Open AccessOrigin of Chaos in the Circulation: Open Loop Analyis With an Artificial Heart
Author(s) -
Tomoyuki Yambe,
S. Nanka,
Shin Kobayashi,
Akira Tanaka,
Makoto Yoshizawa,
Ken Abe,
K Tabayashi,
Hiroshi Takeda,
Shin Ichi Nitta
Publication year - 1998
Publication title -
asaio journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.961
H-Index - 66
eISSN - 1538-943X
pISSN - 1058-2916
DOI - 10.1097/00002480-199809000-00080
Subject(s) - chaotic , artificial heart , computer science , nonlinear system , heart rate , chaos (operating system) , control theory (sociology) , sympathetic nervous system , artificial intelligence , cardiology , physics , medicine , blood pressure , control (management) , computer security , quantum mechanics
To develop the optimal automatic control algorithm for an in vivo artificial heart system, investigation of the basic characteristics of the cardiovascular system may be important. The clinical significance of chaotic dynamics in the cardiovascular system has attracted attention. The circulation is a so-called complex system with many feedback circuits, making it very difficult to investigate the origin of chaos within the system. In this study, we investigated the origin of chaos by open loop analysis with an artificial heart (which has no fluctuation in pumping rate or contraction power) in chronic animal experiments with healthy adult goats. As a result, in the artificial heart circulatory time series data, low dimensional deterministic chaos was discovered by nonlinear mathematical analysis, suggesting the importance of blood vessels in the chaotic dynamics of the cardiovascular system. To investigate the origin of chaos further, sympathetic activity was directly measured in animals with artificial hearts. Chaotic dynamics was also recognized in sympathetic action potentials, even during artificial heart circulation. Coupling of the nonlinear information between blood vessels and sympathetic activity was suggested by analysis of mutual information. In chaotic dynamics, the central nervous system (CNS) played an important role through sympathetic activity. These findings may be useful for the development of an automatic control algorithm for an artificial heart.