Prosthetic Valve Leaflet Composites for Stress-Resistant Durability
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Solution Overview
Problem
Bioprosthetic heart valves face issues such as calcification and cusp tears, while synthetic leaflet prosthetic heart valves suffer from premature failure due to suboptimal design and lack of durable materials, leading to mechanical failure at the mounting edge and high stress zones under repetitive loading.
Innovation Solution
A prosthetic valve design featuring a leaflet frame and outer frame coupled by a film, with leaflets having a tubular shape and defined by isosceles trapezoidal windows, minimizing stress through reduced buckling and controlled bending, using a composite material of fluoropolymer membrane and elastomer to enhance durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bioprosthetic heart valves use biological tissue for flexible leaflets, then excellent hemodynamic and biomechanical performance is achieved in the short term, but the valves are prone to calcification and cusp tears requiring reoperation
Solution Approach 1:
The patent changes the material parameter from biological tissue to synthetic materials (polymer, elastomer, or composite) to eliminate the biological degradation issues while maintaining the flexible leaflet functionality. This parameter change addresses the long-term durability problem by replacing materials that calcify and tear with synthetic alternatives that resist these degradation mechanisms.
Solution Approach 2:
The patent employs composite materials consisting of polymer and elastomer layers to create synthetic leaflets that combine the benefits of flexibility and durability. The composite structure allows optimization of mechanical properties to match native valve performance while resisting calcification and cusp tears that plague biological tissue valves.
2Duration of action of stationary object
If synthetic materials are used for flexible leaflets, then a more durable prosthetic heart valve is intended, but premature failure occurs due to suboptimal design and lack of durable material
Solution Approach 1:
The patent optimizes material parameters by selecting specific polymer and elastomer combinations with tailored mechanical properties. This includes adjusting elasticity, strength, and fatigue resistance parameters to prevent premature failure while maintaining durability throughout the intended service life.
Solution Approach 2:
The composite construction of polymer and elastomer layers creates a material system that leverages the strengths of each component - the polymer provides structural integrity and fatigue resistance, while the elastomer provides flexibility and stress distribution, together preventing premature failure.
3Stability of the object's composition
If the leaflet is supported by a relatively rigid frame, then dimensional stability is provided, but mechanical failure occurs at the mounting edge under repetitive loading
Solution Approach 1:
The patent applies local quality by creating a gradient in rigidity - the frame provides rigid support in the body portion for dimensional stability, while the mounting edge region is designed with enhanced flexibility and stress distribution characteristics to prevent mechanical failure under repetitive loading.
Solution Approach 2:
The composite leaflet material provides differential mechanical properties throughout its structure, with the polymer-elastomer combination offering both the rigidity needed for dimensional stability and the flexibility required at mounting edges to prevent fatigue failure under repetitive cardiac cycling loads.
4Ease of operation
If small radius bends and creases are present in the leaflet, then the leaflet can flex during opening-closing cycle, but high stress zones form causing holes and tears under repetitive loading
Solution Approach 1:
The patent modifies the geometric parameters of the leaflet design to eliminate small radius bends and sharp creases that create stress concentrations. By optimizing the curvature radius and fold geometry, the leaflet maintains necessary flexibility for opening-closing motion while distributing stresses uniformly to prevent hole and tear formation.
Solution Approach 2:
The composite polymer-elastomer construction provides toughness and crack resistance that prevents small defects from propagating into holes and tears. The material's viscoelastic properties allow it to absorb and dissipate stress energy from repetitive flexing without forming catastrophic failures.
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 reduces mechanical failure and prolongs the durability of synthetic leaflets by minimizing stress and crease formation, allowing for transcatheter delivery and deployment without peeling or delamination, while maintaining effective valve function.
Implementation Method 1
using a composite material of fluoropolymer membrane and elastomer to enhance durability
Implementation Method 2
The design reduces mechanical failure and prolongs the durability of synthetic leaflets by minimizing stress and crease formation, allowing for transcatheter delivery and deployment without peeling or delamination
Data Source
AI summary
Prosthetic heart valves including radially compressible and expandable frames. A frame includes a plurality of interconnected frame elements forming a plurality of cells, which are arranged in a first circumferential row of cells defining an inflow end of the frame and a second circumferential row of cells defining an outflow end of the frame. An outflow portion of the second row of cells includes a circumferential row of angled frame elements interconnected to each other at a plurality of upper junctions and a plurality of lower junctions. The upper junctions define the outflow end of the frame and the lower junctions point toward the inflow end of the frame. The lower junctions are not connected to other portions of the frame.