Design of a Mechanical Heart Valve's Occluder to Start Closing by Gravity
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概要
- 論文の詳細を見る
Conventional mechanical mitral valves close rapidly, which is one of the reasons for the attendant hemolysis and the closing click. Safer mechanical valves which close more slowly will be realized if the occluder (opening and closing movement element) starts closing withont any backflow. A new self-closing occluder was designed by adjusting the center of gravity of the occluder. Blood flow becomes nearly zero for around 250 msec from the middle of left ventricular relaxation. The valve is expected to start closing by gravity during the nearly zero flow periods. Thus, the time from the maximally open state to complete closure should be designed to be no more than 250 msec. In this paper, a new design process for a self-closing occluder was proposed. A new prototype occluder made of aluminum alloy was produced by optimizing the center of gravity, torque by gravity and moment of inertia. The prototype occluder with a piano wire as the rotational axis was mounted on an acrylic resin base. The closing motion of the valve was measured by a high-speed video camera (125 pictures per second). The calculation and measurement of the closing motion were carried out, and qualitative agreement was observed with the motion in air. The time from the maximally open state to complete closure by gravity in glycerin solution as a blood substitute was 208 msec, which is thought to be satisfactory available for the cases requiring mitral valve replacement. The results showed the validity of the proposed design process.
- 一般社団法人日本機械学会の論文
- 1999-09-15
著者
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Naemura K
Tokyo Univ. Technol. Tokyo Jpn
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NAEMURA Kiyoshi
Department of Precision Machinery Engineering, The University of Tokyo