Figure 2. Response during ventricular overdrive pacing
Overdrive pacing from right ventricular apex (RVa 1-2) during
tachycardia resulted in a post pacing V-A-V response and a long PPI-TCL
of 177ms. This maneuver excludes a ventricular nodal/Hisian mechanism.
It also demonstrates that the retrograde fast pathway is capable of
conducting faster than the TCL.
Intracardiac electrograms as follows: HRA= high right atrium, CS=
coronary sinus, HIS= His bundle, RVa= right ventricular apex.