Wagner_Marriot's Practical Electrocardiography, 12e

I

aVR

V1

V4

II

aVL

V2

V5

III

aVF

V3

V6

II

F I G U R E 7 . 5 .

Ventricular preexcitation during atrial fibrillation.

Ventricular preexcitation, induced by an accessory pathway, influences the ventricular rate to become rapid in the presence of an atrial tachyarrhythmia such as atrial flutter/ fibrillation (see Chapter 17). During such an episode, the ventricles are no longer “protect- ed” by the slowly conducting AV node. A 12-lead ECG recording with a lead II rhythm strip of a 24-year-old woman with ventricular preexcitation during atrial fibrillation is displayed in Figure 7.5. The irregularities of both the ventricular rate and QRS complex morphology are apparent, especially on the 10-second lead II rhythm strip at the bottom of the figure.

155

CHAPTER 7: Ventricular Preexcitation