Stent Delivery Filament Inversion for Secure Coupling

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Solution Overview

Problem

Conventional stent delivery systems face issues with incomplete uncoupling of stents and pusher catheters, risk of filament entanglement, complexity due to multiple parts, and difficulty in applying systems to stents without flaps, leading to inadvertent uncoupling and increased risk of filament entrapment.

Innovation Solution

A tube stent delivery system featuring a filament with a knot tied to the pusher catheter or stent through a radial opening, with a catching hole that loosely fits the knot, allowing the inner catheter to support the knot's position and prevent inadvertent uncoupling, and enabling the filament to be moved inside the stent for easy removal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a filament loop is positioned within a slot on the stent from outside, then the stent and pusher catheter can be coupled, but the stent and pusher catheter may not be uncoupled completely because the loop may not move out of the slot smoothly

Engineering Contradiction:

Improvecoupling reliabilityVSAvoiduncoupling ease

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The filament is inserted into the stent from the inside through a radial opening, reversing the conventional approach of inserting from outside. This inversion allows the filament to be pulled out cleanly from the inside, enabling complete uncoupling without the loop getting stuck in the slot.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The filament is extracted from the stent through a radial opening from the inside, allowing clean removal without the loop remaining trapped in the slot. This extraction approach ensures complete uncoupling while maintaining secure coupling during delivery.

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If a filament loop is positioned within a passage from outside the stent, then coupling can be achieved, but the loop may be hooked by a flap preventing smooth uncoupling

Engineering Contradiction:

Improvecoupling reliabilityVSAvoiduncoupling ease

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The filament insertion direction is inverted from outside-to-inside to inside-to-outside through a radial opening. This reversal prevents the loop from being hooked by flaps during uncoupling, as the filament is pulled from the inside where it cannot be caught by external flaps.

Inventive Principle:

Principle #13The other way round (Inversion)

3Ease of operation

If the filament is directed to the outside of the stent for removal, then uncoupling can be achieved, but the risk that the filament is caught by the stent increases

Engineering Contradiction:

Improveuncoupling easeVSAvoidfilament entrapment risk

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The filament is inserted from the inside through a radial opening and pulled out from the inside, reversing the conventional outside-to-inside direction. This inversion ensures the filament is pulled from a safe zone where it cannot be caught by the stent structure, eliminating entrapment risk.

Inventive Principle:

Principle #13The other way round (Inversion)

4Reliability

If a locking member or lead-in member is added to secure coupling, then coupling reliability improves, but the number of parts increases and the system becomes complex

Engineering Contradiction:

Improvecoupling reliabilityVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The locking member and lead-in member are completely removed from the system. The coupling security is achieved solely through the filament inserted from the inside, eliminating unnecessary parts while maintaining reliable coupling and enabling clean uncoupling.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The filament serves multiple functions: it provides coupling security, enables controlled uncoupling, and eliminates the need for separate locking mechanisms. This merging of functions reduces system complexity while maintaining reliability.

Inventive Principle:

Principle #5Merging (Combining)

5Reliability

If the knot is tightly fitted in the catching hole, then coupling security improves, but the filament cannot be moved inside the stent for easy removal

Engineering Contradiction:

Improvecoupling securityVSAvoidremoval ease

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The knot's fit in the catching hole is designed to be dynamically adjustable. During delivery, the knot can be pulled tight for secure coupling. During removal, the knot can be loosened and moved inside the stent for clean extraction. This dynamic behavior provides both security and ease of operation.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The catching hole is pre-designed with a size that allows the knot to be pulled through during removal. This preliminary design enables the knot to be moved inside the stent for easy extraction while maintaining secure coupling during delivery.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP2526903B1Stent delivery system

Publication Date: 2017.05.24 GADELIUS MEDICAL

Figure 1~2(c)
Figure 3(a)~3(c)
Figure 4(a)~4(e)

AI summary

A stent delivery system has a pusher catheter (12) having an opening to which a filament (24) is tied to the distal end thereof, and a stent (30) having a catching hole (34). Because a knot (22) is loosely fit in the catching hole from inside, with an inner catheter supporting the loose-fitting, inadvertent uncoupling of the stent and the pusher catheter can be prevented until the inner catheter is pulled out, and the two can be easily uncoupled by pulling out the inner catheter.