Iso-induced atrial ectopic pacemaker in HF RAs. A: locations of ectopic beats in HF RAs. Red circles show the sites of Iso-induced ectopic beats. All of Iso-induced ectopic beats occurred from the lower crista terminalis. Solid line and dotted circles correspond to isochronal map field of B,a and B,b, respectively. B: isochronal maps during ectopic beats appearance. C: change of HR with ZD-7288, pacemaker current (If) blocker, to Iso-induced ectopic beats in normal and HF dogs. ZD-7288 (3 μmol/l) significantly suppressed HR in HF compared with normal dogs (P < 0.001). *P < 0.01 vs. corresponding normal group. Bar is 10 mm.