It's from a 75yr old female. I don't have any other clinical information on this case unfortunately.
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Rate:
- ~145 bpm
- Subtle irregularity in rate
- Periods of fixed rate of 150 bpm leads V1-3
- Periods of rate change best seen in lead V6
- Nil p waves seen
- LAD
- QRS - Prolonged (120-140ms)
- QT - 400ms (QTc Bazette 380-400 ms)
- Discordant ST segment / T wave changes
Additional:
- LBBB morphology
- Sgarbossa negative
- Subtle change in QRS morphology best seen V4-6 as rate changes
- Wide Complex Tachycardia with LBBB morphology and left axis deviation
So what are the differentials ?
One of our electrophysiologists has looked at this ECG and had these comments.
- SVT - with either baseline LBBB, would need old ECG's to compare, or aberrancy / rate related block.
- Most likely mechanism is atrial tachycardia or atrial flutter with 2:1 block with slower variable block at start / end of rhythm strip.
- VT - bundle branch re-entry
- Antidromic AV re-entry tachycardia with atriofascicular pathway
- Pacemaker mediated tachycardia - no obvious pacing spikes but these aren't always seen as in this case from Ed Burns
Dr Razak has also highlighted some excellent resources on this ECG diagnostic challenge:
- Neiger JS, Trohman RG. Differential diagnosis of tachycardia with a typical left bundle branch block morphology. World J Cardiol. 2011 May 26;3(5):127-34. PMID: 21666813 Full text here.
- Sousa PA, Pereira S, Candeias R, de Jesus I. The value of electrocardiography for differential diagnosis in wide QRS complex tachycardia. Rev Port Cardiol. 2014 Mar;33(3):165-73. PMID: 24656320 Full text here
But remember it's all about the patient
- What symptoms does the patient have ?
- Do they have signs of clinical compromise ?
- Do you need to do something now ?
References / Further Reading
Life in the Fast Lane
Textbook
- Chan TC, Brady WJ, Harrigan RA, Ornato JP, Rosen P. ECG in Emergency Medicine and Acute Care. Elsevier Mosby 2005.
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