Comments on: Heart blocks cheat sheet

By: bizzarojeff

bizzarojeff — Fri, 31 Jul 2009 05:16:05 +0000

Remember 3rd degree (AV dissasociation) isn’t always 30-40 range. Had one a few weeks ago that was mid 60’s. Two completely different independent rhythms of the atria and ventricles. The cardiologist was upset when the nurse called him at 0300 for a “rhythm change.” And I got chewed out a little for it, but it was the right call, and he knew it :p
The problem was the previous shift had seen P waves moving through out the rhythm, and assumed a 2nd degree, even though they didn’t measure to see if they were “regular”, which indeed they were.
Anyways, my two cents.

By: Kim

Kim — Sun, 31 May 2009 02:35:16 +0000

I remember spending hours in the Coronary Care Unit back in the day, discussing and arguing over exactly what a particular monitor strip showed. Had a cardiolgist say that if you can’t give at least three possibilities for each strip (including Sinus Rhythm…it could be PEA!), you didn’t know your stuff! : D

Of course, this is debating after the fact, not over the patient! : D

By: Sean

Sean — Sat, 30 May 2009 21:29:48 +0000

Thoroughly enjoyed this post. I love the bantering over how to discern and differentiate the differing rhythms. I guess that’s why EKG is always a sensitive area for most. It’s all in the interpretation.
Yes, we should know what we are looking at, but more importantly it’s what you have to do for them. What is your course of action or treatment for each of yoru findings.
I think this is the biggest factor when evaluating your EKG’s. Semantics will drive you buggy! It’s whether or not it’s a rhythm that needs treated.. and what is the treatment.
LOVED this post.
Thanks!

By: Ambulance Driver

Ambulance Driver — Sun, 24 May 2009 01:19:46 +0000

ACLS’s way of doing it is pretty straightforward. The only time it will ever be wrong is when a Second Degree Type I is so slow that it drops every other beat… in which case it might as well be a Type II anyway. Pure semantics.

Ask these 3 questions, in order, and go no farther than it takes to identify the rhythm:

1. Are there more P waves than QRS complexes? If no, it is not a 2nd or 3rd degree block. If yes, move on to Question 2:

2. Is the PR interval fixed? If yes, it is a Second Degree Type II block. If no, move on to Question 3:

3. Is the rhythm regular? If yes, the rhythm is a 3rd Degree Block, which may have either a junctional or ventricular escape pacemaker. If the rhythm is irregular, it is Second Degree Type I Block.

That will correctly identify the vast majority of heart blocks you will ever encounter.

Incidentally, did you know Wenckebach identified his phenomenon 3 years before Einthoven invented the EKG?

By: DVorah

DVorah — Sat, 23 May 2009 10:58:42 +0000

A fun way to learn this stuff is at Ambulance Driver’s blog:
http://ambulancedriverfiles.blogspot.com/2007/06/sex-relationships-and-cardiac.html

By: notratched

notratched — Fri, 22 May 2009 04:33:58 +0000

Yes, I think of junctional rhythms and bundle branch blocks as still having a (mostly) regular association of P waves with QRS complexes, whereas with a CHB they don’t if you trace them out (note the twice-mentioned caveat that the QRS complexes “eat” some of the P waves). If you have a junctional rhythm, you’ll have no P wave or an inverted or retrograde P wave, but it’ll still appear in the same spot relative to each QRS complex and not migrate all over the strip. Yes? I guess I should have stated the assumption that you’re starting out having figured you’ve got SOME type of a block and your issue is differentiating which type it is. Sometimes I can’t even tell that. We get some crazy rhythms at work. I watch the monitor going “are those P waves? Or T waves? Or are retrograde inverted P waves being eaten by the T waves?” (Or similar.) My favorite rhythm by far, though, is the wandering pacemaker. The mental image causes me to snort every time.

By: wardbunny

wardbunny — Thu, 21 May 2009 23:57:13 +0000

Nice break down!
I’ve never understood them but then again never had too. That’s what we have junior docs for.

By: LIBuff

LIBuff — Thu, 21 May 2009 21:32:14 +0000

her 3rd degree HB explanation is almost correct. as far as Junctional or BBB, or even Ventricular Escape beats, you’re contrasting the speed of the actual ventricular contractions.

i would assume (some cardiologist help me here) because a 3rd degree HB is essentially a diseased AV node, then you would rarely see nodal (junctional) beats which are disassociated with the atrial beats.

therefore, every 3rd degree HB i’ve seen in the field has been Ventricular Escape rhythem coupled with P waves, neither of which have anything to do with each other…

MY 3rd degree HB indication: when the P waves are getting eaten by a QRS complex on a random basis, one should assume and investigate 3rd Degree HB.

By: Canuck Nurse

Canuck Nurse — Thu, 21 May 2009 19:19:22 +0000

Are you including things like Junctional rhythms in 3rd degree blocks? What you’ve described as 3o blocks could be junctional, bundle branch or a few others. Just my two cents…