Prosthetic Heart Valve Leaflet Planar Zone Stress Reduction
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Solution Overview
Problem
Prosthetic heart valve leaflets made from synthetic materials face durability issues due to repetitive loading, leading to mechanical failure at the mounting edge and high stress zones, which can cause holes and tears, especially when modeled after native human valves without considering the unique properties of synthetic materials.
Innovation Solution
The design features flexible leaflets with a planar central zone, specifically a truncated isosceles triangle or isosceles trapezoid shape, to minimize stress and buckling, using a composite material of expanded fluoropolymer membrane combined with an elastomer, and a redundant coaptation zone for full coaptation and reduced crease formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If synthetic leaflets are modeled after native human valve shapes, then the valve can achieve natural flow patterns, but the leaflets experience high stress concentrations at the mounting edge leading to mechanical failure
Solution Approach 1:
The patent applies local quality by creating a planar zone specifically at the mounting edge of the leaflet, while the rest of the leaflet maintains the native valve shape. This localized modification concentrates the beneficial properties where stress is highest (at the mounting edge) without sacrificing the overall natural flow patterns provided by the native-shaped leaflet geometry
Solution Approach 2:
The leaflet is segmented into distinct zones: a planar zone at the mounting edge and a native-shaped zone for the main body. This segmentation allows each zone to serve its specific function - the planar zone handles stress concentration while the native-shaped zone maintains natural flow patterns
2Shape
If the leaflet has small radius bends and creases to follow native valve geometry, then the valve achieves natural hemodynamics, but high stress zones form causing holes and tears under repetitive loading
Solution Approach 1:
The patent introduces a planar zone at the mounting edge where stress concentration occurs, while allowing the rest of the leaflet to maintain the native valve geometry with its characteristic bends and creases. This localized planar region eliminates high stress concentrations without compromising the overall natural hemodynamic performance
3Stability of the object's composition
If the leaflet mounting edge is made rigid to support the leaflet structure, then the leaflet maintains its shape, but stress concentrates at the mounting edge leading to fatigue failure
Solution Approach 1:
The patent uses a planar zone configuration that provides structural stability through its geometry rather than material rigidity. The planar zone distributes loads evenly across the mounting edge, allowing the leaflet to maintain its shape while avoiding stress concentrations that would lead to fatigue failure in rigid structures
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
This configuration reduces stress on the leaflets, enhances durability, and prevents prolapse and regurgitant flow, improving the longevity and performance of synthetic heart valves by distributing loads more evenly and reducing material fatigue.
Implementation Method 1
The durability of synthetic materials used for heart valve leaflets under the repetitive loads of the opening and closing is dependent, in part, on the load distribution between the leaflet and the frame
Implementation Method 2
The durability of the valve leaflets is also a function of the character of bending by the leaflet during the opening-closing cycle. Small radius bends, creases and intersecting creases, can produce high stress zones in the leaflet
Implementation Method 3
A coaptation height is defined as a length of the coaptation zone measured in an axial direction, wherein the coaptation height is greater than zero
Data Source
AI summary
Described embodiments are directed toward prosthetic valve leaflets of a particular shape that allows redundant coaptation height in the leaflets when a planar segment is present in each leaflet.