Here is the conclusion to 47 year old male CC: Crushing chest pain.
You may want to go back and read the original case presentation to see how we got to this point.
When we left off we had this rhythm on the monitor and surprisingly the patient was conscious and talking!
As usual there was an excellent discussion in the comments.
I certainly agree that the first step is to check the leads. I've seen artifact mimic VF before! When I worked in the Critical Care Stepdown Unit as a cardiac monitoring technician this would sometimes happen when a patient brushed their teeth.
However, this time it was the real McCoy (hyperlinked explanation of this idiom for my international friends).
- This has the general appearance of Torsades de Pointes.
- It's fast, wide and polymorphic.
- There appears to be a "streamer" effect.
- The patient is conscious.
However, several features point away from Torsades de Pointes.
- The ventricular rate (using the small block method) is 375
- The QTc of the underlying rhythm is 447 ms
The rate of TdP is typically in the 150 – 300 range. A QTc of 447 while technically prolonged is still < 500 ms which is generally considered to be "safe".
It seems to go against everything we've been taught but could this patient have been conscious with VF on the monitor?
The answer is "Yes!" There are two reasons for this.
First, the onset of VF is often course and slow (relatively speaking). A ventricular rate of 375 is a lot different from a ventricular rate of 720. We like to think of VF as if it's all the same and it usually is from a treatment standpoint. But there is quite a lot of variability as I'm sure anyone who has worked on VF detection algorithms could tell you.
The second reason is that forward blood flow continues for several minutes after the onset of cardiac arrest. That's because there is a pressure gradient between aortic pressure and central venous pressure.
This chart from a white paper on the LUCAS device helps illustrate the point.
This is a busy chart but you will note that it takes several minutes for aortic pressure and central venous pressure to merge together after the onset of VF.
Mark Glencorse over at the (retired) 999Medic.com blog presented another case of transient VF where we had the same lively debate as to whether or not we were dealing with Torsades de Pointes.
Some of you are probably thinking, "It's not VF! It's polymorphic VT!" I will simply ask, isn't VF a form of polymorphic VT? At what rate does polymorphic VT become VF?
From a treatment standpoint it doesn't matter in this case because I'd treat both rhythms exactly the same. I'd apply the combo-pads and I'd give 2 g of magnesium sulfate while I was waiting to see if the patient lost consciousness. Tim Noonan (Scallywag Medic) will be disappointed in me for saying so but you really can't hurt a patient with MgSO4 and it might help.
In this case the treating paramedic didn't carry magnesium sulfate but he did apply the combo-pads.
About a minute and a half later the patient lost consciousness.
Now I think we'll all agree that the patient is in VF and we'll also agree on the treatment!
After another 2 cycles the patient was shocked back into a perfusing rhythm. Interestingly, the patient "woke up" several times during chest compressions.
The patient regained consciousness after return of spontaneous circulation.
Another 12-lead ECG was captured.
Now we're back where we started! (Okay, it's a little worse.)
Advanced notification was given to the receiving hospital and the cardiologist was waiting for the patient. He was taken directly to the cardiac cath lab where angiography revealed a 100% occlusion of the proximal LAD.
The lesion was successfully stented and the patient made a full recovery.
Congratulations to Phil, the Intensive Care Paramedic from Australia (and his crew) for a job well done!
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