Figure 9.

Vulnerability windows to unidirectional conduction block. (A) Examples of propagation following applied S2 stimulus at different time intervals, illustrating conduction block (left), unidirectional conduction (middle) and full conduction (right). (B) Vulnerability windows for control (WT, upper) and PQTa (lower) under baseline, MC-II-157c (I_Kr modification + 40% I_Na block) and I_Kr modulation alone conditions. The lower line in each plot represents the refractory period (time below which no propagation occurs); the upper line represents the earliest time of bidirectional conduction; the area between the lines (shaded yellow) is the region within which unidirectional conduction occurs. Right panel is bar charts summarizing the length (mm) and area (mm.ms) of the vulnerability windows. Dotted lines illustrate the regions of the different cell types (ENDO, left; EPI, right).