Severable Stent Connectors for Axial Flexibility

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Solution Overview

Problem

Stents positioned in blood vessels adjacent to joints or bending planes, such as the superficial femoral artery, experience repeated and extreme axial loads or displacements, leading to inadequate deployment and coverage of the vessel wall, as traditional coiled stents often fail to provide sufficient resilience and flexibility.

Innovation Solution

The development of stents with severable or breakable connectors that can control the separation of stent segments under predetermined axial forces, foreshortening, or cyclic loading, allowing for enhanced flexibility and improved deployment by severing when specific thresholds are met, thereby accommodating vessel movement while maintaining scaffolding functionality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If traditional coiled stents are used to provide axial resilience, then flexibility is improved, but deployment performance and vessel coverage deteriorate

Engineering Contradiction:

Improveaxial flexibilityVSAvoiddeployment performance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The stent is divided into multiple axially adjacent segments that are connected by strain concentrating bridges. These bridges are designed with reduced cross-sectional area or notched features that allow them to yield and separate under extreme axial loads, enabling the stent to transition from a rigid deployed state to a flexible segmented state, thus resolving the contradiction between deployment performance and axial flexibility

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The connector geometry is specifically designed with parameter variations including reduced cross-sectional area, notched features, or slotted portions that create predetermined failure points. These geometric parameter changes allow the connector to withstand normal physiological loads while yielding under extreme axial compression, providing conditional flexibility only when needed

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If stent segments are kept connected to maintain structural integrity, then vessel coverage is improved, but ability to accommodate axial movement deteriorates

Engineering Contradiction:

Improvestructural integrityVSAvoidaxial movement accommodation

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The connector design transitions the stent system from a static permanently connected state to a dynamic conditionally connected state. The strain concentrating bridges remain intact during normal operation to maintain structural integrity, but automatically yield and separate when extreme axial loads exceed the bridge strength, allowing the stent to adapt its connectivity based on loading conditions

Inventive Principle:

Principle #15Dynamics

3Adaptability or versatility

If connector thickness is reduced to enable severing, then flexibility is improved, but connector strength deteriorates

Engineering Contradiction:

ImproveseverabilityVSAvoidconnector strength

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The connector is designed with non-uniform geometry where specific portions have reduced thickness or cross-sectional area while other portions maintain full strength. This local quality variation creates predetermined weak points that will yield under extreme loads while preserving overall connector integrity and strength during normal physiological conditions

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The connector geometry is pre-designed with strain concentrating features such as notches, slots, or thinned sections that create predetermined failure points. This preliminary geometric configuration ensures that when extreme axial loads occur, the connector will fail in a controlled manner at the predetermined location rather than randomly, enabling reliable severability

Inventive Principle:

Principle #10Preliminary action

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 stents with severable connectors demonstrate improved flexibility and deployment efficiency, accommodating significant foreshortening and bending while preventing vessel prolapse, thus enhancing the stent's ability to maintain vessel patency and reduce the risk of restenosis.

Implementation Method 1

The connector is configured such that the third portion thereof severs when the stent experiences either a predetermined axial force, a predetermined axial foreshortening, or a predetermined level of cyclic loading or fatigue

Methodology Applied

Scientific EffectStress concentration:

Implementation Method 2

Methodology Applied

Scientific EffectFatigue: Fatigue

Data Source

PatentEP2816971B1Stent having at least one connecting member configured to controllably sever in vivo

Publication Date: 2018.10.10 CELONOVA STENT

Figure 1
Figure 2A~2B
Figure 3

AI summary

A stent may include a connector having a first portion, a second portion, and a third portion positioned between the first and second portions. The connector may be configured to interconnect axially adjacent stent segments. The connector may be further configured such that the third portion severs in response to a threshold amount of axial force, axial foreshortening, and/or cyclic loading or fatigue, in order to predispose the severance of one or more pre-configured connectors in a controlled manner to minimize any potential harm to the surrounding vasculature of a patient.