多分支心血管循环系统的建模和仿真研究

应用功率键合图方法,建立了一种多分支心血管循环系统的计算机仿真模型,心描述心血管循环系统内血流动力学变量变化规律的状态２方程。该仿真模型较为细致地刻画了心血管系统的生理特性,形成了较完整的人体心血管循环系统的数字计算模型,此模型可模拟心血管系统生物特性,给出了相应的心力管动力学的仿真数据和波形,为进行心血管系统生理和病理等方面的计算机辅助数学和科研工作开辟了广阔途径。     

一种模拟血液循环系统实验研究

目的 研究一种能够准确复现人体血流动力学环境的模拟血液循环系统（mock circulation system,MCS）用于心室辅助装置（ventricular assist device, VAD）、人工心肺机等人工器官研发过程中的体外测试。方法 建立一套包括体肺循环的双心驱动MCS,基本涵盖心血管系统的主要生理特征及功能,其中对瓣膜和动脉的模拟提出采用硅胶材料制作的新方式。该系统可以通过调整控制系统参数或结构参数来模拟正常人体、心衰、瓣膜疾病、动脉硬化以及外周阻性变化等多种生理环境,并利用传感器与控制系统实现压力、流量的实时显示、控制和数据保存。结果 该MCS模拟正常人体和多种病症下的血流动力学环境均与人体实际情况基本一致。并且新的瓣膜和动脉模拟方式减小了压力波动,使模拟效果更好。在模拟心衰病症下使用航天泰心HeartCon型VAD接入系统,可以看到其血流动力学环境（主动脉压力、左心室压力、心排量等）均能恢复到正常范围。结论 该MCS能够准确复现多种生理状态下体肺循环的血流动力学环境,为VAD等人工器官的性能测试和控制策略的设计提供有效的实验平台。同时,采用硅胶材料制作瓣膜和动脉的模拟方式也可以作为MCS研究中的新思路进一步完善。     

循环系统模拟中的后负荷选择

目前国内外现有人工心脏瓣膜测试装置（或称循环系统模拟装置）普遍存在再现人体生理条件差以及测试结果客观性和可比性差的弊病。本文从分析和克服这些弊病出发，放弃仅以压力和流量波形作为判断系统是否正常的传统做法，以血管输入阻抗作为心室后负荷的恰当量度筛选出具有较强再现人体生理条件的后负荷系统，并在此基础上，研制出能较好模拟人体循环系统特性的具有标准后负荷的循环系统模拟装置。     

镍钛记忆合金弹性弓计算机辅助设计的有限元法初步研究

目的:探讨一种用于计算机辅助设计的镍钛记忆合金(NTMA)弹性弓有限元模型的建立方法.方法:用Pro/E软件建立具有半个正弦波形状的镍钛记忆合金弹性弓的几何模型,导入Marc软件,对其进行几何修复后生成实体单元,并按实际模拟边界条件,按镍钛合金定义初始条件和材料特性,最终得到镍钛记忆合金弹性弓有限元模型.结果:建立了用于计算机辅助设计的镍钛记忆合金弹性弓有限元模型,可以预测一定形状的弹性弓在变形过程中(各时段)其本身结构中各节点、单元的受力、位移情况.结论:本研究率先运用镍钛记忆合金有限元模型进行计算机辅助设计,这一技术将有助于提高镍钛记忆合金器件的设计精度,并缩短其设计周期,节约设计成本.     

全分支的体循环混合参数计算机模拟研究

本文提出了一种改进的人体血液动脉系统的计算机模拟方法，即把动脉血流脉搏波传播的非线性（或线性）分布参数模型与线性集中参数流体网络模型混合，构造动脉系统的分布─集中混合参数模型。对模型中分布参数部分，采用非标准Ｇａｌｅｒｋｉｎ半离散空间有限元方法进行处理．通过具体建立人体体动脉系统的这种混合参数模型、并进行计算机模拟研究，结果表明，这种模拟方法既可以从系统的量级上模拟动脉系统的血流动力学特性，又可以对所感兴趣的局部血管处进行较细致的模拟，并且可以研究系统各部分间的相互影响。     

基于UG NX及MasterCAM透明泌尿系统模型设计和制作

目的针对目前模拟人体的泌尿系统模型结构单一、用途局限、不适于体外模拟实验等不足,本文将计算机辅助设计及制作（CAD／CAM）等技术应用于医学模拟模型的开发,设计制作了带双层管壁结构的多用途透明泌尿系统模型。方法利用现有的人体泌尿系统解剖参数,基于UGNX软件完成模型的设计,然后利用MasterCAM软件对模型进行数控编程,通过数字控制车床对模型各部件进行加工,最后组装各部件完成制作。结果完成带双层管壁结构的透明泌尿系统模型的制作,该模型具有功能多、成本低廉、模拟程度高等优点。结论该模型的制作是医工结合的一个新的尝试。     

基于突变理论的心脏运动数学描述

本文基于一个新角度研究了心脏搏动的突变特性 ,并利用突变理论建立了冠心病心脏运动的势函数模型 ,通过对心脏左心室容积变化曲线的模拟 ,表明突变势函数模型优于传统的微分方程模型。本文的工作对于计算机定量诊断心血管疾病 ,具有较为重要的意义。     

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。     

用于微循环实验的交变磁场的三维有限元仿真研究

目的:为深入了解螺线管型交变电磁场磁感应强度的时间和空间分布,本文研究了这种微循环实验中常用的医用磁场的三维有限元模型的建立及分析过程.方法:根据经典电磁场理论,应用Comsol Multiphysics多物理场耦合软件进行计算机辅助设计并赋予模型边界条件后进行网格划分,最后得到该模型的数值解.结果:成功拟合出螺线管型交变电磁场磁感应强度的轴向和径向衰减曲线.拟合结果与实际情况近似,并算出交变电磁场的时空分布.结论:本研究首次系统的建立了螺线管型交变电磁场的三维有限元模型,能够较精确的模拟该磁场磁感应强度分布,为进一步进行的磁场影响微循环系统的实验中磁场的定位问题提供了理论依据,并为进行血流在不同磁场中的血液动力学研究建立了仿真平台.     

改进型五阶集总参数心血管循环系统的建模与仿真

为更好地研究人体心衰的工作机制,为临床诊断与治疗提供理论依据与仿真工具,根据电网络模型法建立了一个改进型五阶集总参数心血管循环系统模型。应用Matlab软件进行仿真。结果表明:该模型简单有效,可模拟健康状态血液动力学特性,模拟得到CO(心输出量)为5.12 L/min,并可通过调节心率、心力、心室前负荷、心室后负荷模拟静息、轻度运动、中度运动、重度运动时的健康血液循环状态,模拟得出CO逐渐增大分别为5.09 L/min、8.86 L/min、10.74 L/min、14.7 L/min;也可以模拟Ⅰ级、Ⅱ级、Ⅲ级、Ⅳ级心衰的血流动力学特性,模拟得出CO逐渐减小分别为5 L/min、4.4 L/min、3.8 L/min、3.2 L/min,仿真结果与实际生理状态及文献中的试验数据相符,对诊断和治疗心衰疾病具有重要意义。     

Development of a new disposable pulsatile pump for cardiopulmonary bypass: computational fluid-dynamic design and in vitro tests

A newly conceived blood pump for pulsatile cardiopulmonary bypass (CPB) is presented. The new device's main design features (fully disposable pumping head with ring shaped valves) were intended to overcome the factors that today limit the use of pulsatile blood pumps, i.e., the complexity and costs of devices. The pump was designed and analyzed by means of three-dimensional computational models, including solid computer assisted design of the pumping head and computational fluid-dynamic (CFD) analyses of the fluid domain and of its interaction with deformable components. A prototype of the device, integrated with the venous reservoir, was built to perform hydraulic in vitro tests with aims of both validating CFD results and verifying the new device's pumping behavior. Functional evaluation of the pump was carried out by using the device in a model circuit made with standard CPB components plus a mock hydraulic bench representing an adult patient's systemic circulation. A roller pump used in pulsatile mode (RP-PM) was used for comparison. At a 5 L/min flow rate, the pulsatile hydraulic power () delivered to the patient was approximately 15 mW for the RP-PM. The new pump proved to be able to deliver up to 40 mW, thus providing a more physiological condition, closer to the delivered by the natural heart (90-140 mW).     

模拟心血管系统装置的研制及其在血液动力学测试中的应用

为研究心血管系统血液动力学特性和评测人工心脏,本文根据弹性腔模型建立了一套能反映血液动力学特性的体外血液循环模拟实验装置,测试血液动力学参量与心室后负荷(即外周阻力R和动脉顺应性C)以及每搏心输出量Vs,心动周期T,心室收缩时间间隔Ts和前负荷等六个参量之间的相互关系,通过改变六个参量的某一个参量而固定其余参量,测试这个参量对动脉血压及流量的影响情况.实验结果与生理情况和数学模型分析相符合,整个模拟装置能够反映血液动力学特性.     

Elastance-Based Control of a Mock Circulatory System

A new control strategy for a mock circulatory system (MCS) has been developed to mimic the Starling response of the natural heart. The control scheme is based on Suga's elastance model, which is implemented using nested elastance and pressure feedback control systems. The elastance control loop calculates the desired chamber pressure using a time-varying elastance function and the ventricular chamber volume signal. The pressure control loop regulates the chamber pressure according to this reference signal. Simulations and tests on MCS hardware showed that the elastance-based controller responds to changes in preload, afterload, and contractility in a manner similar to the natural heart. Since the elastance function is an arbitrary function of time, the controller allows modification of ventricular chamber contractility, giving researchers a new tool to mimic various pathological conditions which can be used in the evaluation of cardiac devices such as ventricular assist devices. © 2001 Biomedical Engineering Society. PAC01: 8719Uv, 8780-y, 8719Rr     

Characterization of an adult mock circulation for testing cardiac support devices

A need exists for a mock circulation that behaves in a physiologic manner for testing cardiac devices in normal and pathologic states. To address this need, an integrated mock cardiovascular system consisting of an atrium, ventricle, and systemic and coronary vasculature was developed specifically for testing ventricular assist devices (VADs). This test configuration enables atrial or ventricular apex inflow and aortic outflow cannulation connections. The objective of this study was to assess the ability of the mock ventricle to mimic the Frank-Starling response of normal, heart failure, and cardiac recovery conditions. The pressure-volume relationship of the mock ventricle was evaluated by varying ventricular volume over a wide range via atrial (preload) and aortic (afterload) occlusions. The input impedance of the mock vasculature was calculated using aortic pressure and flow measurements and also was used to estimate resistance, compliance, and inertial mechanical properties of the circulatory system. Results demonstrated that the mock ventricle pressure-volume loops and the end diastolic and end systolic pressure-volume relationships are representative of the Starling characteristics of the natural heart for each of the test conditions. The mock vasculature can be configured to mimic the input impedance and mechanical properties of native vasculature in the normal state. Although mock circulation testing systems cannot replace in vivo models, this configuration should be well suited for developing experimental protocols, testing device feedback control algorithms, investigating flow profiles, and training surgical staff on the operational procedures of cardiovascular devices.     

完全磁悬浮心室辅助装置的体外模拟循环系统实验研究

目的研究我国自主研发的第3代完全磁悬浮心室辅助装置(CH-VAD)对于心衰患者的循环辅助效果。方法建立一套体外模拟循环系统(mock circulatory system,MCS)。该系统能够模拟人体健康休息状态以及心力衰竭状态,并与CH-VAD协同工作,测试CH-VAD在连续流状态下的辅助效果。另外,对CH-VAD的搏动流控制方法进行测试,该模式采用正弦波速度波形,使CH-VAD的运行与MCS心室周期同步。结果 CH-VAD在正常连续流状态下能够使心衰状态的血流动力学参数(动脉压、心排量)恢复到正常范围。初步的搏动流测试结果显示,当前的速度搏动幅值对血流动力学影响较小,搏动流状态下与连续流状态所对应的平均动脉压、动脉脉压、平均心排量与心排量波形等差异不大。结论 CH-VAD能够通过搏动控制器产生一定程度的速度搏动,提供足够的心室辅助,并可以进一步改良优化,提供符合生理条件的搏动血流。所研制的MCS能够提供心室辅助装置以及其他机械循环辅助装置一个有效、可控的体外测试平台,是机械循环辅助装置设计、优化和验证的重要工具。     

Modeling, analysis, and validation of a pneumatically driven left ventricle for use in mock circulatory systems

In this work a pneumatically driven mock left ventricle and a native left ventricle are modeled and alternatively connected to the numerical model of a closed circulatory system comprising the systemic circulation, the left atrium, and inlet and outlet ventricular valves. By simulating physiological changes of the system working conditions, behavior and preload sensitivity of the pneumatic ventricle have been compared to those of a native ventricle. Results show that a pneumatic ventricle, when used as a fluid actuator in mock circulations, has low flexibility in reproducing different scenarios, its interaction with peripheral circulatory districts is characterized by non-physiological values, and its preload sensitivity is in poor agreement with physiological data. Results' analysis also shows that present mock circulatory systems for testing cardiovascular prostheses are inadequate, if a careful attention is not paid to the pumping action of the pneumatic ventricle. The presented computer model, validated by comparing numerical results with in vitro measurements available in the literature, can be used for designing in vitro experiments, while choosing the best control strategy for pneumatic systems.     

磁力驱动轴流血泵溶血实验和动物实验

目的对研制开发的一种新型的磁力外驱动轴流式心室辅助血泵的血液相容性能进行测试。方法利用特制血袋作为模拟循环管道,羊血作为循环介质,采用标准溶血指数衡量体外溶血实验性能。通过3只山羊12h在体实验衡量其在体适应性。结果实验测得轴流血泵体外实验标准溶血指数(NIH)为(0.158±0.043)mg/L。3例实验动物12h在体辅助无机械故障,血泵辅助后实验动物血液中游离血红蛋白(FHb)开始上升,最高达到164.8mg/L。结论磁力外驱动轴流血泵实验结果比较理想,值得进一步改进。     

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.     

心血管循环系统建模和仿真研究中的功率键合图方法

建立一种心血管循环系统的计算机仿真模型,即描述心血管循环系统内血流动力学变量变化规律的状态方程。该仿真模型可用于生理医学研究及医学辅助教学．文中提出的功率键合图建模方法能够较好地完成对人体循环系统建立仿真模型的工作,并对一个简化的循环系统生理模型进行了计算机仿真研究,仿真结果表明,功率键合图建模方法在生理医学的系统仿真中具有良好的可行性和有效性,作为一种易于理解和统一的建模方法在生理系统仿真领域有