-
Wei Shi,
I. Saito, T. Chinzei,
T. Isoyama,
H. Miura,
A. Kouno,
T. Ono,
H. Nakagawa,
S. Yamaguchi,
Y. Inoue,
A. Kishi,
Y. Abe
[show abstract]
[hide abstract]
ABSTRACT: Development of an implantable artificial heart is very important to save cardiac disease patients. An undulation pump ventricular
assist device (UPVAD) could be a good candidate because of the compact size. Although the implantation improves patient’s
quality of life (QOL) considerably, several implications hamper the development of an implantable artificial heart. The difficulty
in blood pressure measurement is the one of the implications to be solved. We have developed the im-plantable absolute pressure
sensor to be integrated into a UPVAD and the algorithm to infer the blood pressure referred to gauge pressure. Noble feature
of the algorithm is autonomous compensation of the offset drift with the pressure sensor in time. Thus the blood pressure
could be controlled precisely with the implantable UPVAD even if the pressure sensor exhibited certain drift characteristics.
Animal experiment demonstrated the effectiveness in compensating the offset drift
12/2007: pages 66-69;
-
Itsuro Saito, T. Chinzei,
T. Isoyama,
H. Miura,
A. Kouno,
T. Ono,
H. Nakagawa,
S. Yamaguchi-Sekine,
W. Shi,
Y. Inoue,
A. Kishi,
Y. Abe
[show abstract]
[hide abstract]
ABSTRACT: The undulation pump ventricular assist device (UPVAD) is a small implantable ventricular assist device using an undulation
pump. The UPVAD can produce not only continuous flow but also pulsatile flow by changing the motor rotational speed of the
UPVAD. Because the undulation pump is a volume displacement type pump in which the inflow action and outflow action both start
at the same phase, the inflow sucking occurs easily. The purpose of this study is to develop a suitable control method for
the UPVAD. The UPVAD inflow cannula equipped with an implantable blood pressure sensor is inserted into the ventricular. Therefore,
pressure fluctuation that synchronizes with the natural heartbeat is observed in the inflow cannula. By changing the motor
rotational speed that responds to the inflow pressure, the UPVAD can synchronize with the natural heartbeat and the UPVAD
can generate either aco-pulse assist flow or a counter pulse assist flow. The newly developed control method exhibited superior
characteristics than existing ones due to high immunity against pressure sensor drift. The improved control method is implemented
into the microcontroller. The UPVAD generated 5.3 l/min co-pulse assist flow without inflow cannula sucking using this control
method. The assist flow can be increased more than 15% with this control method. This control was implemented one-chip microcontroller
without extra peripheral device. It can reduce the UPVAD controller size. The UPVAD can generate the suitable assist flow
with the developed control method.
12/2007: pages 62-65;
-
Y Abe, T Chinzei,
T Isoyama,
S Mochizuki,
I Saito,
T Ono,
K Iwasaki,
A Kouno,
K Takiura,
H Nakagawa,
M Mitsui,
N Takigu-chi,
K Imachi
ASAIO Journal 02/2004; 50(2):144. · 1.39 Impact Factor
-
E Okamoto,
T Inoue,
K Watanabe,
T Hashimoto,
E Iwazawa,
Y Abe, T Chinzei,
T Isoyama,
S Kobayashi,
I Saito,
F Sato,
H Matsuki,
K Imachi,
Y Mitamura
[show abstract]
[hide abstract]
ABSTRACT: The purpose of this study was to demonstrate the feasibility of the use of an implantable, high-energy, and compact battery system for an undulation pump total artificial heart (UPTAH). The implantable battery system tested consists of six lithium-ion batteries in series, a charge unit, and a charge/discharge control unit. A lithium-ion battery is currently the best energy-storage device because it has more energy density, a better life cycle, and a smaller temperature rise than those of other secondary batteries. The performance of the implantable battery system was evaluated in an in vitro experiment using an electric load that simulated the UPTAH. Also, sufficiently reliable operation of a system for supplying energy to a UPTAH consisting of a transcutaneous energy transmission system (TETS) and an implantable battery system was confirmed in three experiments using goats. The results of the in vitro and in vivo experiments showed that the implantable battery system supplied sufficient current to the UPTAH for maintenance of physiological conditions in the goat with maximum rise in temperature to less than 43 degrees C.
Artificial Organs 03/2003; 27(2):184-8. · 2.00 Impact Factor
-
S Kawano,
T Isoyama,
S Kobayashi,
H Arai,
K Takiura,
I Saito, T Chinzei,
Y Abe,
T Yambe,
S Nitta,
K Imachi,
H Hashimoto
[show abstract]
[hide abstract]
ABSTRACT: The prototype of the miniature vibrating flow pump (VFP) is developed for the external shunt catheter. The cross-slider mechanism is applied to vibrate the tube, which causes the pumping effect. This mechanism results in successful development of the miniature and lightweight VFP. By the use of the prototype VFP, the experiment of the basic pump performance is made in detail based on the authorized procedure in the research field of fluids engineering. The typical H-Q curve of VFP, which is the relationship between the pump head and the flow rate, can be obtained. This result suggests that the miniature VFP developed here can be expected to be used as the booster pump for the external shunt catheter in clinical applications.
Artificial Organs 02/2003; 27(1):73-7. · 2.00 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In order to realize an artificial heart system capable of being controlled by autonomic nervous signals, we have studied the methods of long-term stable recording of autonomic nervous signals as well as methods to control an artificial heart by these signals. In this study, we have focused on algorithms to generate the control commands to an artificial heart system from recorded neural signals. We have chronically recorded signals from a goat's cardiac sympathetic nerve and vagal nerve and circulation parameters such as aortic pressure, and results of the analysis of these signals showed the feasibility of the neural control of artificial heart systems.
Engineering in Medicine and Biology, 2002. 24th Annual Conference and the Annual Fall Meeting of the Biomedical Engineering Society EMBS/BMES Conference, 2002. Proceedings of the Second Joint; 02/2002
-
[show abstract]
[hide abstract]
ABSTRACT: The undulation pump is a unique continuous-flow displacement-type blood pump with high performance. However, the undulation
pump has limited mechanical durability. To eliminate this limitation, the principle of the rotary undulation pump was developed.
The rotary undulation pump is composed of a disk having a pair of convex shapes on both side and pump housing having a shape
such that one side is narrow and the other side is wide. The disk nutates and at the same time rotates at half the speed of
nutation. With this movement of the disk, the disk can rotate through the narrow part of the pump housing and pump mechanism
occurs. Between the disk and the pump housing, four pump rooms are created. The four outputs are added at the outlet port,
and continuous flow is generated. The practical shape was designed with computer graphics. The motion of the disk was calculated
accurately with the computer, and the principle was confirmed. The inlet and outlet port areas were also calculated. Models
were developed to demonstrate the principle. With the magnetic coupling method, up to about 6 l/min of output could be measured
against 100 mmHg of pressure load, and the principle was demonstrated to work. An experimental model to study an electromagnetic
drive method, including a magnetically suspended drive, is being developed for the next step. Although many objectives remain,
the basic principle of the rotary undulation pump was confirmed.
Journal of Artificial Organs 01/2002; 5(2):84-90. · 1.59 Impact Factor
-
Y Abe, T Chinzei,
T Isoyama,
T Ono,
S Mochizuki,
I Saito,
K Iwasaki,
M Ishimaru,
T Karita,
A Kuono,
K Baba,
K Imachi
[show abstract]
[hide abstract]
ABSTRACT: The undulation pump is a small continuous flow displacement-type blood pump. The undulation pump total artificial heart (UPTAH) is a unique implantable total artificial heart using undulation pumps. An adult female goat weighing 45.8 kg was used for implantation. The natural heart was replaced with the UPTAH under extracorporal circulation. The cardiac output (CO) was maintained to 100 ml/kg/min by controlling the right pump manually. To prevent lung edema, the left pump was controlled automatically to maintain the left atrial pressure below 20 mm Hg. The CO was maintained for 2 weeks. Thereafter, the CO gradually decreased. The goat suddenly died because of a brain stroke on the 31st postoperative day. At autopsy, the cavity of the left atrial cuff was almost occupied by the big pannus-like thrombus, which was thought to be the cause of death. Improvement of the atrial cuff is necessary to obtain longer survival and is being modified. No thrombus was found inside the pumps. However, temperature rise in a left motor was a problem. Improvement of the efficiency in a motor is necessary. Although many problems still remained, 1 month survival could be obtained with this unique implantable TAH using continuous flow displacement-type blood pumps.
Artificial Organs 02/2001; 25(1):69-71. · 2.00 Impact Factor
-
T. Suzuki,
M. Mitsui,
F. Inagaki,
M. Ohkura,
T. Saito,
N. Kakutal,
T. Isoyama,
I. Saito, T. Chinzei,
K. Imachi,
K. Mabuchi
[show abstract]
[hide abstract]
ABSTRACT: In order to develop an artificial heart system capable of being controlled by autonomic nervous signals, we have studied the methods of long-term stable recording of autonomic nervous signals and algorithms to utilize those signals to control an artificial heart system optimally. In this study, we have focused on the feasibility of the control of an artificial heart using the signals recorded from the cardiac sympathetic nerve and other nerves through animal experiments.
Engineering in Medicine and Biology Society, 2001. Proceedings of the 23rd Annual International Conference of the IEEE; 02/2001
-
[show abstract]
[hide abstract]
ABSTRACT: It has been reported that skin blood flow and, consequently, skin temperature exhibit several periodic fluctuations. Although the mechanisms and physiological basis underlying these fluctuations are not yet well understood, it is thought that the fluctuations originate in the periodic rhythms of the autonomic nervous system. In this study, a program for a far-infrared thermal imaging system was developed which is capable of displaying topograms of the power spectra of an arbitrary frequency range with respect to changes in skin temperature (i.e. thermal rhythm). Thermographic images were taken using a high-speed far-infrared thermal camera. The change in the skin temperature with respect to time at every pixel was obtained from the time series of the thermograms, and the power spectrum was calculated by the FFT method using the personal computer. The amplitude of the power spectrum at an arbitrary frequency range was changed into pseudo-colors at each pixel, and a 2-dimensional or 3-dimensional color image of the amplitude mapping of the power spectrum at each frequency range was obtained. We are now analyzing differences between healthy subjects and patients with Raynaud's syndrome in the distribution of the rhythms of skin temperature using this system.
Engineering in Medicine and Biology Society, 2001. Proceedings of the 23rd Annual International Conference of the IEEE; 02/2001
-
[show abstract]
[hide abstract]
ABSTRACT: Separate systemic circulations with pulsatile flow were obtained using 1 rotary blood pump as a left ventricular assist device. The outlet of the pump was divided into 2 conduits, 1 connected to the upper half of the body and the other connected to the lower half. An electric actuator that clamped the 2 outlet conduits alternately provided pulsatile flows. An in vitro experiment showed that the pulsatility phases of the upper and lower halves of the body were complementary with pulsatile flow, and an in vivo experiment showed that controlled flow distributions of continuous flows could be obtained.
Artificial Organs 09/2000; 24(8):680-2. · 2.00 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Research of the distributed artificial heart is important not only to acquire the means of individual organ perfusion but also to clarify the characteristics of the organ and the mechanism of blood distribution. To investigate the distributed artificial heart, the miniature undulation pump was developed. The outer diameter and the thickness of the developed pump were 38 mm and 11 mm, respectively. The priming volume of the pump was 3.2 ml. The total size including the motor unit was 38 mm in diameter and 32 mm in length. The total weight was 67.5 g. The total volume was 27.5 ml. The pump was driven with pulse width modulation by using a 1 chip motor controller. More than 5 L/min of continuous output could be obtained. The results showed that the developed miniature undulation pump system had enough performance for individual organ perfusion.
Artificial Organs 09/2000; 24(8):656-8. · 2.00 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Skin temperature is determined by blood-flow rate, structure of
subcutaneous tissue, and activities of the sympathetic nervous system,
which regulate heat dissipation from the body surface. Because of this,
we can noninvasively detect distributions of many physiological
functions from thermal images of the skin surface obtained by far
infrared (FIR) imaging. If we can describe equations by which we
calculate values of some functions from skin temperature, we might be
able to analyze pathophysiological abnormalities by remote sensing.
However, it is clear that we cannot convert a thermal image into other
physiological function images unless we eliminate influences of many
environmental conditions, structural variations, and other physiological
parameters of skin-surface temperature. One solution is to introduce
some physical, chemical, or neurohumoral stress to a patient and then
take time-sequential thermal images. Dynamic fluctuation of such
physiological functions might be revealed by sequential thermal images
taken after stress is applied. We analyzed the theoretical backgrounds
to determine regional skin temperature and thus developed application
software to carry out the process. This article discusses algorithms we
developed for detecting static abnormality or transient change of some
physiological functions such as skin blood-flow rate, blood volume in
cutaneous and subcutaneous vascular beds, and activities of the
sympathetic nervous system
IEEE Engineering in Medicine and Biology Magazine 06/2000; · 2.06 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A conductance and arterial pressure based method (1/R control) to determine the cardiac output (CO) of a total artificial heart (TAH) was developed to provide a central nervous system with control over the output of TAH. In order to clarify the deference in hemodynamic response between natural heart and 1/R control, biventricular bypass was introduced in the goat. After 2 pneumatically driven sac-type blood pumps were connected to the natural heart, the pulmonary artery was totally clamped to acquire 100% right heart bypass, and the ascending aorta was stenosed to acquire about 60 to 90% left heart bypass; 1/R control was performed substituting the output of the right artificial heart for the CO. The results demonstrated that stable control could be achieved. A discrepancy was often seen between the pulse rate (PR) of the artificial heart and the heart rate (HR) in absolute value. However, the relative changes of PR were quite similar to that of HR for the most part, indicating that the responses of 1/R control were the duplication of natural cardiac responses in normal daily activity.
Artificial Organs 05/2000; 24(4):312-5. · 2.00 Impact Factor
-
Y Abe, T Chinzei,
T Ono,
S Mochizuki,
I Saito,
P Guba,
T Karita,
Y p Sun,
A Kouno,
T Isoyama,
K Baba,
K Imachi
[show abstract]
[hide abstract]
ABSTRACT: The undulation pump total artificial heart (UPTAH) was developed by using small-size continuous-flow displacement-type blood pumps (undulation pump). To clarify and improve the problems accompanied by the implantation in the chest, 14 animal experiments were performed on goats weighing 41.3-79.2 kg. The UPTAH could be implanted in the chest of all goats and was driven with a modulation pulsatile mode. The first problem was the atrial suction effect. This problem could be prevented to some extent by developing the soft disk and by improving atrial cuffs. An automatic detection and releasing of the atrial suction effect was also tried. The next problem was acute lung edema accompanied by the postural change of the animal. Development of the automatic control of left atrial pressure could prevent this problem. Small blood leakage from a pinpoint hole in the seal membrane was the next problem. Improvement of the manufacturing procedure of the membrane prevented this. With these improvements, a 10 day survival could be obtained with this unique implantable total artificial heart.
Artificial Organs 11/1999; 23(10):932-8. · 2.00 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: It is desirable that the dynamic behavior of the drive rate of the total artificial heart (TAH) can be as similar as possible to that of the recipient's heart rate (HR) before implantation. This requires a model which can simulate the behavior of HR on the basis of only information measured with the limited number of approvable sensors. The present study aims at deriving the model for simulating the dynamic behavior of HR from a few measurements in order to apply the model to TAH control
[Engineering in Medicine and Biology, 1999. 21st Annual Conf. and the 1999 Annual Fall Meeting of the Biomedical Engineering Soc.] BMES/EMBS Conference, 1999. Proceedings of the First Joint; 11/1999
-
Y Abe, T Chinzei,
T Isoyama,
T Ono,
S Mochizuki,
I Saito,
P Guba,
T Karita,
Y P Sun,
A Kouno,
T Suzuki,
K Baba,
K Mabuchi,
K Imachi
[show abstract]
[hide abstract]
ABSTRACT: At the University of Tokyo, various types of total artificial heart (TAH) systems have been studied since 1959. At the present time, 2 types of implantable TAH have been developed. One is an undulation pump TAH (UPTAH) and the other is a flow transformed pulsatile TAH (FTPTAH). Using the UPTAH, 14 cases of implantation were performed in goats and 10 days' survival obtained. The new type of FTPTAH is under a prototype study. To prevent ring thrombus, a polyurethane membrane valve, a jellyfish valve, has been developed. The longest in vivo experiences with this valve in the TAH blood pump have been 312 days in the left side blood pump and 414 days in the right side blood pump. Conductance and arterial pressure based control (1/R control) can realize the physiological control of the TAH. Using 1/R control, 532 days of survival could be obtained in a goat with a paracorporeal TAH. The technique required to apply this control method to a implantable TAH is under development. We have proposed a new 5 year research project of the implantable TAH entitled "Comprehensive Basic Research on the Development of a Japanese Original Implantable Total Artificial Heart" to The Ministry of Welfare.
Artificial Organs 04/1999; 23(3):221-8. · 2.00 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We aimed to develop a method of accurately identifying the dorsal root for the corresponding peripheral afferent nerve under endoscopic observation. We developed an endoscope with an external diameter of 1.8 mm. After small laminectomy on the lower thoracic vertebrae, we inserted this endoscope carefully into the epidural and then subarachnoid spaces. We observed structures in these spaces with the endoscope. We tried to determine the spatial relationship between these electrodes and dorsal root. After identifying each space, we inserted two electrodes into the visualized space to record evoked potentials; a bipolar electrode (protocol 1) and a catheter-type eight polar electrode (protocol 2). Each pole could be distinguished by marks. To stimulate peripheral nerves, we inserted needle-type electrodes into Th 10, 11 and 12 intercostal nerves. We attempted to record potentials from dorsal surface of the cord generated by intercostal nerve stimulus. Protocol 1: We moved the position of the bipolar recording electrodes between Th 9 and L 1 by 1 cm increment, and obtained evoked potentials correspondingly. Protocol 2: We chose the neighboring pairs of poles sequentially from the tip of the catheter for bipolar recording. At the end of each experiment, we dissected the animal and checked the intercostal nerve originating from the root. With the endoscope, we could clearly observe structures in the epidural and subarachnoid spaces. We could record evoked potentials from the dorsal spinal cord with the electrodes located either in epidural or in subarachnoid spaces. Shapes of evoked potentials changed characteristically according to the relative position between the root and the electrode. The largest potentials were obtained when the electrode was nearest to the dorsal root, of which the peripheral nerve was being stimulated. By combining endoscopy with the electrophysiological technique, we could accurately identify the dorsal roots for the corresponding peripheral afferent nerves. This method may be used for the selective dorsal root blockade under the visual field.
Masui. The Japanese journal of anesthesiology 02/1999; 48(1):9-17.
-
[show abstract]
[hide abstract]
ABSTRACT: In order to use thermography for clinical diagnosis, it is necessary to determine the location of the abnormal thermal areas as well as the degree of the change in body-surface temperature. This necessitates an evaluation of the distribution of the deviation in skin temperature from a standard skin-temperature distribution of the healthy subject. However, there is no standard distribution of the body-surface temperature of a healthy subject because it is affected by so many factors, such as the ambient and internal thermal conditions, age, sex, body weight, etc. Further, it also differs widely with individuals. One of the best ways to eliminate this variability, and to detect and evaluate the change in the body-surface temperature, is to measure the body-surface temperature of each thermograph pixel in the affected area and subtract from it the body-surface temperature of the corresponding pixel in the symmetrically located contralateral healthy area. The aim of this study is to develop a program for a computerized thermographic system that will produce images of the distribution of temperature differences between the affected side and the contralateral healthy side, and also to investigate the feasibility of the program in a clinical setting.
IEEE Engineering in Medicine and Biology Magazine 04/1998; · 2.06 Impact Factor
-
Y Abe, T Chinzei,
K Mabuchi,
A J Snyder,
T Isoyama,
K Imanishi,
T Yonezawa,
H Matsuura,
A Kouno,
T Ono,
K Atsumi,
I Fujimasa,
K Imachi
[show abstract]
[hide abstract]
ABSTRACT: To obtain a physiological response by a total artificial heart (TAH), while eliminating the hemodynamic abnormalities commonly observed with its use, we proposed the use of a conductance- and arterial pressure-based method (1/R control) to determine TAH cardiac output. In this study, we endeavored to make use of a variable more closely tied to central nervous system (CNS) efferents, systemic conductance, to provide the CNS with more direct control over the output of the TAH. The control equation that calculates the target cardiac output of the TAH was constructed on the basis of measurement of blood pressures and TAH flow. The 1/R control method was tested in TAH-recipient goats with an automatic method by using a microcomputer. In 1/R control animals, the typical TAH pathologies, such as mild arterial hypertension and substantial systemic venous hypertension, did not occur. Cardiac output varied according to daily activity level and exercise in a manner similar to that observed in natural heart goats. These results indicate that we have determined a control method for the TAH that avoids hemodynamic abnormalities exhibited by other TAH control systems and that exhibits physiological responses to exercise and daily activities under the conditions tested. The stability of the control and the complete lack of inappropriate excursions in cardiac output is suggestive of CNS involvement in stabilizing the system.
Journal of Applied Physiology 04/1998; 84(3):868-76. · 3.75 Impact Factor
