CHAPTER 7: Ventricular Preexcitation
155
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.
I
aVR
V1
V4
II
II
aVL
V2
V5
III
aVF
V3
V6
F I G U R E 7 . 5 .
Ventricular preexcitation during atrial fibrillation.
