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[in Japanese]
1995 Volume 24 Issue 2 Pages
249
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
JOURNAL
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H WATANABE, H MIYAMURA, J HAYASHI, Y TAKAHASHI, S TATEBE, M SINONAGA, ...
1995 Volume 24 Issue 2 Pages
251-255
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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The diameter and length of descending thoracic aorta in 64 cases of Kawasaki disease were measured at angiography. The diameter and length of descending aorta were correlated to the body length. According to these results, we developed small intraaortic balloons (2, 5, 7 and 10cc) mounted on small catheters (3.6, 4.5, 5.1 and 6.0Fr.). These newly developed balloon catheters have undergone in vitro testing in comparison with Datascope balloon catheters. The inflation time and deflation time of the new balloon were shorter than those of Datascope balloon. Inflation and deflation of the new balloon could match heart rates of 180 bpm. The results of this study demonstrate that the newly developed balloon catheters are suitable for pediatric use.
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Y. YOSHIOKA, N. TSUTSUI
1995 Volume 24 Issue 2 Pages
256-260
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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A new intraaortic balloon catheter is described in this paper. The balloon is a standard single chamber type and its volume is 35cc. The length of balloon catheter is 71cm. The outer annular lumen of the balloon catheter is 12F in size. The inner lumen of it is 6.5F in diameter and permits the insertion of a guiding catheter for coronary angiography (CAG) or percutaneous transluminal coronary angioplasty (PTCA). The bottom has a Y-shaped connector and is attached with a one-way valve Just as a regular sheath introducer. The material of the balloon is polyurethane. With only one puncture of femoral artery, the balloon is used for circulatory support during CAG or PTCA. We experienced five patients who were applied PTCA and one patient CAG, and no complications related to CAG, PTCA and IABP were observed.
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Hirokuni ARAI, Koji FUJIYOSHI, Tohru SAKAMOTO, Akio SUZUKI, Akira SUZU ...
1995 Volume 24 Issue 2 Pages
261-264
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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The optimal balloon timing, when VA-bypass and IABP are applied simultaneously, has not been well known. Using Mock circulation model, we evaluated which deflation timing of IABP balloon is optimal for left ventricular (LV) afterload reduction during VA-bypass. LV afterload due to VA-bypass was not unloaded when balloon was deflated in early presystole (160-120msec prior to R wave of ECG). However, afterload was linealy reduced along with the delayed deflation of balloon until 40 msec after R wave. During VA-bypass, the afterload reduction effect of IABP would be optimal, when balloon is deflated as late presystole as possible.
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S. NITTA, T. YAMBE, S. NAGANUMA, Y. KAKINUMA, H. AKIHO, K. IDUTSU, S. ...
1995 Volume 24 Issue 2 Pages
265-270
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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An newly developed total VAD, which is more practical and proper for mass-production, have been evaluated. This new VAD system is parted into the sac and outer case, inflow and outflow cannulae, and their prosthetic valve built in connectors. Therefore, when we find the partial accident in VAD system, we can exchange only the accidental part. Durability test in the mock circulation and chronic animal experiments using adult goats were performed. THe results show that our VAD system has good property of hydrodynamics and antithrombogenecity and durability. We conclude that our VAD system can be useful for clinical application.
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S. KYO, K. UEDA, H. ASANO, S. KIMURA, K. KENMOKU, A. SEKIGUCHI, Y. YOK ...
1995 Volume 24 Issue 2 Pages
271-276
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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Importance of coronary reconstruction for the succes sful outcome in pos tcardiotomy assisted circulation. To demonstrate the importance of coronary reconstruction for the successful outcome in postcardiotomy LOS, 3 patients who required assisted circulation were studied. Case 1 28y. male) underwent Bentall's operation for acute aortic dissection (DeBakey type I) and developed severe LV failure due to progression of dissection into the left coronary orifice. Case 2 (44y, female) underwent modified Ben tall's operation for acute aortic dissection (DeBakey type I) and developed cardiogemc shock due to left coronary ischemia at 45 days after the initial operation. Case 3 underwent intracardiac repair for Tetralogy of Fallot, however, developed severe RV failure due to injury of right coronary artery which arising from the left anterior descending artery (single coronary artey=left 2a type). Aorto-coronary bypass was placed for these patients using saphenous vein graft and all 3 patients were successfully separated from the assisted circulation after 117 hours. In conclusion, coronary reconstruction is essential for the successful outcome of assisted circulation in patients with postcardiotomy LOS due to coronary ischemia.
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Kohjiro KODERA, Masaya KITAMURA, Hideaki NAKANO, Shigeyuki AOMI, Mitsu ...
1995 Volume 24 Issue 2 Pages
277-280
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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Between 1984 to 1993, mechanical circulatory support more than 3 hours was performed in 17 patients after surgery for valvular heart diseases. Types of support were as follows: venoarterial bypass (VAB) 4 cases, bi ventricular bypass (BVB) 10 cases, left ventricular bypass (LVB) 2 cases and left ventrucular assist device (LVAD) 1 case. Weaning and survival rates by the types of support were 50%, 25% of VAB cases, 70%, 50% of BVB cases, 100%, 50% of LVB cases, and 100%o, 0% of LVAD case, respectively. Resul is of weaning and survival rate were superior in BVB and LVB than those in VAB. Duration of circulatory suport in patients lost after weaning was longer than that in patients survived. Time duration from initial CPB to start of circulatory support was longer in failed cases than weaned cases. Low LV function and renal dysfunction as preoperative associating factors were observed more frequently in lost cases. The whole results of postcardiotomy circulatory support was acceptable (weaning rate 71%, survival rate 41%). Evaluation of cardiac performance and other organ function and early application of appropriate assist system might be the key for successful circulatory support after operation.
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K. IMANISHI, K. IMACHI, T. ISOYAMA, Y. ABE, T. CHINZEI, K. MABUCHI, I. ...
1995 Volume 24 Issue 2 Pages
281-287
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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A new model of percutaneously accessible left ventricular assist device (MAD Type-4) was developed. The system was composed of a pneumatic driven sac type blood pump with 30ml of stroke volume and a cannula. To reduce the flow resistance of inflow and outflow valves, a truncated conical jellyfish valve (TC-JFV) and skirt valves (S-V) were designed. The driver was programmed to provide diastolic augmentation. In the mock circulation study, the maximum flow of 2.34l/min was obtained. In the animal experiment, the cannula was inserted from the subclavian artery and sent into the left ventricle. In the effective case, the aortic flow and the coronary flow increased by 20% and 34%, respectively. In conclusion, the MAD Type-4 could obtain the maximum flow of more than 2l/mmn and provided the effective circulatory assistance in severe circulatory failure.
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K MATSUO, M YANO, K ARAKI, M OSHIKAWA, T ONITSUKA, Y KOGA
1995 Volume 24 Issue 2 Pages
288-292
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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We have developed percutaneous right ventricular assist system (PRVAS) recently. Furthermore, we worked out percutaneous biventricular assist system (PBVAS) by associating percutaneous left ventricular assist system (PLVAS) with PRVAS. Six adult dogs underwent general anesthesia. Each cannula of the PRVAS and PLVAS was inserted percutaneously. The dogs were induced ventricular fibrillation electricaly. Then we confirmed that we could maintain circulation by PBVAS. To clarify the effectiveness of PRVAS in condition of biventricular failure, we measured the change of circulatory dynamics, renal surface blood flow, renal venous flow and renal oxygen consumption before and after PRVAS assistance. It was difficult to maintain circulation with PLVAS alone. During PRVAS assistance and after restarting of PRVAS, mean aortic pressure and renal venous flow remained at almost control level. But renal surface blood flow and renal oxygen consumption did not completely recover to control level 20 minutes after PRVAS had been restarted.
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H SATOH, S NAKANO, Y SHIMAZAKI, Y MIYAMOTO, Y SAWA, T MASAI, A YAGURA, ...
1995 Volume 24 Issue 2 Pages
293-297
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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The purpose of this study is to evaluate the effect of mechanical circulation using pulsatile or nonpulsatile blood pump to shock organs. Methods: Damaged liver was produced by clamping descending aorta clamping at infra-diaphragm in 14 dogs. After 60 minutes of ischemia, LA-FA bypass was started. Pneumatic pulsatile pump (TOYOBO) was used in 7 dogs (Gr.-PP) and centrifugal pump (Biomedicus) in 7 (Gr.-NPP). In both groups the mean arterial pressure was kept at 80mmHg. Mean bypass flow was 96±14ml/kg/min in Gr.-PP, 95±35ml/kg/min in Gr.-NPP. Results: In the both groups the bile flow and arterial keton body ratio (AKBR) decreased significantly after ischemia, and recovered to normal level after 90min of LA-FA bypass. There were no significant difference between the two groups. Conclusion: These results suggested that nonpulsatile circulatory assist is as effective to recover the shock liver as pulsatile circulatory assist.
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T NEMOTO, K KIMURA, T ISHIKAWA, T SHIMIZU, Y MOCHIDA, M KOSUGE, T NAGU ...
1995 Volume 24 Issue 2 Pages
298-303
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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Two cases were reported in which coronary artery flow velocity (CAFV) were observed during Percutaneous Cardiopulmonary Support (PCPS) on and off. The first case is a 43-year-old man with DC-resistent VF due to acute myocardial infarction (AMI). Under the PCPS, PTCA to the right coronary artery was successed, and CAFV was recorded during pump on and off at left anterior descending artery. During pump off, small systolic antegrade flow, systolic flow reversal and steep decline of diastolic antegrade flow were observed under ventricular rhythm. During pump on (3.0L/min), these patterns were improved, and mean CAFV was increased. The second case is a 61-year-old man with electro-mechanical dissociation due to AMI (multi-vessel disease). Under ventricular standstill, CAFV was recorded at left main trunk. There was no effectve antegrade flow during pump off, and non-pulsatile flow was observed during pump on. PCPS may assist the coronary circulation.
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T MURAKAMI, H YOSHIDA, A ISHIDA, A TABUCHI, T FUJIWARA, T KATSUMURA, K ...
1995 Volume 24 Issue 2 Pages
304-307
Published: April 15, 1995
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Over the last 2 years and 8 months, 11 patients received PCPS while in postoperative cardiogenic shock. There were 8 male and 3 female patients ranging in age from 49 to 75 years (average age 61). Four patients underwent surgery for coronary artery bypass grafting, 4 for graft replacement of thoracic aneurysm, 2 for valve replacement and one for patch closure of LV aneurysm. The duration of support ranged from 4 to 192 hours (mean 42.9). Eleven patients were weaned and 4 survived. The 4 survivors have been followed for 18 to 31 months (mean 23.5). Two were in NYHA class II and 2 were in class I. Univariate analysis indicated that renal failure and cardiac failure were the most important predictors of hospital death. The PCPS was effective in supporting circulatory failure, but serious complications were observed frequently in these patients.
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F. IWAYA, T. IGARI, M. TANJI, M. WATANBE, T. ONO, S. HOSHINO, H. HIKIC ...
1995 Volume 24 Issue 2 Pages
308-313
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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To induce a pulsatile flow in a centrifugal pump, we developed a new device (Pulsatile Assist Device for Centrifugal Pump: PAD·CP) using a new concept. This device consists of a flexible polyurethane tube with an air chamber which is connected to the arterial side of the centrifugal pump circuit directly. A mock circulation system was used for evaluation of this PAD·CP. Results: 1) By increasing the driving pressure from 200 to 600mmHg in mock system, 4-48mmHg of pulse pressures was gained accompanied by a decrease in pump flow and increase left atrial pressure. The decreased pump flow and increased left atrial pressure were recovered easily by increasing the flow rate of centrifugal pump. 2) Pressures at proximal site of PAD·CP were less than 500mmHg. The PAD·CP was useful to induce a pulsatile flow in a centrifugal pump.
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THE EFFECT OF CARDIAC FUNCTION AND CORONARY CIRCULATION
M HATA, T HASEGAWA, S SINDOU, M SHIONO, K AKIYAMA, Y ORIME, H HATA, S ...
1995 Volume 24 Issue 2 Pages
314-318
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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In order to evaluate the efficacy of concomitant use of left heart bypass (LHB) and intra-aortic balloon pumping (IABP) for the cardiac function and coronary circulation in post ischemic cardiogenic shock, we made comparison studies in swain. Cardiogenic shock due to acute myocardial infarction was made experimentally by LAD ligation. LHB was performed by centrifugal pump (Bio Medicus BP-80), supporting flows of half cardiac output. IABP balloon catheter (20cc) was inserted to aorta through the femoral artery and pumped. These models were supported by IABP, LHB, and IABP+LHB, comparing each cardiac performance. Myocardial infarcted area was evaluated by epicardial mapping ECG. Coronary blood flow and velocity were analyzed by electrical flow meter and ultrasonic pulsed dopplar velocimeter respectively. In the IABP+LHB group, coronary blood flow were increased remarkably and ishemic areas were significantly reduced and their hearts recovered from cardiogenic shock, demonstrating a good supply and demand balance of myocardial oxygen. The systolic reverse wave of the LAD flow and velocity which was increased due to cardiogenic shock, was reduced remarkably in the IABP+LHB group. These results suggested this concomitant method was suitable assist for coronary circulation because of diastolic augmentation by IABP and cardiac unloading by LHB.
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ANTI-THROMBPGENECITY, HEMOLYSIS AND FLOW PATTERN INSIDE THE PUMP
Y ABE, T CHINZEI, T ISOYAMA, K MABUCHI, K IMANISHI, A KOUNO, K ATSUMI, ...
1995 Volume 24 Issue 2 Pages
319-322
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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New undulation pump (old name PDP: Precessional displacement pump) was developed for the chronic animal experiment. In the animal experiment using left heart bypass with undulation pump in goat, severe hemolysis was occurred. After driving for 12 hours, the thrombus formation inside the pump was found. The flow visualization study was performed by developing transparent undulation pump. The flow pattern showed that the flow inside the pump was very complicated turbulent flow. However, the evidence of the influence of this turbulent flow to the hemolysis and the thrombus formation was not detected. Improvement of the hemolysis and thrombus formation is the next important subject.
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T YAMANE, T IKEDA, T TSUTSUI, T. JIKUYA
1995 Volume 24 Issue 2 Pages
323-326
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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Mono-Pivot Magnetic-Suspension Centrifugal Blood Pump using permanent magnets to eliminate shaft seals or ball bearings is presented for the application to implantable artificial hearts. The suspension system is composed of a pair of repulsive cylindrical magnets for impeller suspension, coupling magnets which transmit motor torque over the casing wall, and a pivot bearing made of ceramics. This mechanism enables the impeller to rotate without contacts except for the pivot. The prototype models based on this concept were made and improved based on the performance testing. Through increasing the axial magnetic force, necessary pump output was attained. The magnetic suspension was stable and the overall efficiency of over 20% was obtained.
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N. KABEI, K. TSUCHIYA
1995 Volume 24 Issue 2 Pages
327-332
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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We have developed small size and right weight oscillating-disk-type centrifugal pumps for an left ventricular assist device and an artificial heart toward intracorporeal implantation. Oscillation angle of the disk in these pumps is 15 degree. The diameter of the disk is 54mm, the maximum inner diameter of the pump housing is 60mm and its maximum outer diameter is 64mm. Total weight and length of the pump for LVAD are 380g and 60mm respectively. Total weight and length of the pump for BVAD or AH are 420g and 90mm respectively. The output flow rate of 5L/min was obtained by the LVAD pump under rotational speed of 3050rpm at 120mmHg mean aortic pressure. Energy conversion efficiency at the specified point was 5.3%. Index of hemolysis of the pump driven under the same condition was 0.0061.
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K. ARAKI, Y. TAENAKA, T. MASUZAWA, Y. WAKISAKA, T. NAKATANI, H. AKAGI, ...
1995 Volume 24 Issue 2 Pages
333-336
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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We investigated the effect of heat and friction around a shaft-sealing on hemolysis in centrifugal blood pumps. The materials were original pumps (Nikkiso HMS-15 and 3M Delphin), vane-removed pumps and a small chamber with a shaft coiled by a nichrome wire (mock pump) to investigate the effect of local heat on hemolysis. In-vitro hemolytic examination was carried out using heparinized fresh blood of a goat. The original pumps were driven at the flow rate of 5L/min and pressure head of 500mmHg, The vane-removed pumps were driven at the same rotation number and the flow of 5L/min was maintained by Bio-pump (1000rpm). Electric power of 0.05, 2 and 10 Watts was supplied to the mock pump and the flow was maintained in the same way. We also measured generated heat of the original pumps and vane-removed pumps with a thermally-insulated water chamber. The results indicated that the heat generated around the shaft-sealing was minimal. The hemolysis of the shaft-sealing was, however, considerable but not principal. The local heat less than l0 Watts did not affect hemolysis. We concluded that a shaft-sealing affects hemolysis by not local heat but the friction, and the main causative factor of hemolysis was supposed to be hydraulic energy loss such as shear stress.
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T. NAKATANI, H. ANAI, Y. WAKISAKA, K. ARAKI, Y. TAENAKA, E. TATSUMI, H ...
1995 Volume 24 Issue 2 Pages
337-340
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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We have developed intravenous axial flow pump for right heart assist. In this study, experlmental evaluation of this system was performed. The pump was positioned in the right heart through a 14mm, low porosity graft anastomosed to the infrarenal inferior vena cava. The pump showed good performance in right heart assistance under induced pulmonary stenosis or induced biventricular failure. Chronic animal experiments were performed using adult goats. There was no difficulties in pump insertion. Level of plasma hemoglobin was acceptable. There was no prominent damages in heart tissues. In conclusion, this pump system is practicable for temporay right heart assist.
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H ANAI, K ARAKI, T NAKATANI, Y WAKISAKA, Y TAENAKA, E TATSUMI, H AKAGI ...
1995 Volume 24 Issue 2 Pages
341-344
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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To decrease hemolysis caused by an axial flow blood pump, we studied whether specific speed at the design point should be kept with in the existing engineering standard range or whether pump speed should be reduced to a minimum. Four pumps were designed at a flow of 5L/min, ahead of 100mmHg and speeds of 14000-26000rpm. Specific speed of each pump was calculated as 758-1407 (m, m3/min, rpm). Hemolytic tests were performed with flesh goat blood in a mock circuit. The lowest level of hemolysis is observed in the pump with the minimum specific speed (758)that is out of the existing engineering standard range. We also studied the influence of change in design of guide vanes on hemolysis. Four guide vanes that had different length and number of vanes were devised for same impellers. In the result of hemolysis test, difference in hemolytic index was not clearly observed among the pumps that had different guide vanes.
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-IMPROVEMENT IN PERFORMANCE OF THE ACTUATOR BY USING LIQUID CRYSTAL AS GAP -FILLING MEDIUM-
N. KABEI, K. TSUCHIYA
1995 Volume 24 Issue 2 Pages
345-350
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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We developed an electrostatic lineer actuator for use as an artificial cardiac muscle which consists of parallel plate capacitors and a slider made of dielectric material. The most effective methods to increase the output force of the actuator are optimizing the dielectric constant of the gap-filling medium, which fills the space between two electrodes of the capacitor, and increasing the dielectric strength of the medium for supplying high voltage to the capacitor. We chose liquid crystal as the gap-filling medium. The maximum velocity of the slider of the actuator was 2.24mm/s. The maximum output force of 56.5mN was generated by the actuator filled with liquid crystal. This value is seven times as large as that generated by the same actuator filled with pure water used as the gap-filling medium in previous experiments.
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H HOTEI, K TAHARA, M WATARI, H NAGATA, N MITSUI, Y KOURA, K ORIHASHI, ...
1995 Volume 24 Issue 2 Pages
351-356
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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We have developed a Direct Mechanical Left Vetricular-Assist Device( DMIVAD), a new assist device for the severe left ventricular failure. It was an ellipsoid-shaped, made of hard epoxy base plate and flexible polyurethane membrane. The device was attached to the free wall of the left ventricle. and directly pressed flexible membrane by a pneumatically driving unit. It was evaluated in a canine left ventricular failure model. After the driving pressure was increased to 50, 100, 150 or 200mmHg, most effective increases in paralneters of APs, LyPs, LVdP/dt, C. O. and Peak Flow were achieved by 17.0%, 23.0%, 49.3%. 30.7% and 133.5%. respectively and only LAPm was decreased by 14.5%. When LAPm was flxed at 10, 15 and 20mmHg, the above-mentioned parameters were increased by 19.1%, 24, 6%, 71, 6%, 45.4% and 156.3%, respectively These primaly results suggested that DMLVAD can be an additional option of circulatory assist for the left ventricular failure, although further evaluation is necessary.
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E OKAMOTO, K YAMAMOTO, Y MITAMURA, T MIKAMI
1995 Volume 24 Issue 2 Pages
357-362
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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We have developed a Small and low power and high performance control system for a motor-driven assist pump.
The control system consists of two microcomputers, a programmable logic device (PLD) for address decoding and electronic commutation, a miniature power-FET module for driving a brushless dc motor, a RS-232 driver/receiver. By employing the PLD and by optimum design of a circuit, we have reduced the number of ICs on acircuit board, and have reduced the size of the control system (board size: 64x64mm). The control system has a 16-bit 1-chip microcomputer including a ROM, a RAM, a PIO, a SIO, an A/D, a Timer, a PWM output, and a universal pulse prooessor. The control system has the following various functions; (a) follow-up control system, (b) bi-directional communication with a host computer outside body, (c) adjustment of pump drive parameters from the host computer, (d) control of charge current to a secondary battery. The controller enables us to change drive condition from the outside of the body and to operate the motor-driven assist pump adaptively, based on motor drive dates obtained by the bi-directional communication and physiological test dates.
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H YASUE, T YASAKI, K KOSHIJI, E SHU, T UTSUNOMIYA, S NIWA, T MASUZAWA, ...
1995 Volume 24 Issue 2 Pages
363-367
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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In this paper, we report charging and discharging control of backing up rechargeable battery inside body for a totally implantable artificial heart. The battery inside body should be safely and quickly charged. We used 2-stage charging method for safely and quickly charging. The rechargeable battery is quickly charged by constant current source until almost fulfilling in the first stage, and then it is charged by trickle charge in the second stage. It is important that we detect the time when recharger is switched from quickly charging to trickle charging. We used to sense-ΔV of the terminal voltage in case of NiCd battery and rate of surface temperature rise of battery in case of Ni-MH for detecting the switching time, respectively. We found that the recharger can be effectively switched from quick to trickle by sensing-ΔV and rate of surface temperature rise of the Ni-MH battery, respectively. We also investigated to sense and integrate charge and discharge current of the battery for switching the recharger. We found that this method is effective for the switching and possible to monitor remainin. genergy of the battery.
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M. HACHIDA, M. KITAMURA, T AKIMOTO, T. NISHINAKA, T. MAEDA, M. ENNDOU, ...
1995 Volume 24 Issue 2 Pages
368-371
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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Novacor left ventricular assist device has been widely used as a bridge to transplantation. In this study, we made experimental implantation of Novacor LVAS using a sheep. The pit falls of experimental implantation was listed as follows; 1) positioning of the out flow and inflow conduit through the diaphragma is important for preventing the graft kinking. 2) the size of myectomy should be large as much as possible. Also position of the drainage cannula should be selected to avoid coronary injury and kinking of graft, 3) the thrombosis and debris in the device should be avoid through the implantation technique. 4) air evacuation is very important and should be perfomed as quickly as possible. These technical pit falls might be important to prevent complications.
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T. NAKATANI, H. ANAI, Y. TAENAKA, E TATSUMI, H. AKAGI, T. MASUZAWA, Y. ...
1995 Volume 24 Issue 2 Pages
372-376
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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We have developed an implantable left ventricular assist system (LVAS) for small sized adult patients. The pump made of segmented polyether polyurethane was pneumatic driven diaphragm type. Thirteen adult goats were used for chronic animal experiments and the pump was placed in the abdominal wall. Eight of them were sacrificed after 4 to 15 weeks and one is on-going (17weeks) while in good physical condition. The electrical impedance-based monitoring and control system (Z system) was developed for adequate automatic control. The performance of the implanted pump was well monitored and the full-fill to full-empty drive was well controlled by the Z system. In conclusion, this LVAS is promising for clinical use.
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-Electrohydraulic total artificial heart with a regenerative pump energy converter-
Toru MASUZAWA, Yoshiyuki TAENAKA, Eisuke TATSUMI, Takeshi NAKATANI, Ha ...
1995 Volume 24 Issue 2 Pages
377-382
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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We have been developing an electrohydraulic total artificial heart (EH) with a motor integrated regenerative pump as an energy converter, The motor and the regenerative pump was improved to move a chronic animal implantation. Three phases and four poles brushless DC motor, which has maximum efficiency of 79% at a motor rotation of 2500rpm with a load of 1kg/cm, was developed for the new actuator. Design of flow channel of the regenerative oil pump was optimized, which resulted in increasing maximum flow rate at one directional motor rotation from 18 to 28L/min. In vitro performance of the EH was evaluated in a mock circulation with 100mmHg of afterload on the left side, 20mmHg on the right side, and 10mmHg of preload on both sides. Maximum output was 10.7L/min at a pump rate of 120bpm Double diaphragm type blood pump (DDP) was also developed to compensate the balance between left and right pump output. Preload sensitive ability of the DDP was evaluated in in vitro experiment. We will turn upon a chronic animal experimental stage with the EH in next few months.
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Yukihiko ORIME, Setsuo TAKATANI, Kimitaka TASAI, Yasuhisa OHARA, Georg ...
1995 Volume 24 Issue 2 Pages
383-390
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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A totally implantable electromechanical total artificial heart (TAH) system has been developed in our institute. This pump is very small (outerdiameter; 97mm, central thickness; 83mm and weight; 620g), demonstrating a good anatomical fit in the pericardial space of 26 heart transplant recipients. The actuation mechanism is simple, and all the components are commercially available with proven long-term durability, thus allowing easier fabrication. The pump can be easily and simply controlled by reliable Hall effect sensors with left masteral ternate (LMA) mode. Four newly fabricated TAH demonstrated quite similar pump performances. This TAH has a reproducible high performance with good quality assurance. In vitro performance mapping demonstrated that the pump canprovide a maximum flow of 9L/min, with a high sensitivity to preload and a low sensitivity to afterload. During four months of accelerated endurance testing in 42°C saline, no electromechanical troubles were observed and power requirement remained constant, which indicated a stable and reliable performance. After modification of the inflow valve angle, excellent flow pattems inside the blood chamber were demonstrated in this study using laser light and a high speed camera. In vivo feasibility tests were performed successfully in eight calves for up to one week, thus demonstrating the readiness to move forward to long-term in vivo studies. This small, simple, reliable and durable mechanically-driven totally implantable TAH system is suitable for a permanent heart replacement.
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H MIZUHARA, T KOSHIJI, M AOTA, K NISHIMURA, S NOMOTO, K MATSUDA, Y OKA ...
1995 Volume 24 Issue 2 Pages
391-394
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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The purpose of this study is to assess the feasibility of the latissmus dorsi muscle (LDM) as energy source for circulatory assist device. We developed a pneumatic chamber (PC). The PC inserted beneath the LDM was compressed by the burst-stimulated LDM and thereby generated pneumatic pressure to drive a ventricular assist device (VAD). The chamber was best funtioned when it was placed proximally (III intercostal space) than placed in middle or distal position. The insertion type skeletal muscle pump of LDM as a energy source generated acceptable hemodynamic work in pulmonary circulation. Though it is difficult to use as a energy source of left ventricular assist device, we could apply it in a fashion of the energy source of counterpulsation with hign preload.
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Y. SUGITA, Y. OKAMURA, Y. MOCHIZUKI, H. IIDA, H. MORI, K. SHIMADA
1995 Volume 24 Issue 2 Pages
395-400
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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The technique of a new wrap onfiguration of double dynamic cardiomyoplasty was performed in eight normal heart dogs. Both left and right latissimus dorsi muscles were dissected. The heart was exposed through a median stemotomy. The heart was lifted and both transvers segment of muscle flap edges were sutured together then sutured flaps were placed under it. The left muscle flap was sutured to the right ventricular epicardium. The right muscle flap was sutured to the left muscle flap overlapping the left ventricle. Both left and right muscle flaps were stimulaled by the cardiac stimulator (BC-03 Fukuda Denshi LTD). Following hemodynamic results (mean±SE) were obtained. Cardiac output increased from 0.96±0.121/min to 1.24±0.161/min (p<0.05). Stroke volume increased from 7.7±1.2ml to 10.2±1.4ml (p<0.05). Left ventricular pressure increased from 1l0±5mmHg to 138±6mmHg (p<0.05). Left ventricular pressure dp/dt increased from 1387±102mmHg/s to 1778±164mmHg/s (p<0.05). Aortic pressure increased from 110±5mmHg to 138±6mmHg (p<0.05). These hemodynamic results indicated that the double dynamic cardiomyoplasty provides significant hemodynamic effebcts on left ventricular function.
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T KOSHIJI, H MIZUHARA, T ODA, K NISHIMURA, Y OKAMOTO, T BAN
1995 Volume 24 Issue 2 Pages
401-404
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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Function of skeletal muscle powered ventricle made from canine rectus abdominis muscle. We have been focused on the utilization of the rectus abdominis muscle (RAM) for a biomechanical substitute alternative to latissimus dorsi muscle. The primary problem in using RAM is the method of stimulation. Therefore differences between segmental nerve stimulation (SNS) and muscle stimulation (MS) of skeletal muscle powered ventricles (SMV) made from RAM were investigated. Unconditioned left RAMs of seven mongrel dogs (mean 13.2Kg) were used in this study. Pressure generating and pumping capabilities of SNS were superior to that of MS at low stimulating amplitude. The conditioning of RAM was also assessed in another three mongrel dogs (mean 13Kg). Histochemical examination by Myosin ATPase stain (pH4.3) after low frequency (2Hz) electrical preconditioning for eight weeks showed complete transformation to Type I fiber. Pressure generating capability of conditioned SMV decreased to 70% of unconditioned SMV.
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CINERADIOGRAPHIC AND DOPPLER ECHOCARDIOGRAPHIC EVALUATION
S. AOYAGI, S. FUKUNAGA, A. ORYOJI, K. KOSUGA, K. OISHI
1995 Volume 24 Issue 2 Pages
405-408
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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Until January 1994, we observed 15 patients with a malfunctioning SJM valve. Normal range of leaflet mobility of a SJM valve by cineradiography and transvalvular hemodynamics by Doppler echocardiography were evaluatedin patients with a normally functioning SJM valve, and the results were compared with those obtained from the patients with a malfunctioning SJM valve. Opening and closing angles measuredby cineradiographyin 10 patients with an obstructed valve were strikingly abnormal, and clearly outside the normal range. Increases of transvalvular peak velocity and pressure gradients were recordedin 7 of 10 patients who underwent Doppler studies. In the other 5, Doppler color flow mapping showed abnormal transvalvular or parapros- thetic blood flow. We believe that cineradiography and Doppler echocardiography are the optimal methods for the diagnosis of malfunction of a SJM valve.
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T. TANAKA, Y. KURIMOTO, H. KOIKE, M. NAKAMURA, N. KIMURA, T. KAZUI, S. ...
1995 Volume 24 Issue 2 Pages
409-411
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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Between January, 1990 and July, 1994, 105 patients had valve replacement using SJM prosthesis. In this study, postoperative hemolysis between Dacron and Teflon sewing cuff was analyzed. They were divided into 2 groups, in group I, 53 patients had SJM prosthesis with Dacron sewing cuff, in group II, 52 patients had SJM prosthesis with Teflon sewing cuff. Parameters of hemolysis using in this study were serum LDH (IU/l), hemoglobin (Hb; g/dl), indirect bilirubin (Bil; mg/dl), serum GOT (IU/l) and serum haptoglobin (Hpt; mg/dl). They were evaluated at one month after surgery. All patients were negative in direct and indirect Coobms test, and also were free from paravalvular leakage and had no liver dysfunction. In the present study, there were no significant differences in hemolytic parameters between 2 groups, and there were no serious complications due to hemolysis in these patients.
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- Is CarboMedics valve superior to St. Jude Medical valve? -
T ONISUKA, M KUWABARA, K NAKAMURA, K ARAKI, M YANO, K MATSUO, Y. KOGA
1995 Volume 24 Issue 2 Pages
412-414
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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CarboMedics (CM) valve is bileaflet mechanical heart valve which is similar to St. Jude Medical (SJM) heart valve. We used these bileaflet valves in the patients with mitral regurgitation and compared CM valve (n=10) with SJM valve (n=23) concerning hemodynamics, valve funcion at early period of 1 to 3 month after surgery, and other complications at late period after MVR. In CM group, NYHA functional classification, CTR, CI and PCWP improved in all patients after MVR as well as in SJM group. There is no significant difference between these two groups. The values of valve area, pressure gradient, and peak flow velocity at mitral position after MVR with CM valve are not significant difference compared with SJM valve. There were no incidences of hemolysis, thrombosed valve, thromboembolism, paravalvular leakage, PVE, and valve failure in CM group. There was one incidence of paravalvular leakage (0.075%/patient-year) in SJM group. These results indicated that CM heart valve was excellent because of nothing any complications and keeping good hemodynamics as well as SJM prosthetic valve after MVR. But we couldn't certify any superiority of CM valve as compare with SJM valve in prevention of hemolysis and other complications.
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T. YAO, H. SHIMIZU, T. HIRAYAMA, M. ISHIKAWA, S. ISHIMARU
1995 Volume 24 Issue 2 Pages
415-418
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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Evaluations of valvular function by cineradio graphy of tha Björk-Shiley prosthetic vavle and Omnicarbon prosthetic valve. Evaluation and comparison of valve function of Bjshikawa, rk-Shiley Convexo Concave prostheticvalve (B-S CC valve), Bjshikawa, rk-Shiley Monos trut prosthetic valva (B-S MO valve) and Omni carbon prosthetic valve (OC valve)was performed using cineradiography.The opening angle of the B-S CC valve AVR group(7 cases) was 59. 8±6.3°, MVR group (9 cases) 59.5±5.0°, the B-S MO valve AVR group (6 cases) was 71.8±2.9°, MVR group (9 cases) was 71.0±4.5°and the OC valve AVR group (3 cases) was 65.8±11.4°and MVR group (5 cases) was 62.5±9.9°. With the OC valve there were 2 AVR case (66%), 4 MVR case (80%) in which the valve seemed to catch then open another 5-15°and the designed opening of 80° was not always obtained. The opening and closing time of all three valves was approximately 0.07-0.09 sesonds, on average.
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H. KAJIWARA, K. HIRANO, Y. IWAI, T. HAMADA, N. HASHIYAMA, S. SATOH
1995 Volume 24 Issue 2 Pages
419-422
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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The function of the Omnicarbon cardiac (OC) valve was evaluated in 22 mitral valve replacement and 24 aortic valve replacement patients by cineradiography in the early postoperative period and at six months postoperative. The maximum opening angle (MOA) in the mitral position was 56.1±10.1 degrees early postoperative and 49.9±2.4 degrees at six months postoperative. The MOA in the aortic position was 69.9±10.4 degrees early postoperative and 63.4±10.4 degees at six months postoperative. No opening resistance was observed. Although a decrease of the MOA was observed in the mitral position, this decrease may have been due to a large measurement error. Further observation was viewed as impossible due to the non-radiopaque OCvalve housing. The opening angle of the occluder was measured considering the blood flow direction in the aortic position. The left ventricular flow axis was determined from the left ventriculogram taken during the cardiac catheterization performed at six months postoperative. The MOA was measured based on the assumption that the housing sits perpendicular to the ventricular flow axis. This opening angle of the occluder to the blood flow direction was measured in 18 patients, 71.0±9.0 (48-85) degrees. Opening angle was lower than 60 degrees in only one patient(5.6%). In conclusion, the OC valve in the aortic position opens sufficientlyin relation to blood flow. This fact supports the good clinical results of the OC valve.
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H. GOTO, Y. MIYAUCHI, J. UTOH
1995 Volume 24 Issue 2 Pages
423-426
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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Since 1990, 52 CarboMedics bileaflet valves (CM) were implanted in 50 patients; 25 aortic valve replacements (AVR), 23 mitral valve replacements (MVR), and 2 double valve replacements (DVR). Between 1982 and 1994, we implanted St. Jude Medical valves (SJM) in 128 patients (AVR: 65, MVR: 55, DVR: 8). The mean follow-up time was 31 months for CM and 53 months for SJM. The early mortality rate was 6.0% (CM) and 4.7% (SJM). The 1-year actuarial survival rate was 87.8% (CM) and 93.7% (SJM), and that for 3 years was 85.6% (CM) and 92.4% (SJM). There were no significant differences in overall survival rates and event-free survival rates between two groups. During the follow-up period, no valve-related death was found in CM group. These results encourage an increasing utilization of the CarboMedics prosthesis.
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K. MORISHITA, T. ABE, K. KAMATA, T. KAZUI, S. KOMATSU
1995 Volume 24 Issue 2 Pages
427-429
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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This study was performed to clear the influence of combination of mechanical prostheses on mid-term results by comparing our patients. The patients were divided into three groups. Group O patients received a Omnicarbon valve in the aortic position and a Duromedics valve in the mitral position (n=27) ; Group S, dual SJM valves (n=32); and Group C, dual CarboMedics valves (n=21). The actuarial survival rate was 81±8% at 9 years in Group O, 87±8% at 6 years in Group S, and 79±10% at 4 years in Group C. The actuarial freedom from all valve-related morbidity and mortality was 58±18% at 9 years in Group O, 80±13% at 6 years in Group S, and 47±15% at 4 years in Group C. There was no stastical difference among the three groups. Group C, however, had a greater incidence of all valve-related morbidity and mortality. In conclusion, dual SJM valves and combining a Omnicarbon valve with a Duromedics valve have excellent mid-term results; additional proven durabillity is necessary in CarboMedics gruop.
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M. OSAKO, R. YOZU, H. ODAGUCHI, A. MORI, A. MITSUMARU, Y. CHO, Y. INOU ...
1995 Volume 24 Issue 2 Pages
430-433
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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The patient was a 52 year-old female who had undergone mitral valve replacement and tricuspid valve replacement with St. Jude Medical prostheses ten years earlier. Three months after surgery, the tricuspid prosthetic valve was found to be stuck in one leaflet. Cineradiography revealed that the prosthetic valve in the tricuspid position was implanted with the hinges oriented vertically to the interventricular septum and the anterior leaflet was fixed in a closed position. Echocardiogram showed no right ventricular dilatation and trivial tricuspid prosthetic valve regurgitation with a valvular area of 2.5cm
2. The patient has recieved anticoagulation therapy using Coumadin in an attempt to control thrombotest between 8 and 10% to prevent prosthetic valve thrombosis. The patient has been free from symptoms without apparent cardiac failure for the last ten years and has been followed by periodic cineradiography. The causes of the stuck valve are unclear, but may be attributed to an improper placement of the prosthetic valve, insufficient anticoagulation therapy or an inappropriately large prosthetic valve.
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K. NAKANO, H. UEDA, K. EISHI, T. MURAKAMI, J. KOBAYASHI, Y. SASAKO, F. ...
1995 Volume 24 Issue 2 Pages
434-436
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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The primary tissue failure (PTF) in the mitral position were compared between Ionescu-Shiley valve (IS) and Carpentier-Edwards pericardial xenograft (CEPX). Between 1979 and 1983, the IS was implanted in 193 patients and, since 1984, the CEPX was implanted in 70 patients. The free from PTF at 10 years was 64.5% in IS and 79.2% in CEPX (not significant). In the pathological findings of the explanted valve at the reoperation, tear was detected 92% of IS and 40% of CEPX. The degeneration change and intracusplar calcification were more prominent in IS than in CEPX. Thus, the pathological findings of the explanted valve suggested that the CEPX can be more durable than the IS.
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H KOHNO, H MAYUMI, M MASUDA, S MORITA, Y TOSHIMA, Y KAWACHI, H YASUI
1995 Volume 24 Issue 2 Pages
437-442
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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Pathology of the Carpentier-Edwards pericardial bioprosthetic heart valve explanted at reoperation. Between February 1985 and March 1994, we implanted 173 Carpentier-Edwards bovine pericardial bioprosthetic heart valves (CEP) in 155 patients. Among them, 13 CEPS were explanted during 3 and 97 months after operation. Primary tissue failure (PTF) occured in 5 valves (4 in the mitral position and 1 in the aortic). Three valves in the mitral position failed with tears at one or two commissures. The Elgifoy wire was fractured in 2 of the 3 PTF valves and one stent was distorted in 1 of them. Another valve in the mitral position showed leaflet prolapse without tear, that was atypical feature of PTF in other pericardial biopros theses. A heavy pannus overgrowth on the inflow side was also found in this valve. Only one valve in the aortic position failed with extensive calcification throughout the belly of each cusp. The other 8 valves were explanted without PTF; 4 for perivalvular leak, 3 for prophylactic removal, and 1 for prosthetic valve endocarditis. In all but two, an X-ray analysis revealed mild to moderate calcification mainly in the belly of the cusp. Also mild to moderate pannus overgrowth was found in 3 non-PTF valves. It is important to know that CEP has some other features of PTF than a leaflet tear or calcification which is a typical failing feature of other bovine pericardial bioprostheses.
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Kazuya AKIYAMA, Jun HIROTA, Akihiko OKADO, Takayuki NAKAJIMA, Yoshitak ...
1995 Volume 24 Issue 2 Pages
443-447
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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Isolated aortic (n=4), mitral (n=9), and double (n=1) valve replacements were performed with the Mitroflow pericardial valve in 14 patients from January to November in 1985. The mean age of these patients was 45.6 years. All patients were followed for a total of 85 patient-years (PY). There was one operative, non-valve related death in the patient with double valve replacement. Valve-related complications included one anticoagulant-related hemorrhage (1.2% of PY). one non-structural valve deterioration (hemolytic anemia) (1.2% of PY), and ten structural deteriorations (12.9% of PY). Afetr 9 years, freedom from reoperation was 8.6±2.6%. We concluded that this second generation pericardial valve, the Mitroflow valve, provides inferior clinical performance compared to the porcine aortic valve and its use has to be discontinued.
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K. NAEMURA, K. IZUMI, T. FUJIMOTO, M. UMEZU, Y. KATUMATA, M. KITAMURA, ...
1995 Volume 24 Issue 2 Pages
448-452
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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In order to evaluate the function of prosthetic heart valve at mitral position, a mechanical circulatory model, which is designed to simulate the inflow characteristics during diastole, has been developed. Anatomically identical designed silastic left atrium (LA) and rubber left ventricle (LV) were driven by pneumatic pressure, a timing of which were basically determined on referable to the physiological data. After several trials, the authors could achieve physiologically identical inflow velocity pattern with two velocity peaks; a rapid filling peak (0.6m/sec) at early diastole and a subsequent peak (0.5m/sec) by the LA contraction. However, following problems were indicated; 1) There was no increase in the stroke volume by the contraction of the LA, 2) Higher end diastolic pressure (23mmHg) was measured. As a result of modifications including a readjustment of the LV compliance (1 3mL/mmHg), and an incorporation of a larger valve (Φ25 Φ29), above problems are successfully settled down.
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- A COMPARATIVE STUDY WITH THE SJM VALVE -
K. KAMADA, T. ABE, K. MORISHITA, K. KOMATSU
1995 Volume 24 Issue 2 Pages
453-455
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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The Bicarbon valve prosthesis (BC) is a new valve made of titanium with a carbon coating. BC was compared with the SJM in terms of cardiac output, cardiac index, ejection fraction, % fractioning shortening, peek gradient, mean gradient, mean velocity by Doppler echo cardiography. There were no significant differences between the BC and the SJM.
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Y YAMAMOTO
1995 Volume 24 Issue 2 Pages
456-461
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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Non-physiological rate response in the pacemaker using activity sensor assessment by rate profile and redraw function. Rate response in the pacemaker using activity sensor is not uniform in the daily activities. We studied the effects of slope, jogging, stairs on rate response quality of SSIR pacemaker DASH (Intermedics Ltd), using internal rate profile and redraw functions. Exercise tests were performed by three protocols. Protocol (1) includes walk on treadmill with slope of 0% and 14% at 2.0mph and 3.4mph for 3min at each stage of exercise. Protocol (2) includes walk on treadmill with 0% slope at 2.0mph, 3.4mph, 4.2mph and jog at 4.2mph. Protocol (3) includes walk and Master two steps tests with constant speed of 100 steps/min. Sinus rate and activity sensor rate profiles of different settings of rate response parameters were compared. As the result, if rate response parameters were set optimal to walk speed, sensor rate was under-responsive both to slope and stairs, and over responsive to jogging. Thus, one setting of rate response parameters was not optimal to all of daily activities. This is a limitation of rate response quality by activity sensor.
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N SUGIURA, T TAKAGI, S MIZUSHINA, T SUGIURA, M KIMURA, T KIMURA, Y HAR ...
1995 Volume 24 Issue 2 Pages
462-467
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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An automatic estimation method of fuzzy rates using a pattern recognition technique has been developed.Three characteristics values(mean square error, peak ratio, and mean minimum distance)are used in the process to compare the fuzzy rates and target rates variations.In order to get the final numerical value for the objective estimation from these three values, fuzzy logic was used.The method was applied to the rate simulation during walking based on minute ventilation and oxygen saturation level as input guide parametersjEstimation results were very similar to those by the conventional subjective judgements.This method is found to be effective for the automatic tuning of membership functions and control rules.
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Y. OHTA, T. DOHI, T. HORIUCHI
1995 Volume 24 Issue 2 Pages
468-472
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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Magnetic stimulation has the drawback of poor focality compared with conventional electric stimulations, because of its dissipation of induced current. That makes it difficult to use magnetic stimulation for deep seated areas inside of a human body. This is a preliminary study for improving the focality of magnetic stimulation by using a conductive material, in this case a small copper ball, which can increase density of induced current inside of a volume conductor. We developed the system for measuring distribution of current induced in saline solution. The system consists of the stimulating coil, the saline solution chamber as a volume conductor, and the induced current probe. Measurements of the induced current are carried out with J without the copper ball. The stimulating coil was supplied with sine wave current by a function generator, and with mono-phasic pulse current by a magnetic stimulator (Dantec, MagPro). As a result, nearly double increase of density of induced current was shown in the vicinity of the copper ball.
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Keiichiro KATSUMOTO, Tatsuru NIIBORI
1995 Volume 24 Issue 2 Pages
473-478
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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Permanent steroid eluting leads are used for the purpose of lowering stimulation threshold elevation due to foreign body reaction. To evaluate the eluting capabilities, a single electrode was placed into a test tube containing 1.0ml of distilled water. After 60 minutes, the lead was taken out of the test tube and the solution was removed for analysis of steroid. Then an another test tube containing 1.0ml of distilled water was prepared and the lead was placed again into the water and waited for the next 120 minutes. These procedures were continued periodically. Analysis of dexamethason sodium phosphate(DSP) was performed by high performance liquid chromatography (HPLC). The highest concentration of DSP was obtained at the first 60 minutes interval in the CAPSURE lead. But during the next 20 hours interval, the SELUTE and the ENCORDEC lead showed much more DSP elution. The DS58V steroid eluting lead which was produced in our institute had 4 holes in the electrode surface and was filled with a mixture of silicon gel and DSPat our institute. In order to slow the rate of steroid elution over time and lengthen the effect of steroid against the myocardium, various kinds of carbon powder were tested adding to the DSP silicon gel complex. DSP silicon gel with activated graphite powder resulted in the best suitable electrode for modification of the eluting capabilities which would inhibit the peaking of the stimulation threshold on the 7th to 10th day after implantation.
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COMPARISON WITH ENDOCARDIAL LEADS
T MASEKI, A ARIKI, K YASUURA, M MURASE, T ISHIHARA
1995 Volume 24 Issue 2 Pages
479-482
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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One hundred and ninety nine myocardial pacing leads were followed up to 26yrs. and their survival probability was reviewed with special reference to lead failure. The survival probability of myocardial leads was compared with that of 1640 endocardial leads. The survival probability (SP) was calculated with Kaplan-Meier method and compared with generalized Wilcoxon test. The SP of myocardial leads was 89%, 79% and 68% at 5, 10 and 15-26yrs, respectively. The mean survival of myocardial leads was 20.2 yrs. The SP of endocardial leads was 83% and 72% at 10 and 20-22 yrs, respectively. Myocardial leads had a significantly poorer survival than endocardial leads (p=0.01). Among myocardial leads no difference of SP was found by models. The average voltage threshold of 104 myocardial leads (Medtronic model 6917) at implant was 0.86V at 0.5msec and that of 180 endocardial leads (Medtronic model 4024) was 0.37V. Myocardial leads had significantly higher voltage thresholds than endocardial leads at implant. From the point of durability and energy saving pacing we recommend to use endocardial leads as a first choice at the permanent pacemaker implantation.
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S. ICHIHARA, N. MIZUTANI, T. KOBAYASHI
1995 Volume 24 Issue 2 Pages
483-488
Published: April 15, 1995
Released on J-STAGE: October 07, 2011
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DDD pacing has been used to maintain AV synchrony and to improve hemodynamics. However, continuous effective atrialsensing unnecessary condition for proper DDD pacing. For this reason, it is wellknown that the possibility ofrapid ventricularpacing exists during atrialtachyarrhythmia (AA). Thirty-one patients (pts) with a ODD or DDDRpacemaker —META DOOR 1250 (n=7), META DDDR 1254 (n=5), Chorus I (n=2), Chorus II (n=5), Relay (n=5), Cosmos (n=7), were studied retrospectively. Inappropriate high rate tracking was observed in 4/7 pts with a conventional DDD pacemaker (Cosmos). Other pacemakers designed to prevent rapid ventricular tracking of AA effectively reduced and regularized the ventricular responses during AA. Despite the successful controlofhigh rate trackmg, sinus tachycardia caused an undesirable mode switch to occur in some pts and every newalgorithm had its own limits. These results suggest that the conventional DDD pacemaker is a poor choice for ptswith AA and that newalgorithms (automatic mode switching) may be an acceptable mode to controlthe ventricular rate in pts with AA and those who require duatchamber pacemaker.
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