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?
 Vereckei A, et al. New algorithm using only lead aVR for differential diagnosis of wide QRS complex tachycardia. Heart Rhythm; 2008 (5): 89-98.