Numerical Modeling of Hemodynamics with Pulsatile Impeller Pump Support

There is significant interest in the development and application of variable speed impeller-pump type ventricular assist devices designed to generate pulsatile blood flow. However, no study has so far been carried out to investigate the systemic cardiovascular response to various aspects of pump motion. In this article, a numerical model is constructed for the simulation of the cardiovascular response in the heart failure condition under representative cases of pulsatile impeller pump support. The native cardiovascular model is based on a previously validated model, and the impeller pump is modeled by directly fitting the pressure–flow curves that describe the pump characteristics. The model developed is applied to study circulatory dynamics under different degrees of phase shift and pulsation ratio in the pump motion profile. The characteristic variables are discussed as criteria for the evaluation of system response for comparison of the pulsatile flows. Simulation results show that a constant pump speed is the most efficient work mode for the rotary pump, and with the application of either a phase shift of 75% and a pulsation ratio of 0.5, or a phase shift of 42% and a pulsation ratio of 0.55, it is possible to generate arterial pulse pressure with the maximal magnitude of about 28 mmHg. However, this is achieved at the cost of reduced cardiac output and pump efficiency.     

Generation of Pulsatile Flow in Rotary Pumps

Biomedical Engineering - A method is proposed for generating pulsatile flow using a self-controlled device attached to the inlet line of a rotary ventricular assist pump. The design is a cylinder...     

用于心室辅助装置血流动力学性能评价的体外模拟循环系统技术进展

体外模拟循环系统(mock circulatory systems,MCS)是一个模拟人体循环系统血流动力学状态的试验平台,被广泛用于心室辅助装置和人工瓣膜等心血管人工器官的体外性能评价和生机电系统中的血流动力学响应研究。通过调整模拟心脏的驱动元件和模拟血管系统的集中参数元件,MCS可以模拟人体健康、运动、心力衰竭等不同生理状态的血流动力学特性。自1960年代至今,MCS研发目标从满足最基本的心室辅助装置或机械瓣膜的系统性能评价要求,已发展到能够复现局部重要器官的血流动力学状态。总结MCS目前的设计原则、系统搭建以及研究进展和未来展望。     

分岔动脉血管内灌注药液时的药物浓度分布

建立了分岔动脉血管二维几何模型和动脉血流平均流速脉动流模型.对分岔动脉血管脉动血流的动力学状况和匀速进行药液注射进行了数值模拟,获得用导管注射药液时的血液流场的变化情况和药液在血液流场内的周期分布.计算结果表明,所建立的几何模型和血液平均流速脉动流模型可以较好地分析解释了临床上所观察到的血流动力学现象和药液传输现象,能够反映出分岔动脉血管脉动流的传质特点.这不但为实施进一步数值模拟提供了可靠的前提,而且本文的计算结果对优化血管性介入治疗等也提供了血流动力学依据.     

分岔动脉血管脉动血流的动力学分析

通过分析血管性肺癌介入治疗的特性，建立了分岔动脉血管二维几何模型和动脉血流平均流速脉动流模型。基于SMPLE算法对分岔动脉血管脉动血流的动力学进行了数值模拟，获得用导管注射药液时血液流场的变化情况。结果表明，建立的典型几何模型和血液平均流速脉动流模型可较好地分析临床上观察到的血流动力学现象，能反映分岔动脉血管脉动流的特点。为实施进一步数值模拟提供了可靠的前提，此项研究的计算结果也为优化血管性介入治疗等提供了血流动力学依据。     

Hemodynamic Modeling of the Intrarenal Circulation

Three dimensional, time dependent numerical simulations of healthy and pathological conditions in a model kidney were performed. Blood flow in a kidney is not commonly investigated by computational approach, in contrast for example, to the flow in a heart. The flow in a kidney is characterized by relatively small Reynolds number (100 < Re < 0.01—laminar regime). The presented results give insight into the structure of such flow, which is hard to measure in vivo. The simulations have suggested that venous thrombosis is more likely than arterial thrombosis—higher shear rate observed. The obtained maximum velocity, as a result of the simulations, agrees with the observed in vivo measurements. The time dependent simulations show separation regimes present in the vicinity of the maximum pressure value. The pathological constriction introduced to the arterial geometry leads to the changes in separation structures. The constriction of a single vessel affects flow in the whole kidney. Pathology results in different flow rate values in healthy and affected branches, as well as, different pulsate cycle characteristic for the whole system.     

Development of a Mathematical Model of the Human Circulatory System

A mathematical lumped parameter model of the human circulatory system (HCS) has been developed to complement in vitro testing of ventricular assist devices. Components included in this model represent the major parts of the systemic HCS loop, with all component parameters based on physiological data available in the literature. Two model configurations are presented in this paper, the first featuring elements with purely linear constitutive relations, and the second featuring nonlinear constitutive relations for the larger vessels. Three different aortic compliance functions are presented, and a pressure-dependent venous flow resistance is used to simulate venous collapse. The mathematical model produces reasonable systemic pressure and flow behaviour, and graphs of this data are included.