Chaos in hemodynamics with artificial heart

In order to analyze the hemodynamics with artificial heart as an entity, not as the decomposed one, non-linear mathematical analyzing technique was utilized in chronic animal experiments using adult goats. For the comparison between the natural and artificial circulation, biventricular assist type total artificial circulation was adopted. After the implantation procedure, the goats were placed in the cage and hemodynamics with natural and artificial circulation were recorded under the awake conditions. Hemodynamic time series data were embedded into the four dimensional phase space and projected into the three dimensional phase space. During artificial circulation, reconstructed attractor showed lower dimensional chaotic behavior compared with natural circulation. Existence of deterministic chaos was suggested by the positive Lyapunov exponents. Our results suggest that circulation with artificial heart may be able to become the flexible and intelligent system by the achievement of the chaotic dynamics.