Figure 206-13

Induction of sustained ventricular tachycardia due to bundle branch reentry (BBR). The surface electrocardiogram and intracardiac tracings are Labeled. Basic cycle Length (S151) is 400 ms during ventricular pacing. Sustained BBR is induced with two extra stimuli (S2S3). Note that the His bundle and right bundle (RB) defLections precede the QRS, suggesting supraventricular tachycardia with aberrant conduction. However, there is 2:1 ventricular atrial (VA) block, indicating the ventricular nature of this tachycardia. Without His bundle/right bundle (HB/RB) recordings, the diagnosis can be difficult and, consequently, the likelihood of inappropriate therapy will be high. RB-RB and V-V (ventricular) intervals are labeled.

(From Jazayeri et al. Reproduced with Dermission from the publisher and authors.)