Figure
2 . Tracings show surface
electrocardiograms in leads I, aVF, and V1, and electrograms of the
tricuspid annulus (TA) and right atrial lateral wall (LW). A: During
atrial tachycardia. Counterclockwise activation was observed in both the
TA and LW. Activation was blocked in LW1, located on the posterior part
of the cavotricuspid isthmus (CTI), and conduction delay was observed
between TA4 and TA1, located on the anterior part of the CTI. B: During
entrainment pacing from the lateral TA. The asterisks indicate the last
captured beats, which returned with the pacing cycle length. The TA was
captured directly by pacing (arrow a), whereas the LW was captured one
cycle later than the TA (arrow b). Note that the LW was captured later
than the proximal CS (TA1). C: During entrainment pacing from the
proximal coronary sinus (TA1). The TA and LW were captured
simultaneously by pacing (arrows c and d).