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Biomedical engineering analysis of effectiveness of cardiovascular surgery: anastomosis methods for coronary artery bypass grafting

Umezu M., Kawai J., Suehiro J., Arita M., Shiraishi Y., Iwasaki K., Tanaka T., Akutsu T., Niinami H.

Biocybernetics and Biomedical Engineering

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2006

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Vol. 26, no. 1

61-67

EN

There are two types of coronary artery bypass grafting (CABG) anastomosis methods: the end-to-side anastomosis (ESAs) and the side-to-side anastomosis (SSAs). The choice of these methods is determined by the surgeon's favor because there is no evidence how to optimize. The ultimate objective of this study is to provide new methodology for the surgeons to enable them to choose the anastomosis methods through both in-vivo and invitro tests. The in-vivo tests were performed on pigs and the energy loss at the anastomosis ESAs and SSAs were compared. The in-vitro tests were conducted in the newly-developed system to evaluate CABG anastomosis methods. This system is composed of the mock circulatory system and the coronary simulator, which originally was designed to reproduce various types of the coronary hemodynamics. Both the in-vivo and the in-vitro tests showed a similar 'tendency of the energy loss: SSAs had a lower energy loss than ESAs under the same conditions. These effects were caused by the difference in the local flow at the anastomosis between ESAs and SSAs. Consequently, SSAs is believed to be an anastomosis method preferable to ESAs.

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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.

3

Left ventricle simulator for surgeons' support

Umezu M., Arita M., Iwasaki K., Shiraishi Y., Tono S., Uchida K.

Biocybernetics and Biomedical Engineering

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2002

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Vol. 22, no. 4

47-53

EN

The authors have been developing various types of mock circulatory systems to evaluate a performance of artificial organs. Among several attempts, it was indicated that a simulation of the mitral valve region was very difficult due to a complicated shape and movement of the valve. In this paper, a new trial to install a porcine valve into the mock circulatory system is introduced. A fresh porcine valve with papillary muscles and chordae was fixed into the mitral position of the modified Windkessel-type mock circulatory system. To allow direct 3-D observation of the mitral annulus, a digital video camera and a laser displacement sensor were employed. A circulation was generated by a pneumatically-driven artificial ventricle. When a normal circulatory condition (pump rate: 70BPM, Flow: 3L/min) was selected, similar opening and closing motion to the natural mitral valve could be reproduced. Moreover, a diseased condition was made by shifting a position of papillary muscles. After this procedure, an abnormal movement, such as significant leakage, could also be reproduced.