Wagner_Marriot's Practical Electrocardiography, 12e

I

II

III

aVR aVL aVF V1 V2

V3

V4 V5 V6

A

I

II

III

aVR aVL aVF V1

V2 V3 V4

V5

V6

B

V2

V3

I

II

III

aVR aVL aVF V1

V4

V5

V6

C

F I G U R E 7 . 8 .

A. Delta waves ( arrows ). B and C. Delta waves mimicking myocardial infarction

( arrows ).

Ventricular preexcitation may mimic a number of other cardiac abnormalities. When there is a wide, positive QRS complex in leads V1 and V2, it may simulate right-bundle- branch block, right-ventricular hypertrophy, or a posterior myocardial infarction. When there is a wide, negative QRS complex in lead V1 or V2, preexcitation may be mistaken for left-bundle-branch block (LBBB; Fig. 7.8A) or left-ventricular hypertrophy. A negative delta wave, producing Q waves in the appropriate leads, may imitate anterior, lateral, or inferior infarction. The prominent Q waves in leads aVF and V1 in Figure 7.8B could be mistaken for inferior or anterior infarction, respectively (see Chapter 12). Similarly, the deep, wide Q wave in lead aVF and broad initial R wave in lead V1 in Figure 7.8C could be mistaken for inferior or posterior infarction, respectively.

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SECTION II: Abnormal Wave Morphology