| Heart failure has become a serious disease to human life and health,the incidence rate showed a rising trend.Heart transplant is the most effective treatment to treat end-stage heart failure,but it is limited by a severe lack of heart donor.In developed countries,ventricular assist device(VAD)has become an main means for treating end-stage heart failure,by implantation of VAD can be temporary or permanent auxiliary or replace the heart function,reduce the heart load,Promote blood circulation.The mock circulatory system(MCS)is a test platform for simulating the hemodynamic status of the human circulatory system and widely used in the evaluation of in vitro performance of cardiovascular prosthetic devices such as VAD.CH-VAD(CH Biomedical,Suzhou,China)is the third generation centrifugal blood pump with fully magnetic suspension.With a small size and light weight characteristics,it is the world's smallest known magnetic levitation VAD and has a good implantability.This in-vitro study aims to investigate the Pulsatility and hemodynamic responses induced by pulsatile operation of the CH-VAD.The main research work is divided into the following three parts:1.Construction of the experimental platform:The experimental platform mainly includes MCS and CH-VAD hardware part and the respective control module.The ultrasonic flowmeter,pressure sensor,displacement sensor and NI data acquisition card are used to measure and collect the physiological parameters.In order to facilitate the data display and motor control,Labview14.0 is used to show the waveform and motor control.2.Debugging of the experimental environment:The experiment was carried out under two physiological conditions of moderate heart failure and extreme heart failure.The CH-VAD auxiliary effect was compared with the hemodynamic parameters of the healthy state.By regulating the ventricular simulator and fine-tune the peripheral resistance to reproduce the different physiological state of human body.3.CH-VAD assisted experiment:connecting CH-VAD to MCS system and operation in the state of heart failure under steady flow and pulsating flow mode.When it is run in pulsating flow mode,adjust the center speed,velocity waveform,amplitude,and the phase shift between CH-VAD and the ventricular simulator,to study the effect of these parameters on hemodynamics,and evaluate its pulsating flow pattern effect of hemodynamics on patients with heart failure.The results show that CH-VAD in the steady flow mode restored the cardiac output,but the sharp decline in blood pulse.When it is running in pulsating flow mode,the change of velocity waveform only affects SHE(surplus hemodynamic energy),with operating in sine wave,it can get better blood pulsation and there was little effect on cardiac output,mean aortic pressure and stroke work.The change in amplitude no effect on cardiac output,but the increase in amplitude will lead to lower mean arterial pressure and increased.pulse pressure and SHE.In addition,SW has a minimum value when the phase shift is 20%and its maximum value happened at the phase shift of 70%The maximum and minimum values of cardiac output and mean aortic pressure were found at 70%and 10%,respectively.While the maximum and minimum values of SHE are happened at the phase shift of 0%and 50%.It has been found that CH-VAD achieves the best assistant effect when the phase shift is 20%with a sine wave of 3500 ± 600 r/min. |
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