• 대한의용생체공학회:의공학회지
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• 제36권4호
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• pp.135-142
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• 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
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• 제54권6호
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• pp.543-546
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• 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.

• 대한기계학회논문집B
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• 제38권8호
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• pp.715-720
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• 2014

좌심실보조장치(LVAD)가 심실부하감소에 미치는 영향을 극대화 하기 위해, 심실보조장치 치료를 위한 최적의 심부전 심각도 단계를 찾는 것은 중요하다. 우리는 심부전 정도에 따른 LVAD 의 박동효율을 이론적으로 예측하였다. 우리는 혈관시스템의 6 컴파트먼트의 Wind-kessel 모델과 연동된 심실의 삼차원 유한요소모델을 사용하였다. 이 모델을 이용하여, LVAD 치료 하에서 심부전의 정도에 따라 심실의 수축성 ATP 소모율, 좌심실압력, 심박출량, 심박출 분획, 1 회심박출량 등과 같은 심장응답을 예측하였다. LVAD 치료 중에 에너지학적 부하조건을 암시하는 수축성 ATP 소모율은 5 단계 심부전 조건에서 가장 크게 감소하였다. 따라서, 우리는 LVAD 를 회복으로의 가교로서 고려하고 있을 때, 심부전 5 단계에서 LVAD 치료를 시작하는 것이 가장 적절하다는 결론을 내린다.

• Journal of Chest Surgery
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• 제53권6호
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• pp.368-374
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• 2020

Background: The extracorporeal ventricular assist device (e-VAD) system is designed for left ventricular support using a permanent life support console. This study aimed to determine the impact of temporary e-VAD implantation bridging on posttransplant outcomes. Methods: We reviewed the clinical records of 6 patients with the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) profile 1, awaiting heart transplantation, who were provided with temporary e-VAD from 2018 to 2019. The circuit comprised a single centrifugal pump without an oxygenator. The e-VAD inflow cannula was inserted into the apex of the left ventricle, and the outflow cannula was positioned in the ascending aorta. The median follow-up duration was 8.4±6.9 months. Results: After e-VAD implantation, lactate dehydrogenase levels significantly decreased, and Sequential Organ Failure Assessment scores significantly improved. Bedside rehabilitation was possible in 5 patients. After a mean e-VAD support duration of 14.5±17.3 days, all patients were successfully bridged to transplantation. After transplantation, 5 patients survived for at least 6 months. Conclusion: e-VAD may reverse end-organ dysfunction and improve outcomes in INTERMACS I heart transplant patients.

• 대한의용생체공학회:의공학회지
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• 제12권1호
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• pp.29-34
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• 1991

Ventricular assist device(VAD) has been clinically applied as a temporary circulatory sup- porting system in the patients with severe heart failure, but small sized VAD for infant is not available. The purpose of tilis paper is to introdIAce small sized VAD and presents the result of in vitro test. Sejong VAD is diaphragmatic type of pneumatic pump and stroke volume is 11cc. Cardiac outputs of the Sejong VAD were measured by overflow tank under variable conditions of driving parameters. The cardiac output was 1.3 1/min at the heart rate of 120 per minute, left atrial pressure of $15cmH_2O$, percent systole of 43%, driving pressure of 240 mmHg, vacuum pressure of -40 mmHg, and mean aortic pressure of 70 mmHg. No mechanical problem was developed during the continuous in vitro test for 3 months.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1998년도 추계학술대회
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• pp.235-236
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• 1998

The purpose of this paper is to develop diaphragm type pneumatic Left Ventricular Assist Device(LVAD) for clinical application and to evaluate its performance through the mock circulation and animal experiment. The blood housing and diaphragm are made by polyurethane. The relations of cardiac output us. beat rate and cardiac output vs. systolic-to-diastolic rate was estimated through the mock test and hemodynamic waves are recorded for the evaluation of VAD. We performed animal experiment and 4 animals survived more than 24hrs. As a result, the hemodynamic data and waves showed this system can be applicable to the animal experiment.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.346-350
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• 1996

This paper presents a Neural Network Identification (NNI) method for modeling of highly complicated nonlinear and time varing human system with a pneumatically driven mock circulation system of Left Ventricular Assist Device(LVD). This system consists of electronic circuits and pneumatic driving circuits. The initation of systole and the pumping duration can be determined by the computer program. The line pressure from a pressure transducer inserted in the pneumatic line was recorded. System modeling is completed using the adaptively trained backpropagation learning algorithms with input variables, Heart Rate(HR), Systole-Diastole Rate(SDR), which can vary state of system, and preload, afterload, which indicate the systemic dynamic characteristics and output parameters are preload, afterload.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1986년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 17-18 Oct. 1986
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• pp.643-647
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• 1986

A new type of motor-driven Total Artificial Heart (TAH) system with rolling-ball mechanism has been developed. To test its performance as a Left Ventricular Assist Device (LVAD), LVAD is controlled to bypass blood for impaired heart triggered by the R-wave in ECG. Results of the test with a Mock Circulation System (MCS) and an animal experiment with a dog are also included. More powerful system using a brushless DC motor has been developed and its control scheme is represented.

• 대한기계학회논문집B
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• 제38권9호
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• pp.739-745
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• 2014

심장 질환 환자에게 약물 치료를 시행하고 있으나, 통상의 약물 치료만으로는 심장질환을 치료하기에는 부족하다. 그러나 LVAD 를 이식한다면 심장기능을 보조하여 심장 이식까지의 가교 역할로서 효과가 있다고 보고되고 있다. 본 연구에서는 선행 연구로 개발된 곡관형 LVAD 인 LibraHeart-I(LH-1)을 이용하여, 대동물(Bovine model, Holstein)과 소동물(canine model, Labrador-retriever)을 대상으로 장기간 동물실험 및 응급상황에서의 생체적합성을 평가하고자 한다. 대동물을 대상으로 실시한 장기간의 동물 실험에서 49 일 생존하였으며, 실험기간 동안 실시한 혈액 검사 및 생징후에서 특이 소견을 관찰되지 않았다. 소동물을 대상으로 한 단기간의 동물 실험에서는 외부 구동부의 동력 지원 없이도 LH-I 내에 혈액이 머무르지 않는 것으로 관찰되었다. 본 연구에서는 장기간 동물실험 및 응급상황에서의 박출 성능을 통해 선행 연구로 개발된 LH-I의 생체적합성을 검증하였다.

• 제어로봇시스템학회논문지
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• 제8권12호
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• pp.1061-1065
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• 2002

Sensors need to be implanted to obtain necessary information for LVAS (Left Ventricular Assist System) operations. Size of the sensors can prevent them from being implanted in a patient and reliabilities of the sensors are questionable for a long term use. In this wort we utilize a developed pump model to estimate flow and pressure difference across the pump without implanted sensors and present a method to obtain the physiological variables as aorta pressure and left ventricle pressure from the pump model and pulsatility of flow estimate or pressure difference estimate. These estimated variables can be used for LVAS control as an index or indices.