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

VirginiaEMT

Forum Lieutenant
247
0
0
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...
 

STXmedic

Forum Burnout
Premium Member
5,018
1,356
113
I use the same methods you mentioned: determining direction of the axis, both with standard axis calculation and V1
 

Christopher

Forum Deputy Chief
1,344
74
48
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:
  1. VT
  2. VT
  3. VT
  4. VT
  5. VT
  6. VT
  7. VT
  8. VT
  9. SVT with Aberrancy (of which for rates <160 is probably sinus tachycardia)
  10. 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
 

STXmedic

Forum Burnout
Premium Member
5,018
1,356
113
You're my hero, Christopher... Great post, Thanks!
 

VFlutter

Flight Nurse
3,728
1,264
113
All WCT is VT until ruled out by an EP study. Problem solved.
 

Brandon O

Puzzled by facies
1,718
337
83
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.
 

chaz90

Community Leader
Community Leader
2,735
1,272
113
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.
 

TheLocalMedic

Grumpy Badger
747
44
28
draft_lens19041822module168675520photo_ca1868e340982e1acaa47.jpg
 

Brandon O

Puzzled by facies
1,718
337
83
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.)
 

18G

Paramedic
1,368
12
38
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.
 

Brandon O

Puzzled by facies
1,718
337
83
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.
 

Burritomedic1127

Forum Captain
257
91
28
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
 

Christopher

Forum Deputy Chief
1,344
74
48
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).
 

unleashedfury

Forum Asst. Chief
729
3
0
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?
 

Christopher

Forum Deputy Chief
1,344
74
48
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.
 
Top