Figure 4.

Basal and Critical Conduction Velocities

(A) Representative depolarization isochrone maps from Ctrl and MI/iAL preparations at baseline (normokalemia, pacing cycle length 1,000 ms). Comparison of basal conduction velocity (CV_b) in the Ctrl, MI, and MI/iAL preparations (Ctrl: n = 11; MI: n = 9; and MI/iAL: n = 10). No significant differences in CV_b were found between the MI or MI/iAL preparations compared with the Ctrl preparations. (B) Representative electrogram tracings recorded at a wide range of pacing rates in the Ctrl, MI, and MI/iAL preparations during hypokalemia challenge. (C) Comparison of average critical conduction velocity (CV_c) (Ctrl: n = 7; MI: n = 4; and MI/iAL: n = 7) indicating significantly decreased levels in the MI/iAL group. Abbreviations as in Figures 1 and 3.