Wagner_Marriot's Practical Electrocardiography, 12e

ELECTROCARDIOGRAPHIC DIAGNOSIS OF VENTRICULAR PREEXCITATION

I

aVR

V1

V4

II

aVL

V2

V5

III

aVF

V3

V6

A

I

aVR

V1

V4

II

aVL

V2

V5

III

aVF

V3

V6

B

F I G U R E 7 . 6 .

Positive and negative delta waves ( arrows ) in two patients.

Typically, with ventricular preexcitation, the PR interval is 0.12 second in duration and the QRS complex is 0.10 second. Ventricular preexcitation produces a prolonged upstroke of the QRS complex, which has been termed a “delta wave.” Positive delta (V1 to V5, I and aVL) and negative delta (II, III, and aVF) waves are illustrated in Figure 7.6.

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SECTION II: Abnormal Wave Morphology