Braided Stent Axial Shortening via Fixed Cross-Links
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Solution Overview
Problem
Existing self-expandable endoluminal stents face challenges with axial shortening, displacement, and reduced radial support force during deployment, particularly in tortuous vascular positions, and are prone to fatigue fracture due to poor flexibility and high incidence of restenosis.
Innovation Solution
A braided self-expandable endoluminal stent design featuring a tubular grid with axial wave bands and fixed cross-linking points, distributed along the circumference, and alternating crossing points, which reduces axial shortening and enhances flexibility and radial support, allowing for accurate positioning and control during deployment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If braided self-expanding stents are made with traditional laser-engraved nickel-titanium alloy tubes, then manufacturing precision is improved, but flexibility and fatigue resistance deteriorate
Solution Approach 1:
The patent combines nickel-titanium alloy wires with elastic filaments to create a composite braided structure. The nickel-titanium alloy provides shape memory and superelasticity for radial support, while the elastic filaments enhance flexibility and fatigue resistance. This composite approach resolves the contradiction by integrating materials with complementary properties.
Solution Approach 2:
The stent is constructed from multiple discrete wire elements braided together rather than a monolithic laser-engraved tube. This segmentation into individual braided wires allows the structure to flex and distribute stresses more effectively, improving fatigue resistance while maintaining manufacturing precision through controlled braiding processes.
2Adaptability or versatility
If braided self-expanding stents are designed with high flexibility, then adaptability to tortuous vessels is improved, but radial support force deteriorates
Solution Approach 1:
The braided structure incorporates varying wire densities and patterns in different regions of the stent. Areas requiring higher radial support have tighter braiding with more nickel-titanium alloy content, while areas needing flexibility have looser braiding with more elastic filament content. This local variation in structure resolves the contradiction between flexibility and radial support.
Solution Approach 2:
The composite of nickel-titanium alloy wires and elastic filaments in the braided structure allows simultaneous achievement of flexibility and radial support. The nickel-titanium provides superelasticity for radial force, while the elastic filaments provide flexibility for vessel adaptation, resolving the contradiction through material composition.
3Ease of operation
If self-expanding stents are deployed in compressed state, then ease of delivery is improved, but axial shortening increases causing positioning difficulty
Solution Approach 1:
The braided structure is designed with dynamic characteristics that allow controlled expansion. The interwoven nickel-titanium and elastic filament wires create a progressive expansion mechanism that reduces sudden axial shortening. The structure dynamically adjusts during deployment, maintaining better positioning control while remaining deliverable in compressed state.
Solution Approach 2:
The patent modifies the braiding parameters including wire diameter, braid angle, and pattern density to optimize the balance between compressibility and axial shortening. By adjusting these parameters, the stent can be compressed for delivery while minimizing expansion-induced axial shortening, thus improving positioning accuracy.
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 stent achieves reduced axial shortening, improved flexibility, and maintained radial support, enabling successful deployment in tortuous vascular positions with reduced risk of restenosis and fatigue fracture, ensuring accurate positioning and stability.
Implementation Method 1
it can automatically return to its original shape by virtue of its own super-elasticity and shape memory characteristic after being released from the sheath
Implementation Method 2
it can automatically return to its original shape by virtue of its own super-elasticity and shape memory characteristic after being released from the sheath
Data Source
AI summary
A braided self-expandable endoluminal stent comprises a tubular grid formed by connection of a plurality of wave bends in the circumferential direction. Each of the wave bands comprises a plurality of crests and troughs of an elastic wire in the axial direction, and is respectively connected with another wave band. On two sides of each of the wave bands, there is a wave band abutted thereto side by side. There is at least one cross-linking point between every two wave bands abutted side by side. Each of the cross-linking points is formed by intersecting one trough on one of the wave bands abutted side by side with one corresponding crest on the other wave band, and at least one part of the cross-linking points are fixed cross-linking points. Each of the wave bands is further staggered and overlapped with at least another wave band, and a plurality of crossing points (12, 14, 22, 23) are formed between the wave bands which are staggered and overlapped with each other. Each of the wave bands, together with at least another wave band, forms a group of parallel wave bands. As the wave bands in this group are similar in wave shape and in parallel to each other, no cross-linking points or crossing points (12, 14, 22, 23) will be formed between the parallel wave bands.