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By Ken Grauer, MD
Figure. ECG obtained from a 55-year-old man with heart failure and emphysema.
Clinical Scenario: The echocardiogram (ECG) in the Figure was obtained from a 55-year-old man with a history of heart failure and emphysema. What might his ECG show?
Interpretation: The rhythm is sinus at a rate of about 90 beats/minute. Occasional PACs (premature atrial contractions) are seen (4th beat in lead V1 and in lead V4). There is a marked right axis deviation (RAD). Assessment for hypertrophy suggests four chamber enlargement. Small q waves are present in the inferior and lateral precordial leads. ST-T wave abnormalities in these same leads is consistent with "strain," although the slight ST segment coving in leads V5, V6 in association with fairly symmetric T wave inversion also could reflect ongoing ischemia.
In general, the ECG is an insensitive indicator of chamber enlargement. When assessment of chamber enlargement and function is essential to patient management, echocardiography should be obtained. That said, interpretation of the ECG pattern in the context of the clinical setting can suggest the anatomic substrate in selected cases.
The patient in this case was known to have pulmonary disease (emphysema) and heart failure. The ECG in the Figure is diagnostic of left ventricular hypertrophy (LVH), in that there is a deep S wave in lead V2, and very tall R waves in leads V5 and V6 that occur in association with ST-T wave changes of "strain."
Although the pattern of RAD seen here is consistent with left posterior hemiblock (LPHB), this type of hemiblock rarely occurs as an isolated conduction defect. Therefore, the RAD seen in this tracing is much more likely to reflect right ventricular hypertrophy (RVH). The deep negative component to the P wave in lead V1 suggests either left or right atrial enlargement also may be present. Lead II P waves appear bifid rather than tall, favoring left atrial enlargement over right.
Dr. Grauer, Professor and Associate Director, Family Practice Residency Program, Department of Community Health and Family Medicine, College of Medicine, University of Florida, Gainesville, is on the Editorial Board of Emergency Medicine Alert.