Yambe T, Nanka S, Naganuma S, Kobayashi S, Akiho H, Kakinuma Y, Ohsawa N, Nitta S, Fukuju T, Miura M
Department of Medical Engineering and Cardiology, Tohoku University, Sendai, Japan.
Int J Artif Organs. 1995 Apr;18(4):190-6.
In order to analyze the hemodynamic parameters in prosthetic circulation as an entity and not as decomposed parts, non linear mathematical analyzing techniques, including the fractal dimension analyzing theory, were utilized. Two pneumatically actuated ventricular assist devices were implanted, as biventricular bypasses (BVB), in chronic animal experiments, using four healthy adult goats. For the comparison between the natural and prosthetic circulation in the same animals, the BVB type complete prosthetic circulation model with ventricular fibrillation, was adopted. All hemodynamic parameters with natural and prosthetic circulation 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 map as the beat-to-beat time series data and fractal dimension analysis were performed to analyze the reconstructed attractor. By the use of the Box counting method, fractal dimension analysis of the hemodynamics was performed. Return map of the hemodynamics during natural and artificial circulation showed fractal characteristics, and fractal dimension analysis of the arterial blood pressure revealed the fact that lower dimensional fractal dynamics were evident during prosthetic circulation. Fractal time series data is suggested to have robustness and error resistance, thus our results suggest that the circulatory regulatory system with an artificial heart may have these desired characteristics.
为了将人工循环作为一个整体而非分解的部分来分析其血流动力学参数，采用了包括分形维分析理论在内的非线性数学分析技术。在慢性动物实验中，使用4只健康成年山羊，植入了两个气动心室辅助装置，作为双心室旁路（BVB）。为了比较同一动物的自然循环和人工循环，采用了伴有心室颤动的BVB型完全人工循环模型。在清醒状态下记录自然循环和人工循环的所有血流动力学参数，并通过个人计算机系统进行计算。使用非线性数学技术，将动脉血压波形作为逐搏时间序列数据嵌入到返回图中，并进行分形维分析以分析重构吸引子。通过盒计数法对血流动力学进行分形维分析。自然循环和人工循环期间血流动力学的返回图显示出分形特征，动脉血压的分形维分析揭示了在人工循环期间低维分形动力学明显的事实。分形时间序列数据被认为具有稳健性和抗误差性，因此我们的结果表明，带有人工心脏的循环调节系统可能具有这些理想特性。
