# What method would YOU use to discern V-Tach from SVT with abbarency?



## VirginiaEMT (Sep 27, 2013)

I have been studying various articles for 2 days now on this subject. I have not run across this issue in the field yet. It appears that ERAD with a positive R wave in V1 is very reliable. Also a axis of -91 to -180 as well. I have read a bit on Brugada criteria as well but need to do some more work on that one.

What method do you use?

Thanks for your help...


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## STXmedic (Sep 27, 2013)

I use the same methods you mentioned: determining direction of the axis, both with standard axis calculation and V1


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## Christopher (Sep 27, 2013)

VirginiaEMT said:


> I have been studying various articles for 2 days now on this subject. I have not run across this issue in the field yet. It appears that ERAD with a positive R wave in V1 is very reliable. Also a axis of -91 to -180 as well. I have read a bit on Brugada criteria as well but need to do some more work on that one.
> 
> What method do you use?
> 
> Thanks for your help...



Axis is useful to *rule in* VT, _but useless to rule out VT_.

Concordance is useful to *rule in* VT, _but useless to rule out VT_.

Fusion and capture beats are very useful to *rule in* VT...when or if you see them.

AV dissociation is relatively useful to *rule in* VT. Whether or not it is easy to discern this in the field is what makes it only relatively useful.

Rate is horrible at ruling in or ruling out VT. _Although VT is much less likely >220-240._

Brugada's criteria is relatively useful to *rule in* VT. The steps pose some practical concerns in the field, unless you're inhuman at memorizing the morphological criteria. It seems fine when used retrospectively, although the morphological criteria seems to get some intraobserver differences.

Vereckei's original aVR criteria (initial monomorphic R-wave; initial r- or q-wave >40ms; notching in the downstroke of negative QRS; Vi/Vt <=1.0) is relatively useful to *rule in* VT. The final step is very impractical in the field, unless you're crazy inhuman. It is harder than Brugada's to use retrospectively.

Vereckei's updated aVR criteria (AV-dissociation; initial monomorphic R in aVR; strange BBB morphology; aVR Vi/Vt <=1.0) is relatively useful to *rule in* VT. The updates are better than his original, for sure, but the final step is still very impractical in the field, unless you're crazy inhuman. It is harder than Brugada's to use retrospectively.

Sasaki's criteria (initial R in aVR; longest RS >100ms; initial r- or q-wave >40ms) is relatively useful to *rule in* VT. It is the most practical of the "measuring" algorithms, but still less practical in the field.

R-wave Peak Time >50ms is relatively useful to *rule in* VT...if you're mildly inhuman.

Ultimately, you really need to be concerned when you try to *rule out* VT during a wide complex tachycardia. Dr. Ken Grauer enjoys preaching the following as the top 10 causes of a WCT:

VT
VT
VT
VT
VT
VT
VT
VT
SVT with Aberrancy (of which for rates <160 is probably sinus tachycardia)
Accessory Pathway (antidromic AVRT)
My personal algorithm in the field (wide and fast is VT until proven otherwise):

If +aVR -> VT
If QRSd >140ms and intrinsicoid deflection is grossly slurred -> VT
If fusion/capture/AV dissociation/concordance -> VT
If patient has Hx of MI/CHF/AICD -> VT (but for CHF go to sinus tachycardia search)
Search for evidence of sinus tachycardia if rate <220-age, clinical picture fits, and textbook LBBB or RBBB is present
If rate is ~150 consider atrial flutter
If at this point, IVCD -> VT
Which translates to:

If able to get a line and reasonably comfortable with patient's status, attempt adenosine if we didn't immediately think VT
If QRSd <170ish procainamide, otherwise lidocaine (or if STEMI/ischemia suspected as cause, lidocaine first line)
Otherwise cardiovert


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## STXmedic (Sep 27, 2013)

You're my hero, Christopher... Great post, Thanks!


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## VFlutter (Sep 27, 2013)

All WCT is VT until ruled out by an EP study. Problem solved.


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## Brandon O (Oct 3, 2013)

VirginiaEMT said:


> I have been studying various articles for 2 days now on this subject. I have not run across this issue in the field yet. It appears that ERAD with a positive R wave in V1 is very reliable. Also a axis of -91 to -180 as well. I have read a bit on Brugada criteria as well but need to do some more work on that one.
> 
> What method do you use?
> 
> Thanks for your help...



Here's one algorithm:

1. IS IT V TACH?

• Yes.


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## VirginiaEMT (Oct 4, 2013)

Brandon O said:


> Here's one algorithm:
> 
> 1. IS IT V TACH?
> 
> • Yes.



So you don't know the answer. That's cool


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## NomadicMedic (Oct 4, 2013)

VirginiaEMT said:


> So you don't know the answer. That's cool



I think it's more along the lines of, "if it looks like vtach and it's symptomatic, it's getting electricity". 

Done and done. 
How's that answer?


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## chaz90 (Oct 4, 2013)

DEmedic said:


> I think it's more along the lines of, "if it looks like vtach and it's symptomatic, it's getting electricity".
> 
> Done and done.
> How's that answer?



I like it! Now let's talk about what defines "symptomatic." Just kidding. Kind of.


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## TheLocalMedic (Oct 4, 2013)




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## Christopher (Oct 4, 2013)

VirginiaEMT said:


> So you don't know the answer. That's cool



If there were one person I could point out who does know the answer...the positive likelihood ratio is in Brandon's favor.


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## teedubbyaw (Oct 5, 2013)

Chase said:


> All WCT is VT until ruled out by an EP study. Problem solved.



Amen


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## Brandon O (Oct 5, 2013)

VirginiaEMT said:


> So you don't know the answer. That's cool



Well, my humor could use some work. But my point is that if you're ever asking the question, the answer is almost certainly V-tach (in real life, not in class or the internet, where people like to showcase cool stuff), and it's also much easier to cause harm by entertaining other possibilities too earnestly. So while it's literally true that your wide-complex tachycardia might be SVT, you can have a long and fruitful career by always assuming that it's not, and forcing the situation to jump through many hoops to convince you otherwise. (By that logic, there's some value to learning rule-in features for SVT, and very little for ways to rule-in VT -- since that's your starting point. But again, if you're treating as SVT, it ought to be waving one of those giant foam fingers and tracing the phrase "HI I'M SUPRAVENTRICULAR" across the strip.)


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## 18G (Dec 2, 2013)

Adenosine is appropriate for regular, WCT. What is the diagnostic success rate of using adenosine to determine VT? For example, if WCT and pt. does not respond to adenosine than VT is the rhythm. Anyone aware of studies on this?

Also, if the patient has a PMH of MI and is over 35 the patient has an 80% chance of being in VT.


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## Brandon O (Dec 2, 2013)

18G said:


> Adenosine is appropriate for regular, WCT. What is the diagnostic success rate of using adenosine to determine VT? For example, if WCT and pt. does not respond to adenosine than VT is the rhythm. Anyone aware of studies on this?



Although supportive, it's not definitive. RVOT VT in particular will sometimes terminate with adenosine.


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## Burritomedic1127 (Dec 20, 2013)

If your pt was stable and you had time to get a 12 lead that showed
1: ERAD
2: Positive aVR
3: Reverse R wave progression

I'd call it Vtach


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## d_miracle36 (Jan 5, 2014)

Christopher, In what cases would you give amiodarone?


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## Christopher (Jan 6, 2014)

d_miracle36 said:


> Christopher, In what cases would you give amiodarone?



I'm not a fan of it, and fortunately have other antiarrhythmics available to me. When required to use it first line I do, but that is not common. Procainamide and lidocaine are my other choices.

If I lacked procainamide, I would use amiodarone over lidocaine when I suspected the VT/VF etiology to be non-ischemic (scar related and enhanced automaticity, but not prolonged-QTi triggered activity).


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## unleashedfury (Jan 6, 2014)

Christopher said:


> I'm not a fan of it, and fortunately have other antiarrhythmics available to me. When required to use it first line I do, but that is not common. Procainamide and lidocaine are my other choices.
> 
> *If I lacked procainamide, I would use amiodarone over lidocaine when I suspected the VT/VF etiology to be non-ischemic (scar related and enhanced automaticity, but not prolonged-QTi triggered activity)*.



Why are you choosing Amio over lido when the VT/VF is suspected to be non ischemic? 

Not triggering a discussion just curious as to which one is more effective and why in certain cases?


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## Christopher (Jan 6, 2014)

unleashedfury said:


> Why are you choosing Amio over lido when the VT/VF is suspected to be non ischemic?
> 
> Not triggering a discussion just curious as to which one is more effective and why in certain cases?



Amio and lido are both pretty poor at VT/VF in _general_.

Lido is very efficacious when the action potential threshold is messed up due to ischemia. So your ischemic VT's should respond very well to lidocaine. It also has the benefit of having little cardiac effects if the patient has normal myocardium and you "guessed wrong" and it was SVT-A.

Amiodarone is a sledgehammer and has a multitude of antiarrhythmic effects. It has a nasty half-life, is packaged with a cardioactive solvent, and can cause lung fibrosis in higher doses. It also is not really that much better than lidocaine overall, and certainly does not beat lido in ischemic VT. The one upside to amiodarone is it is a sledgehammer and will "work" to some degree on most types of arrhythmias.


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## d_miracle36 (Jan 6, 2014)

Christopher said:


> Amio and lido are both pretty poor at VT/VF in _general_.
> 
> Lido is very efficacious when the action potential threshold is messed up due to ischemia. So your ischemic VT's should respond very well to lidocaine. It also has the benefit of having little cardiac effects if the patient has normal myocardium and you "guessed wrong" and it was SVT-A.
> 
> Amiodarone is a sledgehammer and has a multitude of antiarrhythmic effects. It has a nasty half-life, is packaged with a cardioactive solvent, and can cause lung fibrosis in higher doses. It also is not really that much better than lidocaine overall, and certainly does not beat lido in ischemic VT. The one upside to amiodarone is it is a sledgehammer and will "work" to some degree on most types of arrhythmias.



I recently read that Lido is not a good diagnostic agent, and that it can cause v-tach to not be treated as such because it did not respond to lidocaine. What about in a patient who has no response to lidocaine, and you still don't know if it was SVT-A or V-tach? When do you just decide to sedate and cardiovert? Sorry if I got off topic.


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## unleashedfury (Jan 6, 2014)

if Amio and Lido are poor at acting on VF/VT why aren't we just jumping right to cardioversion instead? 

I can understand that it could be a little overwhelming to the patient as you say hey buddy this is gonna hurt as your going after him with paddles..  But if its stable enough to play with antidysrthymics a little analgesic or sedative isn't going to take much longer.


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## Christopher (Jan 6, 2014)

d_miracle36 said:


> I recently read that Lido is not a good diagnostic agent, and that it can cause v-tach to not be treated as such because it did not respond to lidocaine. What about in a patient who has no response to lidocaine, and you still don't know if it was SVT-A or V-tach? When do you just decide to sedate and cardiovert? Sorry if I got off topic.



Adenosine isn't a great diagnostic agent either if you're looking for 100% certainty 

I'm comfortable with sedation and cardioversion, and would choose simple cardioversion without sedation for myself if/when I have an arrhythmia. As for when on a patient? Anything reaaally ugly that I'm not comfortable with antiarrhythmics I will cardiovert.


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## Christopher (Jan 6, 2014)

unleashedfury said:


> if Amio and Lido are poor at acting on VF/VT why aren't we just jumping right to cardioversion instead?



Sedation is deemed riskier than antiarrhythmics perhaps? Also I would imagine a bolus of lidocaine is more "humane" than cardioverting simple VT. I dunno, I've decided to choose cardioversion alone for myself.



unleashedfury said:


> I can understand that it could be a little overwhelming to the patient as you say hey buddy this is gonna hurt as your going after him with paddles..  But if its stable enough to play with antidysrthymics a little analgesic or sedative isn't going to take much longer.



Agreed. The ED is much quicker to cardiovert than we are.


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## rlcpr (Jan 10, 2014)

Quickest and easiest way would be concordance in the precordial leads (usually favors V Tach in that case). Also, I would look for Josephson's/Brugada's if time permitted (for v tach).

But honestly, the pads would be on anyway so it would most likely be a synchronized cardioversion either way. Probably around 100J to start and see if that brings them out.


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