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Robustness and perturbation in the modeled cascade heart rate variability
1Department of Mechanical, Aerospace and Industrial Engineering, Ryerson University, Toronto, Ontario, Canada M5B 2K3.
Summary
Cascade models robustly capture multifractal heart rate variability (HRV) scaling, even with altered time scales. However, modifying the multiplicative rule can shift HRV from multifractal to monofractal patterns, potentially explaining physiological changes.
Area of Science:
- Physiology
- Complex Systems Analysis
- Biophysics
Background:
- Heart rate variability (HRV) exhibits complex, multifractal scaling properties.
- Cascade models are used to describe multifractal dynamics in physiological systems like HRV.
- Understanding the robustness of these models is crucial for accurate physiological interpretation.
Purpose of the Study:
- To investigate the robustness of cascade models in describing multifractal HRV.
- To examine the impact of perturbing hierarchical time scales and multiplicative rules within cascade models.
- To explore the relationship between cascade model perturbations and observed HRV scaling transitions.
Main Methods:
- Conducted numerical experiments to simulate cascade models of HRV.
- Perturbed the hierarchical time scale structure of the cascade.
- Modified the multiplicative rule within the cascade model, including transitions to additive rules.
Main Results:
- A rigid hierarchical time scale structure is not essential for multifractal HRV scaling.
- Cascade models can capture multifractal HRV properties as long as a tree structure for multiplication exists.
- Perturbing the multiplicative rule, especially to an additive one, can cause a qualitative shift from multifractal to monofractal HRV scaling.
Conclusions:
- Cascade models are generally robust for describing multifractal HRV, particularly concerning time scale structures.
- The multiplicative rule's integrity is critical; its perturbation can fundamentally alter HRV scaling.
- This model behavior may explain observed HRV scaling transitions during physiological interventions like parasympathetic nervous system blockade.