Figure 1.

Illustration of the definition of λ²-slope. (A) An example of intermittent fluctuation generated by a cascade model (Kiyono et al., 2007) and (B) the scale dependence of λ², which is proportional to the logarithmic scale. To quantify this kind of intermittent behavior of HRV, λ²-slope is defined as the slope of a regression line between λ² and the logarithmic scale in the range between 20 and 200 s. (C) Scale dependence of λ² for a patient with multiple system atrophy (MSA) and a patient with congestive heart failure (CHF).