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Chaotic behavior of hemodynamics with ventricular assist system
1Department of Medical Engineering and Cardiology, Tohoku University, Sendai, Japan.
The International Journal of Artificial Organs
|January 1, 1995
Summary
Non-linear math revealed complex dynamics in cardiovascular systems with ventricular assist systems (VAS). Counterpulsation mode showed homeochaotic states, suggesting intelligent control, while internal mode exhibited greater dimensional chaos.
Area of Science:
- Cardiovascular physiology
- Non-linear dynamics
- Biomedical engineering
Background:
- Hemodynamic analysis traditionally decomposes complex cardiovascular function.
- Ventricular assist systems (VAS) require integrated analysis of their impact.
Purpose of the Study:
- To analyze hemodynamic parameters during left ventricular assistance as a whole.
- To investigate the non-linear dynamics of the cardiovascular system under different VAS modes.
Main Methods:
- Utilized non-linear mathematical techniques, including phase space embedding and Lyapunov exponents.
- Employed pneumatically actuated VAS in acute animal experiments (dogs).
- Analyzed arterial blood pressure waveforms (AP) in a four-dimensional phase space.
Main Results:
- Deterministic chaos was identified in AP without VAS, characterized by a solid torus attractor.
- Counterpulsation mode VAS demonstrated increased dimensional deterministic chaos.
- Internal mode VAS driving suggested dissipative dynamics, indicating complex circulatory regulatory system behavior.
Conclusions:
- The cardiovascular system with counterpulsation VAS operates in a homeochaotic state, indicative of a flexible control system.
- Internal mode VAS driving reveals greater dimensional complex dynamics in circulatory regulation.
- Non-linear analysis provides novel insights into VAS-mediated hemodynamic alterations.