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Goode, Dylan James Ellingham

University of British Columbia

Valvular heart disease primarily affects the aortic and mitral valves due to higher left-sided heart pressures, often leading to complications like leaflet calcification (stenosis), which impairs valve function and can result in congestive heart failure, necessitating valve replacement. Three forms of valve replacement exist: bioprosthetic valves using bovine or porcine tissue, transcatheter valves combining bioprosthetic components with collapsible stents, and mechanical heart valves (MHVs) made from rigid synthetic materials ensuring unidirectional blood flow. Among MHVs, the bileaflet mechanical heart valve (BMHV) is a modern and durable option that can last a patient’s lifetime, unlike bioprosthetic valves. However, BMHVs require lifelong anticoagulation therapy to prevent thrombosis. Thrombogenicity in BMHVs primarily occurs during the closing phase, where regurgitant flow converts into jets as the orifice narrows, and during hinge washing in the closed phase, which can generate high shear stress and trigger thrombosis. This research addresses the design, testing, and fabrication challenges of developing a novel BMHV that mimics the native valve’s hemodynamics while potentially reducing the need for lifelong anticoagulation therapy. The objectives include: (1) designing a BMHV with improved hemodynamic characteristics; (2) performing structural, kinematic, and kinetic analyses to validate performance; (3) experimentally testing the BMHV under various conditions and comparing it to industry-standard valves; and (4) identifying opportunities for further optimization. The central hypothesis suggests that the novel BMHV will exhibit hemodynamic performance akin to the native valve, potentially reducing or eliminating the need for anticoagulation while ensuring durability. Computational simulations, finite element analysis, and in vitro testing were used to assess the novel BMHV prototypes. Validation results highlighted a stress-dispersing hinge design that minimizes stress concentrations and ensures hinge washing during low-stress forward flow. Kinematic and kinetic findings supported the hypothesis, indicating native-like performance during the valve opening and closing phases, potentially negating the need for anticoagulation therapy. This research offers advancements in cardiovascular care, reducing anticoagulation risks, improving patient outcomes, and enhancing the quality of life for individuals with valvular heart disease.

Text

2024-08-23

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/89015

Mechanical Engineering

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-nd/4.0/