Skip to main content
. Author manuscript; available in PMC: 2011 Jan 27.
Published in final edited form as: Front Physiol. 2010;1:154. doi: 10.3389/fphys.2010.00154

Figure 4. Spatially concordant and discordant alternans (modified from Pastore et al (Pastore et al., 1999)).

Figure 4

A. Concordant alternans. Top: ΔAPD=APDn+1-APDn distribution in space; Middle: sample action potential recordings for two consecutive beats from the sites marked on the upper panel; Bottom: Pseudo-ECG showing TWA. Since APD alternans is concordant, the color in the top panel is uniform in space (ΔAPD everywhere is positive in one beat and negative in the following beat) and since no CV restitution is engaged, no QRS alternans in the ECG. B. Same as A but for discordant alternans. Since APD alternans is discordant, the color in the top panel is no longer uniform in space, but change from one to the other (ΔAPD changes from negative to positive as the color changes from blue to red in space, and color map reverse in the following beat), and since CV restitution is engaged, QRS alternans occurs in the ECG.