block might be operative.

ECG Blog #256 — Reviews another case of "escape-capture" bigeminy (in which retrograde conduction from junctional escape results in "capture").

ECG Blog #33 — Reviews a case showing blocked and aberrantly-conducted PACs. 

ECG Blog #66 — Reviews a case showing blocked and aberrantly-conducted PACs. 

ECG Blog #147 — Reviews a case showing blocked PACs. 

ECG Blog #57 — Reviews a case showing atrial bigeminy with blocked PACs.

ECG Blog #128 — Reviews the concept of Fusion Beats.