This is the conclusion to 90 year old female CC: Seizure. Be sure to start there first!
When we left off, we had completed our initial assessment of a 90 year old patient who, based on bystander accounts, had a seizure. She is pale, cold to the touch, and feels lethargic.
During our assessment she had an increase in her pulse rate and a 12-Lead ECG was obtained:
This is a wide complex tachycardia at a rate of about 200. Our differentials include ventricular tachycardia, SVT with aberrancy, and preexcited wide complex tachycardia from Wolff-Parkinson-White. Regardless, all wide complex tachycardias should be treated as V-Tach until proven otherwise!
When I first saw this ECG, I found the computerized interpretation very interesting because it is almost 100% incorrect.
A quick look at the measured rate shows the cardiac monitor's interpretation cannot be trusted. Using the big block method, the rate is between 150 and 300 bpm, and when calculated is around 206 bpm.
Additionally, the cardiac monitor believes the rhythm to be atrial fibrillation with a rapid ventricular response. However, as many of our astute readers noted, this is clearly ventricular tachycardia.
An initial R-wave in aVR is over 98% specific for ventricular tachycardia1!
If we look at lead aVR, we see the ventricles are depolarizing towards this lead. Clearly this cannot be a supraventricular rhythm such as atrial fibrillation or SVT. In those cases the initial axis will nearly always point away from aVR.
The paramedics in this case correctly diagnosed ventricular tachycardia as well, and began their treatment in the field.
They initially administered 100 mg of lidocaine, however, it had no effect.
Next they elected to use synchronized cardioversion and premedicated the patient with 20 mg of etomidate.
A synchronized shock of 100 J was administered, while the patient was sedated, with a return of a sinus rhythm. A post-conversion 12-Lead was obtained:
This 12-Lead ECG shows a sinus rhythm with a 1st degree AV block and PVCs. There does not appear to be evidence of a STEMI, electrolyte disturbances, or pre-excitation from WPW.
The patient was packaged and had an unremarkable transport to a nearby hospital. The patient was admitted for observation and discharged without incident.
This case highlights a few key points:
- The computerized interpretation is no substitute for a human's interpretation.
- Wide complex tachycardias should be treated as ventricular tachycardia in the field.
- An initial R-wave in aVR is diagnostic of ventricular tachycardia.
What are your thoughts on the case?
[1] Vereckei A, et al. New algorithm using only lead aVR for differential diagnosis of wide QRS complex tachycardia. Heart Rhythm; 2008 (5): 89-98.
I’m confused by the R wave in aVR bit. Given that it’s up, down, up, down, etc – how do you tell whether you’re looking at an RS wave or a QR wave?
Great question Alex,
You can use the leads below it for help, but really in this case the sharper peaks are more likely to be the R's rather than the rounded slumps being S's.
Let me know if this helps!
I wish we had etomidate in our protocol in Mass….we can’t even use lidocaine anymore Amiodarone for everything! EMS did a great job on this call!!
First time posting here. Etomidate would be great to use in Tulsa also christina, we premedicate with versed before cardio version if unstable and use amiodarone as well, no lidocaine here either. Good case though and the interpretation on the 12-leads “doc in the box” is WAY wrong lol.
thanks for an excellent case. the take home point for me is the prominent r wave in aVR. usually pay little if any attention to aVR. i'll be looking there for sure the next time i see a wide complex tachycardia.
I also think it's important to remember that while you can use criteria to rule in VT, such as a prominent R wave in aVR, the absence of such criteria can not be used to rule out VT!
David, whats your thought on where the sync is located. It appears as though we should have paid closer attention to get into a positive lead…
Dana,
It does look like the sync is a bit off! aVL may have been your only option.
Sometimes I wonder if the computer algorithms even contain an interpretation of "Ventricular Tachycardia." I can't recall the last time I saw one….