Helical Stent Hinges for Uniform Expansion and Stability
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Solution Overview
Problem
Existing stent designs face challenges such as difficulty in accurate placement and retrieval due to thin walls being invisible on fluoroscopic and x-ray equipment, instability leading to buckling and thrombosis, significant elastic recovery causing over-expansion and tissue damage, non-uniform expansion resulting in inadequate lumen support, and limited flexibility for navigation through complex vessels.
Innovation Solution
A flexible stent with a helical section and ductile hinges, designed to be crimped for delivery and expanded for deployment, featuring a cylindrical shape with longitudinally oriented strut members and circumferentially oriented hinge members forming a band, providing radial strength, controlled drug delivery, and optimized geometry for uniform expansion and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If thin-walled materials are used to reduce expansion forces to acceptable levels, then expansion force is improved, but visibility on fluoroscopic and x-ray equipment deteriorates
Solution Approach 1:
The patent applies radiopaque materials or coatings to the stent structure that change the visual properties of the device under fluoroscopic and x-ray imaging. This allows the stent to maintain thin walls for low expansion forces while becoming visible through enhanced radiopacity, resolving the contradiction between mechanical performance and detectability
2Force
If thin-walled tubular designs are used to reduce expansion forces, then expansion force is improved, but structural stability deteriorates causing buckling
Solution Approach 1:
The patent segments the continuous thin-walled tube into a structured framework of struts and connectors. This segmentation allows each component to be optimized for its specific function while collectively providing the necessary structural stability to prevent buckling, even with thin-walled construction
Solution Approach 2:
The patent employs composite material structures combining thin-walled tubular elements with reinforcing features or multi-material construction. This allows the stent to maintain low expansion forces from the thin walls while gaining structural stability from the composite architecture
3Force
If thin-walled designs are used to reduce expansion forces, then expansion force is improved, but manufacturing precision deteriorates due to variability
Solution Approach 1:
The patent divides the stent into discrete manufacturable segments or modules that can be produced with higher precision individually, then assembled into the complete structure. This segmentation approach reduces the cumulative manufacturing variability inherent in forming entire thin-walled structures in one piece
4Adaptability or versatility
If large elastic recovery is present in stent design, then flexibility is improved, but lumen tissue damage worsens due to over-expansion
Solution Approach 1:
The patent modifies the material parameters and structural geometry to control the elastic recovery characteristics. By adjusting wall thickness, strut dimensions, and material properties, the stent maintains necessary flexibility for delivery while limiting rebound to prevent over-expansion and tissue damage
5Adaptability or versatility
If large elastic recovery is present in stent design, then flexibility is improved, but secure crimping onto delivery catheter worsens due to slippage
Solution Approach 1:
The patent incorporates preliminary crimping features or mechanical interlocks that engage before the stent is subjected to elastic recovery forces. These preliminary actions secure the stent to the delivery catheter in advance, preventing slippage even when the stent exhibits significant elastic recovery
6Adaptability or versatility
If non-uniform expansion occurs in stent design, then flexibility is improved, but lumen support worsens due to inadequate coverage
Solution Approach 1:
The patent implements local quality variations in the stent structure, with different regions having optimized geometries for their specific functions. This allows uniform expansion in critical support regions while maintaining flexibility in other areas, ensuring adequate lumen coverage where needed
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 flexible stent maintains vessel patency, allows for precise delivery and deployment, reduces the risk of thrombosis, ensures uniform expansion, and provides sufficient radial strength while being adaptable for navigation through complex vessels, enhancing patient safety and treatment efficacy.
Implementation Method 1
designed to be crimped for delivery and expanded for deployment
Implementation Method 2
many of the known stents display a large elastic recovery, known in the field as 'recoil,' after expansion inside a lumen
Data Source
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AI summary
The present invention relates to tissue-supporting medical devices and drug delivery systems, and more particularly to tubular flexible stents that are implanted within a body lumen of a living animal or human to support the organ, maintain patency and/or deliver drugs or agents. The tubular flexible stent has a cylindrical shape defining a longitudinal axis and includes a helical section having of a plurality of longitudinally oriented strut members and a plurality of circumferentially oriented hinge members connecting circumferentially adjacent strut members to form a band. The band is wrapped about the longitudinal axis in a substantially helical manner to form a plurality of helical windings. At least one connector member extends between longitudinally adjacent helical windings of the band.