{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/114716"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/114716","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Development, testing, and evaluation of the central-flow, double- leaflet heart valve","abstract":"A review of the literature revealed that 1) all prosthetic heart valves to date are plagued by certain problems, 2) all prosthetic valves in current clinical use are central-occlusion valves which do not effectively simulate natural valve action, and 3) the development of a true central-flow valve with the potential benefits of reduced pressure drop, turbulence, hemolysis, and thromboembolism could be a significant contribution. A central-flow, double-leaflet valve was developed. The wear, pressure drop, turbulence, and regurgitation associated with the new valve were evaluated. The wear test results indicated the need for additional testing using more wear resistant pin-bearing combinations. The flow tests revealed that the new valve with a 65 degree opening angle produced less pressure drop than other prostheses, but the new valve did not reduce turbulence as compared to other prostheses. In addition, the backflow and mean leak associated with the new valve were too high. Details of the testing procedures are presented and recommendations for future valve modifications and testing are included.","abstract_html":"A review of the literature revealed that 1) all prosthetic heart valves to date are plagued by certain problems, 2) all prosthetic valves in current clinical use are central-occlusion valves which do not effectively simulate natural valve action, and 3) the development of a true central-flow valve with the potential benefits of reduced pressure drop, turbulence, hemolysis, and thromboembolism could be a significant contribution. A central-flow, double-leaflet valve was developed. The wear, pressure drop, turbulence, and regurgitation associated with the new valve were evaluated. The wear test results indicated the need for additional testing using more wear resistant pin-bearing combinations. The flow tests revealed that the new valve with a 65 degree opening angle produced less pressure drop than other prostheses, but the new valve did not reduce turbulence as compared to other prostheses. In addition, the backflow and mean leak associated with the new valve were too high. Details of the testing procedures are presented and recommendations for future valve modifications and testing are included.","abstract_has_math":false,"creators":["Herbert, James Dale"],"institution":"Virginia Polytechnic Institute and State University","degree_name":"M.S.","degree_level":"masters","degree_discipline":"Mechanical Engineering","degree_department":"Mechanical Engineering","school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1975,"date_issued":"1975","date_published":"1975","updated_at":"2026-07-22T22:20:16Z","subjects":[],"languages":["en"],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/10919/114716","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.department","label":"Department","values":["Mechanical Engineering"]},{"key":"dc:creator","label":"Author","values":["Herbert, James Dale"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2023-04-20T14:53:51Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2023-04-20T14:53:51Z"]},{"key":"dc:date.issued","label":"Date","values":["1975"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Polytechnic Institute and State University"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.dcmitype","label":"Dc Type Dcmitype","values":["Text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Mechanical Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10919/114716"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["A review of the literature revealed that 1) all prosthetic heart valves to date are plagued by certain problems, 2) all prosthetic valves in current clinical use are central-occlusion valves which do not effectively simulate natural valve action, and 3) the development of a true central-flow valve with the potential benefits of reduced pressure drop, turbulence, hemolysis, and thromboembolism could be a significant contribution. A central-flow, double-leaflet valve was developed. The wear, pressure drop, turbulence, and regurgitation associated with the new valve were evaluated. The wear test results indicated the need for additional testing using more wear resistant pin-bearing combinations. The flow tests revealed that the new valve with a 65 degree opening angle produced less pressure drop than other prostheses, but the new valve did not reduce turbulence as compared to other prostheses. In addition, the backflow and mean leak associated with the new valve were too high. Details of the testing procedures are presented and recommendations for future valve modifications and testing are included."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["M.S."]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Development, testing, and evaluation of the central-flow, double- leaflet heart valve"]}]}],"canonical_facts":{"dc:contributor.department":["Mechanical Engineering"],"dc:creator":["Herbert, James Dale"],"dc:date.accessioned":["2023-04-20T14:53:51Z"],"dc:date.available":["2023-04-20T14:53:51Z"],"dc:date.issued":["1975"],"dc:description.abstract":["A review of the literature revealed that 1) all prosthetic heart valves to date are plagued by certain problems, 2) all prosthetic valves in current clinical use are central-occlusion valves which do not effectively simulate natural valve action, and 3) the development of a true central-flow valve with the potential benefits of reduced pressure drop, turbulence, hemolysis, and thromboembolism could be a significant contribution. A central-flow, double-leaflet valve was developed. The wear, pressure drop, turbulence, and regurgitation associated with the new valve were evaluated. The wear test results indicated the need for additional testing using more wear resistant pin-bearing combinations. The flow tests revealed that the new valve with a 65 degree opening angle produced less pressure drop than other prostheses, but the new valve did not reduce turbulence as compared to other prostheses. In addition, the backflow and mean leak associated with the new valve were too high. Details of the testing procedures are presented and recommendations for future valve modifications and testing are included."],"dc:description.degree":["M.S."],"dc:format.mimetype":["application/pdf"],"dc:identifier.uri":["http://hdl.handle.net/10919/114716"],"dc:language.iso":["en"],"dc:publisher":["Virginia Polytechnic Institute and State University"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:title":["Development, testing, and evaluation of the central-flow, double- leaflet heart valve"],"dc:type":["Thesis"],"dc:type.dcmitype":["Text"],"thesis:degree_discipline":["Mechanical Engineering"],"thesis:degree_level":["masters"],"thesis:degree_name":["M.S."],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:20:16Z"}