Nested Prosthetic Valve Frames for Synthetic Leaflet Stress Relief
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Solution Overview
Problem
Bioprosthetic heart valves face issues such as calcification, cusp tears, and premature failure due to suboptimal design and lack of durable synthetic materials, while synthetic leaflet prosthetic heart valves suffer from mechanical failure under repetitive loads, especially at the mounting edge, leading to material fatigue and tears.
Innovation Solution
A prosthetic heart valve design featuring a leaflet frame and an outer frame coupled by a film, with the leaflet frame nested within the outer frame in a telescoping manner, providing structural support and minimizing stress through controlled bending and reduced buckling, using materials like fluoropolymer membranes and elastomers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If synthetic materials are used to replace biological tissue in prosthetic heart valves, then durability is improved, but mechanical failure occurs due to suboptimal design and lack of durable synthetic material
Solution Approach 1:
The patent employs composite materials by combining a synthetic leaflet material (such as a fluoropolymer membrane) with a biocompatible frame structure. This composite approach leverages the durability of synthetic materials while using the frame to provide structural support and distribute mechanical loads, preventing stress concentration that would lead to failure.
Solution Approach 2:
The frame structure is designed with varying local properties to match the mechanical demands of different regions. The frame provides enhanced support at critical stress points such as the mounting edge and commissure, while allowing flexibility in other areas. This localized reinforcement prevents mechanical failure without compromising overall durability.
2Stability of the object's composition
If the leaflet is supported by a relatively rigid frame, then dimensional stability is improved, but mechanical failure arises at the mounting edge due to repetitive loading
Solution Approach 1:
The frame material and geometry are specifically designed to optimize the balance between rigidity and flexibility. The frame is made from a material with appropriate elastic modulus to maintain dimensional stability during normal operation while allowing controlled deformation under repetitive loading. The geometry includes rounded transitions and optimized cross-sections that reduce stress concentration at the mounting edge.
Solution Approach 2:
The frame structure incorporates features that preemptively reduce stress concentration at the mounting edge, such as rounded corners, increased thickness at critical points, and optimized attachment geometries. These design elements act as stress-distributing mechanisms that prevent the initiation and propagation of cracks under repetitive loading conditions.
3Productivity
If the leaflet is designed with preferred three-dimensional shapes, then hemodynamic performance is improved, but small radius bends and creases produce high stress zones causing holes and tears
Solution Approach 1:
The leaflet is designed with smooth, continuous curvature throughout its structure, avoiding sharp angles and creases. The three-dimensional shape is optimized to match the natural geometry of native valve leaflets, with gentle transitions and rounded features that distribute stress uniformly during bending and closing motions, preventing the formation of high-stress zones that would lead to holes and tears.
4Adaptability or versatility
If the prosthetic heart valve is designed for transcatheter delivery, then accessibility is improved, but the valve must withstand handling and deployment stresses during compression and expansion
Solution Approach 1:
The frame structure is designed with dynamic characteristics that allow it to withstand the cyclic loading of compression and expansion during transcatheter delivery and deployment. The frame material and geometry provide sufficient rigidity to maintain valve integrity during handling while allowing controlled deformation during delivery. The frame is designed to resist buckling and maintain its shape during expansion, preventing structural failure under these dynamic conditions.
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 design enhances durability and minimizes stress on synthetic materials, preventing peeling and delamination, allowing for uniform compression and expansion, and improving mechanical performance compared to designs based on native valve copies.
Implementation Method 1
The leaflet frame and outer frame are coupled at least in part by a contiguous portion of the film
Implementation Method 2
The leaflet moves under the influence of fluid pressure. In operation, the leaflets open when the upstream fluid pressure exceeds the downstream fluid pressure and close when the downstream fluid pressure exceeds the upstream fluid pressure
Implementation Method 3
The leaflet free edges of the leaflets coapt under the influence of downstream fluid pressure closing the prosthetic heart valve to prevent downstream blood from flowing retrograde through the prosthetic heart valve
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
Described embodiments are directed toward prosthetic valves. A transcatheter valve has a generally tubular leaflet frame coaxially nested within a generally tubular outer frame. The leaflet frame defines a plurality of leaflet windows and a film defines a plurality leaflets extending therefrom. The outer frame provides frame elements that overlay the leaflet windows to provide structural support.