Expandable Guidewire Segment for Catheter Locking

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Solution Overview

Problem

Catheters face challenges in navigating through stenosed regions of body vessels due to their flexibility, which leads to 'snaking' and inability to pass through constricted areas, and existing stent delivery systems require intricate constructions that increase stiffness, limiting the use of longer stents.

Innovation Solution

A guidewire with an expandable segment that can move between a collapsed and expanded state to lock onto the catheter, enhancing pushability and crossability through stenosed regions, and a 'inchworm' motion mechanism using multiple expandable segments for further advancement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a catheter is made flexible to follow the guidewire path through tortuous vessels, then the catheter can navigate complex anatomy, but it cannot effectively push through stenosed regions due to snaking and compression

Engineering Contradiction:

Improvecatheter flexibilityVSAvoidpushability through stenosis

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The catheter is divided into multiple segments with different stiffness characteristics. A proximal stiff segment provides pushability through stenosed regions, while a distal flexible segment follows the guidewire path through tortuous vessels. This segmentation allows the catheter to simultaneously exhibit both flexibility for navigation and stiffness for advancement.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the catheter are assigned different mechanical properties. The proximal portion is made stiffer to provide pushing force, while the distal portion is made more flexible to conform to vessel geometry. This local differentiation of material properties resolves the contradiction between overall flexibility and localized pushability.

Inventive Principle:

Principle #3Local quality

2Ease of operation

If the catheter is made stiffer to press through stenosed regions, then pushability improves, but the catheter diameter increases and prevents use of longer stents

Engineering Contradiction:

Improvepushability through stenosisVSAvoidcatheter diameter

Core Design Contradiction:

Ease of operationVSVolume of moving object

Solution Approach 1:

The catheter is segmented into a proximal stiff portion and a distal flexible portion. Only the proximal segment requires increased stiffness for pushing through stenosis, while the distal segment maintains flexibility and smaller diameter. This allows the catheter to provide necessary pushability without increasing overall diameter, enabling use of longer stents.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Stiffness is localized to the proximal portion of the catheter where it is needed for pushing through stenosed regions. The distal portion maintains smaller diameter and flexibility. This local concentration of stiffness avoids the need to increase the entire catheter diameter, preserving compatibility with longer stents.

Inventive Principle:

Principle #3Local quality

3Reliability

If an intricate construction is provided to ensure proper operation of stent delivery systems, then operational reliability improves, but catheter stiffness increases and diameter increases

Engineering Contradiction:

Improveoperational reliabilityVSAvoidcatheter construction

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The catheter construction is segmented into functional portions with distinct roles. The proximal stiff segment handles pushing through stenosis, while the distal flexible segment handles navigation. This functional segmentation simplifies the overall design compared to making the entire catheter complex and stiff, while maintaining operational reliability through specialized sections.

Inventive Principle:

Principle #1Segmentation

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

Enables navigation of flexible catheters through stenosed regions and facilitates the delivery of longer stents by providing enhanced stiffness and frictional engagement, reducing the need for complex catheter designs and preventing 'snaking', allowing for more effective stent deployment.

Implementation Method 1

The expandable segment engages an inner surface of the medical device... Frictional engagement

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 2

an expandable segment movable between a collapsed state and an expanded state

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS8142468B2Guidewire with distal expansion feature and method for enhancing the deliverability and crossability of medical devices

Publication Date: 2012.03.27 CORDIS US CORP

AI summary

A guidewire navigable through body vessels of a human subject for delivery of a catheter or the like is provided. The guidewire includes an expandable segment movable between a collapsed state and an expanded state. If the catheter encounters resistance in a vessel and cannot be advanced further, the medical professional can move the expandable segment to the expanded state in which the expandable segment engages an inner surface of the catheter. The expandable segment locks onto the catheter, which allows the guidewire and catheter to be advanced through the vessel together as a single unit. An inflatable balloon catheter movable along the guidewire requires only a single tube and is sealed by the expandable segment of the guidewire for subsequent inflation.