1. Volume 11, Issue 1, Pages 163-166 (January 2014)
The value of a rate change in determining the tachycardia mechanism: Which circuits are involved? 
Eduardo Back Sternick, MD, PhD, FHRS, Yash Lokhandwala, MD, DM, FACC, Hein J.J. Wellens, MD, PhD, FACC 
Heart Rhythm 
Volume 11, Issue 1, Pages (January 2014)
DOI: /j.hrthm
Copyright © 2014 Heart Rhythm Society Terms and Conditions

2. Figure 1
Left panel showing a left bundle branch block (LBBB)-like tachycardia spontaneously changing into a narrow QRS complex tachycardia (right panel). Transition from wide to narrow occurs abruptly after a QRS complex showing an intermediate morphology. Note the higher rate of the LBBB-like tachycardia.
Heart Rhythm  , DOI: ( /j.hrthm )
Copyright © 2014 Heart Rhythm Society Terms and Conditions

3. Figure 2
Intracardiac tracing (paper speed 100 mm/s) showing transition from a wide into a narrow QRS complex tachycardia. (See text for discussion.) Note the difference in rate because of the difference in ventriculoatrial (VA) interval during the wide and narrow QRS complex tachycardia. Shown are leads I, II, II, V1, and V6, high lateral right atrium (HRA), coronary sinus (12 = distal, 910 = proximal at the ostium), and His bundle recording (His d = distal; His p = proximal). The potential recorded at the His d channel is probably the right bundle potential as no atrium is present in this electrogram.
Heart Rhythm  , DOI: ( /j.hrthm )
Copyright © 2014 Heart Rhythm Society Terms and Conditions

4. Figure 3
A: A recording of the tachycardia with atrioventricular (AV) conduction over an atriofascicular pathway and ventriculoatrial conduction over a left-sided accessory pathway. The RR interval measures 335 ms. Note that right bundle branch activation before His activation suggests retrograde invasion into the right bundle branch. B: An atrioventricular tachycardia is present with bystander AV conduction over an atriofascicular fiber. The RR interval measures 290 ms identical to the RR interval of the narrow QRS complex in Figure 2. Note that His bundle activation precedes right bundle branch activation.
Heart Rhythm  , DOI: ( /j.hrthm )
Copyright © 2014 Heart Rhythm Society Terms and Conditions