Friday, December 6, 2013

Several Wide Complex Rhythms in One Patient. Test yourself: Will You See What I Did Not See?

This time I'm going to tell you that the case is mine because the mistakes were mine.  I sat down to write one narrative, but as I looked at all the ECGs, I realized that some of my rhythm analyses were wrong and had to write a different narrative.

Now it all looks so clear and obvious when I'm sitting down without a sick patient in front of me.

But, to test yourself, I'm going to let you look at the ECGs before I explain them:

1.  Presenting ECG in a dialysis patient feeling weak:
 2. His previous ECG:


 What treatment would you give?



















3. This happened after immediately giving Calcium:
 4. This was present after about 11 g of calcium gluconate:
 5.  Then when we though all was stable, lots of calcium in, and K was shifted, we saw this:


So here is the story:

A patient with a history of diabetes and renal failure, on dialysis, was found with a very rapid heart rate.  He was awake and responsive.  Here is the rhythm on the monitor:

There is a wide complex tachycardia.  It is difficult to diagnose without a 12-lead ECG.

  A 12-lead was obtained rapidly:
There are no P-waves.  There is a wide complex very similar to LBBB, but quite wide at 161 milliseconds.  However, the initial part of the QRS is rapid - the onset of the R-wave in right precordial leads to the nadir of the S-wave is only 60 ms, and the R-wave itself is approximately 25 ms.  Therefore this appears to be supraventricular tachycardia with aberrancy.
(It did not occur to me at the time that it might be extremely slow atrial flutter with 1:1 block, which is what I now believe it was).  
 
 There was an recent ECG for comparison:
This has very slow atrial flutter (flutter rate about 204) with 2:1 block and a PVC every 4th beat.  There is a wide complex at 135 ms, which also appears to be LBBB and has a similar morphology to the presenting ECG above.  It should have occurred to me at this point that he was still in atrial flutter, but was with a faster and more regular ventricular response due to a slower flutter rate (slower because of hyperK) that could conduct 1:1 (very rapid)!

Thus, the presenting ECG appeared to me to be SVT with LBBB that is wider than baseline.  A wide QRS is due hyperkalemia until proven otherwise, especially if it is very wide (most LBBB is not wider than 160 ms), and particularly/especially in a dialysis patient.

I considered using adenosine was but thought it prudent to start with calcium, so we gave 3 g of calcium gluconate immediately into a rapidly accessed external jugular vein.

He converted to what we thought was atrial fibrillation with RVR, (but was, in retrospect, atrial flutter with variable block) and the same wide complex.  Unfortunately, there is no image of this.

Shortly thereafter, this is what happened:

Ventricular Tachycardia
The patient continued to be responsive and have a pulse.

He went in and out of this VT rhythm spontaneously as we gave successive 3 g doses of calcium gluconate over the next 20 minutes.  This 12-lead was captured during one of the many episodes:
This QRS at 338 milliseconds duration cannot be anything but VT
Each time we gave calcium, the VT converted and stabilized for several minutes.  Dialysis was prepared.  The patient was also given intramuscular terbutaline, 2 doses of insulin and D50, bicarbonate (in spite of the risk of fluid overload), and albuterol by nebulization.

FYI--lowering of K by use of beta-2 adrenergic agonists.
--0.5 mg of IV albuterol reduces K by about 1.2 mEq/L. 
-- A 20 mg neb (most are 2.5 mg) lowers it by about 1.0 mEq/L.  
--A 10 mg neb lowers it by about 0.6 mEq/L.
-- I give 0.25 mg of IM terbutaline to an adult, but only if it is critical, and add nebulized albuterol also.  I've never given it IV, as I'm a bit reluctant to risk the cardiac irritability.


K returned at 7.5 mEq/L, repeat was 6.7 mEq/L

He seemed to stabilize in this rhythm with a much narrower QRS:
Initially I saw this on the monitor and thought it was a conversion from PSVT to atrial fibrillation.  But, looking at it again, it is obviously a very slow atrial flutter at a rate of 168, with alternating block, 1:1 or 1:2, and a resulting ventricular rate of 114.

 Shortly thereafter, he was seen to be in this rhythm:
There is a relatively narrow complex (not bizarrely wide).  There are no clear P-waves.  The rate was 171.

 On the rhythm monitor only, no P-waves could be seen and this was thought to possibly be recurrent PSVT (though of course it is very slow atrial flutter with 1:1 block, as I can see now).  6 mg of adenosine was given without effect.

Then, 12 mg, of adenosine were given rapid push.

This was the result:
Recurrent VT (which had been recurring many times in this case)

Pulses were still intact.  More calcium was given.  The patient was intubated also.

The patient went back into this rhythm:
Same "SVT" as before.  (Really, it is slow flutter with 1:1 block)
A 12-lead was obtained:
There appear to be P-waves in V1.  They are upright, which suggests atrial flutter.  We know the previous atrial flutter rate was 168 (close to 171), so this is now atrial flutter with 1:1 conduction.

I (erroneously) thought the patient was in sinus tachycardia.  Then the question then was "why is this patient in sinus tach?"  A bedside ultrasound showed very poor EF and it appeared to be cardiogenic shock.  BP was  recorded as 214/143 by cuff, so afterload reduction was going to be started.  An arterial line was placed and the real BP was 80/50.  No afterload reduction was done!!

Dialysis was ready and he went for emergent dialysis.  Shortly thereafter, his AV node began to block some of the flutter impulses, and the ventricular response slowed.  This was recorded less than 2 hours later.
Slow atrial flutter with 2:1 block, PVCs, and a narrower LBBB.  K was normalizing.


Why was the flutter rate so slow?   It is uncertain.  He was on no Na channel blocking agents.  But hyperkalemia will slow atrial flutter.  Thus, his initial atrial flutter was much slower than baseline (160 vs. 204), but after treatment for hyperkalemia, the rate was 170.  At either rate, 160 or 170, the flutter is slow enough to conduct 1:1 and result in a very fast ventricular rate.

Slowest possible Atrial Flutter Rate

Our electrophysiologist says he has mapped atrial flutter as slow as 140.  This was new to me.  I did not consider atrial flutter because it was so slow.  K. Wang has an ECG with the flutter rate (not ventricular rate) at 150 in a patient taking Procainamide.

The Paradox: although the calcium was necessary to treat the VT, it also allowed the flutter rate to increase.  This sometimes improved the situation and sometimes made it worse:

1) the AV node could not conduct that fast and so there was alternating 1:1 and 2:1 block, resulting in a SLOWER ventricular rate.
2) sometimes, the AV node could conduct all beats and the ventricular rate went FASTER, at 170, leading to hypotension


Outcome:

The patient dialyzed and electrically stabilized and did well

Diagnoses:

1. HyperK

2. Atrial flutter with variable block and aberrancy due to pre-existing LBBB (or IVCD) with extra widening due to superimposed hyperkalemia.
3. Ventricular Tachycardia due to hyperkalemia

Lessons:

1. Always think of HyperK
2. Remember Calcium, D50 and insulin, Beta-2 agonists, and Bicarb (?)
3. SVT includes atrial flutter, and its rate can be as slow as 140!

7 comments:

  1. Very interesting story! I first thought it was 2:1 flutter on the first EKG. There is that little notch after each QRS and I imagined I could trace another one in the middle in aVR (but it's not easy not having the EKG on paper). But you're probably right and this is a good lesson to remember!

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  2. Replies
    1. 1. Because this is clearly a supra ventricular rhythm with an extra wide BB due to hyperK. 2. Renal failure patients are almost never hypomagnesemic. Usually have elevated Mg. Can be dangerous to give them Mg. 3. Calcium is very safe.

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  3. Forgive me if I am wrong, but I don't get it why it's a LBBB, instead of a RBBB. When I look at V5-6 and I and aVL, I am not convinced. Can anyone explain it to me?

    ReplyDelete
    Replies
    1. Technically, it is IVCD because V5 and V6 do not have the broad monophasic R-wave in every one of the tracings. That is why I said "very similar to LBBB" but did not say "LBBB". I don't think it matters to the rhythm diagnosis or even to ST-T analysis.
      Steve Smith

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