Friday, December 24, 2010

ECG Interpretation Review #10 (Peaked T Waves, Ischemia vs Hyperkalemia vs Normal Variant)

QUESTION: Interpret the 12-lead ECG below, obtained from an older patient with multiple medical problems (and on multiple medications).
  • Clinically  What do you suspect is going on?
  • Is there ECG evidence of ischemia? (What will have to happen before you'll be able to answer this question? )
Figure 1 (ECG reproduced from ECG-2014-ePub )
 Note  Enlarge by clicking on Figures 












      
INTERPRETATION:  The rhythm is sinus at a rate just under 100/minute. The PR and QRS intervals are normal.  The QT looks to be about half the R-R interval, so that it is borderline prolonged. The axis is abnormal. The small amplitude but predominantly negative QRS complex in lead I indicates RAD (Right Axis Deviation) of at least +100 degrees.  There is no chamber enlargement.
  • Q-R-S-T Changes  There appear to be Q waves in leads I,aVL  and QS complexes in V1,V2.  Transition may be slightly delayed, with the QRS becoming more positive only in lead V5. However, the most remarkable finding are the very tall, peaked T waves with narrow base ("Eiffel Tower" effect) in several precordial leads (Figure 2).  This strongly suggests Hyperkalemia.  In addition  T waves are inverted sharply in leads III and aVF of Figure 1, and there is some straight ST segment depression in inferior and anterolateral leads.
Figure 2 - Blow-up of Figure 1  showing tall, peaked T waves ("Eiffel Tower effect" ) of hyperkalemia.
(Reproduced from ECG-2014-ePub )
Clinical PEARL: The ECG is the net result of the heart's electrical activity. It is difficult to know the clinical significance of RAD and the ST depression/T wave inversion seen here given the setting of superimposed hyperkalemia.  One will not know the "true" ECG story until the electrolyte disorder (and the ECG changes of hyperkalemia) have been corrected . . .
  • Axis deviation  QRS widening with changes in QRS morphology  and peaked T wave inversion are all examples of ECG abnormalities that may simply be due to the hyperkalemia.
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ECG Changes of Hyperkalemia: In general  the ECG correlates well with the degree of serum potassium elevation  (Figure 3).
Figure 3  ECG Manifestations of Hyperkalemia.
(Reproduced from ECG-2014-ePub .
  • Panel   shows a normal ST-T wave.
  • Panel   T wave peaking is the earliest change of hyperkalemia.
  • Panel C  The T wave becomes taller and more peaked (K+ ~ 7-8 mEq/L); it almost looks like the Eiffel Tower (tall, peaked, with narrow base in contrast to the T wave that is sometimes seen in healthy individuals (lower right box in Figure 3), in which the T wave is rounded, its sides are not symmetric, and it has a broad base.
  • Panel D  P wave amplitude decreases, the PR interval lengthens, and the QRS widens (K+ >8 mEq/L).
  • Panel E  P waves disappear (sinoventricular rhythm) and the QRS becomes sinusoid (K+ >10 mEq/L).  V Fib usually follows.
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    Final Point: All that produces tall, peaked T waves is not necessarily hyperkalemia! Instead, the finding of Twave peaking should prompt one to consider a differential diagnosis of 3 possible causes  with the clinical situation (as well as specific ECG features) providing KEY clues as to which of the 3 is likely to be present.
    1. Hyperkalemia - Suspect as the cause of T wave peaking when the clinical setting is one likely to produce hyperkalemia (ie, renal failure, volume depletion, acidosis, potassium-retaining drugs and  when T waves are tall, pointed with steep ascent and near equally steep descent with a narrow base (as seen in Figure 2 ).
    2. Normal (RepolarizationVariant  Suspect when T wave peaking has a more rounded summit with assymetric ascent and descent and a broader base  especially IF the patient is otherwise healthy and without any apparent reason to have hyperkalemia (We saw this in Figure 1 of ECG Review #6).
    3. Ischemia - Although a much less common cause of T wave peaking than hyperkalemia and normal repolarization variants  it should be appreciated that myocardial ischemia (in the area of the left ventricular posterior wall) may sometimes present with the ECG finding of tall, peaked T waves in the anterior leads. Be aware of ischemia as a possible cause of T wave peaking in leads V1,V2,V3 when a patient with known (or suspected) coronary artery disease presents with chest pain  especially if there is other evidence on the tracing to suggest ischemia or infarction (ie, inferior T wave inversion or ST depression).
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    • See Section 11.0 on Electrolyte Disturbances (in ECG-2014-ePub) – with the part on Hyperkalemia beginning in Section 11.3.
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    14 comments:

    1. I was a little concerned with the elevation in aVR and V1 and the reciprocal depression in the inferior leads. Could this not be LMCA occlusion?

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    2. Hi Christopher. Your question relates to the "Clinical Pearl" that I wrote in my answer (above) - namely, that even though there are MANY changes of potential concern for ischemia/infarction on this tracing - in light of Hyperkalemia - "all bets are off!" -until you correct the hyperkalemia. Clinically - obtaining troponins and observation in a monitored unit are appropriate - but no conclusions about QRST morphology should be drawn until the hyperkalemia has resolved. Thanks for your comment! - Ken Grauer, MD

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    3. Thank you, is this because of the large influence potassium plays in the electrophysiology? If that is the case, it would make sense that until you correct Hyper-K you may not be able to trust any other findings you may have.

      Which brings up a second question, say this patient was altered (or this is your post arrest rhythm) and received CaCl or calcium gluconate boluses to empirically treat the Hyper-K. At what point do you start trusting your EKG signs? Normalization of serum potassium levels?

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    4. YES - Until you correct Hyper-K you are NOT able to "trust" other findings you may have. You may develop suspicion of what could be going on ... but you can't be sure until K+ is corrected. Shouldn't matter, because you're not going to cath a patient with the T waves seen here ... - KG -

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    5. Im a 28 y/o m no cardiac hx. Been feeling very fatiguefor a few months lately so did an ecg at work and found i have very high peaked t waves should i be concerned.

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      1. Let me first mention obvious disclaimers that this ECG Blog is not intended to serve as a medical consult (and I have retired my license to practice) - so I would recommend you following up with your primary care physician.

        As to your question - you'll note in Figure 3 above (in this Blog) the picture of a "Normal Variant" pattern that manifests T wave peaking. It is relatively common (especially in people of your age) to manifest T wave peaking on ECG that is completely benign. Full assessment of this can be provided by your physician after examination and after seeing your actual ECG. - Ken Grauer, MD -

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    6. Could you tell me more about Q in leads I, aVL and QS in leads V1, V2?

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      1. @ Canxi - Please see Figure 5 in my ECG Blog 94 regarding the QS in V1,V2 - http://ecg-interpretation.blogspot.com/2014/07/ecg-blog-94-basic-concepts-7-qrst.html -

        Please see my ECG Blog #79 regarding when Q waves and T inversion may be normal in the limb leads - http://ecg-interpretation.blogspot.com/2013/11/ecg-interpretation-review-79-normal-q.html

        Let me know if you still have questions after reviewing the above. THANKS for your interest - :)

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    7. I had a client doing the Bruce Protocol, her ECG was normal until the recovery phase, in which T waves on V5 and V6 were taller, much taller than normal. We think it may be hyperkalemia, but we couldn't confirm it.

      Could you please let us know if there is/are something that we are missing?

      What else could cause that abnormal ECG?

      Thank you

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      Replies
      1. Great question that brings out an important point. First — I'll assume that you did NOT initially suspect hyperkalemia, because otherwise you would NOT have done an ETT on this patient! That's important — because hyperkalemia usually occurs as a result of a limited number of causes (ie, K+-retaining meds; dehydration; renal disease; acidosis; trauma). So much (most) of the time if there is no predisposing cause(s) — T wave peaking is not due to hyperkalemia ... The other point to be aware of is that a NORMAL response to exercise in otherwise healthy young adults without underlying heart disease (and with normal electrolytes) — is to develop very tall peaked T waves, esp. during recovery. That is almost certainly what happened in your case.

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    8. Excuse me but I have a basic doubt .. Why does T wave
      Peak for hyper K ?? I mean hyper K stops the heart in
      Diastole yet you still have a T wave ... And that too of above
      Normal magnitude ... Help me understand pls

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    9. Hello Vishnu. The phsyiologic explanation for why the T wave peaks is complex, and to be frank — something I have to look up each time this comes up. This link reviews the pathophysiology — http://www.hcplive.com/medical-news/electrophysiologic_basis — I must admit that I am happy to "accept" that the earliest change of significant hyperkalemia is T wave peaking ...

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    10. Hi sir when we say t wave is tall

      Kindly mention the height of T wave to say it as tall

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      1. @ Anonymous — There is no absolute number of mm amplitude that defines a T wave as "tall". Instead, this is a relative description, based on the overall ECG pattern and QRS appearance in the 12 leads. In this example, there should be NO DOUBT that the T wave in lead V2 is disproportionately tall compared to the QRS complex. The same in V3 to a much lesser extent. Hope that explains your question.

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