Stent flexibility via S-shaped crosslink connectors
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Solution Overview
Problem
Existing intravascular stents face challenges in balancing flexibility and radial strength, leading to excessive shortening under modest longitudinal compressive loads, which affects safety and efficacy.
Innovation Solution
The development of stents with increased flexibility, featuring a configuration of annular supports and crosslink connectors, such as S-shaped and omega-shaped connectors, that allow for greater expansion with reduced foreshortening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If two-link offset peak-to-peak stent pattern is used, then radial strength and radial stiffness are improved, but longitudinal stability deteriorates due to excessive shortening under compressive loads
Solution Approach 1:
The stent is divided into multiple rings connected by links, with each ring containing multiple struts arranged in a peak-to-peak pattern. This segmentation allows the structure to achieve high radial strength through dense packing while distributing longitudinal compressive loads across multiple connection points, preventing excessive shortening.
Solution Approach 2:
The stent employs an offset peak-to-peak pattern where adjacent peaks are circumferentially offset rather than perfectly aligned. This asymmetric arrangement creates a more stable longitudinal structure that resists compressive forces while maintaining high radial strength, eliminating the excessive shortening problem of symmetric offset designs.
2Strength
If stent is designed with high radial rigidity to hold open vessel, then radial strength is improved, but flexibility deteriorates
Solution Approach 1:
Different regions of the stent have optimized local structures: the rings are designed with sufficient rigidity to maintain vessel patency, while the links and connectors are designed with appropriate flexibility to allow navigation through curved vessels. This local optimization enables the stent to simultaneously achieve high radial rigidity and necessary flexibility.
3Strength
If stent is designed with high radial strength to hold back dissected arterial lining, then radial strength is improved, but flexibility and crimpability deteriorate
Solution Approach 1:
The stent structure is designed to be dynamically adaptable, allowing it to be crimped onto a catheter for delivery and then expanded to its full diameter for deployment. The ring-link construction with offset peak-to-peak patterns provides the necessary radial strength when expanded while maintaining the ability to be compressed for delivery, resolving the contradiction between radial strength and crimpability.
Data Source
AI summary
Stents that are adapted to be balloon-expanded and include a plurality of rings of repeating cells, wherein adjacent rings are connected by s-shaped or omega-shaped crosslink connectors or a combination of both connectors. The configurations, materials, and/or dimensions of these devices, including the unit cells and/or crosslink connectors allow the stents to be expanded to a greater extent (e.g., up to or greater than 12 mm of diameter), and optionally with reduced foreshortening and without increasing the strain on the materials forming the crosslink connectors and unit cells. The biphasic arrangement of trapezoidal unit cells, as well as the configuration and arrangement of the s-shaped connectors, may allow these stents to expand while maintaining their radial compression strength and longitudinal compression strength with minimal recoil and stent foreshortening.