Stent Twist Cancellation Geometry for Foreshortening Reduction
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Solution Overview
Problem
Intraluminal medical devices, such as stents, experience foreshortening during deployment, which makes it challenging to accurately position them within the body vessel due to uncertainty in deployed diameter and length, leading to less than optimal performance.
Innovation Solution
The design incorporates adjacent hoop structures that are rotationally out of phase and flexible links with alternating orientations to minimize foreshortening and axial twist during stent deployment, ensuring accurate positioning and reduced compressibility of the stent components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the stent is expanded using a balloon catheter, then the stent can be deployed to the desired location, but the stent experiences foreshortening and axial twist during expansion
Solution Approach 1:
The stent is divided into multiple hoop sections (first hoop section, second hoop section, etc.) that are rotationally out of phase relative to each other. This segmentation allows each section to expand independently, reducing the cumulative foreshortening and axial twist effects that occur in conventional monolithic stent designs during balloon expansion.
Solution Approach 2:
Adjacent hoop sections are designed with asymmetric rotational positioning (out of phase) rather than symmetric alignment. This asymmetric configuration creates a more uniform distribution of stress during expansion, minimizing axial compressive forces and reducing foreshortening while maintaining deployment controllability.
2Strength
If the stent diameter is increased for better vessel support, then the stent provides better mechanical strength, but the stent foreshortening increases making positioning more difficult
Solution Approach 1:
The stent structure is segmented into multiple hoop sections that can be independently positioned and expanded. This segmentation allows the stent to maintain its overall length accuracy even when individual sections experience foreshortening during expansion, as the out-of-phase configuration distributes the length change more uniformly across the entire stent.
Solution Approach 2:
The rotational phase angle between adjacent hoop sections is optimized to minimize the relationship between stent diameter and foreshortening. By adjusting this geometric parameter, the design achieves sufficient vessel wall support at larger diameters while controlling the axial length change during expansion.
3Adaptability or versatility
If the stent is made more flexible to facilitate delivery through curved vessels, then the stent can be delivered to difficult-to-access locations, but the stent experiences greater axial twist and foreshortening during deployment
Solution Approach 1:
The stent is segmented into multiple hoop sections connected by flexible links, allowing the structure to bend and adapt to curved vessel anatomy during delivery. The out-of-phase rotational configuration of these segments provides stability during deployment by distributing and canceling axial twist forces that would otherwise cause significant foreshortening.
Solution Approach 2:
The stent design incorporates dynamic characteristics where the flexible links between hoop sections allow the stent to adapt its shape during delivery through curved vessels, while the out-of-phase hoop configuration provides dynamic stability during deployment by opposing axial twist forces.
Data Source
AI summary
This invention relates generally to an expandable intraluminal medical device for use within a body passageway or duct, and more particularly to a stent having a plurality of hoop sections. Each hoop section comprises a tubular configuration of structural elements having proximal and distal open end, and defining a longitudinal axis extending there between. A set of flex connectors connects each adjacent hoop section. Each set of flex connectors comprises one or more flex connector members arranged in the same geometric orientation. Adjacent sets of flex connectors comprise one or more flex connector members arranged in an opposite geometric orientation.