Fig. 12.

Conduction disturbances elicited by KN93 or H89 are eliminated at very long pacing intervals. A: activation time maps computed for 2 consecutive activations [cycle length (CL) as identified by corresponding labels] generated by left ventricle (LV) pacing at baseline (top) and after 1-h perfusion with KN93 (bottom). White arrowheads indicate the site of pacing in the lateral LV. B: local delay maps depict the distribution of conduction delays for each corresponding activation map in A (one-to-one correspondence as indicated by CL labels). C and D: same layout as A and B but for H89 in place of KN93. White line demarcates the right ventricle (RV) and the LV. Prolongation of the pacing CL to an unphysiologically long interval (4,000–8,000 ms) almost fully eliminates severe slowing (and possibly full block) of conduction in the RV outflow tract induced by KN93 or by H89 at CL = 400 ms.