Figure 5: HF Enhances Susceptibility to Spatially Discordant Alternans, Which Is Prevented by RDN

The contour map of action potential duration alternans (APD-ALT) is shown. The magnitude of APD-ALT (contour intensity) at each mapping point is defined as the mean APD of even beats minus that of odd beats. Red (positive) and blue (negative) colors indicate prolongation and shortening of repolarization, respectively (contour phase). Therefore, red is marked positive phase, yellow is mild positive phase, light blue is mild negative phase and dark blue is marked negative phase. (A) In the representative CTL heart, alternans that is in-phase (concordant alternans) between site a and site b is observed at 600 beats/min PR. In the contour map, concordant alternans is distributed across the whole map region (both site a and site b are dark blue). 1 indicates odd beats, and 2, even beats. (B) In the representative HF heart, alternans that is out of phase between site a and site b (discordant alternans) is observed at a PR of 600 beats/min. At 600 beats/min pacing rate, discordant alternans is observed, as APD of myocytes at site a and site b alternate with opposite phase, depicted by the presence of both red and dark blue contours. (C) In the representative HF heart with RDN, although APD of myocytes at site a and site b alternate with the opposite phase, the magnitude of discordant alternans is substantially decreased, depicted by the presence of both dark blue and yellow contours. Abbreviations as in Figures 1 and 2.