• Title/Summary/Keyword: Korean Artificial Heart

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Assessment of Hemodynamic Properties of Trileaflet Polymer Heart Valve Manufactured By Vacuum Forming Process (진공성형을 이용한 삼엽식 고분자 심장판막의 제작과 혈류역학적 성능평가)

  • Kim, K.H.;Hwang, C.M.;Jeong, G.S.;Ahn, C.B.;Kim, B.S.;Lee, J.J.;Nam, K.W.;Sun, K.
    • Journal of Biomedical Engineering Research
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    • v.27 no.6
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    • pp.418-426
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    • 2006
  • In the artificial heart application, productivity and hemodynamic properties of artificial heart valves are crucial in successiful application to long term in vivo trials. This paper is about manufacture and assessment of trileaflet polymer heart valves using vacuum forming process(VFP). The VFP has many advantages such as reduced fabrication time, reproducibility due to relatively easy and simple process for manufacturing. Prior to VFP of trileaflet polymer heart valves, polyurethane(Pellethane 2363 80AE, Dow Chemical) sheet was prepared by extrusion. The sheets were heated and formed to mold shape by vacuum pressure. The vacuum formed trileaflet polymer heart valves fabrication is composed of two step method, first, leaflet forming and second, conduit forming. This two-step forming process made the leaflet-conduit bonding stable with any organic solvents. Hydrodynamic properties and hemocompatibility of the vacuum formed trileaflet polymer heart valves was compared with sorin bicarbon bileaflet heart valve. The percent effective orifice area of vacuum formed trileaflet polymer heart valves was inferior to bileaflet heart valve, but the increase of plasma free hemoglobin level which reflect blood damage was superior in vacuum formed trileaflet polymer heart valves Vacuum formed trileaflet polymer heart valves has high productivity, and superior hemodynamic property than bileaflet heart valves. Low manufacturing cost and blood compatible trileaflet polymer heart valves shows the advantages of vacuum forming process, and these results give feasibility in in vivo animal trials in near future, and the clinical artificial heart development program.

Reliable Prognostic Cardiopulmonary Function Variables in 110 Patients With Acute Ischemic Heart Disease

  • Lee, Jeong Jae;Park, Chan-hee;You, Joshua (Sung) Hyun
    • Physical Therapy Korea
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    • v.29 no.3
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    • pp.200-207
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    • 2022
  • Background: The oxygen uptake efficiency slope (OUES) is the most important index for accurately measuring cardiopulmonary function in patients with acute ischemic heart disease. However, the relationship between the OUES variables and important cardiopulmonary function parameters remain unelucidated for patients with acute ischemic heart disease, which accounts for the largest proportion of heart disease. Objects: The present cross sectional clinical study aimed to determine the multiple relationships among the cardiopulmonary function variables mentioned above in adults with acute ischemic heart disease. Methods: A convenience sample of 110 adult inpatients with ischemic heart disease (age: 57.4 ± 11.3 y; 95 males, 15 females) was enrolled at the hospital cardiac rehabilitation center. The correlation between the important cardiopulmonary function indicators including peak oxygen uptake (VO2 peak), minute ventilation (VE)/carbon dioxide production (VCO2) slope, heart rate recovery (HRR), and ejection fraction (EF) and OUES was confirmed. Results: This study showed that OUES was highly correlated with VO2 peak, VE/VCO2 slope, and HRR parameters. Conclusion: The OUES can be used as an accurate indicator for cardiopulmonary function. There are other factors that influence aerobic capacity besides EF, so there is no correlation with EF. Effective cardiopulmonary rehabilitation programs can be designed based on OUES during submaximal exercise in patients with acute ischemic heart disease.

Design of A Human Model of the Moving-Actuator Type Total Artificial Heart

  • Chang, Jun-Keun;Min, Byoung-Goo
    • Journal of Biomedical Engineering Research
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    • v.18 no.1
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    • pp.65-70
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    • 1997
  • A human version of Korean total artificial heart(TAM) was designed basso on the magnetic resonance imaging(MRI) data To obtain accurate measurement or human thoracic structure including the valvular sited we analyzed the dimensions of the natural heart of healthy persons and cardiomyopathy(CM) patients. The MRI findings were analyzed to measure the volume of the thoracic cavity that would be occupied by the TAM. The design upgrade of the mechanical performed was also performed with the computer aided design(CAD) system to develop a new version of Korean TAH.

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The Second Animal Tests of Artificial Heart Valves (인공심장판막의 개발과 동물실험 -인공심장판막의 2차 동물실험-)

  • 김형묵
    • Journal of Chest Surgery
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    • v.23 no.4
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    • pp.617-621
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    • 1990
  • A heart supplies blood of about 15, 000 liters to each human organ in a day. A normal function of heart valves is necessary to accomplish these enormous work of heart. The disease of heart valve develops to a narrowness of a closure, resulting in an abnormal circulation of blood. In an attempt to eliminate the affliction of heart valves, the operative method to replace with artificial heart valves has developed and saved numerous patients over past 30 years. This replacement operation has been performed since early 1960`s in Korea, but all the artificial heart valves used are imported from abroad with very high costs until recent years. New artificial heart valves have been developed in Korea Advanced Institute of Science and Technology since early 1980`s. The first developed valve was designed with a free-floating pyrolytic carbon disk that is suspended in a titanium cage. The design of the valve was tested in vitro, and in animals in 1987. The results from this study was that the eccentrically placed struts creates a major and minor orifice when the disc opens and stagnation of flow in the area of the minor orifice has led to valve thrombosis. In this work, the design of the valve was changed from a single - leaflet valve to double - leaflet one in order to resolve the problems observed in the first - year tests. Morphological and hemodynamic studies were made for the newly designed valves through the in vitro and in vivo tests. The design and partial materials of the artificial heart valve was improved comparing with first - year`s model. The disc in the valve was modified from single - leaflet to bi - leaflet, and the material of the cage was changed from titanium metal to silicon - alloyed pyrolytic carbon. A test was made for the valve in order to examine its mechanical performance and stability. Morphological and hemodynamic studies were made for the valve that had been implanted in tricuspid position of mongrel dogs. All the test animals were observed just before the deaths. A new artificial heart valve was designed and fabricated in order to resolve the problems observed in the old model. The new valve was verified to have good stability and high resistance to wear through the performance tests. The hemodynamic properties of the valve after implantation were also estimated to be good in animal tests. Therefore, the results suggest that the newly designed valve in this work has a good quality in view of the biocompatibility. However, valve thrombosis on valve leaflets and annulus were found. This morphological findings were in accordance with results of surface polishing status studies, indicating that a technique of fine polishing of the surface is necessary to develop a valve with higher quality and performance.

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Numerical Simulation of Flow in a Total Artificial Heart (인공심장내의 혈류유동의 컴퓨터 시뮬레이션)

  • ;K.B
    • Journal of Biomedical Engineering Research
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    • v.13 no.2
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    • pp.87-96
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    • 1992
  • In thIns paper, a numerical simulation of steady laminar and turbulent flow in a two dimensional model for the total artificial heart is'presented. A trlleaflet polyurethane valve was simulated at the outflow orifice while the Inflow orifice had a trileaflet or a flap valve. The finite analytic numerical method was employed to obtain solutions to the governing equations in the Cartesian coordinates. The closure for turbulence model was achieved by employing the k-$\varepsilon$-E model. The SIMPLER algo rithm was used to solve the problem in primitive variables. The numerical solutions of the slulated model show that regions of relative stasis and trapped vortices were smaller within the ventricular chamber with the flap valve at the Inflow orifice than that with the trileaflet valve. The predicted Reynolds stresses distal to the inflow valve within the ventricular chamber were also found to be smaller wlth the flap valve than with the trlleaflet valve. These resu1ts also suggest a correlation be- tween high turbulent stresses and the presence of thrombus In the vicinity of the valves in the total artificial hearts. The computed velocity vectors and trubulent stresses were comparable with previ ously reported in vitro measurements in artificial heart chambers. Analysis of the numerical solo talons suggests that geometries similar to the flap valve(or a tilting disc valve) results in a better flow dynamics within the total artificial heart chamber compared to a trileaflet valve.

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Nonlinear Analysis of the Monoleaflet Polymer Valve according to Shape of Supporting Members (지지대 형상에 따른 단엽식 고분자 판막의 비선형 해석)

  • 한근조;안성찬;심재준;김성윤
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.3
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    • pp.120-124
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    • 2003
  • Monoleaflet polymer artificial heart valve was known to show remarkable improvement in antithrombosis and pressure drop compared with other type of artificial valve. In this investigation of monoleaflet heart valve the vertical and horizontal deflection pattern of polymer heart valve with three types of supporting members, straight member and two curved members were analysed using the large deformation nonlinear finite element method.

Hydraulic Force and Impeller Evaluation of a Centrifugal Heart Pump

  • Timms, D.L;Tan, A.C.C;Pearcy, M-J;Mcneil, K;Galbraith, A
    • Journal of Advanced Marine Engineering and Technology
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    • v.28 no.2
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    • pp.376-381
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    • 2004
  • A rig was constructed to test the performance characteristics and compare the hydraulic forces exerted on a centrifugal type artificial heart impeller. A conventional shaft. seal and bearing system. while driven by a small electric motor. supported the impeller which was separated from the pump casing by a six degree of freedom force transducer (JR3 Ine). Radial (x. y) and axial (z) hydraulic forces were recorded and compared. At physiological operating conditions. the results indicate that the double entry/exit centrifugal pump encounters a smaller radial force and significantly reduced axial thrust. These experimental results are valuable in the design of a magnetic bearing system to suspend the impeller of a centrifugal artificial heart pump. This experimental technique may also be applied to evaluate the required capacity and predict the lifetime of contact bearings in marine pumps.

Basic Study for Stress Analysis Using an Unconstrained BCG Monitoring System (무구속 심탄도 모니터링 시스템을 이용한 스트레스 분석 기초연구)

  • Noh, Yun-Hong;Jeong, Do-Un
    • Journal of Sensor Science and Technology
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    • v.20 no.2
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    • pp.118-123
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    • 2011
  • Heart related diseases mainly caused by heavy work load and increasing stress in human daily life. Therefore, researches on mobile healthcare monitoring for daily life has been carried out. Notably, wearable healthcare monitoring system which has least restriction has been tried to provide an emergency alert of abnormal heart rate. In this study, we developed chair type unconstrained BCG measurement system which able to perform continuous heart status monitoring at the office and daily life in the unconstrained way. Furthermore, adaptive threshold is used to detect the heart rate from BCG signals. The HRV(heart rate variability) is calculated from heart rate interval. ECG signal measured using conventional method and BCG signal measured using unconstraint system are carried out simultaneously for the purpose of performance evaluation. From the comparison result, BCG signal shows a similar heart beat characteristic as ECG signal. This proves the possibility of practical implementation of unconstraint healthcare monitoring system. In addition, medical examination like valsalva maneuver is performed to observe the changes in HRV due to stress. By performing valsalva maneuver, heart is said to be placed under an artificial physical stress condition. Under this artificial physical stress condition, the time and frequency domain of HRV parameters are evaluated.

Numerical Simulation of Flow in a Total Artificial Heart (인공심장내의 혈류유동의 컴퓨터 시뮬레이션)

  • Kim, S.H.;Chandran, K.B;Chen, C.J.
    • Proceedings of the KOSOMBE Conference
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    • v.1992 no.05
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    • pp.123-126
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    • 1992
  • In this paper, a numerical simulation of steady laminar and turbulent flow in a two dimensional model for the total artificial heart is presented. A trileaflet polyurethane valve was simulated at the outflow orifice while the inflow orifice had a trileaflet or a flap valve. The numerical solutions of the simulated model show that regions of relative stasis and trapped vortices were smaller wi thin the ventricular chamber wi th the flap valve at the inflow orifice than that with the trileaflet valve. The predicted Reynolds stresses distal to the inflow valve within the ventricular chamber were also found to be smaller with the flap valve than with the trileaflet valve. Analysis of the numerical solutions suggests that geometries similar to the flap valve(or a tilting disc valve) results in a better flow dynamics within the total artificial heart chamber compared to a trileaflet valve.

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A Study on the Control of Brushless DC Motor for Total Artificial Heart (인공심장용 브러시리스 직류전동기 제어에 관한 연구)

  • Kwon, S.I.;Lee, S.H.;Kim, J.T.;Kim, H.C.;Min, B.G.
    • Proceedings of the KIEE Conference
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    • 1987.07b
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    • pp.1317-1321
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    • 1987
  • A new type of motor-driven Total Artificial Heart(TAH) system with rolling cylinder mechanism has been developed. Brushless DC motor was chosen as energy converter and controlled by PI controller according to the given velocity profile under the highly time-varying load. Computer simulation was also performed to calculate the optimal gains of PI controller which minimize the input power, one of the most important parameter in artificial heart system.

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