Figure 9.
Representative examples of Poincaré plots of the QT interval from an anesthetized rabbit treated with the IKr blocker dofetilide (25 μg/kg i.v., DOF) (Panel A), and from another one treated with the IKs blocker HMR 1556 (0.1 mg/kg i.v.) followed by dofetilide (25 μg/kg i.v.) (Panel B). Short‐term QT interval variability was increased after dofetilide administration. Panel C. Combined IKr and IKs block markedly increased QT variability and provoked torsade de pointes arrhythmia (TdP) (Panel D). #P < 0.05 versus control in the same group, *P < 0.05 versus dofetilide treatment, n = 7 animals/group. (Unpublished results from the present authors and Dr. I. Baczkó; partially presented as abstract at the Heart&Rhythm Meeting‐2006; Ref. 80.)