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(Circulation. 2007;115:e200.)
© 2007 American Heart Association, Inc.

Correspondence

Letter by Del-Carpio Munoz et al Regarding Article, "Masking Inferior Infarction by Anterior Myocardial Injury"

Freddy Del-Carpio Munoz, MD; Robert J. Myerburg, MD; Agustin Castellanos, MD

Division of Cardiology Department of Medicine, University of Miami Miller School of Medicine, Miami, Fla

To the Editor:

In the July 25th, 2006, issue of Circulation, Deng and Das¹ conclude that an old inferior myocardial infarction (Figures 1 and 3 of their article) was masked by an acute anterior-wall injury pattern (Figure 2 of their article). They state that the possible mechanism is a well-known electrocardiographic principle: Electrical forces in one zone reciprocally change the QRS vector on the opposite myocardial zone. We agree with this principle, but we disagree with the interpretation of the tracings.

If carefully analyzed, although the second ECG tracing certainly shows the disappearance of the inferior myocardial infarction, there are new and similar pathological Q waves in the left lateral leads (I, aVL). We believe that this ECG demonstrates changes attributable to improper limb–lead positioning, with the left-arm and left-leg electrodes reversed. This conclusion explains all of the ECG changes: Lead I in the original tracing is similar to lead II in the second tracing, and lead II in the first tracing is similar to lead I in the second tracing. Lead III in the first tracing is the opposite (reversed) lead III. Likewise, aVL in the first tracing is similar to aVF in the second tracing, and aVF is similar to aVL in the second tracing. Lead aVR remains unchanged because this cable was correctly placed on all tracings. Finally, the P-wave morphology in leads I and II is reversed.

This ECG presentation emphasizes the importance of adequate ECG interpretation, not only regarding the accurate diagnosis on the basis of theoretical approach, but also in a more practical one. The possibility of technical errors such as lead misplacement should be kept in mind.

	Acknowledgments

 
Disclosures

None.

	References

Top References

 

1. Deng C, Das B. Masking inferior infarction by anterior myocardial injury. Circulation. 2006; 114: e62–e63.[Free Full Text]
   

This Article Extract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Munoz, F. D.-C. Articles by Castellanos, A. Search for Related Content PubMed PubMed Citation Articles by Munoz, F. D.-C. Articles by Castellanos, A. Pubmed/NCBI databases Medline Plus Health Information Heart Attack Related Collections Electrocardiology