3rd Degree Heart Block
I had an interesting strip the other day. We were called to a physician's office for an abnormal ECG. The EMD dispatch sent us "hot." But the prearrival instructions indicated no immediate emergency. Patient was alert talking with good color, no pain and no shortness of breath. And as it usually turns out at a doctor's office, the patient was there for a scheduled appointment, rather than an emergency appointment.
We found a fit 86 year-old female who it turns out had had a syncopal episode several days before while working for several hours ( and more strenuously than usual) in her garden. Other than that, she had no complaint. She was fit, drove a car, walked without a cane, and could carry on quite a conversation.
Her blood pressure was 120/60. Her pulse was 32. She was on a beta blocker, but had been for decades.
The doctor showed me the ECG. No ST abnormalities. A 12-lead from two months ago showed a sinus at 64.
I studied my monitor for a moment, but couldn't make a snap call on the rhythm. It was regular. The Ps seemed to have a relation to the QRS, yet there looked to be a second P emerging from the T. There were no dropped beats.
It wasn't until I ran out a long strip that I was able to see it more clearly. It was a 3rd degree block. The QRSs were all equal and the Ps were all equal. There was, in fact, no traditional relationship between the Ps and QRSs. Where it was tricky was the atrial(Ps) rate was 63, where the ventricular (QRS) rate was 33/34. In other words the P rate was not quite double the QRS, so it took awhile for P/QRS separation to become visible. (Only on the 4th strip can I see it.)
I saw the woman later in the ER and was had a long chat as she lay there, waiting to be taken upstairs to get a pacemaker, her heart still beating strong at 34, a standby pacer attached if her rate should suddenly drop.
posted by PC @ 1:47 AM
12 comments
12 Comments:
Damn.... Nice catch! I would have missed it completely. Great Job!
If her heart rate should suddenly drop to... what, exactly? Never heard of demand pacing at 25, although it's possible. Pads on, ready to turn on, I suppose, should she go asystolic.
am i missing something, or is there a reason you put up lead III's strips? i thought medics read off lead II.
The pacer would be turned on if she suddenly became symptomatic either through her heart rate dropping to whatever, including asystole or is she suddenly dropped her pressure even at 34. They would put the pacer probably somewhere between 60 and 80, whatever the lowest rate that would give them decent perfusion.
The strip says "III," but it is actually something called "S5," which I neglected to label. "S5" is done by putting the left leg lead in the fifth intercostal space just to the right of the sternum and putting the left arm lead just below the suprasternal notch. Then read "Lead III" on the monitor, which instead of giving you an inferior view from the left leg to the left arm gives you a closeup of the right atrium. I read about this lead in a great book called Taigman's Advanced Cardiology. It is an excellent lead to let you get a clear view of the p wave. I most often use it when I am trying to determine if a patient is in afib or not. I will probably post this comment on an addition to my main post with more infor from the book.
Thanks for the comments,
PC
Not something you see every day. Fortunately. Since you had to do a make do lead to find the rhythm, I'm guessing that you guys don't have 12 lead machines. Is that correct?
MCL1 would give you a pretty good view as well. Of course I'd have to look up how to do it since it's been so long.
Anonymous, I can't speak for Peter's outfit, but we monitor 3 leads simultaneously and get 12 leads on 70% or so of our patients. It's pretty much standard of care where I am.
We do have 12 leads. The 12 lead didn't provide a long enough glimpse for the machine to give an accurate interpretation. I did a couple 12 leads and I can't remember what the machine said -- it was either sinus or unrecognizable rythmn. We also run three leads at the same time. The machine defaults to II, III, and AVF, but you can change it to any combination (including any of the 12 leads if you have the 12 lead attached. I just cut the other two leads out with sissors so I could show a continuous strip without taking up so much space.
I put the S5 lead on just to get the best possible artifact-free lead I could.
As I mentioned above, I plan to post more of S5 and some of the other monitor tricks I learned years ago from the Taigman book.
Thanks again for the comments, PC
Great catch and a very interesting strip. I ran on a 3rd degree block a few weeks ago. Check out the strip here:
xsupermonkey.blogspot.com/2008/03/my-patients-last-moments.html
OK, that clears the 12 lead thing up. V1 and V2 are pretty good for rhythm monitoring, but you do have to leave the chest leads on.
Gary
Unless I'm mistaken, it's wildly inaccurate to interpret a 12 lead when a patient has a 3rd degree block.
I would hope that no one is using the machine 12-lead interpretation for patient care.
Thanks for the comments.
The 12 lead machine's interpretions can be wildly inaccurate. I have heard, however, of studies(I'll try to find one) that show they are almost as good as physicans at interpreting, but every now and then they come up with some zany interpretations. I guess they are constantly fine-tuning the software.
I use the machine's interpretions to confirm mine. (I will admit that in at least one case, I allowed the machine's interpretation to lead me astray.)
The primary purpose of the 12 lead is for the ST elevation MI, both pointing it out and then pinpointing where it is occuring.
Thanks again for all comments.
PC
To get MCL1, just move the leg lead to the V1 position and run it in lead III. The same can be used for MCR4, to look for RVI - move the leg lead to where the V4 position would be on the right side (mirror reflection of the normal V4 position) and switch to lead III.
Taigman has some excellent insights on patient care, especially cardiology.
Using the machine's diagnostic interpretation is not a bad thing to do. If it disagrees with your interpretation, you should be more hesitant to treat what you thought you had.
I had an obvious V Tach, but the machine was calling it A Flutter.
Not impossible. VT is not very responsive to prehospital care, so I can wait. If the patient becomes unstable, sedation and electricity are available.
Cardiologist meets us in the ED and agrees it is VT. ED 12 lead (same diagnostic software as my 12 lead) calls it A Flutter.
The biggest problems with the machine interpretation are artifact and misplaced leads. A trained operator should pick up on any malfunctions.
Almost all of the 3rd degree blocks I have treated have been stable - just feeling a little off their game. Walking, talking, driving, but no outwardly visible symptoms. My pacer pads remained unopened for them.
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