高橋 東;岩崎 清隆;松橋 祐輝;平田 麻由紀;山本 祥宜;鈴木 砂良;梅津 光生
バイオエンジニアリング講演会講演論文集2015(27)p.137 - 1382015年01月-2015年01月
松橋 祐輝;岩崎 清隆;高橋 東;平田 麻由紀;山本 祥宜;鈴木 砂良;梅津 光生
バイオエンジニアリング講演会講演論文集2015(27)p.139 - 1402015年01月-2015年01月
平田 麻由紀;岩崎 清隆;松橋 祐輝;高橋 東;永井 美玲;梅津 光生
バイオエンジニアリング講演会講演論文集2015(27)p.141 - 1422015年01月-2015年01月
松橋 祐輝;高橋 東;平田 麻由紀;山本 祥宜;鮫島 啓;青山 祐介;梅津 光生;岩崎 清隆
バイオエンジニアリング講演会講演論文集2016(28)p."1A22 - 1"-"1A22-3"2016年01月-2016年01月
概要：Thrombus formations in medical devices are unsolved issue. If a reliable in vitro real-time visualization method is established, it will contribute the development and improvement of anti-thrombogenic medical devices. The aim of this study is to develop a real-time thrombus visualization system with an optical coherence tomography (OCT) and to reveal an influence of local blood flow on thrombus growth. We focus on the inlet and outlet part of connecters. The circuit was consisted of a roller pump, a reservoir, and resistance. The circuit volume was 50 ml. The blood flow rate and pressure were regulated to 100 ml/min and 70 mmHg. To visualize cross-sectional imaging of thrombus, we used a SS-OCT system with center wave-length of 1330 nm. OCT images were obtained every 10 minutes for 50 minutes. Test were performed 6 times. A fresh porcine whole blood with activated clotting time of approximately 200 sec was circulated. Thrombus-formed area increased with time at the outlet part of the connecter, however, the thrombus-formed area didn't increase at the inlet part. The part where thrombus-formed are increased was related to a flow-separation area. Flow-separation would be a cause to form such an increasingly thrombus. We revealed that the local blood flow is important not only for thrombus formation but also stability of thrombus-formed at the connecter.
高橋 東;須藤 健太;戸部 康貴;松橋 祐輝;鈴木 砂良;八木 高伸;佐々木 崇史;滝沢 研二
バイオエンジニアリング講演会講演論文集2016(28)p."1E35 - 1"-"1E35-5"2016年01月-2016年01月
概要：Computational fluid-structure interaction (FSI) is a technique that can analyze the flow filed with the deformable channel. The methodology is an effective technique to reveal the blood flow around aortic valve with large deformation. On the other hand, the validation of the solution technique is required. In this study, the objective is developing a flow visualization system for aortic valve model with circulation circuit to validate the computational FSI technique. The aortic valve model has opening and closing function as a valve, and is fabricated from transparent silicone for visualization. The circulation circuit simulates pulsating flow and physiological pressure in a living body. The flow visualization system can measure three components of the flow velocity around the aortic valve model under the pulsating flow.
平田 麻由紀;岩崎 清隆;松橋 祐輝;高橋 東;山本 祥宜;鮫島 啓;青山 祐介;梅津 光生
バイオエンジニアリング講演会講演論文集2016(28)p."2B22 - 1"-"2B22-4"2016年01月-2016年01月
概要：Hemofilters are medical devices for assisting deteriorated renal functions, which purify the blood by removing pathogen and wastes. For continuous hemofilters, antithronbogenecity is one of the most important requirements. The aim of this study is to investigate the key parameters for the establishment of a reliable in vitro thrombogenecity testing methodology for continuous hemofilters using human blood from healthy volunteers. This study used adjusted activated clotting time of human blood drawn from healthy volunteers to 150-200 sec using heparin. The blood was circulated in the air-contactless circuit with flow and pressure in a clinical situation was reproduces. The tests were terminated when the inlet pressure elevated to 150 mmHg from the initiation pressure of 70 mmHg at the inlet. The average circulation duration was 6.5±1.7 hours(n=4). The circulation duration using human blood from healthy volunteers were shorter than using porcine blood which was previously reported. Hematocrit of porcine blood was lower than the human blood from healthy volunteers, whereas the hematocrit of porcine blood was comparable to dialysis patients. These data indicated the importance of hematocrit of blood in the assessment of the thrombogenecity of continuous hemofilters.
山本 祥宜;岩崎 清隆;松橋 祐輝;高橋 東;平田 麻由紀;鮫島 啓;青山 祐介;梅津 光生
バイオエンジニアリング講演会講演論文集2016(28)p."2B24 - 1"-"2B24-4"2016年01月-2016年01月
概要：Thrombus formation at the interface between left ventricular wall and the inflow cannula of left ventricular assist device (LVAD) remains to be an unsolved problem that induces complications in clinical practice. The aim of this study is to develop an in vitro airless circuit which produces flow and pressure environments in patients with a LVAD, and to investigate an influence of MPC coating of the inflow cannula of EVAHEART^[○!R] LVAD (Sun Medical Technology Research Co., Japan) on thrombus detachment from the inflow cannula. In the thrombogenicity test, two identical circuits except for the cannula were prepared to form a comparative study. Heparinized blood from a single porcine with activated clotting time ranged within 130-210 sec was circulated for 4.5 hours. The tests were performed under the combinations of the total flow rate of 4 L/min or 5 L/min, and the pump rotational speed of 1800, 1900 or 2000 rpm, respectively. It was elucidated that higher amount of thrombus formed on the MPC non-coated cannula compared with MPC coated cannula. However, there was no difference in the amount of thrombus detached between the two cannula (Student's t-test, p=0.91). From these results, it was elucidated that the MPC non-coated cannula yielded significantly lower proportion of thrombus detachment to thrombus formation than the MPC coated cannula (Student's t-test, p<0.05).
岩崎 清隆;笠貫 宏;伊関 洋;新見 伸吾;[ハイ]島 由二;宮島 敦子;加藤 玲子;迫田 秀行;植松 美幸;松橋 祐輝;梅津 光生
バイオエンジニアリング講演会講演論文集2016(28)p."2B25 - 1"-"2B25-5"2016年01月-2016年01月
概要：We have developed in vitro test methodologies modeling in vivo practical-use situations, to quantitatively assess safety and effectiveness of innovative medical devices. We believe that expediting development of these in vitro methodology not only reinforce preclinical evaluation and enhance timely access to innovative medical devices for patients but also reduce potential risk when used in real-world clinical practice, because controlled clinical trials have certain limitation in fully demonstrating benefit and risk. With the grant from Ministry of Health, Labour and Welfare intended for "Promotional Project for Practical Application of Innovative Pharmaceutical, Medical Device, and Tissue Engineering Products", we have developed drafts on in vitro test guideline for "Durability testing methods for coronary artery stent", "Durability testing methods for vascular stent intended for Superficial femoral - Popliteal artery", and "Method for in vitro thrombogenicity testing for inflow cannula of left ventricular assist system". Further 5 guideline drafts are under preparation. Here, we introduce impacts of in vitro test methods modeling in vivo intended-use situations on expediting availability of new medical devices and timely assessment and management of risk.
高橋 東;松橋 祐輝;鈴木 砂良;青山 祐介;梅津 光生;岩崎 清隆
バイオエンジニアリング講演会講演論文集2016(28)p."2F35 - 1"-"2F35-5"2016年01月-2016年01月
概要：Transcatheter aortic valve replacement (TAVI) is a less invasive therapy and the number of operations is increasing. In some operations of TAVI, valve annulus rupture and failure were happened. Strain measurement method in the blood vessel has not been established and there is no way to evaluate the strain distribution experimentally. It is difficult to measure large deformation of the blood vessel using conventional digital volume correlation with computed tomography. This study presents a new strain measurement method of an elastic blood vessel model using the displacement distribution measured by tomographic particle image velocimetry. Tracer particles were distributed in the blood vessel model and displacement distribution was measured by tracking the particles. The displacement measuring accuracy affected by the amount of displacement and spatial resolutions was assessed. The strain yielded in the blood vessel model, when it was 10% expanded, was measured in the optimal condition determined by the accuracy measurement. In this study, the optimal displacement spatial resolutions and displacement condition were 64 X 64 X 64 voxel^3 and 90-150 μm respectively. This experimental investigation revealed that the higher strain was yielded in the inner wall of the blood vessel model and the strain becomes lower toward the outer wall.
Matsuhashi, Yuki; Sameshima, Kei; Yamamoto, Yoshiki; Umezu, Mitsuo; Umezu, Mitsuo; Iwasaki, Kiyotaka; Iwasaki, Kiyotaka
Journal of Artificial Organs20(4)p.293 - 3022017年12月-2017年12月
概要：© 2017, The Author(s). Thrombus formation at the interface between connectors and tubes is a potential risk factor for complications. We investigated time-dependent relationships between formation of thrombus and hemodynamic factors at the interface between connectors and tubes using optical coherence tomography (OCT) under pulsatile flow. A swept-source OCT with the center wavelength of 1330 nm was employed. The sequential process of thrombus formation at the interface of connectors and tubes in the inlet and outlet was investigated. Connectors with and without tapers were tested using identical 50-ml air-contactless circuits. Fresh human blood from healthy volunteers was circulated under pulsatile flow. Thrombus initially formed at the interface between the connector tip and the tube. Geometries of thrombus growth were different between the 2 connectors, and between the inlet and the outlet. Growth of thrombus was observed at the interface between the connectors and tubes over time in 60 min circulation, except at the outlet part of connector without tapers. At the connector without tapers outlet, thrombus propagation length from the connector edge toward the flow downstream was comparable at 10 and 60 min (0.55 ± 0.35 vs. 0.51 ± 0.32 mm, p = 0.83). Analysis using particle image velocimetry showed the presence of a flow reattachment point 1.5 mm downstream from the connector edge. These results suggest that the flow reattachment point inhibits downstream thrombus growth. We quantitatively demonstrated sequential thrombus process at the interface between the connectors and tubes under pulsatile flow of human blood using OCT.
Matsuhashi, Yuki; Sameshima, Kei; Yamamoto, Yoshiki; Umezu, Mitsuo; Umezu, Mitsuo; Iwasaki, Kiyotaka; Iwasaki, Kiyotaka; Iwasaki, Kiyotaka
概要：© 2017 Matsuhashi et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Background: Blood-contacting devices have contributed to improving the treatment of patients. However, thrombus formation at the interface between a connector and tube is still a potential source of thrombus-related complications that induce stroke or myocardial infarction. We aimed to develop a non-blood-contacting real-time method for visualizing thrombus formation, and to experimentally investigate the time-dependent phenomenon of thrombus formation at the interface between a connector and a tube in a medical device. Methods and findings: An optical coherence tomography device with a center wavelength of 1330 nm was used to visualize thrombus formation during porcine blood circulation for 50 min in a closed 50-mL circulation system isolated from ambient air. The thrombus formation sites at the interface between a tube and connector were visualized. The area of the thrombus formation at the interface between the inlet of the connector and the tube was found to be 0.012 ± 0.011 mm 2 . Conversely, at the interface between the outlet of the connector and the tube, the area was found to be 0.637 ± 0.306 mm 2 . Thus, significantly larger amounts of thrombus were formed at the outlet interface (p < 0.01). The thrombus formation area at the outlet interface increased over time. Conversely, the area of thrombus formation showed repeated increasing and decreasing behavior at the inlet interface. Flow visualization with particle image velocimetry showed the presence of a flow separated area in the minimal f low phase at the inlet interface and a large recirculating slow flow region at the outlet interface in the minimal flow phase. These data suggested that the recirculating stagnant flow region contributed to thrombus growth. Conclusions: The method presented here was effective in quantitatively assessing time-dependent phenomena of thrombus formation at the connector-tube interface. The method may contribute to the assessment of thrombogenicity of a novel design of connector.
|Integrative Bioscience and Biomedical Engineering B||大学院先進理工学研究科||2019||秋学期|