Figure 2.

Transition from concordant to discordant alternans. Illustrative example of the transition from concordant to discordant alternans during dynamic pacing in the guinea pig heart. Representative traces from basal and apical regions are shown, along with representative isochronal maps of activation time, regional action potential duration and total repolarisation time across the guinea pig left ventricle during concordant and discordant alternans. Beats or regions with relatively long or short action potentials are labeled. ^*denotes a region of tissue with a steep repolarisation gradient, secondary to discordant alternans, that results in regional condition slowing (^**) on the next beat.