Stent Movable Protrusion for Stable Indwelling

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Solution Overview

Problem

Existing stents face challenges in maintaining a stable position within a living body lumen due to interference from body fluids and misalignment during deployment, as they can follow bidirectional movement of the sheath, leading to poor indwelling and potential obstruction of fluid flow.

Innovation Solution

A stent with a movable protruded portion that locks onto the sheath's ridge portion in the contracted state, preventing movement and minimizing fluid interference, and is formed with a shape memory alloy for easy expansion and contraction, ensuring accurate placement and stable indwelling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the rivet protrudes beyond the inner side of the stent to prevent it from following sheath movement, then the stent can be restricted from moving along the shaft, but interference with the flow of body fluid occurs

Engineering Contradiction:

Improvestent position stabilityVSAvoidbody fluid flow interference

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The stent incorporates a movable protruded portion that can dynamically change its position between protruding (for locking) and retracted (for fluid flow). This dynamic structure allows the stent to adapt its configuration based on operational requirements, resolving the contradiction between needing protrusion for stability and retraction for fluid flow.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The protruded portion changes its protrusion parameter based on the stent's state. In the contracted state, it protrudes to engage with the ridge portion for reliable positioning. In the expanded state, it retracts to minimize fluid interference. This parameter change resolves the contradiction by adapting the protrusion level to different operational phases.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If the stent is exposed by sheath rearward movement to achieve lesion placement, then the stent can be positioned in the living body lumen, but poor indwelling or misalignment may occur

Engineering Contradiction:

Improvestent deployment flexibilityVSAvoidstent indwelling accuracy

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The stent is pre-configured with the movable protruded portion that automatically engages with the ridge portion during sheath movement. This preliminary configuration ensures that as the sheath moves rearward to expose the stent, the protruded portion is already positioned to lock onto the ridge, preventing misalignment and ensuring accurate indwelling from the outset.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The interaction between the movable protruded portion and the ridge portion provides mechanical feedback during deployment. As the sheath moves, the protruded portion's engagement status gives real-time feedback on stent positioning, allowing the operator to confirm proper indwelling and make adjustments if misalignment occurs.

Inventive Principle:

Principle #23Feedback

3Ease of operation

If the stent follows bidirectional sheath movement to maintain sheath-stent connection, then the stent can be easily delivered, but accurate expansion at desired position becomes difficult

Engineering Contradiction:

Improvestent delivery easeVSAvoidstent expansion position accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The stent structure is segmented into the main stent body and the movable protruded portion. This segmentation allows the protruded portion to independently interact with the ridge portion during delivery, providing restriction force that prevents the stent from following sheath movement bidirectionally, thereby enabling accurate positioning while maintaining ease of delivery.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The movable protruded portion acts as an intermediary mechanism between the stent and the ridge portion. It mediates the interaction by engaging with the ridge to provide restriction force during delivery, preventing unwanted stent movement, while allowing controlled expansion at the desired position without following bidirectional sheath movement.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 stent effectively prevents movement relative to the sheath, allowing for precise expansion and stable indwelling, minimizing fluid interference and ensuring reliable placement within the body lumen.

Implementation Method 1

the stent is formed with a shape memory alloy for easy expansion and contraction

Methodology Applied

Scientific EffectShape memory alloy: Shape Memory Alloy

Data Source

PatentUS9925073B2Stent

Publication Date: 2018.03.27 TERUMO KK

AI summary

A stent is disclosed, which is formed in a cylindrical shape and has a cavity portion, and is freely switched between an expanded state and a contracted state where the stent contracts to a central axis (O) side from the expanded state. The stent has an anchor portion which protrudes to a central axis (O) side relative to an inner surface surrounding the cavity portion in the contracted state, and which is displaced to the inner surface side in the expanded state relative to a protruded position in the contracted state.