A complete mechanical model of a BHV must therefore include FSI. Both of these phenomena likely contribute to long-term structural fatigue, but neither can be modeled without accounting for the surrounding hemodynamics. The effect of hydrostatic forcing on a closed BHV may be modeled as a prescribed pressure load and simulated using standard FEM (see, e.g., ), but such models cannot capture the transient response of an opening valve or the so-called “water hammer effect” in a closing valve. Ĭomputational modeling of continuum mechanics has proven tremendously beneficial to the design process of many other products, but BHVs present unique challenges for computational analysis, and cannot yet be conveniently simulated using “off-the-shelf” software. There is thus a profound need for the development of novel simulation technologies that combine state-of-the-art fluid–structure interaction (FSI) analysis with novel constitutive models of BHV biomaterial responses, to simulate long-term cyclic loading. Thus, despite decades of clinical BHV usage and growing popularity, there exists no acceptable method for simulating BHV durability in any design context.
Yet, current BHV assessment relies exclusively on device-level evaluations, which are confounded by simultaneous and highly coupled biomaterial mechanical fatigue, valve design, hemodynamics, and calcification. Improved durability remains an important clinical goal and represents a unique cardiovascular engineering challenge, resulting from the extreme valvular mechanical demands. In spite of this long-standing problem, BHV material technologies have not changed since their introduction more than 30 years ago. However, BHVs are less durable than their mechanical counterparts and require replacement, typically after 10–15 years, due to calcification and structural damage. BHVs do not induce blood damage that can occur due to prostheses composed of rigid mechanical parts. BHVs imitate the structure of the native valves, consisting of flexible leaflets fabricated from chemically-treated soft tissues. The most popular class of prostheses are bioprosthetic heart valves (BHVs). Hundreds of thousands of such devices are implanted in patients every year. Primarily in aortic heart valves, the leaflets may become diseased and, in some cases, valves must be replaced by prostheses. Heart valves consist of thin, flexible leaflets that open and close passively, in response to blood flow and the movements of the attached cardiac structures. Heart valves serve to ensure unidirectional flow of blood through the circulatory systems of humans and many animals.
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