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Introduction: Real-time, non-invasive monitoring of thrombus formation in extracorporeal circuits has yet to be achieved. To address the challenges of conventional optical thrombus detection methods requiring large devices that limit detection capacity, we developed a micro-optical thrombus sensor. Methods: The proposed micro-optical thrombus sensor can detect the intensity of light scattered by blood at wavelengths of 660 and 855 nm. Two thrombus sensors were installed on in vitro circuit: one at the rotary blood pump and one at a flow channel. To evaluate the variation in the ratio of incident light intensity at each wavelength of the two sensors, Rfluct (for 660 nm) and Ifluct (for 855 nm) were defined. Using fresh porcine blood as a working fluid, we performed in vitro tests of haematocrit (Hct) and oxygen saturation (SaO2) variation and thrombus detection. Thrombus tests were terminated after Rfluct or Ifluct showed a larger change than the maximum range of those in the Hct and SaO2 variation test. Results: In all three thrombus detection tests, Ifluct showed a larger change than the maximum range of those in the Hct and SaO2 variation test. After the tests, thrombus formation was confirmed in the pump, and there was no thrombus in the flow channel. The results indicate that Ifluct is an effective parameter for identifying the presence of a thrombus. Conclusion: Thrombus detection in an extracorporeal circuit using the developed micro-optical sensors was successfully demonstrated in an in vitro test.

Multi-center, retrospective cohort study.To determine the epidemiology, identify predictors of early mortality, and develop predictive models for traumatic spinal cord injury (SCI).Despite improved initial care and management strategies, traumatic SCI remains a devastating event. Knowledge of the epidemiological state and predictive factors for mortality is important for developing strategies and counseling; however, they have not been adequately investigated, and predictive modeling regarding outcomes remains an underused modality for patients with traumatic SCI.Using a nationwide trauma registry-the Japan Trauma Data Bank-we identified adult (≥18 yrs) patients with SCI between 2004 and 2015. The endpoint was in-hospital mortality. Characteristics of each patient were described. Multivariate logistic regression analyses were performed to identify factors significantly associated with in-hospital mortality and develop a predictive model.In total, 236,698 patients were registered in the database. Of the 215,835 adult patients, 8069 (3.7%) had SCI. The majority had SCI at the cervical level with falls at ground level being the primary etiology. Over the study period, median age, the proportion of cervical SCI, and the etiology of falls at ground level increased. The mortality rate was 5.6%. The following eight factors, age, sex, Glasgow Coma Scale on arrival (GCS), hypotension on arrival, bradycardia on arrival, severe head injury, Injury Severity Score (ISS), and neurological severity of SCI, were independently associated with mortality. A predictive model consisting of these variables predicted mortality with area under the receiver operating characteristic curve of 0.88 (95% confidence interval [CI], 0.86-0.90).Over the 12-year period, patient characteristics, etiology, and post-SCI outcomes significantly changed. We identified eight prognostic factors of early mortality. A predictive model including these factors showed excellent performance and may improve treatment strategies, healthcare resource allocation, and counseling.3.

Multi-vessel cervical arterial injury after blunt trauma is rare, and its pathophysiology is unclear. Although blunt cerebrovascular injury is a common cause of cerebral ischemia, its management is still controversial. We describe a 23-year-old man in previously good health who developed three-vessel cervical arterial dissections due to blunt trauma. He was admitted to our emergency and critical care center after a motor vehicle crash. Computed tomography showed a thin, acute subdural hematoma in the right hemisphere and fractures of the odontoid process (Anderson type III), pelvis, and extremities. He was treated conservatively, and about 1 month later, he developed bleariness. Computed tomography angiography showed bilateral internal carotid and left vertebral artery dissection. Aspirin therapy was started immediately, and then clopidogrel was added to the regimen. Two weeks later, magnetic resonance angiography (MRA) showed improved blood flow of the vessels. Only aspirin therapy was continued. About 3 months after discharge, MRA demonstrated further improvement of the blood flow of both internal carotid arteries, but the dissection flap on the right side remained. Therefore, we extended the duration of antiplatelet therapy. On the basis of our experience with this case, we think that antithrombotic therapy is crucial for the management of multi-vessel cervical arterial injury, and agents should be used properly according to the injury grade and phase; however, further study is needed to confirm this recommendation.

The effect of the flow path geometry of the impeller on the lift-off and tilt of the rotational axis of the impeller against the hydrodynamic force was investigated in a centrifugal blood pump with an impeller supported by a single-contact pivot bearing. Four types of impeller were compared: the FR model with the flow path having both front and rear cutouts on the tip, the F model with the flow path having only a front cutout, the R model with only a rear cutout, and the N model with a straight flow path. First, the axial thrust and the movement about the pivot point, which was loaded on the surface of the impeller, were calculated using computational fluid dynamics (CFD) analysis. Next, the lift-off point and the tilt of the rotational axis of the impeller were measured experimentally. The CFD analysis showed that the axial thrust increased gently in the FR and R models as the flow rate increased, whereas it increased drastically in the F and N models. This difference in axial thrust was likely from the higher pressure caused by the smaller circumferential velocity in the gap between the top surface of the impeller and the casing in the FR and R models than in the F and N models, which was caused by the rear cutout. These results corresponded with the experimental results showing that the impellers lifted off in the F and N models as the flow rate increased, whereas it did not in the FR and R models. Conversely, the movement about the pivot point increased in the direction opposite the side with the pump outlet as the flow rate increased. However, the tilt of the rotational axis of the impeller, which oriented away from the pump outlet, was less than 0.8° in any model under any conditions, and was considered to negligibly affect the rotational attitude of the impeller. These results confirm that a rear cutout prevents lift-off of the impeller caused by a decrease in the axial thrust.

A production technique with the capacity to significantly improve the mechanical properties of powder metallurgy (PM) parts is high-velocity compaction (HVC). To extend the usage of the HVC method, detailed knowledge of the HVC process is important. To facilitate the development of production processes, numerical simulations can be utilised. In the development of high-precision simulation models, constitutive data of HVC specimens at high strain rates are required. In this study, the dynamic compressive properties of cylindrical specimens made by HVC were measured using a split Hopkinson pressure bar (Kolsky bar) assembly. For this technique, a specimen is placed between two elastic bars. The impact loading is achieved by a projectile accelerating inside an air gun, which impacts the end of the input bar and generates elastic-wave propagation. The powder material used for the experiments is a press-ready iron-based premix. Among specimens made by HVC and conventional compaction (CC), the effects of the specimen density and the strain rate on the compressive properties, such as failure stress, Young's modulus and failure behaviour, are investigated. During dynamic compression, the failure behaviour of the specimens was also recorded using a high-speed video camera. The difference in the mechanical behaviour between HVC-pressed specimens and conventionally pressed specimens are also investigated. The stress–strain curves of HVC-pressed specimens are identical to those of conventionally pressed specimens, but the failure behaviour differs are concluded. A well-established numerical method for forming simulations also conducted for powder compaction is the finite element method (FEM). The impact loading of the powder is modelled and simulated using nonlinear three-dimensional FEM. To model the impact process, a constitutive relation for the powder behaviour is proposed, taking into account the strain rate and density variations. To capture the global response caused by cracking during impact, a damage model is implemented. The numerical results in terms of the stress and strain history in the specimen during impact are compared with the experimental measurements. In conclusion, the proposed material model captures the increase in the yield stress due to the higher strain rates and the decrease in stress due to cracking.

This review was created based on a translation of the Japanese review written in the Japanese Journal of Artificial Organs in 2015 (Vol.44, No. 3, pp.130–135), with some modifications regarding several references published in 2015 or later.

Background Cerebral regional oxygen saturation (rSO2) can be measured immediately and noninvasively just after arrival at the hospital and may be useful for evaluating the futility of resuscitation for a patient with out-of-hospital cardiopulmonary arrest (OHCA). We examined the best practices involving cerebral rSO2 as an indicator of the futility of resuscitation. Methods This study was a single-center, prospective, observational analysis of a cohort of consecutive adult OHCA patients who were transported to the University of Tokyo Hospital from October 1, 2012, to September 30, 2013, and whose cerebral rSO2 values were measured. Results During the study period, 69 adult OHCA patients were enrolled. Of the 54 patients with initial lower cerebral rSO2 values of 26% or less, 47 patients failed to achieve return of spontaneous circulation (ROSC) in the receiver operating characteristic curve analysis (optimal cutoff, 26%; sensitivity, 88.7%; specificity, 56.3%; positive predictive value, 87.0%; negative predictive value, 60.0%; area under the curve [AUC], 0.714; P = .0033). The AUC for the initial lower cerebral rSO2 value was greater than that for blood pH (AUC, 0.620; P = .1687) or lactate values (AUC, 0.627; P = .1081) measured upon arrival at the hospital as well as that for initial higher (AUC, 0.650; P = .1788) or average (AUC, 0.677; P = .0235) cerebral rSO2 values. The adjusted odds ratio of the initial lower cerebral rSO2 values of 26% or less for ROSC was 0.11 (95% confidence interval, 0.01-0.63; P = .0129). Conclusions Initial lower cerebral rSO2 just after arrival at the hospital, as a static indicator, is associated with non-ROSC. However, an initially lower cerebral rSO2 alone does not yield a diagnosis performance sufficient for evaluating the futility of resuscitation.

The local interfacial strength is a key factor in designing and fabricating advanced three-dimensional large-scale integration interconnect structures. In this paper, both local fracture tests and three-dimensional elastic–plastic crack propagation analysis for a 10 μm × 10 μm specimen were performed, and the local interfacial adhesion between a Cu interconnect and a SiN cap layer were evaluated. The three-dimensional elastic–plastic crack propagation simulation was developed to evaluate the interfacial adhesion that eliminated the effect of progressive plastic dissipation energy during crack propagation. The results show that the average interfacial adhesion for Cu/SiN is 4.46 ± 0.17 J/m2. The crack propagation behavior and fracture pattern depend on the interfacial adhesion, and these differences are due to the plastic yielding of the side edge of the specimen. The critical interfacial adhesion for the onset of shear fracture is 4.92 J/m2, which is the upper bound of the interfacial adhesion evaluation for the 10 μm × 10 μm specimen.

An impeller the same geometry as the impeller of a commercial monopivot cardiopulmonary bypass pump was manufactured using 3D printing. The 3D-printed impeller was integrated into the pump casing of the commercially available pump to form a 3D-printed pump model. The surface roughness of the impeller, the hydraulic performance, the axial displacement of the rotating impeller, and the hemolytic properties of the 3D-printed model were measured and compared with those of the commercially available model. Although the surface roughness of the 3D-printed model was significantly larger than that of the commercially available model, the hydraulic performance of the two models almost coincided. The hemolysis level of the 3D-printed model roughly coincided with that of the commercially available model under low-pressure head conditions, but increased greatly under high-pressure head conditions, as a result of the narrow gap between the rotating impeller and the pump casing. The gap became narrow under high-pressure head conditions, because the axial thrust applied to the impeller increased with increasing impeller rotational speed. Moreover, the axial displacement of the rotating impeller was twice that of the commercially available model, confirming that the elastic deformation of the 3D-printed impeller was larger than that of the commercially available impeller. These results suggest that trial models manufactured by 3D printing can reproduce the hydraulic performance of the commercial product. However, both the surface roughness and the deformation of the trial models must be considered to precisely evaluate the hemolytic properties of the model.

Heart failure is a condition in which the heart cannot pump sufficiently because its contractile force has deteriorated. Patients with heart failure can sometimes undergo heart transplantation, but in number these patients comprise less than 10 % of patients actually requiring heart transplantation. Thus, mechanical circulatory assistance plays an important role in substituting for heart transplantation wherein the pump function of the heart is assisted by an artificial blood pump called a ventricular assist device. On the other hand, cardiopulmonary bypass is a form of extracorporeal circulation that temporarily takes over the function of the heart and lungs to maintain the circulation of blood and the oxygen content of the body during surgery for heart failure and aneurysms of the thoracic aorta. This chapter describes the vascular engineering of circulatory assist devices. Particular emphasis is placed on recent progress in ventricular assist devices and cardiopulmonary bypass pumps. These important medical devices assist with human circulation at either the chronic or the acute phase. Because these devices are derived from an industrial pump, a great many studies have been conducted not only from the medical perspective but also from industrial and engineering perspectives. In this chapter, current ventricular assist devices and cardiopulmonary bypass pumps, their specifications, their classifications, and methods for their design and evaluating are presented, including flow analysis inside the pump to optimize the geometry.

長期埋め込み人工心臓の前に4週間以内のつなぎに使用できる、補助循環遠心ポンプを製品化することに成功した。独自の軸受として採用した1点支持型のモノピボット軸受は、世界に先駆けて提唱した機構である。医工連携として大学医学部と意見交換をする中から、動物実験前の設計検証のために提唱した流れの可視化実験で血液適合性を定量的に評価・改良し、独自に開発した模擬血栓試験で抗血栓性を評価・改良し、最小限の動物実験数で生体適合性の評価を実施できた。技術シーズを提供して一つの製品を世に出したばかりでなく、その評価技術を他機関の製品化にも提供し、さらに医療機器ガイドライン事業にも協力して広く産業界に貢献している。

The first global interoperability experiment of GMPLS controlled Ethernet with VLAN tag swapping between two different implementations is successfully demonstrated. High definition video streaming is realized through a newly established Layer 2 Label Switched Path (L2-LSP). The results of this experiment can be applied to designing reliable Layer 2 networks.

The hemocompatibility of a newly developed monopivot circulatory assist pump was evaluated by the computational fluid dynamic (CFD) analyses with the particle tracking velocimetry measurement. Results were compared with those of the hemolysis test and in vitro antithrombogenic test to prevent hemolysis and thrombus formation inside the pump. The results of the CFD analysis and the particle tracking velocimetry had a good agreement with each other. The flow distributions by the CFD analysis indicated that the radial jet out of the impeller was adequately weak so that the wall shear stress was lower than 300 Pa on the volute casing wall. It corresponded with the hemolysis tests results, indicating that the hemolysis level was lower than that of the commercially available pump. However, the flow distributions also indicated that the pivot that was easy to stagnate was washed out, not only by the secondary flow through the back gap of the impeller, but also by the vortices generated by the secondary vanes. It corresponded with the in vitro antithrombogenic test results, indicating that thrombus formation could be removed only by redesigning the geometry of the secondary vanes.

A multi-domain GMPLS layer-2 switch capable network with VLAN tag swapping is demonstrated for the first time. In this demonstration, we verify three new features, establishing path with designating VLAN IDs, swapping VLAN ID on prototype switch, and management of VLAN IDs per domain. Using those three features, carrier-class Ethernet backbone networks which supports path route designation in multi-domain network can be established.

The setting parameters of the image enhancement times, the threshold level of the image binarization, and the size of the detecting area were investigated to confirm the accuracy of the four-time-step PTV. The particle density formed the peak distribution as a function of the threshold level of image binarization, and the peak decreased and flattened with the increase of the image enhancement times. Therefore, the wide valid selection of the threshold level of the image binarization and the preservation of high particle density were realized when the image sharpness times was set to be the upper limit of the adequate particle density for four-time-step PTV. Furthermore, as the tendency of the occurring ratio between the correct and error velocity suddenly changed with the variation of the size of detecting area of four-time-step PTV, the size of detecting area was set around that boarder to acquire the velocity field effectively.

Turbidity variation is one of the major limitations in Raman spectroscopy for quantifying blood components, such as glucose, non-invasively. To overcome this limitation, we have developed a Raman scattering simulation using a photon-cell interactive Monte Carlo (pciMC) model that tracks photon migration in both the extra- and intracellular spaces without relying on the macroscopic scattering phase function and anisotropy factor. The interaction of photons at the plasma-cell boundary of randomly oriented three-dimensionally biconcave red blood cells (RBCs) is modeled using geometric optics. The validity of the developed pciMCRaman was investigated by comparing simulation and experimental results of Raman spectroscopy of glucose level in a bovine blood sample. The scattering of the excitation laser at a wavelength of 785 nm was simulated considering the changes in the refractive index of the extracellular solution. Based on the excitation laser photon distribution within the blood, the Raman photon derived from the hemoglobin and glucose molecule at the Raman shift of 1140 cm(-1) = 862 nm was generated, and the photons reaching the detection area were counted. The simulation and experimental results showed good correlation. It is speculated that pciMCRaman can provide information about the ability and limitations of the measurement of blood glucose level.

This paper describes the critical importance of interfacial strength between copper lines and cap layer for catastrophic failure due to chip-package interaction (CPI). Recently, copper interconnects and insulating layers are stacked alternately in semiconductor devices. Especially, copper/low-k structures are widely selected. However, the low-k materials have weak mechanical properties, which sometimes induces reliability issues, especially, chip package interactions. In our previous works, the interfacial strength of Cu/Cap has been successfully measured on the sub-micron scale. In this paper, based on the measured results, we try to simulate the initiation and propagation of failure in interconnect structures and discuss the scenario for catastrophic failure under CPI.

Iron ore pellets are sintered, centimetre-sized spheres of ore with high iron content. Together with carbonized coal, iron ore pellets are used in the production of steel. In the transportation from the pelletizing plants to the customers, the iron ore pellets are exposed to different loading situations, resulting in degradation of strength and in some cases fragmentation. For future reliable numerical simulations of the handling and transportation of iron ore pellets, knowledge about their mechanical properties is needed. This paper describes the experimental work to investigate the dynamic mechanical properties of blast furnace iron ore pellets. To study the dynamic fracture of iron ore pellets a number of split Hopkinson pressure bar tests are carried out and analysed.

Impact tensile strength of iron green bodies with densities of 7.2 and 7.4 g/cm3 was examined by Brazilian test using the split-Hopkinson pressure bar (Kolsky bar) method. The powder material used for the experiments was a press-ready premix containing Distaloy AE, graphite, and lubricant. During dynamic compression, the failure behavior of specimens was observed using a high-speed video camera. The failure stress and failure behavior of dynamic compressive tests were compared with those of static compressive tests.

Flow mechanisms within a monopivot centrifugal pump were clarified in order to prevent stagnation around the pivot bearing, which may cause thrombogenesis. We focused on the geometric effects of the pump, which included the effects of the washout hole diameter, the pivot friction area and the back gap width of the impeller relative to the washout around the pivot bearing. Flow patterns were carefully examined around the pivot bearing, including the region inside the washout hole and the back gap of the impeller, by computational fluid dynamic analysis. Based on the results from the computational fluid dynamic analyses, we found that a balance relationship between the washout hole diameter and the back gap width of the impeller affected the secondary flow toward the pivot bearing that eliminated the stagnation around the pivot bearing. In addition, while increasing in the pivot friction area eliminated stagnation around the pivot bearing, it also increased hemolysis within the pump.

One of the most important problems for stroke patients is nutritional management. Malnutrition results in poor prognosis with many complications. Many patients with consciousness disturbance and dysphagia undergo enteral nutrition. PEG facilitates a smooth rehabilitation and increases QOL.

The functional roles of endothelin ET A and ET B receptors in the development of monocrotaline (MCT)-induced pulmonary hypertension were investigated using MCT-treated rats in the absence or presence of a daily administration of A-192621, a selective ET B receptor antagonist, ABT-627, a selective ET A receptor antagonist, or a combination of both drugs. Four weeks after the injection of saline or MCT (60 mg/kg, s.c.), cardiac hypertrophy, right ventricular systolic pressure and morphologic changes of pulmonary arteries were evaluated. Compared with the control animals, MCT produced marked pulmonary hypertension associated with increases in right ventricular pressure and hypertrophy, and pulmonary arterial medial thickening. These MCT-induced alterations were markedly suppressed by daily treatment with ABT-627 for 4 weeks (10 mg/kg/d, twice daily), whereas treatment with A-192621 significantly aggravated the above MCT-induced pathologic changes. The blockade of both receptor subtypes by a combination of A-192621 and ABT-627 also significantly improved the MCT-induced pathologic changes, to the same extent as with ABT-627 administration. Thus, an exaggerated response to MCT during ET B receptor blockade also seems to be mediated by ET A receptor activation, thereby suggesting that ET A receptor-mediated action is exclusively contributive to the pathogenesis of MCT-induced pulmonary hypertension, although we cannot rule out a protective role of ET B receptor-mediated action.

Carotid endarterectomy (CEA) is becoming a standard treatment of the internal carotid artery (ICA) stenosis in Japan. But frequency of high-risk patients for CEA and management of high-risk patients to reduce operative complications have not been well established. The purpose of this study is to determine frequency of high-risk patients for CEA and to discuss management of high-risk patients. Between 1984 and 2002, 230 CEAs under general anesthesia were performed in our institute. High-risk patients for CEA were defined according to the following criteria: (1) patients older than 71 years, (2) patients with stenosis positioned higher than the second cervical vertebra, (3) patients vulnerable to ischemia during cross-clamping of the ICA, (4) patients at risk of hyperperfusion, and (5) patients with ischemic heart disease. Fifty-one high-aged patients (22%) were operated without any complications due to high age. Twenty-one patients (14%) had high-positioned stenosis. There were no complications due to high position. Cerebral ischemia after cross-clamping of the ICA occurred in 24% of the patients according to the intraoperative monitorings of ICA stump pressure, somatosensory evoked potential, and oxygenation of the cerebral cortex. Hyperperfusion, diagnosed by the ICA flow, velocity of the middle cerebral artery by TCD, and postoperative measurement of cerebral blood flow, occurred in about 5% of the patients. To avoid ischemic complications, we have routinely used a T-shaped internal shunt and maintained the systemic blood pressure during CEA. Management of hyperperfusion comprised strict control of the systemic blood pressure and barbiturate therapy. Ischemic heart disease was associated in 24% of the patients. Coronary artery revascularization such as coronary artery bypass grafting (CABG), coronary angioplasty, or stenting were performed in 4 patients before CEA. We have not done combined CABG and CEA. There was no myocardiac infarction in the perioperative time. In this series, perioperative mortality and morbidity were 0% and 1.7%, respectively. Although there were fewer perioperative complications, proper management for high-risk patients is essential.

The hemodynamics in the vertebrobasilar artery (VBA) system were investigated in patients with vertebrobasilar insufficiency (VBI). Vertebral artery (VA) stump pressure and blood flows in the VA and common carotid artery (CCA) were intraoperatively measured in 45 patients who underwent surgical correction of the first segment of the VA (V1) for angiographic tortuosity, kinking, and/or stenosis manifesting as symptomatic VBI. The effects of changes in the systemic arterial blood pressure (SABP) induced by trimethaphan, phenylephrine, and cervical epidural anesthesia were also investigated. The VA stump pressure was 79.3 +/- 13.6 (mean +/- SD) mmHg and the ratio of the VA stump pressure to the SABP was 0.87 +/- 0.08. The baseline values were SABP 90.5 +/- 10.1 mmHg, VA blood flow 53.4 +/- 33.0 ml/min, and CCA blood flow 204.3 +/- 50.3 ml/min. During changes in the SABP, autoregulation of the blood flow in the VA appeared tighter than in the CCA. During cervical epidural anesthesia, blood flows in both the VA and CCA were significantly reduced in response to SABP reduction. This study demonstrated that the VBA system maintains excellent autoregulation with good collateral flows and cervical sympathetic nerve function. However, this autoregulatory capacity may be overwhelmed by unexpected occlusion of the VA due to postural changes associated with tortuosity, kinking, and/or stenosis of the V1 segment.

Object. We intended to evaluate the usefulness of intraoperative ultrasound imaging for assistance during neurosurgical operations.Methods. Thirty-four consecutive patients (19 with brain tumor, 9 with subarachnoid hemorrhage, 4 with intracerebral hemorrhage, 2 with hydrocephalus) underwent neurosurgical operations with the assistance of intraoperative ultrasound imaging. A total of 46 operations (removal of tumor in 18 patients, biopsy in one, removal of intracerebral hematoma in 4, ventricular drainage in 16, and ventriculo-peritoneal (VP) shunt in 7) were performed. Two different types of ultrasound machines (General Electric, RT4600 and LOGIQ 500) were used in this series, and their probes were the sector (3.3 and 3.5 MHz) linear (6.7 MHz), and pencil (5 MHz) types.Results. Ventricular drainage and placement of the ventricular tube were easily accomplished under real-time visualization of the ventricles by B-mode imaging. Tumors were clearly demonstrated over the dura mater and then the shortest approach to the tumor could be determined. Arteries and veins around the tumors were detected by color Doppler imaging. Intracerebral hematoma was easily detected and the appropriate site for evacuation could be determined.Conclusion. Intraoperative ultrasound imaging can contribute to the safety and precision of ventricular drainage and VP shunt, and removal of brain tumor and intracerebral hemorrhage.

The authors reported carotid surgeries of carotid endarterectomy (CEA) and reconstruction of occlusive lesion due to blunt injury. Two hundred four CEAs were performed with a routine use of T-shaped shunt system and under intraoperative multimodal monitoring system. There was no perioperative death and four patients (2%) showed permanent neurological deficits. Six patients with occlusive carotid lesions after blunt injuries were treated by replacement of injured common carotid artery (CCA) with Dacron prosthesis. Postoperative carotid angiography demonstrated good flow through the prosthesis in all patients.

Treatment of cervical carotid stenosis with the contralateral internal carotid artery (ICA) occlusion or severe stenosis has not been established because of its specific cerebral circulation. We sought to clarify the clinical features and best surgical treatment of cervical severe carotid stenosis with contralateral ICA occlusion or severe stenosis.We studied 8 patients with bilateral severe ICA stenosis (≥70%) and 5 patients with ICA severe stenosis and contralateral ICA occlusion. To evaluate cerebral circulation, regional cerebral blood flow (rCBF) of the middle cerebral arterial territory and stump pressure of the ICA were measured. rCBF was measured before and after CEA. Rates of association of systemic diseases were analyzed. There was no perioperative complication or new stroke in the follow-up time (2-138 months) in this series. In 3 of the 8 patients, rCBFs were bilaterally decreased below 40 ml/100 g/min. rCBF of severe ICA stenosis with contralateral ICA occlusion or severe stenosis was lower than that of unilateral ICA stenosis. In 6 of 9 patients who underwent CEA, rCBF increased over 15% after operation. Stump pressures of the ICA in the patients with severe ICA stenosis associated with contralateral ICA occlusion or severe stenosis were significantly (p

International cooperative studies have almost established carotid endarterectomy (CEA) as the surgical treatment for carotid artery stenosis to prevent cerebral infarction. However, the procedure's success depends on ability of a surgeon's technique and perioperative control with complication under 3% for aymptomatic stenosis. There is little experience with CEA in Japan, so reports of long-term follow-up studies are rare. We have performed CEA with a stable team for the past 17 years, and review surgical outcomes and follow-up results.The mean age of 203 CEAs was 64. There were 175 men. We have routinely used a shunt system and intraoperative monitoring under general anesthesia. These patients were followed up for 6.5 years on average, and a change of ADL was evaluated with Glasgow Outcome Scale.Four patients (2.0%) showed neurological deficits such as hemipapresis. The causes were cerebral embolism, wound hemorrhage, cerebral ischaemia by carotid artery hemostasis, and hyperperfusion syndrome. However, all of them were seen in the initial period of more than 10 years before. Mortality was 0%. One hundred and sixty patients were followed up for more than a year. Three patients had re-stenosis and occlusion of the operated internal carotid artery, and 2 of them were operated on again while asymptomatic. Four patients (2.5%) had ischemic attack in the operated side, but all of the lesions were at intracranial sites. Aggravation of ADL was recognized in 28 patients with no carotid lesions. There were 19 deaths, 10 of which were caused by cancers. Twenty-seven patients had ischemic heart diseases, 6 of whom died.CEA is effective for prevention of cerebral infarction, when practiced surgeons perform with intraoperative monitoring. However, general examination and treatment with cardiologists are necessary, because patients often have cardiovascular diseases.

Background The aim of this study was to assess morphological changes in the endarterectomized carotid region using B-mode ultrasonography (USG). METHODS USG examinations were performed on 54 Japanese patients who underwent carotid endarterectomy (CEA). The endarterectomized regions were periodically investigated and the intima-media thickness (IMT) was measured. RESULTS Postoperative USGs revealed an evident step formation (type I: 20.4%), a gentle slope (type II: 42.6%), or complete smoothness (type III: 37.0%) at the junction of the endarterectomized carotid region and the common carotid artery (CCA). The IMT of the CCA progressively increased from type I to type III. Patients were followed up for an average of 2.7 years. The new intima-media complex (IMC) was confirmed in all cases after 9 months; it was visualized as an isoechoic layer (7%) or a mixture of iso- and hypoechoic layers (93%). Changes in the IMT during the follow-up period were classified into three groups: no change (group I: 23.1%), decrease (group II: 15.4%), and increase (group III: 61.5%). CONCLUSIONS USG is useful to clarify the complicated healing processes of the endarterectomized carotid artery.

In this paper, an acoustic lens is designed and built in order to determine wave velocities from measured critical angles of waves, using the complex V(z) curve method. The properties of the new lens are evaluated by the transfer function of the lens and the time-domain response of the transducer. The performance of the new lens is examined using specimens of fused quartz and glass. These results are compared with those of a lens using the conventional V(z) method. It is shown that the critical angles of the waves can be determined clearly and simultaneously using the new lens.

With a 250% scaled-up pump model, high speed video camera, and argon ion laser light sheet, flow patterns related to hemolysis were visualized and analyzed with 4 frame particle tracking software. Different flow patterns and shear distributions were clarified by flow visualization for pumps modified to have different hemolysis levels. A combination of in vitro hemolysis tests, flow visualization, and CFD analysis suggested a close relationship between hemolysis and high shear caused by small impeller/casing gaps. Because arbitrary cross sections can be illuminated by laser light sheet, flow visualization is a useful tool in finding locations related to hemolysis in the design process of rotary blood pumps.

To establish quantitative, efficient design theories for centrifugal blood pumps, computational fluid dynamics (CFD) analyses were compared to the results of flow visualization tests and hemolysis tests, mainly on the Nikkiso centrifugal blood pump. The results turned out to coincide in the velocity vector plots. CFD analysis revealed that the smaller the gap is, the greater the shear stress becomes. This tendency becomes even greater with a radial gap change. Hemolysis study also indicated that the smaller the gap is, the greater the hemolysis. CFD analysis in comparison with hemolysis tests could be a useful index for developing blood pumps in the future.

Background and Purpose —The efficacy of superficial temporal artery–middle cerebral artery (STA-MCA) anastomosis in adult moyamoya disease was evaluated by clinicopathophysiological studies. Methods —Fifteen patients with cerebral ischemic attacks (ischemia group) and 15 patients with intracranial hemorrhages (hemorrhage group) were investigated. Clinicoangiographic features and regional cerebral blood flow (rCBF) of the MCA territory were preoperatively and postoperatively investigated, and cortical arterial pressure (CAP) and anastomotic blood flow (AF) were intraoperatively measured. Results —In the ischemia group, the preoperative rCBF of 38.4 mL/100 g per minute was significantly increased to 42.1 mL/100 g per minute with a diminution of angiographic moyamoya vessels in 67% of patients after surgery. The mean CAP and AF were 25.6 mm Hg and 34.7 mL/min, respectively. Proximal and distal cerebral vascular resistance (PCVR=[Mean Systemic Arterial Blood Pressure−Mean CAP]/rCBF and DCVR=[Mean CAP/rCBF]) were 1.78 and 0.68, respectively. One patient died perioperatively as a result of intracerebral hemorrhage. During follow-up (mean, 67 months), 12 of 14 patients recovered without neurological deficits, 1 was moderately disabled because of the initial insult, and another patient experienced an intracerebral hemorrhage but recovered fully. In the hemorrhage group, the preoperative rCBF of 38.0 mL/100 g per minute was significantly increased to 42.7 mL/100 g per minute with a diminution of moyamoya vessels in 60% after surgery. The mean CAP and AF were 29.1 mm Hg and 24.1 mL/min, respectively. PCVR and DCVR were 1.72 and 0.77, respectively. One patient became hemiparetic because of perioperative intracerebral hemorrhage. During follow-up (mean, 94 months), 3 patients had fatal intracranial hemorrhages, 10 had good recoveries, and 2 had moderate disabilities. Conclusions —This study revealed a high PCVR and a very low DCVR in both the ischemia and hemorrhage groups of patients. STA-MCA anastomosis partially normalized cerebral circulation and decreased moyamoya vessels but did not completely prevent rebleeding.

TCD findings used for evaluating vasospasm (VSP) due to ruptured aneurysm are controversial. To clarify these TCD findings, intra-arterial DSA (IA-DSA) was applied to study morphological changes and to measure cerebral circulation time (CCT) . Forty-six patients with ruptured aneurysms treated by neck clipping at the acute stage were investigated. Clinical grade and CT findings were estimated using the Hunt and Hess classification and Fisher's classification, respectively. Mean flow velocity (MFV) in the M1 segment was measured by TCD. IA-DSA was performed on the day 7-13 day. Angiographic VSP was categorized by Fisher's classification. CCT was defined by the time difference between the two peak optical density curves recorded by IA-DSA at the carotid artery (C3-4) and the ascending vein. Mean CCT was 3.7 sec in patients without VSP and 4.3 sec in those with slight to moderate VSP, which were significantly different from mean CCT, 6.2 sec, in patients with severe VSP. MFV in patients with no, slight to moderate, and severe VSP was 82, 104 and 124 cm/sec, respectively, none of the differences being significant. Additionally, patients with diffuse VSP extending from the M2 to peripheral sites showed increased CCT values and an unchanged MFV value. These findings suggest that use of the MFV at the M1 segement for estimating the severity of diffuse peripheral VSP is problematic.

Activation studies of cerebral circulation are important for evaluation of cerebrovascular reactivity (CVR) . In this study, CVR was investigated in 52 healthy subjects, 25 patients with chronic severe hypertension and 16 patients with hyperlipidemia. All the patients had normal findings of neurological studies, brain CT and neck vessel echo-Doppler. The CVR was assessed by TCD recording of blood flow velocity in the middle cerebral artery (MCAFV) under resting conditions and at 5, 10, 15 and 20 min after i.v. injection of 1g Acz. Additionally, we performed an Acz-activated 133Xe-CT study in 8 healthy patients (16 hemispheres) who had mild carotid stenosis on MR-angiography. The regional cerebral blood flow (rCBF) in the MCA territory was measured and the CVR was also analyzed. MCAFV and CVR determined by TCD study showed a non-significant tendency to be reduced in the group aged over 60 yr. The MCAFV under resting conditions was nearly the same in the normal controls and in the patients with hypertension, but the CVR was decreased in patients even without stroke. The normal value of CVR seemed to be 40-50% in this study. When planning surgical treatment for asymptomatic patients (e.g.; those with occlusive cerebrovascular disease and unruptured cerebral aneurysm) with decreased CVR, they should be treated carefully using prophylaxis for ischemic complications.

剖検や経食道心エコー図検査 (TEE) で大動脈における動脈硬化病変と虚血性脳血管障害との関連性が指摘されて以来, TEEが大動脈における動脈硬化病変の評価に利用されている.しかし, TEEは侵襲的検査法であり, 全ての患者で探触子が挿入できるわけではない.さらに, 上行大動脈の遠位側は気管の走行によりTEEによる評価が困難である.そこで, 筆者らは右鎖骨上窩からBモード法で大動脈における動脈硬化の評価を試み, その所見をTEEと比較した.右鎖骨上窩からのBモード検査には7.5MHzの周波数を有するlinear型の探触子を, TEEには5-7MHzの可変周波数を有するmultiplane探触子を用いた.お互いの検査所見を知らない異なる検者が20症例で二つの検査を行い, 上行大動脈と大動脈弓部をそれぞれ近位部と遠位部に分けて, 各部位における単純動脈硬化病変 (4mm未満) と複合動脈硬化病変 (4mmを越える) の有無を調べた.近位上行大動脈ではTEEで8個の単純動脈硬化病変を検出したが, 右鎖骨上窩からのBモード検査ではいずれも検出できなかった.遠位上行大動脈では1つの複合動脈硬化病変が両検査でみられ, 右鎖骨上窩からのBモード検査は単純と複合動脈硬化病変をさらに1ずつ検出した.近位大動脈弓部では両検査で6つの複合動脈硬化病変と5つの単純動脈硬化病変がみられ, さらにTEEはもう1つの複合動脈硬化病変を検出した.遠位大動脈弓部ではTEEが2ずつの単純と複合動脈硬化病変を見いだし, 右鎖骨上窩からのBモード検査が3つの複合動脈硬化病変を見いだした.以上の結果から, TEEは近位上行大動脈の評価に, 右鎖骨上窩からのBモード検査は遠位上行大動脈の評価に優れており, 右鎖骨上窩からのBモード検査は上行大動脈と大動脈弓部の評価におけるTEEの所見を補う検査法といえるであろうと結論している.

The purpose of this study is to examine the relationship between the flow condition and hemolysis level by integrating hemolysis test, flow visualization and computational fluid dynamics(CFD)to establish design criteria for the good hemocompatible centrifugal pump. Axial and radial gaps between the impeller tip and casing wall of Nikkiso centrifugal blood pump were modified independently and flow condition and hemolytic property of these pumps were examined. Examined gaps were 1.5, 1.0, and 0.5 mm for axial gap and 3.0, 2.0, 1.0, and 0.5 mm for radial gap, respectively. The pumps with the axial gap of 0.5 mm and the radial gap of 0.5 mm showed higher hemolysis level than the other pumps showed. Maximum shear stress in the pump, estimated by CFD, were increased by decreasing the radial gap from 3.0 to 0.5 mm. Regional flow pattern change at the tongue region by decreasing radial gap was observed by flow visualization. Gaps between impeller tip and casing wall are dominant factors to determine hemolytic property of the centrifugal pump. Relationship between regional flow pattern and blood trauma should be investigated in the future.

邦人の頸部頸動脈狭窄病変に対するシャントシステムをルーチンに用いた血栓内膜剥離術(CEA : carotid endarterectomy)155例,170側の臨床結果を報告する.TIA,RIND,MCS及び無症候性病変症例が各々51,23,45,51例であった.病変の狭窄度と広がりは,各々平均74%,1.2cmであった.術中SEP検査などから約20%に頸動脈遮断による重篤な脳虚血が推察された.手術成績は,mortalityゼロ,morbidity4例であった.長期追跡調査では無症候性の再狭窄,閉塞を3例に認めた.脳虚血発作は,4例に認められたが,CEA部に起因する再発作はみられなかった.死亡例は12例で,原因疾患は7例が癌,2例が心疾患であった.以上より著者らのCEAは,邦人の頸部頸動脈狭窄病変に対する安全かつ有効な手術法であることが示唆された.