Non-uniform Thickness Leaflets for Prosthetic Heart Valve Durability
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Solution Overview
Problem
Prosthetic heart valves made from animal tissue face challenges such as calcification, limited lifespan, and the need for invasive surgical procedures due to variability in natural tissue, which affects their durability and requires further improvements in leaflet materials resistant to calcification and capable of long-term functionality.
Innovation Solution
The development of prosthetic heart valves with leaflets having a non-uniform thickness, where the sewing edge is thicker than the free edge, and the incorporation of collagen-producing cells to enhance tissue strength, along with methods like stretching, compressing, and molding to achieve specific thickness profiles, and fixation with glutaraldehyde to stabilize the tissue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If uniform thickness leaflet material is used, then manufacturing is simpler, but durability and resistance to calcification are reduced
Solution Approach 1:
The patent applies local quality by creating a non-uniform thickness profile in the leaflet material, where the thickness varies across different regions. Specifically, the leaflet has a greater thickness at the sewing edge region and a smaller thickness at the free edge region. This localized variation in thickness provides enhanced durability and calcification resistance at the sewing edge where structural integrity is most critical, while maintaining thinner material at the free edge to reduce overall mass and improve valve dynamics.
2Reliability
If thicker leaflet material is used, then durability is improved, but the valve cannot be collapsed to a small size for minimally invasive delivery
Solution Approach 1:
The patent resolves this contradiction by implementing local quality through spatially varying thickness. The leaflet material is engineered to be thicker only in specific regions (particularly the sewing edge) where durability is most needed, while remaining thinner in other regions. This allows the overall leaflet to maintain sufficient structural strength and durability without increasing the total volume or mass, enabling the valve to be collapsed to a small size for minimally invasive delivery while still providing durable performance during operation.
3Reliability
If animal tissue is used for leaflets, then biocompatibility is achieved, but calcification occurs limiting lifespan
Solution Approach 1:
The patent applies parameter changes by modifying the physical and chemical parameters of the leaflet material. The tissue is subjected to stretching and/or compressing processes that alter its thickness distribution, density, and mechanical properties. These parameter changes result in a non-uniform thickness profile that reduces overall material volume and mass while enhancing durability in critical regions. The modified material parameters also appear to reduce susceptibility to calcification, thereby extending the functional lifespan of the biocompatible animal tissue leaflets.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The non-uniform thickness design and collagen incorporation improve the durability and resistance to calcification of prosthetic heart valve leaflets, extending their lifespan and enabling minimally invasive delivery and deployment, thus addressing the limitations of traditional animal tissue-based valves.
Implementation Method 1
Collagen-producing cells may be incorporated into the tissue. The collagen-producing cells may be smooth-muscle cells, fibroblasts or stem cells. The collagen-producing cells may be incubated on the tissue so as to produce collagen on the tissue.
Implementation Method 2
Typically prior to implantation, the biological tissue is chemically cross-linked or fixed with agents, such as glutaraldehyde or formaldehyde, in order to prevent rejection when implanted in a recipient, to provide sterilization, and to help stabilize the proteins in the tissue
Data Source
AI summary
A prosthetic heart valve includes a support structure and a valve assembly disposed within the support structure, the valve assembly including a plurality of leaflets. Each leaflet includes a sewing edge and a free edge. The leaflet is formed from a sheet of leaflet material which is processed so that the resulting leaflet has a non-uniform thickness. Various methods may be used to form the leaflet with a non-uniform thickness.