CAN THE ARTIFICIAL-HEART MAKE THE CIRCULATION BECOME FRACTAL

In order to analyze the hemodynamic parameters in prosthetic circulati on as an entity and not as decomposed parts, non linear mathematical a nalyzing techniques, including the fractal dimension analyzing theory, were utilized. Two pneumatically actuated ventricular assist devices were implanted, as biventricular bypasses (BVB), in chronic animal exp eriments, using four healthy adult goats. For the comparison between t he natural and prosthetic circulation in the same animals, the BVB typ e complete prosthetic circulation model with ventricular fibrillation, was adopted. All hemodynamic parameters with natural and prosthetic c irculation were recorded under awake conditions, and calculated with a personal computer system. Using the non-linear mathematical technique , the arterial blood pressure waveform was embedded into the return ma p as the beat-to-beat time series data and fractal dimension analysis were performed to analyze the reconstructed attractor. By the use of t he Box counting method, fractal dimension analysis of the hemodynamics was performed. Return map of the hemodynamics during natural and arti ficial circulation showed fractal characteristics, and fractal dimensi on analysis of the arterial blood pressure revealed the fact that lowe r dimensional fractal dynamics were evident during prosthetic circulat ion. Fractal time series data is suggested to have robustness and erro r resistance, thus our results suggest that the circulatory regulatory system with an artificial heart may have these desired characteristic s.