• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.04a
• /
• pp.150-155
• /
• 1997

In this paper,we present neural network for control of Left Ventricular Assist Device(LVAD)system with a pneumatically driven mock cirulation system. It is necessary to apply high perfomance control techniques, since the LVAD system represent nonlinear and time-varing characteristics. Fortunately, the neural network can be applied to control of a nonliner dynamic system by learning capability. In this study,we identify the LVAD system with neural network and control the LVAD system by PID controller and neural network feedforward controller. The ability and effectiveness of controlling the LVAD system using the proposed algorithm will be demonstrated by computer simulation and experiment.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1996.11a
• /
• pp.260-266
• /
• 1996

In this paper, we presents neural network identification and control of highly complicated nonlinear Left Ventricular Assist Device(LVAD) system with a pneumatically driven mock circulation system. Generally the LVAD system need to compensate nonlinearities. Hence, it is necessary to apply high performance control techniques. Fortunately, the neural network can be applied to control of a nonlinear dynamic system by learning capability. In this study, we identify the LVAD system with Neural Network Identification. Once the NNI has learned the dynamic model of LVAD system, the other network, called Neural Network Controller(NNC), is designed for control of a LVAD system. The ability and effectiveness of identifying and controlling a LVAD system using the proposed algorithm will be demonstrated by computer simulation.

• Journal of Institute of Control, Robotics and Systems
• /
• v.4 no.3
• /
• pp.315-320
• /
• 1998

In this paper, we present the PID control method for the controlling flow rate of highly complicated nonlinear Left Ventricular Assist Device(LVAD) with pneumatically driven mock circulatory system. Beat Rate (BR), Systole-Diastole Rate (SDR) and flow rate are used as the main variables of the LVAD system. System modeling is completed using the neural network with input variables (BR, SDR, their derivatives, actual flow) and an output valiable(actual flow). Then, as the basis of this model, we perform the simulation of PID control to predict the performance and tendency of the system and control the flow rate of LVAD system using the PID controller. The ability and effectiveness of identifying and controlling a LVAD system using the proposed algorithm will be demonstrated through computer simulation and experiments.

• Journal of Chest Surgery
• /
• v.54 no.6
• /
• pp.543-546
• /
• 2021

A 55-year-old woman who had received an implantable left ventricular assist device 3 months earlier presented with dyspnea and a low-flow alarm of the device. Computed tomography and log-file analysis of the device system suggested inflow cannula obstruction. Since the patient had cardiogenic shock due to pump failure, venoarterial extracorporeal membrane oxygenation (ECMO) was initiated. With ECMO, surgical exchange of the pump was considered. However, the obstruction spontaneously resolved without surgical intervention. It turned out that an obstructive thrombus was washed out by rebooting the pump. Moreover, the thrombus was embolized in the patient's left subclavian artery. The patient underwent heart transplantation 4 months after the pump obstruction accident and continued to do well.

• Journal of Biomedical Engineering Research
• /
• v.25 no.1
• /
• pp.65-70
• /
• 2004

In this paper, we described 23 cases of animal experiment with our pneumatic ventricular assist device and new durability-improvement method. The blood pump consists of blood housing, and back plate made by the injection molding of isoplast, and the diaphragm fabricated by dipping of polyurethane solution onto the aluminum mold. Its volume was 75 $m\ell$ and in-vitro test showed that maximum output was 4.5 $\ell$/min at the 100 mmHg. The adult female sheep with weight of 50 ＋ 10 kg were employed for tile in-vivo experiments and the mean blood flow was sustained at 3.0 1/min. 4 animals survived more than 15 days and the longest survival time was 28 days. In the prior 10 cases, the major causes of death were the tearing of diaphragm at the diaphragm to blood housing junction. By the new mesh and alumina ball milling methods, the durability was enhanced, and its qualitative and quantitative improvement was proved via the in-vivo and in-vitro methods. Animal experiments demonstrated that all the physiologic parameters a ere maintained within the permissible ranges and no thrombus formation was observed through the visual and blood test. The in-vivo experiments demonstrated our pneumatic ventricular assist device to he one month's bridge to transplantation device.

• Journal of Biomedical Engineering Research
• /
• v.22 no.4
• /
• pp.349-358
• /
• 2001

A novel electro-mechanical implantable ventricular assist system is developed as a bridge to transplantation or recovery for patients with end-stage heart failure. The developed system is composed of an implanted blood pump, an external monitoring system which stores data, and a wearable system including a portable external driver and a portable power supply system. The blood pump is designed to be implanted into the left upper abdominal space and provides blood flow from the left ventricular apex to the aorta. The pulsatile blood flow is generated by a double cylindrical cam. There was mo excessive heat emission from the blood pump into the temperature-controlled chamber in the heat test and no stagnated flow within the blood sac by the observation in the flow visualization test. Animal experiments were performed using sheep and calves. The maximum assist flow rate reached 7.85L/min in the animal experiment. The evaluation results showed that the developed system was feasible for the implantable ventricular assist system. The long-term in vitro durability test and mid-term in vivo experiments are in progress and mow the modified next model is under development.

• Journal of Biomedical Engineering Research
• /
• v.23 no.1
• /
• pp.33-38
• /
• 2002

A Ventricular Assist Device(YAD) is used to support the injured natural heart So. when considering a control algorithm for YAD. it is important to reduce a natural heart's load to enhance its recovery condition. To reduce natural heart's load, a counterpulsation algorithm is used commonly. In this study, we developed a counterpulsation control algorithm for moving-actuator type VAD and tested its usefulness using in vitro MOCK circulatory system. To notice a natural heart's Pumping status, electrocardiogram(ECG) signal was used and as a result of test. the counterpulsation effect between YAD and a natural heart was occurred and Automatic Control Mode Transition was occurred properly.

• Journal of Biomedical Engineering Research
• /
• v.19 no.1
• /
• pp.39-46
• /
• 1998

In this paper, we present a neural network identification and a control of highly complicated nonlinear left ventricular assist device(LVAD) system with a pneumatically driven mock circulation system. Generally, the LVAD system needs to compensate for nonlinearities. It is necessary to apply high performance control techniques. Fortunately, the neural network can be applied to control of a nonlinear dynamic system by learning capability. In this study, we identify the LVAD system with neural network identification(NNI). Once the NNI has learned the dynamic model of the LVAD system, the other network, called neural network controller(NNC), is designed for a control of the LVAD system. The ability and effectiveness of identifying and controlling the LVAD system using the proposed algorithm will be demonstrated by computer simulation.

• Journal of Biomedical Engineering Research
• /
• v.36 no.4
• /
• pp.135-142
• /
• 2015

Outflow cannulation site of left ventricular assist device(LVAD) chosen by considering anatomical structure of thoracic cavity and vascular system. Though outflow cannulation site influences blood perfusion at each branch, there is no standard rule or quantitative data. In this study, we computed the amount of blood perfusion at each arterial branch numerically according to outflow cannulation sites(ascending aorta, aortic arch, descending aorta). We generated computational meshes to the three-dimensionally reconstructed arterial system. Clinically measured arterial pressure were used for inlet boundary condition, porous media were applied to mimic blood flow resistance. Blood perfusion through left common carotid artery was 2.5 times higher than other cases, and that through right common carotid artery was 1.1 times higher than other branches. Although this is simulation study, will be useful reference data for the clinical study of LVAD which considers blood perfusion efficiency.

• Journal of Chest Surgery
• /
• v.45 no.2
• /
• pp.116-119
• /
• 2012

A 61-year-old female patient was diagnosed with dilated cardiomyopathy with severe left ventricle dysfunction. Two days after admission, continuous renal replacement therapy was performed due to oliguria and lactic acidosis. On the fifth day, an intra-aortic balloon pump was inserted due to low cardiac output syndrome. Beginning 4 days after admission, she was supported for 15 days thereafter with an extracorporeal left ventricular assist device (LVAD) because of heart failure with multi-organ failure. A heart transplant was performed while the patient was stabilized with the LVAD. She developed several complications after the surgery, such as cytomegalovirus pneumonia, pulmonary tuberculosis, wound dehiscence, and H1N1 infection. On postoperative day 19, she was discharged from the hospital with close follow-up and treatment for infection. She received follow-up care for 10 months without any immune rejection reaction.