Korea Artificial Organ Center

Seoul, South Korea

Korea Artificial Organ Center

Seoul, South Korea
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Jung J.S.,Korea University | Jung J.S.,Korea Artificial Organ Center | Son H.S.,Korea University | Son H.S.,Korea Artificial Organ Center | And 5 more authors.
Transplantation Proceedings | Year: 2013

After heart transplantation (HT), transient right heart failure (RHF) is common. If it does not improve with appropriate medical therapy, we must consider mechanical support. Recently, extracorporeal membrane oxygenation (ECMO) has shown better results than a right ventricular assist device or retransplantation. Two HT patients with hypertrophic cardiomyopathy had cold ischemic times beyond >240 minutes. After HT, their right heart function worsened and was unresponsive to medical therapy. After our application of ECMO, weaning was successful and the patients were discharged without complication. Early application of ECMO for RHF after HT is a good option. © 2013 by Elsevier Inc. All rights reserved.


Lee J.J.,Korea Artificial Organ Center | Ahn C.B.,Korea Artificial Organ Center | Ahn C.B.,Korea University | Choi J.,Korea Artificial Organ Center | And 7 more authors.
Artificial Organs | Year: 2011

A magnetic bearing system is a crucial component in a third-generation blood pump, particularly when we consider aspects such as system durability and blood compatibility. Many factors such as efficiency, occupying volume, hemodynamic stability in the flow path, mechanical stability, and stiffness need to be considered for the use of a magnetic bearing system in a third-generation blood pump, and a number of studies have been conducted to develop novel magnetic bearing design for better handling of these factors. In this study, we developed and evaluated a new magnetic bearing system having a motor for a new third-generation blood pump. This magnetic bearing system consists of a magnetic levitation compartment and a brushless direct current (BLDC) motor compartment. The active-control degree of freedom is one; this control is used for controlling the levitation in the axial direction. The levitation in the radial direction has a passive magnetic levitation structure. In order to improve the system efficiency, we separated the magnetic circuit for axial levitation by using a magnetic circuit for motor drive. Each magnetic circuit in the bearing system was designed to have a minimum gap by placing mechanical parts, such as the impeller blades, outside the circuit. A custom-designed noncontact gap sensor was used for minimizing the system volume. We fabricated an experimental prototype of the proposed magnetic bearing system and evaluated its performance by a control system using the Matlab xPC Target system. The noncontact gap sensor was an eddy current gap sensor with an outer diameter of 2.38mm, thickness of 0.88mm, and resolution of 5μm. The BLDC motor compartment was designed to have an outer diameter of 20mm, length of 28.75mm, and power of 4.5W. It exhibited a torque of 8.6mNm at 5000rpm. The entire bearing system, including the motor and the sensor, had an outer diameter of 22mm and a length of 97mm. The prototype exhibited sufficient levitation performance in the stop state and the rotation state with a gap of 0.2mm between the rotor and the stator. The system had a steady position error of 0.01μm in the stop state and a position error of 0.02μm at a rotational speed of 5000rpm; the current consumption rates were 0.15A and 0.17A in the stop state and the rotation state, respectively. In summary, we developed and evaluated a unique magnetic bearing system with an integrated motor. We believe that our design will be an important basis for the further development of the design of an entire third-generation blood pump system. © 2011, Copyright the Authors. Artificial Organs © 2011, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.


Park J.W.,Korea Artificial Organ Center | Park J.W.,Korea University | Choi J.,Korea Artificial Organ Center | Choi J.,Korea University | And 4 more authors.
Artificial Organs | Year: 2011

In manual or robot-assisted catheter intervention, excessive manipulation force may cause tissue perforation. Using images acquired by an imaging device routinely used for catheter interventions such as X-ray fluoroscopy, the structure and size of blood vessels and the relative position of the catheter tip inside the vessel can be obtained. To prevent collision of the catheter tip and the vessel wall, vision-assisted control methods using forbidden-region virtual fixture (FRVF) technique can be utilized and an experimental implementation has been performed in this study. A master-slave configured robotic platform for cardiac catheter was used for this study. The robotic master handle can provide haptic rendering to the user. A vessel phantom model mimicking human vasculature for the inner radii was fabricated for simulated intervention experiments. A digital optical camera was used for image acquisition. After the vessel phantom and the catheter tip were segmented, distance between the vessel centerline and the catheter tip was calculated and the forbidden region that the catheter tip should keep away from was set for the safe catheter manipulation. Virtual force generation algorithm was implemented for feeding the signal indicating the catheter tip penetrating into the forbidden region back to the user in the robotic master handle. To validate the suggested method, in vitro experiments were conducted. Through a chain of image filtering procedures including edge detection, the catheter tip and the vessel wall were able to be well segmented. The virtual force generator worked appropriately. The developed FRVF technique could provide helpful auxiliary information to clinicians for safer manipulation of catheters in cardiac catheterization procedures. © 2011, Copyright the Authors. Artificial Organs © 2011, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.


Song S.-J.,Korea Artificial Organ Center | Song S.-J.,Korea University | Choi J.,Korea Artificial Organ Center | Choi J.,Korea University | And 10 more authors.
Artificial Organs | Year: 2011

Bioprinting is a technology for constructing bioartificial tissue or organs of complex three-dimensional (3-D) structure with high-precision spatial shape forming ability in larger scale than conventional tissue engineering methods and simultaneous multiple components composition ability. It utilizes computer-controlled 3-D printer mechanism or solid free-form fabrication technologies. In this study, sodium alginate hydrogel that can be utilized for large-dimension tissue fabrication with its fast gelation property was studied regarding material-specific printing technique and printing parameters using a multinozzle bioprinting system developed by the authors. A sodium alginate solution was prepared with a concentration of 1% (wt/vol), and 1% CaCl 2 solution was used as cross-linker for the gelation. The two materials were loaded in each of two nozzles in the multinozzle bioprinting system that has a total of four nozzles of which the injection speed can be independently controlled. A 3-D alginate structure was fabricated through layer-by-layer printing. Each layer was formed through two phases of printing, the first phase with the sodium alginate solution and the second phase with the calcium chloride solution, in identical printing pattern and speed condition. The target patterns were lattice shaped with 2-mm spacing and two different line widths. The nozzle moving speed was 6.67mm/s, and the injection head speed was 10μm/s. For the two different line widths, two injection needles with inner diameters of 260 and 410μm were used. The number of layers accumulated was five in this experiment. By varying the nozzle moving speed and the injection speed, various pattern widths could be achieved. The feasibility of sodium alginate hydrogel free-form formation by alternate printing of alginate solution and sodium chloride solution was confirmed in the developed multinozzle bioprinting system. © 2011, Copyright the Authors. Artificial Organs © 2011, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.


Jung J.S.,Korea University | Jung J.S.,Korea Artificial Organ Center | Son K.H.,Korea University | Son K.H.,Korea Artificial Organ Center | And 6 more authors.
Artificial Organs | Year: 2011

Vessel lumens that have been chronically narrowed by atherosclerosis should be increased in flow velocity and intrastenotic area pressure to maintain an equal flow. This might be followed by a decrease in hemodynamic energy, leading to a reduction of tissue perfusion. In this study, we compared hemodynamic energies according to degrees of stenotic vasculature between pulsatile flow and nonpulsatile flow. Cannuale with 25, 50, and 75% diameter stenosis (DS) were located at the outlet cannula. Using the Korea Hybrid ventricular assist device (KH-VAD) (pulsatile pump: group A) and Biopump (nonpulsatile pump: group B), constant flow of 2L/min was maintained then real-time flow and velocity in the proximal and distal part of the stenotic cannula were measured. The hemodynamic energies of two groups were compared. At 75% DS, proximal energy equivalent pressure (EEP) delivered to the distal end was only 41.9% (group A) and 42.5% (group B). As the percent EEP fell below 10%, pulsatility disappeared from the 50% stenosis in group A. The surplus hemodynamic energy (SHE) of group B at all degrees of stenosis must have been 0, which was also the case of group A at 75% stenosis. This research evaluated the hemodynamic energy on various degrees of DS in both pulsatile and nonpulsatile flow with mock system. Using a pulsatile pump, pulsatility disappeared above 50% DS while hemodynamic energy was maintained. Therefore, our results suggest that pulsatile flow has a better effect than nonpulsatile flow in reserving hemodynamic energy after stenotic lesion. © 2011, Copyright the Authors. Artificial Organs © 2011, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.


Ahn C.B.,Korea Artificial Organ Center | Son K.H.,Korea Artificial Organ Center | Son K.H.,Korea University | Lee J.J.,Korea Artificial Organ Center | And 12 more authors.
Artificial Organs | Year: 2011

Blood viscosity during operation of ventricular assist device (VAD) can be changed by various conditions such as anemia. It is known generally that the blood viscosity can affect vascular resistance and lead to change of blood flow. In this study, the effect of fluid viscosity variation on hemodynamic energy was evaluated with a pulsatile blood pump in a mock system. Six solutions were used for experiments, which were composed of water and glycerin and had different viscosities of 2, 2.5, 3, 3.5, 4, and 4.5cP. The hemodynamic energy at the outlet cannula was measured. Experimental results showed that mean pressure was increased in accordance with the viscosity increase. When the viscosity increased, the mean pressure was also increased. However, the flow was decreased according to the viscosity increase. Energy equivalent pressure value was increased according to the viscosity-induced pressure rise; however, surplus hemodynamic energy value did not show any apparent changing trend. The hemodynamic energy made by the pulsatile VAD was affected by the viscosity of the circulating fluid. © 2011, Copyright the Authors. Artificial Organs © 2011, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.


Son K.H.,Korea University | Son K.H.,Korea Artificial Organ Center | Ahn C.B.,Korea Artificial Organ Center | Lee S.H.,Korea University | And 8 more authors.
Clinical Hemorheology and Microcirculation | Year: 2011

Purpose: The advantages of blood cardioplegia, which is used for myocardial protection during open heart surgeries, include superior oxygen-carrying capacities, better osmotic properties, and the presence of more antioxidants than a crystalloid counterpart. Although, hyperkalemic organ-preserving solutions for transplantation surgeries are known to decrease RBC deformability essential for tissue perfusion, only few studies have addressed the changes in RBC deformability after exposure to cardioplegic additives. The purpose of this study was to measure deformability and oxygen-delivery capacities in various blood cardioplegic solutions. Methods: Blood from eight healthy volunteers was used. Each sample (100 ml) was divided into 5 groups of 16 ml, and cardioplegia solutions were added (group NS; blood + normal saline, group K; blood + KCl, group D; blood + KCl + diltiazem, group A: blood + KCl + adenosine, group E: blood + KCl + neutrophil elastase inhibitor [Sivelestat]). All samples were incubated at a temperature of 8°C for 10 minutes. Deformability, NO level, 2,3-DPG, and ATP were measured. Results: There was no statistically significant difference (p = 0.92) in deformability between the groups. The NO levels were not significantly different (p = 0.86). The 2,3-DPG (p = 0.27) and ATP levels (p = 0.40) were not significantly different. Conclusions: The deformability and oxygen carrying functions of RBCs did not show a significant difference according to various components of cold blood cardioplegia during 10 minutes of incubation. © 2011 - IOS Press and the authors. All rights reserved.


Song S.-J.,Korea Artificial Organ Center | Choi J.,Korea Artificial Organ Center | Park Y.-D.,Korea Artificial Organ Center | Lee J.-J.,Korea Artificial Organ Center | And 3 more authors.
Artificial Organs | Year: 2010

Bioprinting is an emerging technology for constructing tissue or bioartificial organs with complex three-dimensional (3D) structures. It provides high-precision spatial shape forming ability on a larger scale than conventional tissue engineering methods, and simultaneous multiple components composition ability. Bioprinting utilizes a computer-controlled 3D printer mechanism for 3D biological structure construction. To implement minimal pattern width in a hydrogel-based bioprinting system, a study on printing characteristics was performed by varying printer control parameters. The experimental results showed that printing pattern width depends on associated printer control parameters such as printing flow rate, nozzle diameter, and nozzle velocity. The system under development showed acceptable feasibility of potential use for accurate printing pattern implementation in tissue engineering applications and is another example of novel techniques for regenerative medicine based on computer-aided biofabrication system. © 2010, the Authors. Artificial Organs © 2010, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.


Kim H.J.,Korea University | Yoo S.M.,Korea Artificial Organ Center | Jung J.S.,Korea University | Lee S.H.,Korea University | And 2 more authors.
Anaesthesia | Year: 2015

Summary We measured heating of isotonic saline by three fluid warmers in six experiments: saline at 5 C or 20 C delivered at 30, 50 or 100 ml.min-1. At the three flow rates, the enFLOW®, buddy lite™ and ThermoSens® systems heated 5 C saline to mean (SD) temperatures of: 41.1 (0.5) C, 37.7 (0.6) C and 39.1 (0.6) C; to 40.3 (0.8) C, 33.9 (1.6) C and 39.3 (0.7) C; and to 37.1 (0.8) C, 24.0 (1.3) C and 37.6 (1.0) C, respectively, p < 0.0001 for each experiment. The mean (SD) times taken to heat 5 C saline were: 16.6 (1.7) s, 258.4 (58.9) s and 134.2 (79.6) s; 16.9 (1.8) s, 256.2 (62.2) s and 182.5 (74.5) s; and 21.5 (1.5) s, 275.9 (49.3) s and 313.5 (18.0) s, respectively, p < 0.0003 for each experiment. The results for saline at 20 C were similar. The enFLOW system heated saline above 36 C faster than the ThermoSens system, whereas the buddy lite often failed to achieve 36 C. © 2014 The Association of Anaesthetists of Great Britain and Ireland.


PubMed | Korea Artificial Organ Center and Korea University
Type: Journal Article | Journal: Clinical hemorheology and microcirculation | Year: 2016

A newly developed fluid warmer (ThermoSens) has a direct blood warming plate, which can result in hemolysis or red blood cell injury during heating. Therefore, to evaluate the safety of heating blood products with a fluid warmer, we conducted laboratory tests to study hemolysis and erythrocyte rheology.We used outdated human blood taken from a Korean blood bank. Packed red blood cells mixed with 100mL isotonic saline was passed through the fluid warmer. Blood flow was achieved by either gravity or 300 mmHg pressure. Blood samples were analyzed before and after heating for hemolysis marker and erythrocyte rheology parameters.The temperatures at the outlet were higher than 38C at gravity and 300 mmHg pressure, respectively. There were no significant differences in hemolysis markers (hemoglobin, hematocrit, lactate dehydrogenase, and plasma free hemoglobin) or erythrocyte rheology (deformability, disaggregating shear stress, and aggregation index) between before and after heating (p> 0.05) except LDH at gravity (p=0.0001).The ThermoSens fluid warmer caused no erythrocyte injury or negative effects on rheology during heating. Regarding medical device development, hemorheologic analysis can be useful for safety evaluation of medical devices that directly contact blood for temperature modulation.

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