Differential diagnosis of wide complex tachycardias – Part IV

Let’s look at a more typical case of wide complex tachycardia.

This case comes from Lt. Jason Kinley of Xenia Fire Division. If you’re not familiar with Xenia Fire Division in Xenia, OH, they have an outstanding prehospital 12 lead ECG program. Jason is also one of the co-moderators at the EMS-to-Balloon (E2B) Challenge! listserv at Yahoo!

Here’s the story.

EMS is called for a 89 year old male with chest pain. Onset 30 minutes ago. Non-radiating. Patient is A+OX4. Skin is moist. Skin color is good. No increase in respiratory effort. Meds for diabetes, hypertension, and unspecified heart problem (patient is a poor historian). The patient is reluctant to go to the hospital. He states he was seen 4 days ago for a possible TIA.



Yes, I know the computerized interpretive statement has been removed. That’s my fault!

Here are the computer measurements:

HR: 150
PR: *
QRS: 126
QT/QTc: 304/475
P-R-T: * -51 110

The treating paramedics correctly identified this as a regular wide complex tachycardia. Because the patient was hemodynamically stable, they initiated a 150 mg bolus of Amiodarone over 10 minutes, with no change to the heart rhythm.

Why Amiodarone?

Because according to the 2005 AHA ECC guidelines, that’s the drug you give for undifferentiated regular wide complex tachycardia. It’s supposed to be therapeutic for both ventricular and supraventricular tachycardias.

You will remember the patient stated that he was seen 4 days prior for a possible TIA. Well, it turns out that the same EMS system brought him to the hospital. As luck would have it, they performed a prehospital 12 lead ECG at that time.

Here it is.


Computer measurements:

HR: 100
PR: 232
QRS: 134
QT/QTc: 350/451
P-R-T: 50 -56 91

Now compare the QRS morphology in the first PH12ECG to the PH12ECG taken 4 days prior, when the patient was in borderline sinus tachycardia with 1°AVB.*

Is it a match? You bet! This patient has a pre-existing intraventricular conduction defect (or atypical LBBB). Note the S wave in lead V6.

Was this patient in ventricular tachycardia? No.

Considering the heart rate of exactly 150, the pseudo-R wave in lead V1 during the tachycardia, and the recently history of possible TIA, 2:1 atrial flutter is the most likely explanation.

However, the first rule applies! In the absence of an “old” ECG for comparison, it’s VT until proven otherwise.

The patient didn’t covert to sinus rhythm, but it was a well-executed call, and no harm came to the patient.

* 3:1 atrial flutter is also a possibility. Note the heart rate of exactly 100.

See also:

Differential diagnosis of wide complex tachycardias – Part I

Differential diagnosis of wide complex tachycardias – Part II

Differential diagnosis of wide complex tachycardias – Part III

Differential diagnosis of wide complex tachycardias – Part IV

Differential diagnosis of wide complex tachycardias – Part V

Differential diagnosis of wide complex tachycardias – Part VI

3 Comments

  • Vince D says:

    Just trudging through the site looking for a-flutter cases and came across this post. I'm thinking this one may actually be a case of juntional tach. True, the rate is perfect for flutter, but although I see signs of atrial activity in I, II, aVR, and V1 (the pseudo-S you noted), I'm not convinced that p' wave has a partner 400ms after it to clinch the diagnosis of flutter, leaving retograde conduction from the junction as the most likely culprit (in my opinion). The abnormall flat T-Q segments in the limb leads also strike me at pointing towards a sub-atrial pacemaker.

  • Vince D. – It's a nuanced case. This was discussed a number of years ago on the EKG Club at Yahoo! At the time Tomas Garcia, M.D. (author of 12-Lead ECG – The Art of Interpretation) felt that it was 2:1 atrial flutter.

    http://health.groups.yahoo.com/group/ekg_club/message/1814

    Unfortunately, the really cool graphic he created to help explain it was not retained by the archives.

  • VinceD says:

    Thanks for the quick response, and although I'm still not entirely convinced, I'm finding it very hard to disagree as Dr. Garcia is a very smart man. I suppose I'll just file it away and take a look at it down the line to see what I think then.

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EMS 12-Lead

Cardiac Rhythm Analysis, 12-Lead ECG Interpretation, Resuscitation

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Comments
Stuart
Anterior T wave inversions and PE.
Studies (can't remember them off the top of my head) have shown that TWI in V1-4 + III is 85% likely to be RV strain, 15% ischemia. If I see anterior TWI, the very next lead I look to is III
2014-11-23 18:00:51
Arlene R
The Trouble with Sinus Tachycardia
It has been very insightful for me as i read this post. Thanks to the may people who commented. Like many nurses, I was also taught to differentiate svt from st by rate and now I stand corrected. I have a Telemetry test coming up soon, I wont have the patient in front of me…
2014-11-20 19:59:33
Nick
100 yof CC: Rib pain and intermittent spasms
Can't be a potassium imbalance. The TW's wouldn't change and then change back. If it was coronary spasm, I would expect some ST segment elevation. The TW'S are also not hyperacute (peaked). Does she wear some sort of electronic stimulator?
2014-11-19 01:05:43
Anterior T wave inversions and PE. | EMS 12 Lead
Not just S1Q3T3: Look at the other 10 leads!
[…] Last week, I described the case of a middle-aged male with a vague history of heart failure who had been having progressive shortness of breath for 4-5 days. On the day he called 911, he had been walking a short distance when he syncoped. EMS obtained an ECG: […]
2014-11-18 18:33:47
Christine
100 yof CC: Rib pain and intermittent spasms
I believe this may be coronary artery vasospasm.
2014-11-18 11:02:45

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