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Figure 7 Pacing site-dependent changes in QT interval, R-on-T ventricular extrasystoles, and the onset of torsades de pointes (TdP). Right ventricular endocardial pacing (RVEndoP; RR interval of 840 ms) yielded a QT interval of 485 ms and a T peak–T end interval of 92 ms. After switching to left ventricular epicardial pacing (LVEpiP; mode VOO), the QT interval increased to 580 ms and T peak–T end to 133 ms. Ventricular extrasystoles appeared at the 46th beat of LVEpiP (B) and initiated one episode of TdP after the 55th beat (C). The TdP was terminated by an implantable cardioverter-defibrillator shock. Modified and reprinted, with permission, from Medina-Ravell et al. (4).