Covered Stent Wire Head Stability and Deployment
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Solution Overview
Problem
Existing covered stents face issues with loose wire heads at the small wave ring ends, leading to potential breakage, type IV endoleaks, and incomplete deployment due to poor fatigue resistance and tilting wire heads, which can cause type I endoleaks and affect the therapeutic efficacy and surgical risks.
Innovation Solution
A covered stent design featuring a first wave ring formed by braided wires with wound wire heads and limiting units that restrict axial and radial movement of the wire heads relative to the wire rod, using strip structures or projections to enhance stability and prevent tilting, and optionally incorporating a covering unit to protect the film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the wire heads are simply wound around the wire rod to form a stable closed ring structure, then the manufacturing process is simple and the ring structure is stable, but the wire heads can easily become loose after compression and release, causing tilting and breakage
Solution Approach 1:
The wire heads are pre-formed with specific curvature and diameter before winding around the wire rod. This preliminary shaping ensures that when the wire heads are wound and compressed, they maintain their form and do not tilt or break, resolving the issue of wire head instability while keeping the manufacturing process simple
Solution Approach 2:
The wire heads are designed with specific parameters (curvature radius, diameter) that are optimized to prevent tilting and breakage during compression and release. By controlling these geometric parameters, the wire heads maintain stability without requiring complex fixation structures
2Reliability
If a stainless steel sheath or complicated winding method is used to fix the wire heads, then the wire head stability is improved, but the small diameter wire is likely to break or damage, resulting in poor fatigue resistance
Solution Approach 1:
The wire heads are designed with locally optimized properties - specifically, they have a larger diameter and different curvature characteristics compared to the main wire body. This local quality enhancement provides stability and prevents breakage at the wire head region without compromising the fatigue resistance of the overall structure
Solution Approach 2:
Instead of using a stainless steel sheath or complicated winding method to fix wire heads (which causes breakage), the invention inverts the approach by making the wire heads themselves have inherent stability through optimized geometry and material properties, eliminating the need for external fixation that would compromise fatigue resistance
3Reliability
If the wire heads are made with larger diameter and different curvature, then the adherence to vessel wall is improved and sealing performance is increased, but the wire heads may catch the covering film during deployment, causing incomplete deployment and type I endoleak
Solution Approach 1:
The wire heads are designed with specific parameter ranges (diameter, curvature radius) that balance sealing performance with deployment ease. The curvature radius is carefully controlled to ensure the wire heads can pass through the covering film during deployment without catching it, while still providing adequate sealing against the vessel wall
Solution Approach 2:
The wire heads are designed with flexible curvature characteristics that allow them to adapt dynamically during deployment. The curvature can flex and adjust as the stent is deployed, enabling the wire heads to pass through the covering film smoothly while maintaining sealing contact with the vessel wall after deployment
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 solution effectively prevents wire head loosening and tilting, enhancing the structural stability of the stent, reducing the risk of endoleaks, and ensuring complete deployment, thereby improving the therapeutic effectiveness and safety of the device.
Implementation Method 1
the strip structure is made of hot-melt material and is bonded to the wire rod and the wire head by means of heat treatment
Data Source
AI summary
A covered stent (100) includes a first wave ring (20) provided on at least one end of the covered stent (100), wherein the first wave ring (20) is formed of braided wires by means of braiding; each of the braided wires has wire heads (21) and a wire rod (22), with the wire heads (21) being located at two ends of the wire rod (22); and the wire heads (21) of the braided wire are wound around the adjacent wire rod (22); and the covered stent (100) further includes a limiting unit (40), with the limiting unit (40) being arranged on the wire head (21) and the wire rod (22) adjacent to the wire head (21), and the limiting unit (40) limiting the range of axial and/or radial movement of the wire head (21) relative to the wire rod (22).