Flow rate in a blood pump for mechanical circulatory support is controlled to improve QOL (Quality Of Life) of a patient. In this study, flow rate in a centrifugal blood pump is estimated without additional sensing system by using magnetically levitated (maglev) impeller dynamics of passive stabilization. Radial displacements of a maglev impeller which was stabilized passively in a centrifugal blood pump were measured using laser displacement sensors in a mock circulation loop with a glycerol-water solution (3.1 mPas) and a saline (0.92 mPas). Relationships between the displacement and the flow rate were approximated linearly with a high determination coefficient, R²=0.993 (glycerol solution) and 0.975 (saline). There was little difference between a correlation equation with the glycerol solution and that with the saline. These results indicate that better accuracy and resolution can be achieved in the present estimation approach even if blood viscosity of a patient is unknown.

We have been studying the transcutaneous communication system(TCS) using the intra-body communication, and we developed the implantable miniature TCS in which a Lithium battery was integrated on a circuit board. We examined the implantable TCS in the animal experiment, and the implanted TCS inside the goat' thoracic cavity was not able to communication with the external unit at all. From the in vitro experiment for verification of the animal experiment showed that the amplitude of the receiving signal on the receiver is proposal to the distance between the battery and the circuit board on the transmitter, and integration of the battery on the transmitter circuit board is difficult to achieve data communication. From the results, we develop a new implantable miniature TCS unit in which the battery is separated from a circuit board. In addition, the receiver circuit is redesigned in order to improve receiving sensitivity.

The purpose of this study was to compare the clotting parameters of animal models for preclinical sudy of medicl devices to determine which animals most effectively mimic human clotting parameters. The clotting parameters of the different species were assessed in whole blood by in vitro thromboelastometry using the clotting activators, such as tissue factor and partial thromboplastin phospholipid. The measurements were performed using norml blood samples from human, calf, goat and pig. Extrinsic clotting time (CT) and the intrinsic CT were significantly prolonged in calves compared to humans, respectively. In Max Clot firmness (MCF), maximum strength of coagulated clot in domestic animals was harder than one of humans, and calves and goats exhibited longer time to MCF (MCF-t) than did humans and pigs. Our results show that there are significant differences in clotting parameters between species. CT, MCF, and MCF-t in the extrinsic clotting reaction differed between humans and animals.

In the developments of medical fluidics with blood flows such as artificial organs, white thrombus of platelet activation by high shear flow is one of the serious problems. It is necessary to develop computational fluid dynamics (CFD) tools for design of these devices. In this investigation, the transport process including platelet and other coagulation contents with biological chemical reaction are computed by finite difference method (FDM) and aggregation of platelet are computed by dissipative particle dynamics (DPD) method. By combining these two methods (hybrid method), white thrombus formation with consideration of aggregation can be computed. In this paper, the computational objects are orifice pipe shear flows which have been used for visualization of thrombus formation by laser sheet. As results, effects of hybridization of two methods and other parameters are shown, and the computational predictions are also compared with the experimental ones.

When transplanting small diameter regenerated blood vessels with an inner diameter of 6 mm or less, thrombus formation occurs due to a difference in mechanical properties from the native blood vessels. The native blood vessels have a characteristic that the changes in outer diameter occurs with a larger manner as the internal pressure becomes low. In this study, in order to make the mechanical property of vascular scaffolds closer to that of native blood vessel, the outer diameter of nano fiber collection part was continuously changes during electro spinning and was made scaffolds with sparse and dense structure. The relationship between internal pressure and outer diameter change of these scaffolds are measured and are confirmed that the biodegradable polymer scaffolds having the controlled residual stress could reproduce the mechanical properties peculiar to native blood vessels.

The purpose of this study is to observe angiogenesis in vivo under application of electric stimulations. We developed an implantable device equipped with a CMOS-camera and electrodes for real-time observation. The device was implanted under the skin of a goat, and applied the electric stimulations for 60 days. The electric stimulations were applied with a 60 kHz sinusoidal waveform and a current density of 300 uA/mm2. Angiogenesis occurred in 94.7um/day in the non-stimulated device, while no angiogenesis was observed in the device without stimulation. These results show that electric stimulations of this condition are effective for suppressing angiogenesis.

Engineering three-dimensional tissues in vitro for the purpose of regenerative therapy is highly desired. Our laboratory succeeded in constructing a pulsating myocardial tissue by layering cardiomyocyte sheets on vascular beds. Vascular beds are the perfusion assist device which enables perfusion induction to the vascular system. For further development , the aim of this study is to create a human implantable vascular bed derived from porcine tissue to realize the transplantation therapy. Porcine small intestine with intact arteriovenous loop was selected for the vascular bed. After harvesting a tissue, the tissue was decellularized by sequentially perfusing three reagents through the artery. Subsequently, HUVECs were seeded into the decellularized intestinal vasculature and cultured to re-endothelialize the lumina. From the results of re-endothelialization, luminal coating with FBS and perfusion culture enabled the cell to adhere to the blood vessel walls and form complete luminal structures.

Joint forces are highly relevant to initiation or progression of joint diseases such as osteoarthritis. Gait modification is one of nonsurgical approaches for reducing the joint forces in patients with the joint disease. For the hip, not only the magnitude of the force but also the direction of the force would be relevant to the joint condition. In this study, we examined effects of gait modifications on the both hip joint force magnitudes and directions. Healthy subjects participated in this study. The subjects were asked to modify their step width from their original width within comfortable level. After gait modifications, the subjects achieved joint force reductions around the force peak phase.

The sacroiliac joint, a joint located in the pelvis, posses an important role in transmitting the load of the upper body to the lower body. Abnormal motion, repeated loading, etc. may cause sacroiliac joint dysfunction associated with pain. When the dysfunction is severe, sacroiliac joint fusion surgery can be taken. In the surgery, a fixation device is implanted into the joint for stabilization. A fixation of the sacroiliac joint with anterior plates has been commonly used however a sacroiliac joint screw fixation from the posterior side has recently suggested for less invasive operation. In this study, a finite element analysis was performed on pelvic bones with implants to evaluate stress ditribution in pelvic bones, joints, ligaments and implants for better sacroiliac joint fixation.

Functional electrical stimulation (FES), which artificially induces muscle contraction by applying electrical stimulation to the peripheral nerve from the outside, has been widely studied in the field of rehabilitation and assistance. However, simple and versatile stimulation methods for the delicate movement of fingers are not established. In addition, surface electrodes have advantage of less burden on the user but it is difficult to control a finger with high accuracy. Focusing on the control strategy of the central nervous system, we know an equilibrium point hypothesis that multiple muscles around a single joint are controlled by the equilibrium point and the rigidity of joint. In this study, we applied this hypothesis to control a finger and we modeled the system which regarded FES as input and the metacarpophalangeal (MP) joint angle as output. We measured a finger joint angle by a special device with the link mechanism.

Three-dimensional finite element models of the lumbar spine, both intact and following pedicle-lengthening osteotomy (PLO), were developed to investigate the kinematics and biomechanical effects of the lumbar spine finite element model after pedicle-lengthening osteotomy, which is a novel surgical procedure indicated for lumbar spinal stenosis. After applying a moment of 10 Nm in flexion, extension, lateral bending and axial rotation, biomechanical effect parameters, such as the range of motion (ROM), stress in the discs and pedicle-lengthening screws, contact force of facet joints at adjacent segments and spinal load-sharing were evaluated. Results turn out that pedicle-lengthening osteotomy did not alter the kinematics of the lumbar spine, but affected its biomechanical properties, particularly at adjacent segments.

Feet with hallux valgus increases deformation from too much weight put on a position of the foot and causes symptoms. And three-dimensional evaluation should offer more accurate pathological information because of three-dimensional deformity of hallux valgus. Therefore, we created a loading device and we evaluated the mobility of the joint that composed first ray and around the cuneiform in hallux valgus patients and healthy volunteer three-dimensionally using weight-bearing CT. Our results suggested that they had instability in the whole first ray of the foot and intercuneiform 1-2 joint compared with the healthy control group. Our technique and data were considered useful for clarifying the pathological condition of hallux valgus as well as for selecting and developing the treatment method.

This study aims to develop a noise reduction algorithm for amyloid PET imaging. A visualization of a small amyloid-β (Aβ) deposit is required for early diagnosis of Alzheimer's disease (AD) pathology, and a noise in amyloid image should be reduced without any loss of spatial resolution. Conventional noise reduction algorithms use spatial averaging, but our proposed algorithm, CAKS, averages pixels that have similar kinetics of administered PET radiopharmaceutical. As a result of CAKS applying to actual clinical images, the noise is reduced and the image quality is improved. The contrast between gray and white matters is significantly improved (p<.05). We concluded that CAKS is applied to clinical amyloid PET imaging is useful for diagnosis of AD pathology.

Background/11C-Methionie PET is a well-established imaging tool in fields of brain tumor. Tumor boundary is often better described on MET PET than on MR imaging. Also,convolutional neural network (CNN) has played important roles to automatically classify and segment images. The purpose of this study was to evaluate the performance of CNN to delineate tumor on MET PETMethod/A total of 43 glioma patients were targeted and divided into training group (N=38) and testing group (N=5). From each image, all squares consisting of 15 times 15 pixels, were generated. After the training phase using the squares from 38 patients, the squares from 5 patients were used to test the performance of the trained model.Result/The learned model categorized squares into in-tumor or out-of-tumor with accuracy of 95.2 % on average.Conclusion/Considering the correct rate of tumor determination, it was possible to determine almost exactly the location of the tumor.

It is desirable to distinguish surface skin blood flow signals and brain functional signals for fNIR imaging. In this study, two methods, depth selective filter method, which is linear inverse filters for observation data with plural source detector separation, and hemodynamic separation method are studied. Both methods have good performance of removing the surface layer blood flow signal component, though each has advantages and disadvantages. In this study the performances of the two methods are compared through simulations and experiments.

Though neural decoding of imagery has been extensively studied in the motor and visual domain, less effort has been made for auditory imagery. Here, we tested classification of 64-channel EEG data during participants imaging a tone that is an octave higher or lower than a standard tone for 2 seconds. Significant differences of time-frequency representations of the data between two conditions were individually detected for each channels and used as features for machine learning. While imaging higher tones, a stronger activity compared to the lower-tone imagery was observed in the frontal regions in the high-beta and gamma bands from 300 to 1000 ms after starting imagery. Eventually, machine learning achieved classification of the data with an accuracy of 75%. The results indicate that frontal high-frequency oscillations reflect more attentional demand for imagining higher pitch and that these time-frequency characteristics are keys to decode auditory imagery.

In this study, we investigated the resting-state fMRI signals of healthy control (HC) participants and patients with Internet addiction disorder (IAD). 3T-fMRI recordings were conducted. The HC group consisted of 21 males (19-24ys) who had a score of Internet addiction test less than 40. The IAD patients were dragonized at Kurihama medical center, consisting of 25 males (13-17ys). We calculated the correlation coefficient for 2492 voxels in a size of 8*8*8mm within the whole brain, excluding the cerebellum. We determined paired regions showing differences in the correlation between the HC and IAD groups. Significant connectivity differences between NC and IAD were found in the regions of pairs nodes including paracentral lobule, precentral gyri, and right temporal areas, suggesting that the functional connectivity was altered, toward deterioration, in the IAD patients. Confounding with age effects is an issue of further study because of large age difference existing between the two groups.

Few studies have focused on maze tasks for human. The purpose of this study is to investigate factors influencing on the difficulty of mazes for human. We conducted an experiment. Subjects search for a goal of mazes by using a computer. Subjects explore mazes for two days. In making mazes, we set the number of steps required to reach the goal and the number of T-junctions from start to goal. If a subject can reach the goal three consecutive times without extra steps, the subject moves on to the next maze. We make a new parameter "maze cost". Moreover, if the learning amount is changed, we change the order of value for the variable in the "maze cost". The new values are named the modified maze cost. The result on each day, the modified maze cost can more strictly express the difficulty of maze tasks than the maze cost.

The purpose of the present work is to study the transition between illusory melodies heard during the presentation of an ambiguous melody. The proposed ambiguous melody consisted, for example, of continuous A4 and E5 tones and and intermittently repeated C5 tone and can elicit the perception of two illusory melodies, DOWN (C5-A4- - -) and UP (C5-E5- - -). Down or Up melody was explicitly presented preceding the ambiguous melody to induce the listener to hear the same melody immediately after the onset of the ambiguous melody. Subjects pushed a designated key whenever a spontaneous change of melodies occurred. State transition probabilities such as p(D/U), the probability of changing to Down from Up, were measured. Thus we found how the perception of illusory melodies was influenced by the interval relationships among these three notes, which may give insight into the recognition of melodies in the auditory system.

The proposed ambiguity in music exists between the illusory melody C5-A4-C5-A4 (Down) and C5-E5-C5-E5 (Up) that may be heard when listening to intermittently repeated tone C5 inserted between two sustained tones A4 and E5. In this study, we changed the methods to obtain clearer images of brain activities than shown in previous report; (1) scanning and stimulus presentation used to be alternately given to prevent scanning noise from interfering with the stimulus but now given simultaneously (2) each of three (Down, Up and Neutral) categories of stimuli is presented 10 times in a series instead of given in random order as in the previous study (3) visual presentation of the implicit melodies is given instead of auditory presentation of a preceding phrase. The prefrontal cortex including the orbitofrontal cortex showed increased activities for the contrasts Down vs Neutral and Up vs Neutral, implying the involvement of working memory and motivation.

Development of a Brain-Machine Interface (BMI) in clinical applications is under way to help patients suffering from motor function impairment. For more accurate estimation of movement intentions in BMI, it is important to develop a multichannel recording system that has more than 1,000 ch. In the view point of the patient QOL, we should develop the implanatable and wireless BMI system. However, in such multichannel wireless BMI system, more than 100 Mbps throughput is needed, which exceeds the generally used wireless LAN communication speed, and the power consumption must be increased as data rate.In this report, we introduce a new broadband backscatter transmission technology combining high-density modulation and adaptive waveform compensation. We demonstrate at 15 Mbps data transmission from the measurement result of the developed prototype board, which is the fastest speed in the world for the battery-less backscatter transmission.

A dual magnetoencephalograph (MEG) system would be a powerful tool to analyze brain relating to interpersonal communication. However, because individual MEGs are rarely located in close proximity to one another, only a few dual MEG systems have been developed. We have recently developed a dual MEG system by connecting two MEGs located at Hokkaido University with fiber-optic cables, since the distance between the two MEGs is only 500 m. The signal transmission latency through the cables is 4 us and the two MEGs can be synchronized within a millisecond by trigger signals. Also, the dual MEG system is equipped with an audiovisual (AV) interface based on fiber-optic transmission, which enables virtual face-to-face communication between two subjects. Unlike internet-based interfaces, the latency in the present AV interface is constant, around 100 ms. Consequently, our system will permit natural communication between two subjects, and synchronized MEG recording of their brain activity.

Currently, the development of an automatic control system of physiological state of brain is desired for promoting the brain resuscitation. In this research, the fluid migration compartment model in brain tissue was constructed and analyzed for its verification, because the control simulation based on a mathematical model is necessary for such development.The constructed model has total 14 compartments. The twelve of them are the brain tissue divided depending on the difference of left or right hemisphere, the perfusing region of each cerebral artery, and the difference of gray or white matter. The other 2 compartments are those of the cerebral ventricle and the subarachnoid space. The equations of fluid flow, pressure, volume, and colloid concentration in/between compartments were derived, and their analysis program was written in C. As a result of the analysis, this model reasonably represented the fluid migration in brain tissue.

The integrated management of brain temperature (BT), intracranial pressure (ICP) and cerebral blood flow (CBF) is essential for brain resuscitation. Thus, the realization of the control system automating such management is expected to improve treatment effect, and to reduce staff's burden and medical cost. However, a mathematical integrated model of BT, ICP and CBF, which is necessary for the control simulation, has not been constructed yet as far as we know. Therefore, in this research, a brain heat transfer model was constructed as a part of such integrated model. This model consist of 17 compartments corresponding to each part of brain tissue, ventricle, subarachnoid space, venous sinus, cranial bone and scalp, and enable to analyze the heat balance of each compartment.As the result of the analyzing this model for its verification, the calculated temperature of each compartment under several different conditions were consistent with the previous findings.

We aim to clarify relationship between resolution of a retina and SSVEPs. However, it is difficult to observe resolution of a retina in human. Therefore, we clarify relationship between resolution of a retina in a goldfish and SSVEPs. We do not know whether it is possible to observe SSVEPs in a goldfish. In this paper, we measure the nerve potential in an optic tectum and confirm the response of the neuron.We present a flashing white LED to a goldfish eye for 60[sec]. The flashing frequency is 1Hz.As results, we recorded the neuron activity which has on-off response. This neuron responded strongly when a LED light was turned off and when a LED light was turned on. From these results, it was confirmed that the neuron with the receptive field is located between the photoreceptor cells and the optic tectum in a goldfish.

In recent years, regenerative medicine using stem cells is expected to be applied to the treatment of injuries which is currently difficult to treat. For example, umbilical cord blood is rich in stem cells such as hematopoietic stem cells and mesenchymal stem cells in the blood. For this reason, clinical applications such as cord blood hematopoietic stem cell transplantation using umbilical cord blood have been carried out. Therefore, in this study, we investigate the effect of umbilical cord blood on hypoxic encephalopathy (HIE: Hypoxic Ischemic Encephalopathy), which is a brain disorder for which no effective treatment has been confirmed.Because of preservation and recovery of brain functions can be expected by the action of umbilical cord blood, as a study on HIE treatment using umbilical cord blood, we consider and report on a method of administrating umbilical cord blood to HIE model rat at first.

In order to determine drastic temperature dependence of collagen and skin specific heat ranging 25-75℃, we performed a non-equilibrium heat conduction experiment and its calculation. The specific heat was varied to minimize the error between the measured temperature and calculated temperature. The equation which is able to calculate composite material specific heat was applied to determine collagen specific heat by above mentioned method. Determined specific heat of collagen was described as follows: 3.06± 0.28 J/g·K (T<50℃), 7.61± 0.74 J/g·K (50≦T<55℃) and 5.61 ± 0.74 J/g·K(55℃≦T). The specific heat of porcine skin was determined by the same method. Determined specific heat of the skin was described as follows: 3.06± 0.36 J/g·K (T<55℃), 6.26± 0.22 J/g·K (55≦T<60℃), 3.26 ± 0.22 J/g·K (60℃≦T)

Bone-conducted ultrasound (BCU) is perceived even by the profoundly sensorineural deaf and applied to a novel hearing aid, however, there is room for improvement especially in terms of the method of wearing vibrator. The vibrator is usually pressed onto a part of the cranial bone behind the ear (mastoid process), however, BCU can also be heard on distal parts of the body; i.e, the muscle of the neck, the clavicle, and the upper limb. In this study, to assess basic properties of distal-presented BCU hearing, detection threshold and temporal resolution were measured when 30-kHz BCU were presented to the neck and the upper and lower arms in normal hearing participants. The results showed that BCUs can be perceived even at the lower arms. Also, the temporal resolutions of the BCU hearing at the distal parts were comparable to that at the mastoid process.

The vestibular system has a critical role in sensing body tilt and receives information from other sensory systems such as the visual system. Because of the technical difficulty in designing a neuroimaging experiment for testing the vestibular system, however, little is known about the interaction between vestibular and visual information. Here, we measured EEG signals for a falling movie presented through a virtual reality display with the participant's body tilt manipulated. ERP analysis revealed that continuous attenuation of visual activity was observed from 100-200 ms after the start timing of visual falling in the inverted body condition as compared with the upright condition, irrespective of the visual direction. Moreover, Granger causality analysis showed significant feedback connection from the temporoparietal vestibular area to the visual area. These findings indicate that visual activity is suppressed by unusual vestibular information and that visual-vestibular interaction begins at a relatively early stage of visual processing.

The purpose of this study is developing the multi-point pressure sensor and the display system of this sensor. The sensor output connected vibration motor's control circuit and the intensity of the vibration is continuous or 4steps. A feedback device was attached to the right arm of each 3 subjects, a pen as, a ball, and a cap of a plastic bottle were pressed to the sensor against. After, randomly selected objects of each shape were pressed against the sensor and the subjects answered it, and this was repeated 20 times.When was continuous, the correct answers rate of the pen was 60%, the ball was 5.6%, and the cap was 44%. And when it was 4steps, the correct answers rate of the pen was 81.3%, the ball was 52.6%, and the cap was 64%. Therefore, 4 steps one is better than continuous one.

We measured the interfacial pressure between a balloon and an arterial wall using a piezo film to clarify the interaction between the balloon and arterial wall by the balloon dilation. To obtain a sufficient arterial dilatation by the balloon dilatation, arterial injuries are unavoidable. It is a problem that the therapeutic efficacy greatly varies depending on the degree of the arterial wall destruction. We measured the interfacial pressure between the balloon and arterial wall. The measured piezo film output voltage was converted into the interfacial pressure using the calibration curve. To know the expansion effect, the outer diameter of the artery was measured. Almost the same knowledge was obtained from both experiments. Considering the interaction and expansion effect, the deformation of the artery wall by the balloon dilatation might be classified into the elastic, plastic, and destruction region.

Introduction

Intra-aortic balloon pumping of the auxiliary circulation is evolving. The pressure generated during the auxiliary circulation was experimentally investigated.

Methods

A balloon (A: 30cc, B: 35cc, C: 40cc) was inserted into the test circuit with a pulsatile flow of 60 bpm. Pressure measurements of 50 waveforms, at the distal (P1) and proximal (P2) ends of the balloon, were recorded.

Results

P1 pressure amplitude (mmHg) is A: 149.10±12.81, B: 131.08±5.28, C: 118.18±7.65, and P2 pressure amplitude (mmHg) is A: 135.44±16.81, B: 144.62±10.41, C: 99.22±8.79.

Conclusions

The pressure generated by the balloon during the auxiliary circulation was checked.

A beat synchronized control of left ventricular assist devices has some advantages in comparison with constant rotational speed control. On the contrary, dynamic change in rotational speed involves the risk of suction and regurgitation. We have developed the beat synchronized control method without external sensors such as ECG. The aim of this study is to introduce suction prevention algorithm and countermeasure for cardiac hypofunction. In the proposed algorithm, the beat timing signal is calculated from disturbance of instantaneous rotational speed estimation. The signal may have the information of suction and cardiac function because the disturbance is related to ventricular pumping. After suction prevention and cardiac function estimation algorithms using the signal was introduced, the basic control behaviors were evaluated by experiment using hybrid mock circulatory system combining computer simulator and mock circulatory system. The result indicated that the proposed algorithm can prevent suctions and detect cardiac hypofunction.

The beat synchronized control has the advantage of ventricular unloading by increasing pump speed at systolic phase. However this advantage cannot be obtained when the timing is delayed. The aims of this study are to investigate the influence of synchronization delay on ventricular load and to propose the online evaluation method for the lag. In the case that the pump flow was obtained, it was possible to detect the time lag from systole and the instant of pump speed change. From the point of view of the pump model equations, the second order differential value of motor current has the information of the relationship between change in pump flow and speed during ramp-wise change in rotational speed. The experimental results indicated that the lag may be able to be evaluated without pump flow by using the second differential value of motor current while pump speed increased.

A valve-sparing aortic root replacement procedure conserves patients' natural aortic valve and replaces diseased aortic root with vascular prostheses. There are two major procedures; Remodeling (RM) and Reimplantation (RI) methods. In this study, we newly developed a pulsatile circulatory system and evaluated three different types of aortic root models; a) natural porcine aortic root, b) with RM, c) with RI under the same pulsatile condition (each n=6). As a result, back flow rate and mean pressure gradient of three aortic root models were successfully obtained from the pulsatile circulatory system. Back flow rate in the RI model was lower than extracted porcine model, and mean pressure gradient in the RI model was higher than extracted porcine model. The pulsatile circulatory system developed in this study can be useful for the quantitative performance evaluation of the valve-sparing aortic root replacement.

We have been developing the mock circulation system for a ventricular assist device. An artificial valves are important components for generating physiological load in such a system. In this study, we designed a trilobal-shaped valve intended for low pressure loss and high leaflet mobility. It was double structure with hard inner cylinder in order to suppress excessive deformation of the leaflets. Three types of valves with different the leaflets lengths were designed (S, M, L) and experimentally made with rubber like and hard resin using 3D modeling apparatus. These valves and conventional duckbill valve were mounted in the inlet and outlet of the pump of our mock system. The pressure across the outflow valve were measured in each valve. As a results, the pressure gradient of the produced valve was small compared with the duckbill. The index dP/dt of the after load showed the maximum value in the M type.

It is demanded to research the durability of a transcatheter aortic valve to lower age limits. And there are reports about deformation caused by calcifications of patients. So we aimed to develop an accelerated durability tester using patient-specific aortic valve models.We inserted the load cell between the motor and the valve to measure the load. Also, we put patient-specific models to match deformations of the valve. We used the voice coil motor to develop an accelerated durability tester and drove it with 20 Hz. Then we could goal the requirement of differential pressure determined by ISO5840-3. Next, we compared the valve implanted to the patient-specific model and the valve implanted to the perfect circle tube. The load with the tube were bigger than the one with the patient-specific model. Finally a shape of paravalvular blood vessel turned out to be important.

We have been developing a dynamic flow regulation clip for Fontan circulation to eliminate backflow during the exhalation phase in the patients with congenital heart failure. The clip has been designed to increase hydrodynamic resistance through the bypass from the inferior vena cava to pulmonary artery during the respiration. The mechanism of the resistance change is to be controlled from outside of the graft by the contraction of shape memory alloy fibers. In this study, we developed a mock circulation system simulating backflow of Fontan circulation using a linear actuation mechanism for respiratory hydrodynamic pressure changes. Consequently, it was suggested that the control parameter and the resistance values of Fontan regulation clip could be obtained.

Hemolysis during hemodialysis was compared between conventional dialysis (double needle hemodialysis: DND) and single needle dialysis (SND). Bovine blood was perfused to a hemodialyzer for 4 hrs. Bovine blood and hemodialyzer was immersed in a water bath at 37°C, and hemolysis of "blank" was measured by absorbance of hemoglobin in plasma. To eliminate the possible influence of stirring on hemolysis data, this "blank" data was subtracted for correction. Blood flow rate was 200 mL/min in DND, but mean blood flow rate in SND was approximately 100 mL/min because of the intermittent movement of blood pump. As a result, the hemolysis extent in SND was not different from that in conventional DND. It may be because, in hemodialysis, hemolysis is mainly induced by negative pressure at pre-pump. In conclusion, no characteristic effect of SND on hemolysis was observed using bovine blood compared with conventional DND.

The abnormality of blood occurring during extracorporeal circulation is the formation of thrombus. It is known from a clinical point of view that blood viscosity rises at the time of thrombus formation, and it is extremely important for medical staff to grasp changes in blood viscosity. In this study, we investigated whether the change in blood viscosity can be detected indirectly from the extracorporeal circuit using ultrasound. The ultrasonic sensor's receiver and transmitter were made to face each other and a tube was fastened. After that, the transmitted wave was measured. As a result, the propagation speed of ultrasonic waves varied depending on the viscosity of the liquid flowing inside. It was considered possible to use it as an index of change in blood viscosity by detecting this change in propagation velocity in blood whose viscosity changes with time.

Slicing sample preparation in optical coefficient measurement makes variety of coefficients which seems to exceed individual optical differences. We proposed the use of a bulk biological tissue through an optical fiber puncturing into a bulk tissue to avoid an instability using sliced tissue preparation. The combination of light intensity measurement experiment and ray tracing calculation using the Monte Carlo method was employed. We changed not only the depth of the fiber tip in the bulk tissue but also its field of view (FOV) to increase optical information. The absorption coefficient and reduced scattering coefficient were adjusted in the calculation to be in agreement with the dependence of the attenuation coefficient on FOV obtained by the experimental result. We examined the accuracy of our particular method using an optical solution model and demonstrated optical coefficient measurement using porcine myocardium.

An accident by doze driving are regarded as a problem socially. It is thought that sleep apnea syndrome has a big influence as a cause. This disease is symptoms appear during sleep. In this study, we are developing a neckband type respiration monitoring hybrid device that grasps the sleeping state every day. Previous studies have succeeded in detecting apnea / hypopnea during sleeping from the oral and throat sounds by this device. However, in the guideline, judgment by breathing alone is said to be insufficient. This paper aims to grasp the influence of the body by apnea / hypopnea from the pulse rate in detail by adding a photoelectric plethysmography sensor to the device. We propose a Square Root Band spectrum method to estimate the pulse rate from the signal obtained by photoelectric plethysmography. As a result of comparison with conventional analysis method, usefulness was seen. Therefore we report these.

The purpose of this study is to compare the signal-to-noise ratio of photo-plethysmogram (PPG) with or without electromagnetic shielding (damping performance 40 dB). We measured PPGs at the wavelength of 1185 nm, which wavelength was reported as to sensitive to alcohol. Preliminary experiments were conducted on 12 healthy young adults. The PPG sensor was attached to the tip of the right finger in the inside or outside of electromagnetic shields room, and the measurement was performed for 60 seconds in each conditions. We also measured electrocardiogram as a reference. As a result, it was confirmed that there was no significant differences in signal-to-noise ratio between inside and outside electromagnetic shield room. Results showed that the electromagnetic field do not affect the accuracy of PPG measurement.

A novel method of T-wave alternans (TWA) verification in Holter ECG recording is proposed. Although the detection of TWA in the long-term ECG record is a promising mean for the cardiac risk assessment, the presence of artefacts suffers the reliability of the detection. Authors have proposed the use of AR percentile value (ARP) to prevent the artefact effects. The ARP is shown to be effective to avoid the errors introduced by artefact. However, the method misses the accurate AR values when the data are clean. To overcome this problem, a novel method to verify the AR values is proposed. In the new method, the valid maximum AR value is selected by evaluating the T-wave consistency in each one-minute segment from which AR value is estimated. To confirm the usefulness of the proposed method, the AR value distribution over a day is compared among subject group with different cardiac risks

We developed a non-invasive measurement method of blood absorption spectrum to realize the daily blood test for the early detection of lifestyle diseases. This method monitors the spectra of the finger transmitted Near-infrared light, and calculates the blood absorption spectrum by analyzing the pulsation signal. The blood absorption spectrum, which was calculated by this method, showed the similar form with the spectrum of in-vitro blood sample. Then, we applied this method to the blood triglyceride (TG) measurement, and used 1000 nm absorbance at the blood absorption spectrum as the blood TG indicator, because TG increases the blood turbidity (absorbance) at short wavelength. As a result, this non-invasive blood absorbance was correlated to the actual TG values. This result indicates that our method is useful for non-invasive blood TG measurement.

The aim of this study is to compare the heart rate (HR) derived from electrocardiogram (ECG) with the pulse rate (PR) derived from the green light ear photo-plethysmogram (PPG) using an earphone. The PPG sensor comprising a green LED and phototransistor was embedded into an earphone. In 10 subjects, simultaneous measurements of ECG, and green light (525 nm) PPG from the front of tragus were made at the following treadmill speeds: 0, 2, 4 km/h. During walking (2, 4 km/h), the results showed that the PR derived from the green light PPG from the ear significantly related to HR derived from ECG (r = 0.98). In addition, the limit of agreement in Bland-Altman plots between these indices were ± 3.95 (1.96 SD) bpm. In conclusion, these findings suggest that the green light ear PPG using earphone might be practical measurement for monitoring HR during walking.

This study aims to estimate BP with only PPG sensor. Previous studies have problems unstable by fluctuation of the baseline, and uncertainty of dicrotic notch in the waveform.This study proposes to extract features from the waveform with normalized by the pulse width, and the pulse intensity. We report the effectiveness of proposed method.

The aim of this study is to investigate the frequency characteristic of the noise on the head lead electrocardiogram (ECG). We measured the head lead ECG with or without electromyogram (EMG) in the inside or outside electromagnetic shield room (damping performance 40dB). The experiments were conducted on 25 healthy subjects. Three electrodes were attached to the mastoid area behind the ear. We also measured EMG activity of neck, which frequency band was overlapped with ECG. As a result, it was confirmed that the frequency band of the EMG noise and electromagnetic noise on the head lead ECG were about 10 Hz and 60 Hz. The effect of the electromagnetic on the head lead ECG appeared varied greatly among individuals. In conclusion, these findings suggest that the head lead ECG might be usable as the HR monitoring with carefully designed filter.

In this study, we report on a wearable device for measuring electrocardiogram (ECG) and blood pressure pulse wave simultaneously. The size of device is 125 mm × 85 mm × 75 mm, the mass of the main body and the battery are 130.6 g and 177.4 g, respectively. Our device consists of an ECG module for measuring ECG and triaxial force sensors for measuring blood pressure pulse wave. We could simultaneously measure the clear waveform of blood pressure pulse wave and ECG by our wearable device simultaneously. We extracted characteristic parameters from blood pressure pulse wave and ECG. It was compared each other. The correlation between the peak interval of the blood pressure pulse wave and the RR interval of the ECG was 0.91. We compared blood pressure pulse wave to ECG, and confirmed that the correlation between several parameters were high.

Appropriate characterization of state-dependent Heart Rate Variability Dynamics (HRVD) has been explored.We analyzed the difference between state-dependent HRVD and the HRVD of Slow Wave Sleep (SWS: the deepest sleep), together with subjective sleep evaluation. The results showed that the subjective sleep evaluation differentiates the relationship between the state-dependent HRVD with reference to those in SWS. A future study will be further investigation of sleep quality and dynamics of cardiovascular control system.