| Developing and manufacturing but before the clinical trials,artificial heart need to be assessed the performance of the pump.Artificial heart in the research and development design process requires repeated tests to optimize and improve.At present,some research institutes use animal living body to do experimental research.Although it is helpful to solve the problem to a certain extent,the animal heart is different from the human heart in the end.So the collected data are different from the human body,and the living experimental period is longer,higher cost.Therefore,it is extremely important to in vitro accurately reproduce the data of physiologic pulsatile circadian blood flow in normal human heart and heart failure.These data can help to calibrate some unknown parameters in the process of artificial heart development or use.To achieve this function,it is very important to set up an in vitro pulsatile circulation mock system platform,which can’t completely replace the clinical trials,but can shorten the development cycle of the artificial heart,which will provide a good platform for related heart disease research and medical device development.The pulsating fluid load of the target parameter can be applied and the related physiological performance tests can be completed.The blood circulation system comprises the heart,blood vessels,blood.The blood circulation system is not only complicated,there are some non-linear friction of blood vessels affect the blood energy pumped out of the heart transferring.The challenges in setting up heart pulse circulatory simulation system in vitro are:(1)Short cardiac cycle time result in large fluctuations in the system unit cycle.Simulation in vitro of long-term high-frequency load is a challenge;(2)Simulation of blood flow state during cardiovascular disease,such as how the aortic aneurysm directly reflects the effect of aortic pressure on aortic aneurysm;(3)How to simulate aortic compliance and blood supply lagging when pumping blood?Previous reports both at home and abroad simplified the diastolic/systolic time to be equal,resulting in the same shape of transient pulse pressure waveforms at different heart rates,making it difficult to characterize the aortic transient pressure waveform and to simulate the state of blood flow during cardiovascular events.In this paper,extracting the main features of the blood circulation system and the establishment of the corresponding mathematical model was made using lumped parameter modeling.The elastic cavity theory is used to derive and adopt the appropriate activation function.It derived the elastic chamber specifications of the ventricle and the aorta,respectively,and selecting appropriate components.Finally,the design,assembling and data collection of the new cardiac pulse circulatory simulation system are completed.The system can be set at different heart rates and different systolic and diastolic accounted for the time ratio.Blood flow setting range is 5-35L/min.Normal physiological,high blood pressure,heart failure and other aortic transient pressure waveform are coincide basically with the real physiological conditions.After completing the design and assembling of the aneurysm simulator,it can imitate the real aneurysm change process.It intuitively reflect the aneurysm load that the aortic blood pulse imposed on,which can be used for surgical simulator development.Self-developed software interface control combining with hardware,the aortic pressure of the circulatory system can be regulated and controlled.By analyzing the blood pressure transient waveform and flow,it can correctly reflect the hemodynamic properties.The feasibility of simulating the real physiological condition of the heart in vitro pulsatile circulation system was verified.The main contents of the dissertation are as follows:(1).The cardiopulmonary medical anatomy,pumping blood function and vascular network were briefly reviewed.Hemodynamics involved in the blood flow resistance,blood flow,blood pressure were respectively outlined.The physiological pressure and blood flow of normal physiology and heart failure were compared.(2).Establish the corresponding mathematical model for the human circulation system.The mathematical model of left ventricle and atrium were established by using time-varying elastic model.The modeling of arterial and venous elastic cavities was established using lumped parameter modeling.The peripheral resistance and vascular network were also simulated.In particular,the calculation of the elastic cavity model for the introduction of the resistance and compliance meets the characteristics of the pulsatile circulation mock system in vitro.(3).Design the principle diagram of the pulsatile circulation mock system in vitro,selecting the centrifugal pump,solenoid valve,throttle valve and other components needed in the system,especially the selection of flow sensor and pressure sensor,and finally completing the system platform.The aneurysm simulator was connected to the system,which can simulate changing process of aneurysm when the aortic pulse load application to simulator.(4).Completing the platform system components and hardware,software connections and interface control.Solving electromagnetic interference to the system,and debugging the computer control surface.For aortic pressure controlling,respectively narrating the cardiac cycle controlling,peripheral resistance controlling and left ventricular controlling.By the platform of experiments,finished real-time measurement and display of hemodynamic parameters such as aortic pressure and system flow.Experiments mock the circulatory characteristics of the human body under normal and heart failure physiological conditions.Instantaneous blood pressure waveform and circulation system blood flow waveforms were a good fit for the real physiological conditions.It can correctly reflect the hemodynamic properties.At last,the test verified the feasibility of heart in vitro pulsatile circulation mock system.It is also verified that it is feasible to connect the system into the aneurysm simulator as a surgical simulator. |
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