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[in Japanese]
2000 Volume 29 Issue 2 Pages
299-300
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
JOURNAL
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E Okamoto, K Baba, S Suzuki, S Fukuoka, E Iwasawa, E Mitamura, I Saito ...
2000 Volume 29 Issue 2 Pages
301-307
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
JOURNAL
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We have developed and improved a transcutaneous electromagnetic bi-directional data transmission system for an artificial heart. In this system, ASK (Amplitude Shift Keying) modulation with carrier frequencies of 4 MHz and 10 MHz is employed in consideration of electromagnetic permittivity into tissue, and which involves less interference for bi-directional transmission. To miniaturize each TDT unit size, the TDT system consists primarily of a one·chip microcomputer with circuit boards designed by CAD and CAM technology. The model for molding the electronics circuit is designed by CAD, and manufactured by CAM and a 3-axial NC machine. The size of each unit is 45 mm in diameter and 8 mm in thickness. In vitro experimental results showed that the TDT system could transmit data, via a transcutaneous energy transmission system, a within an area of axial direction of 7.5 cm and a radial direction of 4 cm without interference. The results of animal experiments in which the TDT system was implanted inside a goat showed excellent fitting and stable operation during a period of 87 days. This demonstrates the convenience of the TDT system for transcutaneous bi-directional communication in an implantable artificial heart system.
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E Okamoto, S Suzuki, K Baba, S Fukuoka, E Iwasawa, Y Mitamura
2000 Volume 29 Issue 2 Pages
308-314
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
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We have developed a new estimation method that uses neural networks within the remote monitoring system of artificial heart implants, which estimates blood pressure based on artificial heart driving data (motor current and motor rotational angle data). The blood pressure is estimated by separating the mean pressure component from the pulsatile pressure component and by calculating each pressure component with respect to the corresponding neural network. Neural networks learn by means of referring to the actual blood pressure of patients leave the hospital, neural networks estimate blood pressure by using artificial heart driving data that have been transmitted by a PHS (personal handy phone system). Results of in vitro experiments show that blood pressure in mock circulation can be estimated with excellent results in the cases of a change in the pump drive rate, change in arterial resistance, or a malfunction of an artificial heart actuator. These results demonstrate that estimation of the blood pressure using neural networks is effective for a remote monitoring system of patients with artificial heart implants.
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D Tanigawa, K Shiba, K Koshiji, K Tsuchimoto, K Tsukahara, E Tatsumi, ...
2000 Volume 29 Issue 2 Pages
315-321
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
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In this paper, a transcutaneous optical coupler consisting of three laser diodes (LD) as light emitting devices and three PIN photodiodes (PINPD) as light receiving devices was made on an experimental basis, and was investigated and compared to the conventional coupler consisting of an LD and PINPD. In order to ease implantation of the transcutaneous optical coupler in the body, the experimental coupler had a disklike shape with a radius of 20 mm and a thickness of 15 mm, and was coated with silicone. The relative light intensity radiated from the coupler was measured, and the maximum permissible deviation and the rotational slide between the couplers was also evaluated. As well, the coupler consisting of three LDs and three PINPDs was investigated in terms of power consumption. As a result, we found that the experimental coupler was permitted a rotational slide of 360 degrees, consisting a permissible deviation much greater than that conventional coupler, and its power consumption was much lower than that of the TAH.
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A Yuhki, E Hatoh, M Nogawa, S Takatani
2000 Volume 29 Issue 2 Pages
322-327
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
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In this study, a tripod-supported, seal-less centrifugal blood pump, as an implantable ventricular assist device has been developed using a specially designed DC brush-less motor and fabricated. The tripod structure consisted of three ceramic balls and a polyethylene groove. The follower magnet inside the impeller was coupled to the driver magnet of the motor, thus allowing the impeller to slide-rotate in the polyethylene groove. The pump driver had a weight of 230 g and a diameter of 60 mm. The acrylic housing had a weight of 220 g with a priming volume of 25 ml. At a pump RPM of 1000 to 2200 rpm, the generated head pressure ranged from 30 to 150 mmHg, having a maximum system efficiency of 12%. When the prototype pump was used in the pulsatile mock loop, a strong correlation was obtained between the motor current and bypass flow waveforms. The waveform deformation index (WDI), defined as the ratio of the fundamental to the higher order harmonics, of the motor current power spectral density was computed to possibly detect the presence of suction. When the WDI was kept under the value of 0.20 by adjusting the motor RPM, it was successful in suppressing the occurrence of suction. The prototype seal-less, centrifugal pump, with the control method based on the motor current waveform analysis, may offer a temporary to inter-mediate circulatory support to heart transplantation.
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H Furukawa, H Nishida, G Ohtsuka, K Yamazaki, A Kawai, S Aomi, M Hachi ...
2000 Volume 29 Issue 2 Pages
328-331
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
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The percutaneous cardiopulmonary support system (PCPS) has been widely used as a simple and quick set-up system for circulatory collapse. We evaluated the clinical experience of PCPS in emergency circulatory failure. Moreover, we prepared modified PCPS to expand its ability to identify a greater range of clinical conditions by utilizing the advantages of the original system. Thirty-five patients (M: F=22: 13, age 26-78 years, mean age 59.2 years) underwent PCPS in our institute from 1992 to 1999. The circulatory support time was 62 minutes-167 hours (mean: 47.3 hours). Thirteen patients (37.1%) were successfully weaned from PCPS and 5 patients (14.3%) were discharged. Our experience demonstrates that modifications of PCPS can expand the PCPS's ability to identify a greater range of clinical conditions.
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H Ide, K Nonaka, T Fujiki, M Sato, H Endo, K Sudo
2000 Volume 29 Issue 2 Pages
332-336
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
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A new Teflon intraaortic balloon catheter was developed whose balloon size 35 cc, length 65 cm, and tube diameter is 7 F. Inside its balloon portion, another tube (outer diameter: 5 mm, length: 20 cm, made of polyurethane) is incorporated and permits the insertion of a left ventricle (LV) vent catheter (outer diameter 12 F, length 95 cm, made of Teflon) through this tube. On the tip of the tube, a silicon valve is attached to prevent blood regurgitation after removal of the vent catheter. This system enables concomitant exertion of transaortic valve LV venting and intraaortic ballon pumping (IABP) while applying PCPS support, and exclusive removal of the vent catheter during weaning from the PCPS. Mock circulation study estimated that the maximal vent flow of the corresponding vent catheter is 600 ml/ min.
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K Imanishi, K Imachi, Y Abe, T Chinzei, S Mochizuki, T Isoyama, I Sait ...
2000 Volume 29 Issue 2 Pages
337-344
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
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A new type of left ventricular assist device named the Heart Ranger for postcardiotomy cardiogenic shock patients has been developed. The Heart Ranger is composed of an air-driven blood pump and cannula in which inflow and outflow valves have been installed. The Heart Ranger was designed to be inserted in the ascending aorta and proceed into the left ventricle through the aortic valve. Four types of cannula were designed in accordance with the different body sizes of patients. In the Heart Ranger, any type of air-driven drivers (IABP or Artificial Heart) can be connected. In a mock circulatory study, a maximum pump flow of 3.7
l/min was observed using an AH driver. In an animal experiment using a goat, a left thoracotomy was performed and the insertion port was anastomosed to the descending aorta. Then a cannula was inserted through the insertion port into the left ventricle on the guidewire. During 13 postoperative pumping days, a stable assist flow was maintained. More than 2
l/min of assist flow by the Heart Ranger were maintained throughout the pumping days. The Assist rate compared with the cardiac output was 41-69% in the chronic phase. In conclusion, the Heart Ranger provided pressure and flow support with a maximum flow of 3.7
l/min. and the Heart Ranger was thought to provide effective circulatory assistance in the treatment of postcardiotomy cardiogenic shock patients.
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M Satou, H Ide, T Fujiki, H Endou, K Sudou
2000 Volume 29 Issue 2 Pages
345-350
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
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Although percutaneous cardioplumonary support (PCPS) is effective as an emergency measure for circulatory collapse, lower extremity ischemia and myonephrotic metabolic syndrome is still considered to be its major lethal side effect. Twenty-six consecutive patients who necessitated PCPS support were enrolled in this study. Seven patients (27%) were found clinically to have lower extremity ischemia of the cannulated side, of whom two patients died of myonephro metabolic syndrome. Regard' to their basal disease, 50% of the patients with ischemic heart disease are shown to have lower extremity ischemia, and 7% of those are without ischemic heart disease, showing a significant difference. As for plasma enzymal analysis, plasma CPK level is shown to be a significant index for exclusively evaluating lower extremity ischemia. Concomitant extremity perfusion of the PCPS cannulated side using a 14G needle is found to be effective for preventing lower extremity ischemia.
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E Hatoh, A Yuhki, M Nogawa, D Kikugawa, T Murakami, S Takatani
2000 Volume 29 Issue 2 Pages
351-355
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
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In this study, the control system for a seal-less pivot-bearing supported centrifugal pump bypassing the left ventricular apex to descending aorta was designed based on motor current waveform analysis, and the performance of this system was evaluated in a mock circulatory loop. The control system consisted of an IBM-compatible personal computer and a digital signal processor. The control algorithm consisted of two phases; an initial phase for a rough setting of the pump RPM to provide required pump flow for a given heart rate, and a second phase for fine-tuning the RPM to minimize the suction and regurgitation, that may be present at the pre-set RPM level. Using this control system, we first obtained the native heart rate, then calculated the nominal cardiac output for that heart rate based on the predetermined native heart pump characteristics. This was followed by the estimation of the centrifugal pump RPM, to roughly provide the pump output based on the characteristic curves of the centrifugal pump. Then the suction and regurgitation detection algorithm, based on the motor current waveform analysis, was employed to examine the presence of suction and regurgitation. The threshold level of WDI (waveform deformation index: ratio of the fundamental to the higher order harmonics) set below 0.2, indicated the suction and regurgitation-free operation of the centrifugal pump. The control system responded adequately for sudden changes in the pump afterload and native heart rate. Further study is necessary to evaluate the performance of the system in animal experiments.
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M Morita, R Yozu, T Matayoshi, T Katogi, T Ueda, H Shin, R Aeba, H Shi ...
2000 Volume 29 Issue 2 Pages
356-359
Published: May 15, 2000
Released on J-STAGE: June 02, 2011
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In recent years Vacuum Assisted Venous Return (VAVR) has been gaining popularity as a method of augmented venous drainage. One can easily apply VAVR using existing extra-corporeal circuits which employ a vacuum controller. However, the use of circuits specifically designed for VAVR applications would maximize the benefits of VAVR. Our circuit for VAVR has an additional line bypassing a venous reservoir proximally to the venous inlet to distal to the venous outlet. From October in 1996 to April in 1999, cardiopulmonary bypasses in 325 cases have been performed using this VAVR circuit. The applications of VAVR have made use of smaller cannula and have made possible the reduction of prime volume. Utilizing the line bypassing a venous reservoir during weaning has facilitated the more effective management of CPB.
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I Taga, A Funakubo, T Kumagai, T Yasuda, S Ahmed, T Kawamura, Y Fukui
2000 Volume 29 Issue 2 Pages
360-364
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
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In this study, CFD analysis was applied to evaluate the pressure drop and velocity distribution in an extracapillary membrane oxygenator. In most cases, the performance of the extracapillary membrane oxygenator depends on the blood flow conditions. In our previous study with flow visualization, it was indicated that the CFD flow pattern showed a flow condition that was similar to an actual oxygenator. In this study, we focused on pressure drop and velocity distribution with a CFD simulation value and compared those values with those of an in-vitro experiment. In our simulation, the pressure drop increased with the increase of flow rate. During a lower flow rate, both the experimental value and the simulated pressure drop showed almost the same tendency. However, during a higher flow rate condition, the pressure drop of the simulation was 10 mmHg smaller than that of the experimental value. In the case of velocity distribution, we observed an area of stagnation that seems to have been correlated with a thrombus formation area. Therefore, we highly recommended CFD simulation as an effective method of optimizing the design of an artificial lung.
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K Nakamura, M Yano, T Onitsuka
2000 Volume 29 Issue 2 Pages
365-368
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
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Hemostasis is a significant problem in thoracic aortic surgery which requires deep hypothermia. Nafamostat mesilate (NM), a protease inhibitor, has been reported to reduce blood loss in open heart surgery. To evaluate the role of NM during hypothermic cardiopulmonary bypass, we have retrospectively reviewed results in 25 patients who underwent aortic arch replacement. These patients were divided into three groups: Group A (
n=6) heparin of 3 mg/kg was administered and NM was not administered during cardiopulmonary bypass (CPB): Group B (
n=9) heparin of 3 mg/kg and NM of 80 mg/hour were administered: Group C (
n=8) heparin of 1.5 mg/kg and NM of 80 mg/h were administered. All data were analyzed using a two-way analysis of variance. A significant difference was observed in the mean operative blood loss (Group A; 4076 ± 2371 ml, Group B; 1581 ± 1354 ml, Group C; 1997 ± 904 m, p <0.05) and in the number of packed red blood cells which were used during CPB (Group A; 7.7 ± 2.1 U, Group B; 7.5 ± 2.1 U, Group C; 3.8 ± 2.7 U, p < 0.05). This data demonstrates that NM administration reduces blood loss in aortic arch replacement using deep hypothermia.
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H Murayama, S Tamaki, N Kato, Y Narita, J Yokote, M Mutsuga, M Okada, ...
2000 Volume 29 Issue 2 Pages
369-374
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
JOURNAL
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Nearinfrared spectroscopy (NIR) is a procedure which permits noninvasive measurement of cerebral oxygenated and deoxygenated hemoglobin. The purpose of this study is to examine how accurately NIR represents separate and nonoverlapping dimensions among monitoring modalities during cardiopulmonary bypass (CPB). In 66 patients (50 male, 16 female, age 30-74 (mean 63.8 ±9.9) yrs) who underwent coronary artery bypass grafting during CPB, 321 sampling points were defined. Arterial blood pressure, central venous pressure, pulmonary arterial pressure, perfusion index, arterial hemoglobin concentration, and esophageal temperature were recorded at every sampling point. Oxygen and carbondioxide partial pressure and oxygen saturation were measured in arterial and venous blood. Cerebral oxygenated, deoxygenated, and total hemoglobin were measured by NIR spectroscopy. We used the multivariate statistical technique of factor analysis. Seven factors are extracted and rotated orthogonally through the Varimax procedure. Bartlett's chi-square test of the correlation matrix is significant at the 0.0001 level. We have named the factors Oxygen, Cerebral Oxygen, Carbondioxide, Left-Heart, Right-Heart, Perfusion Index, and Hemoglobin. Cerebral Oxygen factor contains NIR-measured cerebral oxygenated and deoxygenated hemoglobin. We conclude that NIR spectroscopy monitored separate and distinct clinical dimensions during CPB. NIR may be a useful new monitoring tool for assessing cerebral oxygenation in open-heart surgery.
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S Kamiyashiki, T Someya, K Hashimoto
2000 Volume 29 Issue 2 Pages
375-378
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
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This study was designed to investigate the effects of blood temperature on cer-ebral circulation. during cardiopulmonary bypass (CPB). Method: Thirty patients underwent elective coronary bypass surgery. The patients were divided into three groups (10 patients each) according to their perfusion temperature (C group: 30°C, W group: 36°C) and p group: by addition of pulsatile at aperfusion temperature at 36°C. Results: (1) No cerebal complication wasobserved in this series. (2) Apparent da-mage of brain evidenced by the leak of CPK-BB was not seen, but the leaking levelin the C group was much severer than those of the W and the P groups during the rewarming phase. (3) Lower Sjo2 levels and higher lactate levels (but not significant) suggested that normothermic perfusion was disadvantageous. Conclusion: Normothermic CPB was relatively safe but might lead to an increased risk of neurological deficits. The addition ofpulsatile flow increased safety of normothermic perfusion.
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M Miura, T Tsujino
2000 Volume 29 Issue 2 Pages
379-383
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
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In order to investigate the relationship between high-intensity transient signals (HITS) detected in midcerebral artery and cavitation bubble formation arround artificial valves, an in vitro experiment was conducted. A cavitation channel device mounted with bileaflet valve models was employed and cavitation formation was detected with high speed video and high speed strobe scope. The opening angle of the leaflets was restricted to 60°, 55°, 40°, 35°, respectively. Cavitation was incepted at 10.2
l/min of forward flow in the 60° model. The bubbles were 0.05-0.4 mm in diameter and disappeared within 15 cm downstream from the valve. However, with Coulter Counter methods, microbubble nuclei of 5-25 μm in diameter were detected at the 60 cm downstream from the valve. Both the diameter and the number density were increased with the flow rate. Our results suggest that etiology of HITS may be the microbubbles generated arround artificial valves.
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K Iwasaki, M Umezu, K Imachi, T Fujimoto
2000 Volume 29 Issue 2 Pages
385-389
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
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A methodology for an accelerated fatigue test for polymer valves has not yet been established by ISO. First, durability testers were employed to ascertain the durability of Jellyfish valves under physiologic temperature as well as pressure difference at valve closure. Then, the validity of ISO requirements was checked. The results indicated that neither fracture location nor lifetime was coincident between accelerated fatigue tests (1200 BPM) and an animal experiment (105 BPM). For the next step, finite element analysis was performed to clarify the reason for different fracture locations. The results revealed that a brittle fracture occurred at a stress-concentrated area in the fatigue tests, whereas a ductile fracture occurred at a strain-concentrated area in the animal experiment. These findings emphasized that the fracture mechanism was different between practical in vitro fatigue tests and the animal experiment. As a result, it was found that the current accelerated fatigue test recommended by ISO has limitations for predicting the durability of polymer valves.
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Y Matsui, T Miyatake, E Hatta, T Kunihara, T Nishibe, N Shiiya, T Mura ...
2000 Volume 29 Issue 2 Pages
390-393
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
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We experienced seven cases of reoperation necessitated by mechanical prosthetic valve obstruction (2 SJM valves, 5 Omniscience valves). The patients were 34-68 years old (3 males, 4 females) and 6/7 had atrial fibrillation. The interval from the primary operation to the reoperation for mitral valve replacement (MVR) with the Omniscience valves was 60+/-33 months, and the opening angle was only 23-55 deg. In one case of aortic valve replacement (AVR), this interval was 187 months, and the opening angle was 30 deg. In one case of MVR with a SJM valve, the valve had been implanted in the direction of anatomical position, and the posterior side of the leaflet was completely obstructed at 62 months postoperatively. In an AVR case with a SJM valve, doppler flow showed the pressure gradient through the valve to be 55 mmHg, even with full opening of the leaflets 219 months postoperatively. In all cases, tissue overgrowth (pannus formation) was the cause of obstruction. In the Omniscence valve cases, even a small pannus was easily trapped at the pivotal site. In the SJM AVR case, long after the valve had been installed, a large pannus could cause an obstruction without any interference of leaflet movement.
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H Ogawa, T Ishikawa, S Sumita, I Kobayashi, T Sugano, T Shigemasa, T E ...
2000 Volume 29 Issue 2 Pages
394-397
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
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We studied P wave amplitude (PWA) histogram in 6 patients with implanted single pass lead VDD pacemakers.The pacemakers detected PWA automatically at 6-minute intervals and data were expressed on histograms by eight bins. The average age of patients was 62.3±17.8 years (mean±SD). The half-amplitudes of the atrial sensing threshold measured by conventional method correlated positively to those assessed by PWA histogram (
r=0.77,
p<0.0001). Incidences of atrial sensing failure were documented by the records of PWA histograms. In conclusion, PWA histogram is useful to determine adequate atrial sensitivity in patients with implanted single pass lead VDD pacemakers.
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S Yokose, J Miyamoto
2000 Volume 29 Issue 2 Pages
399-406
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
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In this study, 15 CRF patients prone to hypotension were placed on hemodialysis with Constant UFR, Blood Volume Monitor (BVM) and BVM+Blood Temperature Monitor (BTM). We compared their mean arterial pressure (MAP), and frequency of nursing intervention for hypotensive episodes. The MAP for treatments with Constant UFR dropped in the latter part of sessions, but decrease of MAP in the latter part of sessions could be avoided by the use of BVM. In case of the patients with DM, the MAP declined during the high set point of UFR controlled by BVM, however this declining tendency was significantly reduced by using BVM+BTM. With Constant UFR and BVM, the arterial blood temperature (Tart) had tendency to increase as sessions went on, however using BVM+BTM, Tart stayed constant by varying dialysate temperature thought the session. During sessions, the MAP maintenance order was Constant UFR<BVM<BVM+BTM; therefore it proves not only using BVM controlling UFR, but also using both BVM and BTM controlling, body temperature of patients improves hemodynamic stability more efficiently.
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K Nishiki, K Yamagata, C Tomida, Y Watanabe, A Koyama
2000 Volume 29 Issue 2 Pages
407-410
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
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Recently, many ESRD (end stage renal disease) patients often undergone open heart surgery. However, fluid volume control of these patients after surgery is difficult. In this study, we obtained blood pressure, cardiac output, right atrial pressure, pulmonary artery pressure and body weight measurements from 10 dialysis-independent patients every 6 hours after surgery. These parameters, except for body weight, were diverse due to use of diuretics, cathecholamines and other medications. The mean body weight gain was 1.07 kg (1.9%) 6 hours after the operation, and later body weight reduction gradually reached-3.29 kg (4.4%) after 48 hours. After this, we used a body-weight-based approach to body fluid control in 4 dialysis-dependent patients after open heart surgery. Dialysis sessions were started soon after the operations by continuous hemofiltration in 2 patients, continuous hemodiafiltration in 1 patient and continuous automated per-itoneal dialysis in 1 patient. Body fluid removal was started 12 hours after the operations, and fluid removal speed was controlled and made to resemble the pattern of body weight changes of dialysis-independent patients. Through these methods, blood pressure and other parameters were kept stable, at least during the perioperative period. In conclusion, body-weight-based fluid removal was found to be a useful and safe method of fluid volume control in ESRD patients after open heart surgery.
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M Fukuda, T Hiyoshi, K Sakai, K Kokubo
2000 Volume 29 Issue 2 Pages
411-418
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
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«BIOREX AM-BC-X» is a new cellulosic membrane whose pore size is distributed asymmetrically in the membrane wall. The objectives of the present study are to clarify the phenomenon of solute transfer occurring inside dialyzers made from asymmetric membranes, to examine the structure of the asymmetric membrane capable of suppressing the inflow of endotoxins from dialysate, and thereby to contribute to the design of a more effective dialysis mem-brane. Using membranes that have tight layers on both sides (drum-shaped membrane), «(BIOREX AM-BC-X») with the outer one tighter, solutes are more easily transferred from the inside out than from the outside in, leading to effective removal of pathogenic substances from blood and a significant lowering of endotoxin inflow from the dialysate. In asymmetric dialysis membranes, the anisotropy of solute permeability is caused by the difference in the amount of solute transfer due to filtration from the inside out and from the outside in.
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Measurement of Hydroxy Radical Deactivity in Patient Serum by Hemodialysis
S Takashima, N Hayashi, S Nakaji, H Naitoh, T Miyazaki, A Fujimori, M. ...
2000 Volume 29 Issue 2 Pages
419-425
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
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It is important to protect the activity against the active oxygen spec-ies formed in patient's blood which were deduced to be affected to the row mater-ials of the hollow fiber in the dialyzers.As the active oxygen species are the very low concentrations and have only very difficult to observe the behavior of act-ive oxygen species.In this study, an attempt to observe changes in the hydroxy radical (·OH) deactivity in serum during hemodialysis has been performed in 12 patients employing 4 different meterials in 3 dialyzers applying Fenton's reaction.During the hemodialysis, the tendency toward slight increase in absorption at 423 nm was observed on the visible ray spectrum.It is guessed that the ·OH rad-ical deactivity of patient serum is incr-esed by hemodialysis.
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Y Sakai, K Furuwaka, K Naruse, T Ushida, Y Harihara, M Makuuchi, T Tat ...
2000 Volume 29 Issue 2 Pages
426-432
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
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To enhance the various liver-specific functions of porcine hepatocyte aggre-gates without the addition of exogeneous growth factors or hormones, polylactic acid-polyglycolic acid (PLGA) /gelatin microcapsules that release epidermal growth factor, insulin, and dexamethasone were prepared and incorporated into the hepatocyte aggregates. A fibronectin (FN) precoating of the formed microcapsules was necessary for their incorporation into the aggregates in a continuous suspension culture. In a growth factor-free culture medium, such microcapsule-containing aggregates showed approximately twice the unit-cell-number based functions that of the aggregates containing control microcapsules (w/o growth factors) during the initial week of culture. Over the remaining study period up to the fourth week, total functions were sustained at remarkably higher levels mainly due to good cell number maintenance in culture. Our results suggest that the performance of bioartificial liver systems can be enhanced more than expected due to the maintenance of the cell number and cell functions by using such growth-factor-and hormone-releasing microcapsules.
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M Hoshino, Y Haraguchi, M Sakai, K Hayashi, H Saegusa, H Ohsawa
2000 Volume 29 Issue 2 Pages
433-439
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
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The accuracy of blood glucose (BG) measurement by bedside-type artificial pancreas (BG
AP) performed for 253 days, as well as related factors and countermeasures, were analyzed in 14 septic patients with glucose intolerance. [Method] Indicator of accuracy (X): The product of the daily proportion of BG
AP in relation to true BG. The surface of the blood sampling tube and the electrode for BG measurement was studied with an electron-microscope. [Results] 1) Mean of maximum, minimum, and final X were 113. 6 ± 15.4, 54.1 ± 24.8, and 65. 7 ± 31.7%, respectively. 2) Daily increase of X by more than 15% and prompt increase of BGAP after the blood sampling route was flushed occurred on 10.3% and 7.1% of the cumulative days, respectively. 3) Acute decrease of X (X
d) (daily decrease of more than 15%/day) occurred on 13.8% of the cumulative days (17 times). X
d disturbed the operation of AP and necessitated countermeasures, including a change of the sampling route on 41% (7 times). Leukocytes and fibrin-like substances were detected by electronmicroscope. Changing the sampling route did not improve X
d in 2 patients. [Conclusion] Increase of X seems to occur via removal of blood- derived substances deposited to the route (S) and is contributed to by other factors, including decreased function of the multichannel pump. Countermea-sures included adjustment of BG
AP and route flushing. Decrease of X seems to occur via factors that disturb blood sampling, including (S) and the proximity of the catheter tip to the venous wall. In the case of X
d, countermeasures include changing the route and/or changing the location of the catheter tip.
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Y Yoshimi, K Sakai
2000 Volume 29 Issue 2 Pages
441-445
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
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Molecular imprinting is a new technology used for synthe-sis of polymers potentially useful in sensing or separating devices with antibody-like specificity. Here we report that a thin layer of molecularly imprinted copolymer has the property of increasing its diffusive permeability in the presence of its template. A thin layer of molecularly imprinted poly (methacrylic acid -co- ethyleneglycol dimethacrylate) against theophylline was formed on the surface of indium-tin oxide (ITO). Cyclic voltammetry was performed with ferrocyanide using the copolymer-grafted ITO as a working electrode in the presence or absence of the template. The presence of the template remarkably enhanced the anodic current. This result suggests that the diffusive permeability of the thin layer of molecularly imprinted polymer is sensitive to the presence of its template molecule. This hypothesis is supported by atomic force micrography, in which the surface porosity of the layer of molecularly imprinted polymer is increased by the presence of its template. We conclude that the structure and diffusive permeability of a thin layer of molecularly imprinted poly (methacrylic acid -co- ethyleneglycol dimethacrylate) is sensitive to the presence of its template.
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Synthesis of Thermoresponsive Hyaluronic Acid and Its Supramolecular Organization.
S Ohya, Y Nakayama, T Matsuda
2000 Volume 29 Issue 2 Pages
446-451
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
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rtificial Extracellular Matrix Design in Tissue Engineering: Synthesis of Thermoresponsive Hyaluronic Acid and Its Supramolecular Organization. Thermore-sponsive hyaluronic acid was prepared by graft copolymerization of N-isopropylacrylamide (NIPAM) using the iniferter-based quasi-living radical polymerization method. The degree of substitution of the graft chain in hyaluronic acid was controlled to be 0.4, 3.1, and 7.5% per repeating disaccharide unit of hyaluronic acid, and the chain length was controlled to be about 5, 000, 11, 000, 46, 000 and 84, 000, respectively. The cloud point of PNIPAM-grafted hyaluronic acid in water was 34°C, regardless of the degree of substitution and chain length of PNIPAM. Equilibrium transmittance decreased with an increase in PNIPAM chain length and in the degree of substitution of PNIPAM. Markedly reduced adhesion of endothelial cells was observed on the surface coated with PNIPAM-grafted hyaluronic acid at 37°, indicating that PNIPAM-grafted hyaluronic acid serves as a non-cell adhesive matrix. Scanning electron microscopic observation showed that, thermally insolublized PNIPAM-grafted hyaluronic acid gel tended to form a fibrous structure with a little randomicity as compared with that of non-grafted hyaluronic acid.
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A Kishida, T Taguchi, M Akashi
2000 Volume 29 Issue 2 Pages
452-456
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
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Conferring biocompatibility to the surface of artificial organs is an essential goal for the further development of their implantability. In this study, we propose a new strategy for alternating the surface of artificial organs to induce bio-adhesivity. This strategy is based on the effect of using hydroxyapatite (HAp). The authors have developed an alternate soaking process, which is based on the well-known wet process of apatite preparation and involves alternate soaking in two kinds of solutions. We investigated HAp formation by this process on various materials used as components of artificial organs. HAp was successfully formed on all materials, while the amount of HAp formed was effected by the surface of the material. A high amount of HAp formed on inorganic materials such as stainless steel and glass. When the surface of the organic polymer was altered to hydrophilic, the amount of HAp was increased, as well as the adhesive strength. The alternate soaking process was proven to be effective for endowing bio-adhesivity to various kinds of biomaterials.
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F Miyawaki, M Kaibara, T Tsuji, Y Fukui
2000 Volume 29 Issue 2 Pages
457-462
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
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We investigated the antithrombogenicity of magnetite (Fe
3O
4) by comparison with both segmented polyurethane (SPU) and glass. 1) Eight non-porous SPU tubes were made from 10% SPU solution by dipping an 8-mm glass rod 6 times into the solution. Each tube was then divided transversely in two. The inner surface of one part was covered with magnetite and the other part remained untreated. 2) Seven of 14 glass tubes were also covered with magnetite, and the others remained untreated. 3) Antithrombogenicity was evaluated from the clotting time of blood contained in each tube. The clotting time was determined with a damped oscillation-type rheometer. Magnetite-coated tubes and their respective non-coated counterparts were tested simultane-ously using the same blood. The clotting times in the magnetite-coated and non-coated SPU tubes were 39.9 ± 13.1 and 26.9 ± 8.9 min, respectively (
p= 0.036). The clotting times in the magnetite-coated and non-coated glass tubes were 28.5 ± 6.9 and 2.7 ± 0.2 min, respectively (
p= 0.018). A magnetite coating converted glass from a potent thrombogenic material to an antithrombogenic one, and also provided the surface even of SPU with significantly better antithrombogenicity. These results suggest that magnetite is antithrombogenic.
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G Chen, T Ushida, T Tateishi
2000 Volume 29 Issue 2 Pages
463-467
Published: May 15, 2000
Released on J-STAGE: June 02, 2011
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A biodegradable hybrid sponge of poly (DL-lactic-co-glycolic acid) (PLGA) and collagen was prepared by forming microsponges of bovine type I collagen in the pores of PLGA sponge. Observation of the PLGA-collagen hybrid sponge by SEM showed that microsponges made of collagen with interconnecting pore structures were formed in the pores of PLGA sponge. This hybrid structure was further confirmed by the detection of elemental nitrogen using SEM-electron probe microanalysis (SEM-EPMA). Elemental nitrogen was detected in the microsponges of collagen and on the pore surfaces of PLGA, but not in the cross-sections of PLGA regions. The formation of collagen microsponges was dependent on collagen concentration. Wettability with water was improved by hybridization with collagen, and the hybrid sponge showed higher mechanical strength than both PLGA and collagen sponges. Bovine articular chondrocytes adhered to the microsponges of collagen in the hybrid sponge, proliferated, regenerated the cartilaginous matrix, and maintained their natural round morphology.
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F Hirai, E Ogino, S Furuyoshi, N Tani
2000 Volume 29 Issue 2 Pages
468-472
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
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We have investigated an adsorbent which is able to both decrease endotoxin activity and adsorb cytokines in the blood. Several kinds of materials were tested for TNF-a adsorption in vitro. Marked TNF-α adsorption was observed in RCP160, which is a high porous strong acid cation exchange resin (Mitsubishi Chemical). Next, we examined this resin's adsorption characteristics for other cytokines and its effect on endotoxin activity (Limulus gelation activity and ability to produce cytokines). This resin showed adsorption for other inflammatory cytokines such as IL-1β, IL-6 and IL-8. The Limulus gelation activity of endotoxins decreased after treatment with this resin. The production of TNF-α, IL-β and IL-6 by endotoxin-stimulated blood cells also decreased after treatment with this resin. These results suggest that RCP160 has potential to be a useful adsorbent in the treatment of not only Gram-negative sepsis but also other diseases with hypercytokinemia.
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M Yonekawa, K Kukita, J Meguro, T Tamaki, A Kawamura, E Sakashita
2000 Volume 29 Issue 2 Pages
473-477
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
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The strategy of cryofiltration is to reduce EDA (+) FN levels in plasma, with heparin drawing EDA (+) fibronectin from a second space (that means an exception of blood) because of its high affinity. Cryofiltration can efficiently remove EDA (+) fibronectin from plasma. The purpose of this study was to calculate the amount of EDA (+) fibronectin drawn from a second space to blood, and to study the relationship between plasma levels and the reduction in EDA (+) fibronectin levels in patients treated by cryofiltration. In each case, with the exception of multiple myeloma, the amount of EDA (+) fibronectin drawn from the second space correlated well with the plasma levels. The amount drawn from the second space in relation to the total reduction was more than 70%. Plasma levels and the amount of EDA (+) fibronectin reduced from the first space (that means a blood) were almost the same in patients with rheumatoid arthritis and multiple myeloma, but more EDA (+) fibronectin was drawn from the second space in patients with rheumatoid arthritis than in those with multiple myeloma, suggesting that patients with rheumatoid arthritis might retain some EDA (+) fibronectin in the second space.
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[in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...
2000 Volume 29 Issue 2 Pages
478-482
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
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Kukita K, Uchida Y, Masuko Y, Horie T, Tanaka M, Tamaki T, Meguro J, Yonekawa M, Kawamkura A Weakness of the Double Lumen Catheter (DLC) for Blood Purification and Their Possible Improvement. We discuss the problems we encountered using the DLC for blood purification and its possible improvement. The main problems are the possibility of infection and insufficient blood flow during blood purification due to intraluminal thrombosis, “attachment phenomenon”, and thrombosis of the venous wall. Individual problems have been addressed, though complete improvement of the DLC has not been achieved. The creation of a uniformly effective DLC is desired in the near future. Keywords: double lumen catheter, thrombosis, infection, blood access problems Jpn J Artif Organs 29 (2), 478-482
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[in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...
2000 Volume 29 Issue 2 Pages
483-487
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
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Osako M, Sato T, Nakao Y, Yamamura T, Fujiwara H, Hattori R, Fujii H, Ninomiya H, Otani H, Imamura H Usefulness of Rapid Physiological Atrial Pacing and PVC Synchronous Atrial Stimulation for Prevention of Arrhythmia after Pacemaker Implantation. We examined a 75 year-old male who had syncope caused by sinus pause (maximum 7.2 s) and PVC with sick sinus syndrome (Rubenstein type III). Atrial fibrillation occurred mainly onexertion. The patient was implanted with a physiological pacemaker, which was DDD mode with automatic mode switching and PVC synchronous atrial stimulation. Parameters were programmed as DDD mode, minimum rate 80 ppm and maximum rate 140 ppm, and taken an A-V delay of 150 ms. Follow-up counters data 7 days after pacemaker implantation were follows: atrial pacing rate 64%, ventricular pacing rate 64%, A-V synchronous rate 70%, pathological rate 1%, PVC rate 21%. Retrograde conduction after PVC was detected at 104 days after implantation. We observed that PVC synchronous atrial stimulation blocked retrograde conduction. At 223 days after implantation, the data were follows: atrial pacing rate 91%, ventricular pacing rate 94%, A-V synchronous rate 96%, pathological rate 0%, PVC rate 4%. Parameters after pacemaker implantation have not changed during the entire follow-up period. The patient has been free of symptoms for 285 days after pacemaker implantation. The rapid physiological atrial pacing and PVC synchronous atrial stimulation inhibited transient atrial fibrillation and PVC. These functions might be useful for the prevention of arrhythmia after pacemaker implantation. Keywords: atrial fibrillation, sick sinus syndrome, retrograde conduction, rapid atrial pacing, PVC synchronous atrial pacing Jpn J Artif Organs 29 (2), 483-487
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[in Japanese], [in Japanese], [in Japanese], [in Japanese]
2000 Volume 29 Issue 2 Pages
489-495
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
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Iwasaki K, Umezu M, Imachi K, Fujimoto T Biomechanical Analysis of an Accelerated Fatigue Test Method for Polymer Valves. Jpn J Artif Organs 29 (2), 489-495 A method for performing accelerated fatigue tests for polymer valves has not yet been established. We performed preliminary trials regarding an accelerated fatigue test on Jellyfish valve wherein the fracture pattern can be consistent with that obtained in an animal experiment. The influence of maximum load at valve closure as well as the influence of water temperature on the fracture mode of Jellyfish valve was specifically focused. When the value of maximum load at valve closure in the accelerated fatigue test was decreased to half as compared with that obtained in a mock loop under 105 bpm, the fracture mode was not consistent with that of the animal experiment, even if the water temperature was elevated from 40°C to 60°C. However, when the maximum load was decreased to quarter value in 60°C water, the fracture mode in the accelerated fatigue test was successfully consistent with that of the animal experiment. Therefore, it was confirmed that both maximum load at valve closure and water temperature were essential parameters for the accelerated fatigue test of polymer valves. In this case, following are recommended: maximum load at valve closure should be decreased, while water temperature should be elevated. Keywords: accelerated fatigue test method, polymer valve, fracture mode, maximum load at valve closure, water temperature
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[in Japanese], [in Japanese], [in Japanese], [in Japanese]
2000 Volume 29 Issue 2 Pages
496-499
Published: May 15, 2000
Released on J-STAGE: June 02, 2011
JOURNAL
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Jpn J Artif Organs 29 (2), 496-499 (2000) Artificial organs including heart valves and pacemakers are well-followed by medical doctors after implantations because patients with those devices come to the outpatient clinic regularly. However, in most patients with other types of implanta-ble medical devices, the device's later performance and the cause of patient death are difficult to investigate. At our institute, since July 1968, 86 patients underwent left ventricular repair due to left ventricle aneurysm. 76 were discharged from the hospital after surgery. We tried to trace these patients using mail, telephone, and other methods, and after obtaining special permission from the Ministry of Justice to pursue our follow up, 83 of 86 patients were located, with the remaining 3 being two males and one alien female. We realized the difficulty of investigation without a nation-wide implant data system, our experience demonstrating the necessity of establishing a nation-wide implant data system. Keywords: medical device, implant data system
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[in Japanese], [in Japanese], [in Japanese], [in Japanese]
2000 Volume 29 Issue 2 Pages
501-506
Published: May 15, 2000
Released on J-STAGE: October 28, 2010
JOURNAL
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Nojima T, Oda T, Ono H, Ashida A Extraction of Infected Endocardial Pacemaker Electrodes: Two Successful Cases. J Artif Organs 29 (2) 501-504 (2000) Infections of three endocardial pacemaker electrodes were experienced in two patients. The first patient had two infected electrodes. The electrodes of the patient were infected with Pseudomonous species, and both were extracted using locking stylets and sheaths 154 months after implantation. In the second patient, one electrode became infected with Staphylococcus aureus and was extracted using direct traction 3 months after implantation. Patients survived and neither had recurrent infection. Our experiences proved that preoperative management focused on the preservation of electrode could minimize the risks for the extraction of the infected pacemaker electrodes.
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