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Figure 2 Entrainment of orthodromic reciprocating tachycardia (ORT) using a right posteroseptal bypass tract from the right ventricular apex (RVA) at a cycle length of 440 ms. (A) The ventriculo-atrial (VA) interval and tachycardia cycle length (TCL) are measured immediately before entrainment. (B) The stimulus-atrial (S-A) interval is measured from the last pacing stimulus to the last entrained high right atrial (HRA) electrogram, and the post-pacing interval (PPI) is measured from the last pacing stimulus to the return cycle RV electrogram. The S-A–VA interval is 40 ms, and the PPI–TCL is 80 ms. HBD = His bundle distal; S = stimulus.