Auxetic Venous Stent Geometry to Prevent Adjacent Vein Narrowing

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Solution Overview

Problem

Current stents designed for arterial use in venous stenosis treatment often occlude due to the redistribution of radial force into longitudinal forces, causing adjacent vein narrowing and incomplete expansion, which is exacerbated in post-thrombotic veins with increased stiffness.

Innovation Solution

The use of auxetic stents that expand longitudinally with radial expansion, controlling both radial and longitudinal biomechanical forces to improve luminal gain and prevent adjacent vein narrowing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If conventional stents are expanded radially in venous stenosis treatment, then radial force is applied to the vein, but longitudinal forces are redistributed causing adjacent vein narrowing and incomplete expansion

Engineering Contradiction:

Improveradial forceVSAvoidadjacent vein narrowing

Core Design Contradiction:

ForceVSObject-affected harmful factors

Solution Approach 1:

The patent applies the inversion principle by designing a stent with negative Poisson's ratio behavior, where radial expansion is coupled with longitudinal expansion instead of longitudinal compression. This inverts the conventional stent behavior and prevents the redistribution of radial force into harmful longitudinal forces that cause adjacent vein narrowing.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the Poisson's ratio parameter from positive (conventional) to negative (auxetic), fundamentally altering how the stent responds to radial expansion. This parameter change ensures that longitudinal forces are controlled and do not redistribute to cause adjacent vein narrowing, while still achieving effective radial expansion at the stenosis site.

Inventive Principle:

Principle #35Parameter changes

2Volume of moving object

If stents are used in post-thrombotic veins with increased stiffness, then venous luminal gain is needed, but the stiffness exacerbates force redistribution and occlusion risk

Engineering Contradiction:

Improvevenous luminal volumeVSAvoidocclusion risk

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The patent changes the Poisson's ratio parameter from positive to negative, which fundamentally alters the mechanical response of the stent in stiff post-thrombotic veins. This parameter change ensures that radial expansion does not convert into longitudinal compression, thereby reducing force redistribution and occlusion risk while achieving necessary luminal gain.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent inverts the conventional stent behavior by using auxetic geometry that expands longitudinally during radial expansion. This inversion is particularly beneficial in stiff post-thrombotic veins where conventional stents would redistribute forces and increase occlusion risk, while auxetic stents maintain controlled force distribution and improve reliability.

Inventive Principle:

Principle #13The other way round (Inversion)

3Ease of operation

If conventional stents expand radially, then stenosis is treated, but longitudinal compression occurs reducing treatment efficacy

Engineering Contradiction:

Improvestent deploymentVSAvoidexpansion control

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent inverts the conventional expansion behavior by designing auxetic stent geometry where radial expansion is coupled with longitudinal expansion rather than compression. This inversion allows for more predictable and controlled expansion characteristics, improving manufacturing precision and treatment efficacy.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the Poisson's ratio parameter to negative values, which provides more predictable expansion characteristics during deployment. This parameter change allows for better control over both radial and longitudinal dimensions, improving manufacturing precision and reducing variability in treatment outcomes.

Inventive Principle:

Principle #35Parameter changes

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

Auxetic stents enhance venous luminal volume and flow by actively managing longitudinal forces, reducing the likelihood of vein occlusion and improving treatment efficacy.

Implementation Method 1

The use of auxetic stents that expand longitudinally with radial expansion, controlling both radial and longitudinal biomechanical forces

Methodology Applied

Scientific EffectAuxetic effect: Auxetic Materials

Data Source

PatentUS12508139B2Auxetic stents for managing venous stenosis

Publication Date: 2025.12.30 OREGON HEALTH & SCI UNIV

AI summary

Stents useable for treating venous stenosis are disclosed. In embodiments, a stent is configured to be auxetic, expanding axially as it is expanded radially, to prevent the imposition of tension on portions of a blood vessel adjacent to the stented portion of the blood vessel, and thereby prevent a narrowing of the adjacent portions and improving luminal gain. The stent may include one or more cross members that are deformable axially, to allow the axial length of the stent to be adjusted while maintaining a constant diameter, and further to allow the stent to be curved to conform to vessel curvature.