Nitta S, Yambe T, Kobayashi S, Hashimoto H, Yoshizawa M, Mastuki H, Tabayashi K, Takeda H
Department of Medical Engineering and Cardiology, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan.
Artif Organs. 1999 Jan;23(1):119-23. doi: 10.1046/j.1525-1594.1999.06288.x.
For the development of a totally implantable ventricular assist system (VAS), we have been developing the vibrating flow pump (VFP), which can generate oscillated blood flow with a relative high frequency (10-50 Hz) for a totally implantable system. In this study, the effects of left ventricular assistance with this unique oscillated blood flow were analyzed by the use of nonlinear mathematics for evaluation as the whole circulatory regulatory system, not as the decomposed parts of the system. Left heart bypasses using the VFP from the left atrium to the descending aorta were performed in chronic animal experiments using healthy adult goats. The ECG, arterial blood pressure, VFP pump flow, and the flow of the descending aorta were recorded in the data recorder during awake conditions and analyzed in a personal computer system through an A-D convertor. By the use of nonlinear mathematics, time series data were embedded into the phase space, the Lyapunov numerical method, fractal dimension analysis, and power spectrum analysis were performed to evaluate nonlinear dynamics. During left ventricular assistance with the VFP, Mayer wave fluctuations were decreased in the power spectrum, the fractal dimension of the hemodynamics was significantly decreased, and peripheral vascular resistance was significantly decreased. These results suggest that nonlinear dynamics, which mediate the cardiovascular dynamics, may be affected during left ventricular (LV) bypass with oscillated flow. The decreased power of the Mayer wave in the spectrum caused the limit cycle attractor of the hemodynamics and decreased peripheral resistance. Decreased sympathetic discharges may be the origin of the decreased Mayer wave and fractal dimension. These nonlinear dynamic analyses may be useful to design optimal VAS control.
为了开发一种完全可植入的心室辅助系统（VAS），我们一直在研发振动流泵（VFP），对于一个完全可植入系统而言，该泵能够产生相对高频（10 - 50Hz）的振荡血流。在本研究中，我们运用非线性数学方法，将这种独特的振荡血流对左心室的辅助作用作为一个完整的循环调节系统进行评估，而非该系统的各个分解部分。在使用健康成年山羊的慢性动物实验中，进行了从左心房到降主动脉的使用VFP的左心旁路手术。在清醒状态下，通过数据记录器记录心电图、动脉血压、VFP泵流量以及降主动脉的流量，并通过模数转换器在个人计算机系统中进行分析。运用非线性数学方法，将时间序列数据嵌入相空间，进行李雅普诺夫数值方法、分形维数分析和功率谱分析，以评估非线性动力学。在使用VFP进行左心室辅助期间，功率谱中的迈尔波波动减小，血流动力学的分形维数显著降低，外周血管阻力显著降低。这些结果表明，介导心血管动力学的非线性动力学在振荡流左心室（LV）旁路手术期间可能会受到影响。频谱中迈尔波功率的降低导致了血流动力学的极限环吸引子并降低了外周阻力。交感神经放电减少可能是迈尔波和分形维数降低的原因。这些非线性动力学分析可能有助于设计最佳的VAS控制。
