ECG Review
Any Acute Changes?
By Ken Grauer, MD, Professor Emeritus in Family Medicine, College of Medicine, University of Florida. Dr. Grauer is the sole proprietor of KG-EKG Press, and publisher of an ECG pocket brain book.
Scenario: The 12-lead ECG shown above was obtained from a 72-year-old woman seen in the emergency department (ED) with new-onset chest discomfort. No prior ECGs were available for comparison. The tracing was interpreted as "showing no acute changes." Do you agree? What else do you see?
Interpretation: The rhythm is sinus at a rate of ~75/minute. All intervals and the axis are normal. There is no chamber enlargement. With regard to Q-R-S-T changes, there are several findings of note:
1) There are Q waves (QS complexes) in anteroseptal leads V1-through-V3. A small positive deflection (r wave) finally develops by lead V4. Thus, transition is delayed (only occurring between leads V4-to-V5).
2) There is subtle (but real) ST segment elevation in lead aVL.
3) Support that the subtle ST elevation in aVL is truly a real finding is forthcoming from the ST segment flattening and subtle (but real) ST depression seen in each of the inferior leads (II, III, aVF).
It is important to remember that the shape of ST elevation is more important than the amount of elevation. Acute myocardial infarction (MI) may sometimes occur with only minimal ST elevation. We judge ST segment deviations (elevation or depression) with respect to the PR segment baseline. Of the five lateral leads (I, aVL, V4, V5, V6), lead aVL views the heart from the highest and most peripheral perspective (looking down at the heart from the left shoulder). As a result, lead aVL may sometimes be the only lateral lead to show acute changes (as may be the case here).
Given the clinical history of a 72-year-old woman presenting to the ED with new-onset chest discomfort and no prior tracing available for comparison, the findings in the ECG shown are clearly of concern. Lack of any r wave at all until lead V4 suggests prior anteroseptal infarction. The subtle (but real) ST elevation in lead aVL with equally subtle (but real) "reciprocal changes" in leads II, III, and aVF suggest that the patient may be in the process of evolving an acute high lateral MI. ECG changes of acute MI may evolve quickly sometimes in less than an hour. Careful observation, presumptive initial treatment measures, serum troponins, and repeating the ECG in short order should clarify the clinical picture.
Scenario: The 12-lead ECG shown above was obtained from a 72-year-old woman seen in the emergency department (ED) with new-onset chest discomfort. No prior ECGs were available for comparison. The tracing was interpreted as "showing no acute changes." Do you agree? What else do you see?You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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