Figure 6.

The augmented transmural dispersion of repolarization (TDR) can increase tissue vulnerability to unidirectional conduction block. The repolarization time (A), spatial gradients of repolarization time (B), TDR (C) and vulnerable window (VW) (D) are shown under normal, #1, #2, #3, and #4 conditions. The VW progressively grew when TDR was augmented. The threshold of unidirectional conduction block in post acidosis was equal to 420 ms when suprathreshold DADs occurred in single cells. (E) A premature ventricular complex (PVC) occurred without tissue's VW under the normal condition and produced a bidirectional conduction, whereas a unidirectional conduction formed when a PVC occurred within tissue's VW under the #2 condition (F).