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1
Content available remote A study on a newly designed aortofemoral prosthetic Y graft
Fujimoto T., Nakano S., Iwamura H., Shiraishi Y., Yambe T., Umezu M.
Biocybernetics and Biomedical Engineering
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2008
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Vol. 28, no. 1
59-63
EN
Aortofemoral prosthetic Y grafts are applied for treating abdominal aortic aneurysms. In this study, experiments were conducted in order to demonstrate the effects of an incremental increase in branch diameter in a newly designed aortofemoral Y graft under conditions of both steady and pulsatile flow conditions. It was revealed that in Y grafts, the incremental increase by only 4 mm in the branch diameter affects hydrodynamic characteristics drastically under conditions of both steady and pulsatile flow conditions.
2
Content available remote Characteristics of spiral vortex pump driven by two different drivers
Ito K., Sudo T., Shima T., Kouno Y., Ohnishi Y., Tanaka T., Iwasaki K., Fujimoto T., Umezu M.
Biocybernetics and Biomedical Engineering
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2007
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Vol. 27, no. 1-2
121-132
EN
Here we describe a cardio-ventricular support system that combines a spiral vortex blood pump with an intra-aortic balloon pump driver. To reduce cost, we replaced the conventional ventricular assist driver with one used for an aortic balloon pump. We characterized the hydrodynamics of both drivers by recording pressure and flow waveforms during a single pulse for typical conditions of the pump. The pressure pulse of the ventricular assist driver was rectangular in shape, and the flow was maximal in the systolic fraction, when balanced conditions were achieved. By contrast, the triangle shaped pressure pulse of the balloon pump driver produced a constant volume. Flow increased in proportion to the rate of pulsation and drive volume. A minimum requirement set flow to 5 liters after 80 beats per minute. The balloon pump driver met the requirement with a 44 ml volume. Thus, the balloon pump driver effectively substituted for the ventricular assist driver. Our findings suggest that combining a spiral vortex pump with a balloon pump driver is cost-effective for left ventricular support during acute cardiac failure.
3
Content available remote A newly-designed myocardial assist device using a sophisticated shape memory alloy fibre
Shiraishi Y., Yambe T., Sekine K., Ogawa D., Nagatoshi J., Itoh S., Park Y., Uematsu M., Sakata R., Wada Y., Saijo Y., Higa M., Hori Y., Liu H., Wang Q., Konno S., Kuwayama T., Olegario P., Tanaka A., Masumoto N., Ibuki R., Maruyama S., Okamoto E., Fujimoto T., Yoshizawa M., Umezu M., Imachi K., Nitta S.-I., Sasada H., Tabayashi K., Homma D.
Biocybernetics and Biomedical Engineering
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2007
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Vol. 27, no. 1-2
147-154
EN
Recently, the ventricular assist devices are widely applied for a surgical treatment of the final stage of severe heart failure as the bridge to heart transplantation or the destination therapy. However, it was anticipated that the artificial components in the ventricular assist devices might cause the problems concerning thrombosis and infection. As heart failure involves the decrease in myocardial contractile function, the mechanical assistance by using an artificial myocardium might be effective. In this study, the authors developed a mechano-electric artificial myocardial assist system (artificial myocardium), which is capable of supporting natural contractile function from the outside of the ventricle.
4
Content available remote Evaluation of freestyle bioprosthesis behavior in mechanical circulatory system
Fujimoto T., Kawaguchi D., Shiraishi Y., Iwasaki K., Arita M., Umezu M.
Biocybernetics and Biomedical Engineering
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2003
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Vol. 23, no. 2
51-55
EN
A freestyle prosthetic heart valve using a porcine aortic root is expected to yield high performance. In this study, Subcoronary and Full-root techniques, that are mainly used for implanting the freestyle bioprosthesis into the aorta, were simulated under conditions in which the degree of elasticity around the bioprosthesis at the aortic root position was varied in a mechanical circulatory system. As a result, the forward flow at the bioprosthesis in the case of the Subcoronary was 11% greater than that of the Full-root. The variation in the elasticity around the bioprosthesis was suggested to influence the hydrodynamic characteristics.
5
Content available remote In vitro evaluating system for prosthetic heart valves in a case of the Jyros valve
Fujimoto T., Tsutsumi Y., Shiraishi Y., Iwasaki K., Yoshida M., Umezu M., Begg J., Woodard J.
Biocybernetics and Biomedical Engineering
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2002
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Vol. 22, no. 4
41-46
EN
The Jyros valve has unique hydrodynamic characteristics comparing with other types of valves. In this study, precise hydrodynamic characteristics of the valve were examined using a mock circulatory system, which we have developed. Further, the influence of leaflet rotation is shown to reduce flow resistance under the rotational flow condition which was produced by a spiral vortex pump. However, hemolysis was not revealed to be reduced by the Jyros.
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