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  • Walter de Gruyter GmbH  (2)
  • 2015-2019  (2)
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  • Walter de Gruyter GmbH  (2)
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  • 2015-2019  (2)
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  • 1
    Online Resource
    Online Resource
    Walter de Gruyter GmbH ; 2018
    In:  Current Directions in Biomedical Engineering Vol. 4, No. 1 ( 2018-09-01), p. 149-151
    In: Current Directions in Biomedical Engineering, Walter de Gruyter GmbH, Vol. 4, No. 1 ( 2018-09-01), p. 149-151
    Abstract: Venous ulcers of the lower limbs are one clinical manifestation of chronic venous insufficiency. Currently, there is no venous valve prosthesis available. This study presents novel venous valve prostheses made of threedimensional electrospun fibrous nonwoven leaflets. The aim of this study was to prove the feasibility of the manufacturing process as well as to investigate design features of the venous valve prostheses from a hemodynamic point of view. An adapted pulse duplicator system (ViVitrolabs, Victoria, BC, CA) was used for characterization of the hydrodynamic performance. For eight different venous valve prototypes flow rate, effective orifice area and regurgitation fraction was investigated in vitro. In particular, tricusp valve designs showed an up to 40% higher effective orifice area as well as 15% higher maximum flowrate compared to bicusp valve designs. However, the regurgitation fraction of the bicusp valve designs is up to 86% lower compared to tricusp valve. Additionally, the hemodynamic performance of the tricuspid valves showed a high sensitivity regarding the leaflet length. Bicuspid valves are less sensitive to changes of design parameters, more sufficient and therefore highly reliable.
    Type of Medium: Online Resource
    ISSN: 2364-5504
    Language: English
    Publisher: Walter de Gruyter GmbH
    Publication Date: 2018
    detail.hit.zdb_id: 2835398-5
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  • 2
    In: Current Directions in Biomedical Engineering, Walter de Gruyter GmbH, Vol. 5, No. 1 ( 2019-09-01), p. 477-479
    Abstract: Chronic venous insufficiency (CVI) is a common disease characterized by impaired venous drainage leading to congestion in the lower limbs. Currently, there are no artificial or biological venous valve prostheses commercially available. Previous minimally invasive design concepts failed to achieve sufficient long term results in animal or in vitro studies. The aim was to implement structural numerical simulation of clinically relevant loading cases for minimally invasive implantable venous valve prostheses. A bicuspid valve design was chosen as it showed superior results compared to tricuspid valves in previous studies. The selfexpanding support structure was developed by using diamond-shaped elements. Using finite-element analysis (FEA), various loading cases, including expansion and crimping of the stent structure and the release into a venous vessel, were simulated. A hyperelastic constitutive law for the vascular model was generated from uniaxial tensile test data of unfixated human vein walls. This study also compared numerical and experimental results regarding compliance and tensile tests to validate the vein material model. The calculated performance concerning expansion and crimping, as well as the release of the stent into a venous vessel, demonstrated the suitability of the stent design for minimally invasive application.
    Type of Medium: Online Resource
    ISSN: 2364-5504
    Language: English
    Publisher: Walter de Gruyter GmbH
    Publication Date: 2019
    detail.hit.zdb_id: 2835398-5
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
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