Case A13. Posterior Infarction with Lateral Ischaemia. St Emlyn’s ECG Library

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The ECG was recorded from a 78 year old man admitted to the emergency department with severe chest pain radiating into the centre of the back.

ECG

There are raised ST segments typical of acute infarction in leads I, II, aVL, V5 and V6. There are pathological Q waves in the same leads. The appearances are those of lateral infarction. In lead VI and V2 there are tall R waves greater than .04 seconds in duration accompanied by ST depression that extends to V3. In this record the technician has recorded additional leads V7, V8 and V9 which look specifically at the lateral and posterior surface of the heart. The typical raised ST segments of acute infarction are present in these leads and pathological Q waves are also present.

Comment

The typical appearances of acute lateral and true posterior infarction are present and the evidence for this has been extended by recording additional leads that look specifically at the areas of interest. The presence of true posterior infarction is inferred by the findings in leads VI and V2. The tall R waves are the reciprocal of the Q wave seen in a lead overlying the posterior of the heart (eg lead V9) and the depressed ST segments in VI and V2 are the reciprocal of the ST elevation seen in a lead recording over the infarcted area. As the ST segment in a posteriorly placed lead returns to the baseline and T wave inversion occurs, the reciprocal change of a tall peaked T wave tvill appear in VI and V2.

NB Lead V7, V8 and V9 are all taken at the same level as V6: in the posterior axillary line in V7, mid scapular line in V8, and in the left paravertebral line in V9. As a rough guide 0.5mm of elevation is considered significant in the posterior leads, but morphology is arguably as important when interpreting these ECGs in the ED.

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