ECG Review
What's There to Worry About?
By Ken Grauer, MD, Professor, Department of Community Health and Family Medicine, University of Florida Dr. Grauer is the sole proprietor of KG-EKG Press, and publisher of an ECG pocket brain book.
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Clinical Scenario
The ECG shown above was obtained from a 63-year-old man with chest pain. How would you interpret his tracing and accompanying lead II rhythm strip? What is there to worry about?
Interpretation/Answer
There is a lot to be concerned with on this tracing. The rhythm is irregularly irregular at an average rate of more than 100/minute. Although there are fine undulations in the baseline, no definite P waves are seen. Thus, the rhythm is atrial fibrillation with a fairly rapid ventricular response. The QRS complex is clearly wide. QRS morphology in leads V1 and V6 is consistent with a bifascicular block pattern of RBBB (right bundle branch block) with LAHB (left anterior hemiblock). However, the monophasic R wave in lead I is not consistent with RBBB, but rather with a LBBB (left bundle branch block) pattern. Description of QRS morphology in this tracing might therefore better be classified as IVCD with LAD (intraventricular conduction delay with left axis deviation). In view of this patient's presentation (ie, chest pain) the most important finding on this tracing is the subtle appearance of Q waves with slight but definite ST segment coving and elevation in leads V1 and V2. T wave inversion in these two leads is an expected accompaniment of RBBB, but the ST segment elevation is not. At times, a QR rather than RSR' complex may be seen in lead V1 with RBBB but a Q wave will usually not be seen in both leads V1 and V2 with RBBB unless there has been infarction.
Detection of acute myocardial infarction is always more challenging in the presence of a conduction defect. This is especially true with LBBB, since infarction Q waves are rarely written, and ST-T wave changes will often be masked by the underlying LBBB. Recognition of acute ischemia or infarction is still challenging in the presence of RBBB, but the findings seen in leads V1 and V2 of this tracing in the setting of new-onset chest pain should suggest the possibility that acute infarction may be occurring. Clinical correlation and comparison with a prior tracing on this patient would help clarify if the findings in leads V1 and V2 are new or old.
The ECG shown above was obtained from a 63-year-old man with chest pain. How would you interpret his tracing and accompanying lead II rhythm strip? What is there to worry about?You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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