TY - JOUR
T1 - Origin of chaos in the circulation
T2 - Open loop analysis with an artificial heart
AU - Yambe, Tomoyuki
AU - Nanka, Shun Suke
AU - Kobayashi, Shin Ichi
AU - Tanaka, Akira
AU - Yoshizawa, Makoto
AU - Abe, Ken Ichi
AU - Tabayashi, Kouichi
AU - Takeda, Hiroshi
AU - Nitta, Shin Ichi
PY - 1998
Y1 - 1998
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=0032170945&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0032170945&partnerID=8YFLogxK
U2 - 10.1097/00002480-199809000-00080
DO - 10.1097/00002480-199809000-00080
M3 - Article
C2 - 9804525
AN - SCOPUS:0032170945
SN - 1058-2916
VL - 44
SP - M700-M703
JO - ASAIO Journal
JF - ASAIO Journal
IS - 5
ER -