Monday, February 23, 2015

ECG Blog #106 (Sinus Tachycardia - Hyperkalemia - DeWinter T Waves - Heart Rate)

Interpret the ECG shown in Figure 1 — obtained from a middle-aged adult.
  • Are there DeWinter T waves in the chest leads of Figure-1? Is this patient about to occlude his proximal LAD (Left Anterior Descending) coronary artery?
  • OR — Does this patient have hyperkalemia?
  • HINT: What is missing (that should never be missing)?
Figure 1: ECG obtained from a middle-aged adult. Are these DeWinter T waves? Does the patient have hyperkalemia? NOTE — Enlarge by clicking on Figures — Right-Click to open in a separate window.
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Systematic Interpretation of Figure 1: There is some baseline movement with slight artifact. The overall rhythm is regular — with upright P waves in lead II, so that the rhythm is Sinus Tachycardia. The rate is ~160/minute (the R-R interval is just under 2 large boxes in duration).
  • The PR interval is normal — and the QRS complex is narrow. The QT interval is probably normal given the exceedingly rapid heart rate.
  • The axis is indeterminate (QRS complexes are nearly isoelectric in virtually all limb leads).
  • There is no chamber enlargement.
Regarding Q-R-S-T Changes:
  • There appears to be a Q wave in lead aVL.
  • Transition is slightly delayed to between V4-to-V5 (as the point where the R wave becomes taller than the S wave is deep).
  • The most remarkable finding on this tracing are the rather tall and peaked T waves, especially in leads V2-thru-V4. In a patient with chest pain — this appearance resembles that of the DeWinter T waves that herald proximal LAD occlusion. There is even suggestion of some J-point ST depression in leads V3,V4 and V5 prior to the steep rise in T wave ascent. In a patient predisposed to hyperkalemia — the T wave peaking seen here should also prompt consideration of this electrolyte disorder.
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QUESTION: What is missing from this presentation?
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ANSWER: No history was given ...
  • It turns out that this 12-lead ECG was recorded as part of an exercise stress test on an otherwise healthy and asymptomatic middle-aged man. The purpose of this test was to assess exercise capacity. There was no chest pain — and no history of renal disease or other medical problems.
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The LESSON to Be Learned: ECGs cannot be intelligently interpreted in a vacuum. If told that this patient was having new-onset worrisome chest pain — We would wonder why he is so tachycardic, and we would clearly be concerned that the prominent T wave peaking might be ischemic or a DeWinter T wave equivalent. We would check serum K+ values as part of our evaluation, especially if the patient had any factors potentially predisposing to hyperkalemia.
  • T wave peaking as seen here commonly occurs in healthy adults during exercise. This T wave change is transient — and resolves after termination of exercise.
  • Rapid-upsloping ST segment depression as seen here in several chest leads is a normal response to exercise.
  • This patient had excellent exercise capacity for his age. His exercise test was entirely normal — and he was cleared to perform vigorous aerobic activity. No laboratory testing was done (as none was necessary).
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- For more information  GO TO:
  • For review of the Systematic Approach to ECG Interpretation — Check out our ECG Blog #93
  • For review on DeWinter T Waves — Check out our ECG Blog #53.
  • For review on Hyperkalemia — Check out our ECG Blog #10.
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3 comments:

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  2. I find these interpretations extremely helpful. As a technician and frequent contributor to http://www.ekgtechniciansalary.org/ I try to make sure that I convey the importance of considering the condition in the context of the symptoms and patient complaints. Ultimately, I'm very happy to work with licensed personnel who are very skilled in the interpretation of electrocardiograms.

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