Multi-Material Stent Braid Layout for X-Ray Visibility
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Solution Overview
Problem
Self-expanding stents are difficult to locate with X-ray due to their small size and low radiopacity, which complicates accurate placement and subsequent examination, often requiring a trade-off between radiopacity and mechanical properties.
Innovation Solution
A tubular metallic braid pattern is created using a combination of filaments made from different materials, including radiopaque and support materials, arranged in specific configurations to enhance radiopacity without compromising mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the stent is made with fine-meshed braided configuration to reduce size and improve flexibility, then the stent can be delivered through small and curved vessels, but the radiopacity is significantly reduced making it extremely difficult to locate with X-ray
Solution Approach 1:
The stent is constructed as a composite braid incorporating multiple materials with different properties: radiopaque materials (such as platinum, iridium, or their alloys) combined with biocompatible metallic materials (such as cobalt-chromium alloys, stainless steel, or nitinol). This composite structure allows the stent to maintain fine-meshed configuration for deliverability while incorporating sufficient radiopaque material for X-ray visibility. The radiopaque material can be applied as coatings, claddings, or integrated into the braid structure itself.
2Difficulty of detecting and measuring
If the radiopaque material content is increased to enhance X-ray visibility, then the stent can be easily located during placement and examination, but the mechanical properties such as strength, ductility, and fatigue resistance are compromised
Solution Approach 1:
The radiopaque material is applied locally rather than uniformly throughout the entire stent structure. Specific regions or segments of the braid are enhanced with radiopaque material, such as at the ends of the stent, at specific radial struts, or in a segmented pattern along the length. This localized approach provides sufficient X-ray visibility for placement and examination while preserving the mechanical properties of the bulk stent structure made from high-strength biocompatible materials.
Solution Approach 2:
The stent employs a composite construction where radiopaque materials are combined with high-strength biocompatible materials in a controlled ratio and configuration. The radiopaque material content is optimized to provide adequate radiopacity without compromising the overall mechanical integrity. The biocompatible metallic framework provides the primary structural support, while the radiopaque components provide imaging visibility.
3Length of moving object
If the stent diameter is reduced to treat smaller vessels, then the stent can be delivered through smaller vessels, but the mass and thickness of radiopaque parts decrease making them even more difficult to visualize
Solution Approach 1:
For small-diameter stents, the radiopaque material is concentrated in specific local regions where it provides maximum imaging benefit. This may include enhanced radiopaque markings at the proximal and distal ends of the stent to define its position, or radiopaque reinforcement at specific radial struts. The localized concentration of radiopaque material compensates for the reduced overall mass and thickness inherent in small-diameter stents.
Solution Approach 2:
Small-diameter stents utilize composite construction with a higher proportion of radiopaque material integrated into the braid structure compared to larger stents. The radiopaque material may be applied as thin claddings on the biocompatible framework, creating a composite structure that maintains the small overall diameter while providing sufficient radiopaque signal for X-ray visualization of placement and deployment.
Data Source
AI summary
An implantable metallic braid is formed out of groups of filaments of a first material, groups of filaments of a second material different from the first material, and groups of filaments of a third material different from the first material and the second material. The filaments are braided together by a braiding machine and are arranged in a starting filament arrangement on the braiding machine before braiding begins, wherein the first material is a radiopaque material, the second material is a support material, and the third material is a DFT comprising the first and second materials. Different arrangements of the filaments in the starting filament arrangement and in the braid result in different levels of detail that can be observed in images of the braid, wherein certain arrangements of the filaments result in enhanced radiopacity without affecting other mechanical properties of the braid.