Atraumatic Stent Loop Ends and Composite Wire Welds
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing stents with mechanical welds often have sharp ends that can irritate delivery systems or bodily vessels and may fatigue over time, leading to undesirable failure.
Innovation Solution
A stent with atraumatic looped ends and improved welds is developed, using composite wires with radiopaque materials for enhanced visibility and fluoroscopic imaging, and welds that are offset and overlapping to increase fatigue life, with wire ends smoothed to remove sharp edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical welding is used to close loose wire ends, then the stent structure is secured, but sharp ends are created that can score the delivery system and irritate bodily vessels
Solution Approach 1:
The wire ends are formed into loops with rounded contours instead of sharp ends. The looping process creates curved geometries that eliminate sharp edges, reducing trauma to the delivery system and bodily vessels while maintaining structural security through the closed-loop configuration.
Solution Approach 2:
The welding process, which originally created harmful sharp ends, is modified to create beneficial rounded loop structures. The welds are positioned to form smooth, continuous curves that convert the potential harm of sharp wire ends into the benefit ofatraumatic, structurally sound closed loops.
2Ease of manufacture
If traditional welds are used to join wires, then the stent is assembled, but the welds may fatigue over time leading to failure
Solution Approach 1:
The wire ends are pre-formed into loops with rounded contours before welding. This preliminary shaping ensures that the welds connect smooth, curved surfaces rather than sharp edges, distributing stress more evenly and reducing fatigue initiation points before the stent is even assembled.
Solution Approach 2:
The welded joints are designed with curved, rounded geometries rather than sharp angles. This curvature distributes mechanical stresses more uniformly across the weld zone, reducing stress concentration points that would otherwise initiate fatigue cracks over time.
3Adaptability or versatility
If standard metallic wires are used, then the stent is flexible and biocompatible, but visibility for imaging is reduced
Solution Approach 1:
The stent uses composite wire construction combining biocompatible metallic materials with radiopaque materials. This composite structure maintains the flexibility and biocompatibility of medical-grade metals while adding radiopaque properties for enhanced visibility during fluoroscopic and x-ray imaging procedures.
Solution Approach 2:
The wire structure incorporates radiopaque materials that alter its interaction with imaging radiation, making the stent visible under fluoroscopic and x-ray imaging. This is analogous to changing the optical properties of a material to make it detectable, but in the context of radiographic imaging rather than visible light.
Data Source
AI summary
An implantable stent includes a plurality of elongate wires braided to form a hollow tubular structure having a tubular wall to define an interior surface and an exterior surface and having opposed open first and second ends, wherein the opposed open first and second ends are atraumatic ends The atraumatic ends of the stent are desirably free of any loose wire ends. The wires include composite wires to enhance visibility of the wires to provide improved external imaging of the wires in the body. The elongate composite wires of the stent may be metallic wires having an outer metallic portion including a first metal, such as nitinol, and an inner metallic core portion including a second metal, which is a radiopaque material, such as gold, barium sulfate, ferritic particles, platinum, platinum-tungsten, palladium, platinum-iridium, rhodium, tantalum or combinations thereof.