EXTRA COPY- ECG Blog #525- Another Wide Tachycardia- EXTRA COPY

The ECG in Figure-1 was obtained from an older woman who presented with new-onset palpitations. She was hemodynamically stable in association with this tracing.

QUESTIONS:

• How would you interpret the ECG in Figure-1?
• How specific can you be with your interpretation?
• What is the treatment of choice? 

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

MY Thoughts on this Tracing:

The ECG in Figure-1 is a regular WCT (Wide-Complex Tachycardia) at a rate of ~185/minute without clear sign of atrial activity.

• QRS morphology is consistent with LBBB conduction in the chest leads (ie, predominantly negative QRS in the anterior leads — with an all-positive QRS in lateral chest leads) — with RAD (Right Axis Deviation) in the frontal plane (as determined by the all-positive QRS in inferior leads — with an equiphasic QRS in lead I).

Impression:

The above description is virtually diagnostic of RVOT VT (Right Ventricular Outflow Track Ventricular Tachycardia).

• PEARL #1: Once you are familiar with the entity of RVOT VT — You should be able to make this diagnosis with high accuracy within seconds of seeing an ECG that looks like the tracing in Figure-1. 
• As we’ve shown on multiple posts on this ECG Blog — RVOT VT is one of the two most common forms of idiopathic VT (See ECG Blog #489 — Blog #346 — Blog #323 — among many others). This term “idiopathic” VT simply refers to the ~10% of patients who present with VT without underlying heart disease.

I review the KEY distinguishing points of the idiopathic VTs in the ADDENDUM to today’s post (See my summarizing info sheet in Figure-4 — and my 8-minute Audio Pearl below).

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Figure-2: The repeat ECG, recorded after cardioversion.

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Figure-3: Comparison between the 2 ECGs in today's case.

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Acknowledgment: My appreciation to Kianseng Ng (from Kluang, Johore, Malaysia) for making me aware of this case and allowing me to use this tracing.

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ADDENDUM (3/XXX/2026):

• In Figure-4 — I summarize KEY features regarding idiopathic VT.

Figure-4: Review of KEY features regarding Idiopathic VT (See text).

—  —

ECG Media PEARL #14 (8 minutes Audio) — What is Idiopathic VT? 

— WHY do we care? Special attention to the 2 most common forms 

= RVOT (Right Ventricular Outflow Track) VT and Fascicular VT. 

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Another Regular WCT = VT- from Kianseng (3/21/2026)

Klanseng Ng- Aequanimitas <plusultra.ng@gmail.com>

Hi Kianseng. This is RVOT VT! (This is your corrected Power Point — :)

• Regular WCT at ~185/minute without atrial activity.
• LBBB-like configuration in the chest leads with marked right axis in the limb leads.
• As per the attached review on Idiopathic VT — the less common LVOT is unlikely given transition between V3-to-V4. (My Audio-Pearl on this topic in the Addendum of ECG Blog #489 —
• Cardiology assessment (in light blue on page 3) — in my opinion takes longer to consider, includes (as you note) some errors — and is not needed (again = my opinion) —because it should take seconds to recognize that this regular WCT with LBBB-like configuration in the chest leads and right axis without P waves is almost certain to be RVOT VT.
• LBBB does not have a right axis with this type of fragmented lead I — and LBBB conduction typically continues with smaller R waves than we see by V3 — and almost always (unless there is “something else” = prior infarction, cardiomyopathy) almost alway has a later transition than we see here.
• The post-conversion ECG proves VT — because of the obvious PVC that shows identical QRS morphology in leads V4,5,6 as seen during the WCT.

 

The most popular Blog posts are the WCT rhythms — so I want to use this case for an ECG Blog. I’ll let you know when I publish this case! — BEST — :) Ken

 

P.S.: Just wondering why Adenosine was not tried? Why Amiodarone was not started after the 2nd cardioversion? If the patient was referred for EP testing? There are of course many ways to manage patients — but the above would be my thoughts — :)