Stent Braid Pattern for Radial Strength and Deliverability
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Solution Overview
Problem
Existing stents face challenges in maintaining structural integrity and fluid flow while being constrained within small diameters, such as those required for bile duct placement, which can lead to migration and reduced efficacy in maintaining lumen patency.
Innovation Solution
The stent design incorporates a tubular body with a helical thread arranged along its length, providing enhanced axial and radial strength, improved fluid flow, and reduced resistance to migration. The stent is formed from a plurality of wires that create a mesh structure and twisted wire structure, optimizing performance when constrained within a delivery catheter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the stent is constrained within a small diameter delivery catheter, then the stent can be delivered to the target site, but the stent experiences increased radial compression and risk of migration
Solution Approach 1:
The stent employs a dynamic braid pattern with varying wire angles along its length. The wires are arranged at different angles (e.g., 45 degrees in the midportion, 30 degrees in the proximal/distal portions) to create zones with different mechanical properties. This dynamic structural variation allows the stent to flex and compress during delivery while maintaining radial strength when deployed
Solution Approach 2:
The stent is constructed from multiple wires woven together in a braid pattern, creating a composite structure. This woven architecture combines the properties of individual wires to achieve both compressibility for delivery and radial strength for vessel support, resolving the contradiction between deliverability and radial strength
2Reliability
If the stent is made with a more rigid structure to prevent migration, then structural integrity is improved, but the stent becomes more resistant to lateral flexion and harder to deliver
Solution Approach 1:
The stent is divided into multiple segments or zones along its length, with different braid patterns in each zone. The midportion has a different wire angle configuration compared to the proximal and distal portions. This segmentation allows each zone to perform its specific function: the midportion provides radial strength while the end portions provide flexibility for navigation and delivery
Solution Approach 2:
The stent utilizes parameter changes in the braid pattern, specifically varying the wire angles and pitch along the length of the stent. By changing these geometric parameters, the stent achieves different mechanical characteristics in different zones, balancing migration resistance with deliverability
3Ease of operation
If the stent elongates more than 150% when constrained, then the stent can accommodate delivery catheter constraints, but the stent loses structural integrity and radial strength
Solution Approach 1:
The dynamic braid pattern with varying wire angles creates zones that differently respond to compression. The configuration allows controlled elongation within acceptable limits while maintaining the overall structural integrity of the stent framework
Solution Approach 2:
The woven wire structure acts as a composite material system where the interlacing wires provide both flexibility for compression and structural integrity. The braid pattern ensures that elongation is distributed throughout the structure rather than concentrating stress at specific points
Data Source
AI summary
Stents described herein can comprise a tubular body having a midbody that extends to a first end and also extends to an opposing second end. The midbody can include a helical thread arranged along at least a portion of its length. The helical thread includes a plurality of turns with an interthread space disposed between the turns. The stent is formed from a plurality of wires woven or braided to form a mesh structure and a twisted wire structure. The twisted wire structure includes one or more pairs of wires longitudinally twisted together. The twisted wire structure can be disposed at one or more of the interthread space, the first end, and the second end.