Abberancy or VTach?

[EMS49393]

You cannot use the frontal plane axis to rule out VT. This kind of thinking is extremely dangerous. Wide and fast is VT until proven otherwise! This ECG shows RBBB morphology in lead V1 and left axis deviation. In other words, bifascicular morphology (RBBB/LAFB) which is the exact morphology we could expect if the VT originated in the left posterior fascicle of the left ventricle. In other words, one of the EXPECTED morphologies of VT. ERDoc used Brugada's critiera in the only responsible way, in my opinion, and that is to rule-in VT. Failure to rule-in VT does not rule-out VT and these criteria do more harm than good, especially in the prehospital setting.... by a large margin.

Tom

Did you bother to read the entire context of the response? It doesn't meet the criteria that particular person was using to verify v-tach. I didn't comment either way on whether or not this was v-tach, my comment was based on the typical and very limited criteria a particular poster used to determine the rhythm. Unfortunately most paramedics in the United States have very limited cardiology and couldn't determine a rhythm with the most basic of criteria guidelines let alone be able to comprehend anything more advanced. I proved my point with my response. If a medic can't even determine if a complex has a positive or negative deflection, how can you expect them to be able to comprehend Brugada's criteria?

Maybe if they started requiring a little more anatomy and physiology before they let people go to paramedic school they would understand how the heart functions thus understanding how to determine cardiac rhythms and treat patients appropriately. More education, novel concept.

[Mateo_1387]

You cannot use the frontal plane axis to rule out VT. This kind of thinking is extremely dangerous. Wide and fast is VT until proven otherwise! This ECG shows RBBB morphology in lead V1 and left axis deviation. In other words, bifascicular morphology (RBBB/LAFB) which is the exact morphology we could expect if the VT originated in the left posterior fascicle of the left ventricle. In other words, one of the EXPECTED morphologies of VT. ERDoc used Brugada's critiera in the only responsible way, in my opinion, and that is to rule-in VT. Failure to rule-in VT does not rule-out VT and these criteria do more harm than good, especially in the prehospital setting.... by a large margin.

Tom

Care to provide some more information on the highlighted parts? From what I read on the Brugada link by ER Doc, it is safe to rule SVT with aberrancy if the VTach criteria is not met. How do you know the criteria does more harm than good in the prehospital setting?

[Tom B.]

Care to provide some more information on the highlighted parts? From what I read on the Brugada link by ER Doc, it is safe to rule SVT with aberrancy if the VTach criteria is not met. How do you know the criteria does more harm than good in the prehospital setting?

The problem is that mistakes are made (as high as 50% of the time) and there is poor inter-observer agreement (certainly the case every single time one of these threads hits the EMS bulletin boards). The most common error is misclassifying VT as SVT with aberrancy (as in this case) which has been proven to lead to clinical misadventure, including death. The algorithms have limited applicability for patients with preexisting intraventricular conduction defect (atypical right or left bundle branch block) and patients with an accessory pathway (antidromic AVRT). For a complete discussion about this see the ACLS Reference Textbook and Experienced Provider Manual (2003). Chapter 16: Stable Wide Complex Tachycardias. Some excerpts can be found here. I say the danger is greater in the prehospital setting because it's debatable as to whether or not antiarrhythmics are good or necessary in the prehospital setting in the first place. If the patient is hemodynamically unstable they should be cardioverted. If the patient is hemodynamically stable then there is time for expert consultation. Anitarrhythmic medications are dangerous and we should be handling them with the utmost respect.

Tom

[crotchitymedic1986]

Sorry dudes and dudettes, this IS NOT VTACH. Treat your patient, not the monitor. And you may be amazed to know that there are patients who go in and out of VTACH, SVT, and have arrests that last greater than 6 seconds several times per day, and live without a Paragod's intervention (although they usually get a pacemaker or internal defibrillator shortly after it is found).

Edited September 6, 2010 by crotchitymedic1986

[Job13_5]

No one has mentioned the AVR criteria here yet. According to such this 12-lead would be positive for VT because of the initial R-wave in AVR.

Here's a quick article that describes AVR criteria in brief: WCT Algorithms

In the article it reports the accuracy of the AVR criteria being at 90.3% with a P of 0.006 vs 84.8% overall for Brugada's.

I would feel very confident calling this VT for several of the reasons stated previously, with the addition of the positive AVR criteria.

[crotchitymedic1986]

Treat the patient not the monitor !!!!!!!!

[Job13_5]

Treat the patient not the monitor !!!!!!!!

I fail to see your point. Isn't this an exercise in examining the 12-lead? The question posted by the OP is "Aberrancy or VT?" My answer is VT. If I'm wrong, I would sure like to know about it so I don't make the mistake when it matters.

[Tom B.]

Job13_5 -

Thanks for chiming in.

From an academic perspective there are things I like about this algorithm, but there are problems with it also. In the first place, can we honestly say it's simplified? Consider Fig. 7.

Out of 453 wide complex tachycardias:

35 showed AV dissociation > presumed to be VT

127 showed an initial R-wave in lead aVR > presumed to be VT

156 showed atypical BBB or bifascicular morphology > presumed to be VT (Note: Requires the clinician to understand typical vs. atypical patterns.)

Now we're down to 135 of the original 453.

44 have an initial voltage (in the first 40 ms of a bi- or multi-phasic QRS complex) greater than the terminal voltage (in the last 40 ms of the QRS complex) > presumed to be VT (Note: I am simplifying this criterion because the stipulations for selecting the right QRS complex are bewildering).

Do you think this criterion will be correctly applied by anyone other than EPs? I don't.

Even if by some miracle this final criterion is correctly applied in the field (and no other mistakes are made) 15 of the remaining 91 patients (16%) were misidentified as having SVT with aberrancy when in fact they were experiencing VT. Do you like those odds?

76 of the original 453 patients (17%) were correctly identified (by exclusion) as having SVT with aberrancy.

So again, the burden of proof is entirely on the person who says a wide complex tachycardia is something other than VT.

The most important criterion of all is "wide and fast" but sadly, that's the criterion more and more paramedics are willing to ignore.

The default diagnosis for a wide complex tachycardia should always be VT.

I have no quarrel with the idea that we should "treat the patient, not the monitor" but if that's your position then why do you feel the need to make the pronouncement that it isn't VT? Call it a wide complex tachycardia that is well tolerated by the patient and transport the patient to the nearest hospital.

That's a lot better than killing the patient with a calcium channel blocker.

Tom

[ERDoc]

Treat the patient not the monitor !!!!!!!!

Please stop with this totally incorrect mantra. How are you going to treat the pt without knowing what the monitor says? Let's say that this pt in VTach is presenting with dizziness. Are we just going to assume that it is VTach and shock them? Are we going to shotgun our treatment and treat every possible cause of dizziness? So we'll shock the pt for VTach/VFib, push some adenosine for SVT (though the shock may take care of that), we'll give meclizine for vertigo, push tPA for their MI and ischemic stroke (hope this doesn't complicate their hemorhagic stroke or GI bleed which can both cause dizziness), give toradol, benadryl and compazine for the migraine, steroids for their MS, transfuse for their anemia, push an Amp of D50 for hypoglycemia, while at the same time giving insulin for the uncontrolled hyperglycemia, I could go on but I think you get the idea. That's pretty cost effective and safe for the pt, no?

There is a reason we have the tools we have. They help us to do what is best for the pt. Anyone who has worked in medicine for any reasonable time (and I really question if you have), knows that you develop your differential diagnosis based in the history and physical exam. You then use the tools you have available (monitor, EKG, labs, radiology, etc) to narrow down your differential to a single diagnosis. You then treat what is wrong. "Treat the patient, not the monitor," is the gospel spoken by those who have no clue as to what practicing medicine means.

Tom, I have to agree with the "newer" criteria. I find the Brugada criteria easier to use (one of the purposes of making a clinical decision rule). In practice I can see the "newer" rules being more difficult to use, resulting in a higher error rate. I had to read it several times before it started to make sense. I can see a medic pulling out his calipers while being bounced around on a bumpy road. It might be interesting to watch, lol.

[spenac]

I can see a medic pulling out his calipers while being bounced around on a bumpy road. It might be interesting to watch, lol.

Wish someone would have suggested soft tips on my calipers before that bouncy ride. Hey is there a warning on them? HMMMMMMM

Thanks Doc and Tom for some good reasoning on this discussion.