Heart Blocks and Risk for SCA

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absolutxj

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I'm starting a critical care class and have a question regarding some preclass EKG work. I'm doing exercises which involve interpreting a 12 lead and determining, among other things, risk for SCA, complete HB, and hemodynamic compromise. I'm having a hard time figuring out how to determine these three risks from only a 12 lead strip. Any takers?

Example

ekg.jpg

ekg1.jpg
 
So you can tell if the patient has an increased risk for SCA based of a prolonged QT segment and an increased risk for CHB from fasicular blocks.

Anyone who says you can say the level of hemodynamic compromise from a 12 lead that doesn't show vfib or asystole is feeding you a line of crap. You can guess, but that's it.
 
absolutxj said:
I'm starting a critical care class and have a question regarding some preclass EKG work. I'm doing exercises which involve interpreting a 12 lead and determining, among other things, risk for SCA, complete HB, and hemodynamic compromise. I'm having a hard time figuring out how to determine these three risks from only a 12 lead strip. Any takers?

Example

View attachment 890

View attachment 891
Click to expand...

I'm with you there.

The first strip you've got Controlled a.fib with a bifascicular block (RBBB + LAHB). Maybe RVH as well? You've got some fairly big R waves in V1-V3. S waves in V5, V6... Perhaps? QTc is long at 0.47.

So I guess, It's suggesting that there's a risk for complete AV block because right now we've got a nuked right bundle and anterior fascicle, and all that's left is the posterior fascicle? If this becomes blocked then we have infranodal complete AV block. Is bifascicular block always pathologic? It seems like you'd need some clinical information to make that judgment.

And I'm guessing the cardiac arrest risk is because of the long QT? Although it's hard to know if the QTc of .469 is really that accurate if the RR interval is irregular. I just noticed there seem to be some U waves floating around. But these can be physiologic too, right?

I'm not sure what it's asking for with "risk for hemodynamic compromise". I mean, this ECG isn't incompatible with normal hemodynamics in the way a VF ECG would be, or an IVR of 16, but we have no clinical information here. We have no real way of judging SV, SVR, etc.

Second strip.

sinus rhythm, RBBB, normal axis so no hemiblock, no ectopy, STs and PR are isoelectric. Long QT. But like the previous example we have BBB, so is it as big a concern?

Gah...

I'd say no to all three here. But I have a feeling I'm flailing a little. I don't know how you're really supposed to answer these questions without having more information about the patient's condition from other sources.

What's the book called? It seems interesting.
 
Conventional wisdom (take it for what it's worth) is that a bifasicular block is pathological and increases the risk for both CHB and vfib. Don't ask me for literature, I'm just parroting what I've been told (which I hate).
 
usalsfyre said:
Conventional wisdom (take it for what it's worth) is that a bifasicular block is pathological and increases the risk for both CHB and vfib. Don't ask me for literature, I'm just parroting what I've been told (which I hate).
Click to expand...

Found a couple of papers, at least one of them was free access. They seem to support what you're saying, especially if there's a history of unexplained syncope. Although it does sound like it's difficult to extract the effect of the bifascicular block from other comorbidities.


http://europace.oxfordjournals.org/content/11/9/1201.full
http://europace.oxfordjournals.org/content/11/9/1140.full
http://www.ncbi.nlm.nih.gov/pubmed/16789976
 
Bifascicular block suggests that a patient with a chief complaint of syncope or chest pain may be at risk of sudden complete heart block which may not have an escape rhythm especially if the patient takes oral antiarrhythmics. On the other hand many patients live for years and years with bifascicular block and never develop complete heart block. So, although some will say to break out the combo-pads any time you see bifascicular block I think you need to look at the history and clinical presentation.
 
Thanks for the replys guys. Im glad I'm not the only one that can't figure out what they're asking for. The book is "12 Lead ECG for Acute and Critical Care Providers" by Page. It's been a great book so far and I've enjoyed the indepthness (?) of the chapters. It's far better than the paramedic practice books which are just full of practice strips.
 
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