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.