EXTRA COPY — ECG Blog #531: WCT: What to Do? — EXTRA COPY

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

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for LBBB conduction/morphology

See ECG Blog #204 (video, pdf, etc)

https://ecg-interpretation.blogspot.com/2021/03/ecg-blog-204-ecg-mp-22-bundle-branch.html

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ECG Blog #287 — working thru Dx of AFlutter (audio, pdf, lewis leads)

https://ecg-interpretation.blogspot.com/2022/02/ecg-blog-287-sinus-tach-with-st.html

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The November 12, 2019 post in Dr. Smith's ECG Blog — in which I review my approach to a Regular SVT rhythm.

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PEARL #4: The method that I favor to try first — is to simply LOOK for flutter waves! The diagnosis of AFlutter can be established in a regular SVT at ~150/minute — IF you are able to identify regular atrial activity at ~300/minute. Nothing else results in regular atrial activity at this fast of a rate (Atrial tachycardia will rarely be faster than 250/minute ...).

• The way in which I look for flutter waves is to carefully set my calipers at precisely HALF the R-R interval of the regular SVT (since IF the rhythm is AFlutter — then the atrial rate should be twice the ventricular rate if there is 2:1 AV conduction). The short RED lines in leads II and aVF of Figure-2 confirm that there is indeed 2:1 atrial activity in this tracing — which tells us even before application of a vagal maneuver or administration of Adenosine (or other AV blocker) that the rhythm is virtually certain to be AFlutter.
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• PEARL #5: My usual "GO TO" leads for identifying atrial activity are i) Lead II — which is typically the BEST lead for identifying atrial activity. In AFlutter — leads III and aVF also usually provide ready evidence of 2:1 atrial activity; ii) Lead V1 — Next to lead II, lead V1 is often the 2nd-best lead in my experience for identifying atrial activity. With AFlutter — one will often see small amplitude positive deflections of AFlutter in this V1 lead; iii) Lead aVR is often surprisingly helpful for identifying atrial activity; and, iv) IF none of the above leads suggest atrial activity — then I’ll survey the remaining 7 leads as I look for atrial activity. That said, AFlutter will almost always provide ready evidence of atrial activity in one or more of my “Go To” leads.
• The reason the diagnosis of AFlutter is so subtle in today's case — is that except for leads II and aVF, flutter waves in other leads are almost perfectly hidden within the QRS complex!

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Acknowledgment: My appreciation to Sanooj Op (from Calicut, India) for making me aware of this case and allowing me to use this tracing.

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Relevant ECG Blog Posts to Today’s Post: 

• See ECG Blog #185 — for review of the Systematic Ps, Qs, 3R Approach to Rhythm Interpretation.
• ECG Blog #205 — Reviews my Systematic Approach to 12-lead ECG Interpretation.
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• ECG Blog #204 — Reviews a user-friendly approach to the ECG Diagnosis of conduction defects (ie, LBBB — RBBB — IVCD).
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• ECG Blog #287 — Working through the diagnosis of AFlutter (with Audio Pearls, PDF, Lewis Lead).
• The November 12, 2019 post in Dr. Smith's ECG Blog — in which I review my approach to a Regular SVT rhythm.

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O.p. Sanooj — FB Messenger (5-12.1-2026)

from Calicut, India — I am from Calicut, India. Myself Dr Sanooj Op

Sir..does the ecg show SVT? This patient is hemodynamically stable. If it is an SVT, I can give adenosine IV bolus. Otherwise I can give amiodarone. Am I right sir? Here the clinical dilemma is to differentiate

MY REPLY:

Great CASE! And your overall reasoning IS correct. But there are several things that need to be considered. #1) Is this your patient? If not — Is this from the internet? ( IF SO — Please ALWAYS give me the EXACT LINK to the post where this tracing is from so I can check it out and interact). #2) What this is (ie, SVT vs VT) often DEPENDS A LOT on the clinical situation (ie, Young otherwise healthy adult — in which case things like idiopathic VT (in which there is NO underlying heart disease) vs older adult with heart disease (in which case VT is much more likely). #3) It is important to ALWAYS first DESCRIBE what you see !!! This greatly narrows your differential diagnosis (ie, this is a regular WCT at ~150/minute without regular P waves). #4) Now go further — QRS morphology here is PERFECTLY CONSISTENT with LBBB conduction! All upright R in lateral leads I and V6 and predominantly negative in anterior leads with a VERY steep downslope = LBBB conduction is VERY likely — therefore this very likely is supraventricular — so if pt is stable and esp. if a younger adult without heart disease or an older adult with a history of SVT — I'd try Adenosine first. #5) Looking further and GETTING YOUR CALIPERS OUT — we see what looks like "spikes" midway thru the QRS which is probably atrial activity — but it is upright, so not retrograde — AND — my description of a regular rhythm at about 150/minute tells me to LOOK FOR FLUTTER — and my calipers can walk out perfect 2:1 atrial activity — so this is almost certain to be AFLUTTER — so I'd treat this for AFlutter. Adenosine would slow the rate temporarily but not convert the rhythm — so I'd probably try IV Amiodarone. So this is a GREAT case — If you could tell me what happened (and/or give me the link where the blog is from) — I'll contact the author and might want to use it for an ECG Blog (that I have just described for you how to assess this rhythm! —

MY REPLY:

Hi. I worked on the original figure that you sent — and I think it looks different enough from the original that no one will recognize where this comes from. So I with your permission — I want to go ahead and publish this as an ECG Blog, as it is an EXCELLENT CASE for others to learn from.

If you do have any follow-up — Please let me know — but I am confident enough that this is AFlutter with 2:1 AV conduction and LBBB conduction even without follow-up.

THANKS — :)