Figure 2.

Induction of premature ventricular complexes (PVCs) with local noradrenaline (NA) application

A, ECG during local NA application showing the induction of two PVCs. B, V_m activation maps for the last beat of intrinsic rhythm, the first and second PVCs (PVC 1, PVC 2), showing earliest epicardial activation during intrinsic rhythm distant from the needle site (*) and activation arising from the needle site during PVCs. Ca²⁺ activation maps are also shown, along with V_m–Ca²⁺ delay maps for each, indicating abnormal V_m–Ca²⁺ delay (∼0–2 ms, green areas) around the NA application site during PVCs. C, superimposed APs (black traces) and Ca²⁺ transients (red traces), from the site of earliest epicardial activation. D, corresponding V_m/Ca²⁺ phase plots demonstrate the abnormal V_m/Ca²⁺ relationship at sites of focal activation during PVCs. E, summary data for the occurrence of PVCs following local application of normal Tyrode solution (NT, open bars) and NA (filled bars), under control conditions and in the presence of BaCl₂ + Caff (hatched bars). Continuous data were compared using a one-way ANOVA with Bonferroni post testing and categorical testing using Fisher's exact test. *P < 0.05, ***P < 0.001, ****P < 0.0001.