Saturday, June 6, 2015

Very Wide and Very Fast, What is it? How would you treat?

This was contributed by one of our EM residents, Lauren Klein, with some editing by Smith.


An elderly male who missed dialysis presented to the emergency department complaining of 1 day of chest pain and shortness of breath at rest.  Upon arrival to the ED, he was awake and well perfused and neurologically intact, and this ECG was obtained:
What is it and how would you treat it?


This is a very wide complex tachycardia with a sine wave morphology at a rate of about 160 and a QRS duration of about 220 ms.  Hyperkalemia by itself can have exactly this morphology (sine wave), but should not be so fast.  On the other hand, ventricular tachycardia is fast but rarely has such a sine wave morphology with such a super wide QRS.  Thus, this is very likely ventricular tachycardia in the presence of hyperkalemia, especially as VT is a common complication of severe hyperkalemia. 

Hyperkalemia with extreme tachycardia may be present without VT in severely ill patients, as in this case (this is worth a look).  However, this patient is not extremely ill and it would be more common to have a heart rate like this one.

It would be appropriate to treat for both (use cardioversion and Calcium and Potassium shifting therapy).

Case continued

The ED providers went on to give the patient calcium gluconate, IV insulin and dextrose to shift the patient's (presumed) hyperkalemia. As they were doing this the potassium came back at 7.4 mEq/L.
The next ECG at 19 minutes later looked like this:
The rate remains very fast, but the QRS width is now about 180 ms.  
 Third ECG at 34 minutes looked identical.

Treatment of hyperkalemia will shorten the QRS duration of VT or of SVT with aberrancy.

As emergent dialysis was being prepared, the patient's mental status began to decline and the decision was made to intubate and cardiovert the patient. After intubation he was cardioverted (synchronized, 100J) with a single shock. This was his subsequent ECG.
There is now sinus rhythm at a rate of approximately 100 with RBBB and a QRS duration of 175 ms (long for RBBB, but typical for RBBB with hyperkalemia).  There is also a left anterior fascicular block.    This confirms that the previous fast rhythm was indeed a re-entrant shockable rhythm, VT vs. SVT with aberrancy.   

Smith Comment: It would have probably worked very well to shock earlier.  I would not use propofol for this, but would give a small dose of ketamine.  I believe that intubation could have been avoided if cardioversion with ketamine had been done early.

VT or SVT with aberrancy?  My friend from France, Pierre Taboulet, of, makes the accurate point that the QRS morphology of the fast rhythm has the same RBBB configuration as the sinus rhythm, so that the fast rhythm was probably SVT with RBBB/LAFB aberrancy, extra wide due to the hyperkalemia.  Thus, adenosine may well have worked!

Of note, the patient did have a baseline RBBB morphology, but, his QRS was not typically this wide. RBBB alone should have a QRS duration less than 170 ms (see this post) 

Later, after more decline in the potassium, this ECG was recorded: 
Now the QRS is still shorter, at 157 ms, more typical of standard RBBB.

The patient went on to emergent dialysis, was extubated later that day. He was discharged and is doing well. 


  1. I miss an echo in this report
    Did the patient have an old infarction as it looks like by the ECGs?

    1. Adolfo,
      sorry, I do not know. But, as you say, it a appears so on the ECG.

  2. Hi Dr Smith,

    Nice case again.

    Would the use of Amiodarone be warranted in the first stage of care as the patient was seemingly haemodynamically stable (I'm referring to his good perfusion and good neurological status)? Or would it be in conflict with the treatment of hyperkalemia, given Amiodarone’s K+ channel blocker properties?

    On the different ECGs: in the first one, we can determine a visible “extreme” leftward axis (Beyond -60° with positive aVL and isoelectric aVR) which remains during the course of the treatment until the rhythm reverts back to sinus. As expected, a more or less deep S-wave is visible in lead I the width of which narrows as the QRS duration shortens; however, such S-wave would also be obviously apparent on a more leftward lead as is aVL, yet it is never to be seen, be it in the VT ECGs or the sinus ones.

    This is really a minor detail, but for some reason it really caught my eye !

    Best regards,


    1. Olivier,
      You will see that I have changed my interpretation. I believe it was SVT with aberrancy. Adenosine would probably have worked. In any case, cardioversion is good as long as the sedation used does not have adverse hemodynamic effects.

  3. Very nice case
    But I dont agree with
    "This confirms that the previous fast rhythm was indeed a re-entrant shockable rhythm, probably VT."
    it was probably a SVT (the QRS look very much the same per tachycardia and per sinus rhythm)
    Pierre T

  4. Great case.
    Thanks Dr. Smith.
    I follow you, always with great interest.
    Greetings from Italy.

    1. Thanks, Vittorio! Always good to hear from you.

  5. Thank you for this interesting case, sir.

    In patients with both severe hyperkalemia and WCT like this case, should we treatment hyperkalemia first or cardioversion first, sir? And should we give calci gluconate to protect the heart before electrical shock? I'm afraid that electrical shock in severe hyperkalemia may not be effective and lead to ventricular fibrillation.

  6. How can u differentiate between hyperkalemia and V tach in ECG ?

    1. no single way. Keep reading this blog, search for both in the search box, look at the index (labels) for both.


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