動脈弁の弁葉に与えた構造的工夫が弁機能におよぼす影響

Abstract

Recently novel artificial heart valves, which are made by using tissue regeneration techniques or the latest biocompatible materials, are actively developing. The purpose of this study is to clarify the effects of mechanical anisotropy of valve leaflet on valve functions because the new materials and human native heart valves are anisotropic. We fabricated the human aortic valve model made of polyurethane with mechanical anisotropy in valve leaflet by adding spatially periodical surface asperities. Furthermore, to determine the optimal anisotropic property of the valve leaflet, the amount of sheet thickness and the spacing of surface asperities were varied as experimental parameters. Using our fabricated in-vitro simulator, experiments were conducted under the physiological conditions of healthy adults to compare valve function between isotropic and anisotropic models. The valve function was evaluated on basis of the ISO 5840-1 and ISO 5840-2 international standards for artificial valves. The obtained results indicate that anisotropic models with 3 mm spacing were found to have the best valve function, and isotropic models and anisotropic models with 1 mm spacing were found to have similar performance. Furthermore, comparison with data from clinically used prosthetic valves showed that among anisotropic models with 3 mm spacing, the valve leaflet thickness of 280 μm was superior in both opening and closing performance.