Fig. 6.

Entrainment and ablation of monomorphic ventricular tachycardia (MMVT). Top panel: an MMVT with a cycle length of 590 ms is entrained at 560 ms. The post-pacing interval (PPI) is 590 ms, and exactly matches the TCL. The stimulus to QRS (Stim-QRS) interval shown on the last paced complex is 190 ms, which also exactly matches the electrogram to QRS (EGM-QRS) interval at 190 ms. The entrainment demonstrated here is also concealed (paced QRS morphology is identical to MMVT QRS morphology, i.e. no evidence of QRS fusion) These conditions (PPI = TCL, Stim-QRS = EGM-QRS, and concealed entrainment) confirm that the site is a protected and critical isthmus for this MMVT. Lower panel: Ablation at the site with entrainment characteristics demonstrated above terminates MMVT immediately.

Adapted from Tung R, Boyle NG, Shivkumar K. Circulation. 2011;123(20):2284–2288.