Kung Ethan O, Taylor Charles A
Departments of Bioengineering, Stanford University, Stanford, California, USA.
Departments of Bioengineering, Stanford University, Stanford, California, USA ; Surgery, Stanford University, Stanford, California, USA.
Cardiovasc Eng Technol. 2011 Mar;2(1):2-14. doi: 10.1007/s13239-010-0030-6.
To create and characterize a physical Windkessel module that can provide realistic and predictable vascular impedances for in-vitro flow experiments used for computational fluid dynamics validation, and other investigations of the cardiovascular system and medical devices.
We developed practical design and manufacturing methods for constructing flow resistance and capacitance units. Using these units we assembled a Windkessel impedance module and defined its corresponding analytical model incorporating an inductance to account for fluid momentum. We tested various resistance units and Windkessel modules using a flow system, and compared experimental measurements to analytical predictions of pressure, flow, and impedance.
The resistance modules exhibited stable resistance values over wide ranges of flow rates. The resistance value variations of any particular resistor are typically within 5% across the range of flow that it is expected to accommodate under physiologic flow conditions. In the Windkessel impedance modules, the measured flow and pressure waveforms agreed very favorably with the analytical calculations for four different flow conditions used to test each module. The shapes and magnitudes of the impedance modulus and phase agree well between experiment and theoretical values, and also with those measured in-vivo in previous studies.
The Windkessel impedance module we developed can be used as a practical tool to provide realistic vascular impedance for in-vitro cardiovascular studies. Upon proper characterization of the impedance module, its analytical model can accurately predict its measured behavior under different flow conditions.
创建并表征一种物理风箱模块，该模块可为用于计算流体动力学验证的体外流动实验以及心血管系统和医疗设备的其他研究提供现实且可预测的血管阻抗。
我们开发了用于构建流动阻力和电容单元的实用设计和制造方法。利用这些单元，我们组装了一个风箱阻抗模块，并定义了其相应的分析模型，该模型纳入了电感以考虑流体动量。我们使用流动系统测试了各种阻力单元和风箱模块，并将实验测量结果与压力、流量和阻抗的分析预测进行了比较。
阻力模块在很宽的流量范围内表现出稳定的阻力值。任何特定电阻器的电阻值变化在其预期在生理流动条件下所能适应的流量范围内通常在5%以内。在风箱阻抗模块中，对于用于测试每个模块的四种不同流动条件，测量的流量和压力波形与分析计算结果非常吻合。阻抗模量和相位的形状及大小在实验值与理论值之间以及与先前研究中体内测量值之间都非常吻合。
我们开发的风箱阻抗模块可作为一种实用工具，为体外心血管研究提供现实的血管阻抗。在对阻抗模块进行适当表征后，其分析模型可准确预测其在不同流动条件下的测量行为。
