Polymeric Stent Delivery System Crimping Control

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Solution Overview

Problem

Conventional stent delivery systems for polymeric tubular implants face challenges such as damage during delivery, stress relaxation due to prolonged crimped configuration, and inadequate control over implant release, particularly for self-expanding stents.

Innovation Solution

A delivery system comprising an inner shaft with a soft tip, an expandable member, and a tubular outer shaft, allowing for controlled crimping and self-expansion of polymeric tubular implants, enabling loading just prior to implantation and minimizing stress on the implant during shipping and storage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If polymeric stents are crimped for extended shipping and storage, then delivery is enabled, but stress relaxation and permanent deformation occur

Engineering Contradiction:

Improvedelivery capabilityVSAvoidstress relaxation

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The stent is crimped onto the inner shaft immediately before implantation rather than in advance, eliminating prolonged crimped storage. The expandable member is pre-positioned but only engages the stent when deployed, performing the crimping action at the last possible moment to avoid stress relaxation during shipping.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The delivery system divides the crimping function across multiple components: the inner shaft provides the crimping surface, the expandable member provides radial compression force, and the outer shaft protects the assembly. This segmentation allows controlled crimping only when all components are properly positioned, preventing premature or excessive compression.

Inventive Principle:

Principle #1Segmentation

2Strength

If conventional delivery systems grasp stent at isolated locations, then stent retention is achieved, but localized stress and permanent deformation occur

Engineering Contradiction:

Improvestent retentionVSAvoidlocalized stress

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The expandable member transforms the stress distribution from localized (conventional) to distributed (innovative). When expanded, it applies radial compression force uniformly across the entire circumference of the stent, ensuring even stress distribution and preventing permanent deformation at any single location while maintaining secure retention.

Inventive Principle:

Principle #3Local quality

3Object-affected harmful factors

If polymeric stents are made less strong than metallic counterparts, then biocompatibility improves, but structural integrity during delivery deteriorates

Engineering Contradiction:

ImprovebiocompatibilityVSAvoidstructural integrity

Core Design Contradiction:

Object-affected harmful factorsVSStrength

Solution Approach 1:

The expandable member acts as a cushioning element that protects the polymeric stent from excessive mechanical stress during delivery. By providing controlled radial support and distributing compression forces evenly, it prevents localized stress concentrations that could cause permanent deformation, thereby compensating for the polymer's lower inherent strength compared to metal.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

4Device complexity

If conventional delivery systems lack control over stent release, then delivery simplicity is maintained, but implantation precision deteriorates

Engineering Contradiction:

Improvedelivery simplicityVSAvoidimplantation precision

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The system incorporates mechanical feedback through the interaction between the expandable member and the stent. As the expandable member expands, it progressively engages and compresses the stent, providing tactile and mechanical feedback that ensures complete engagement before release. This feedback mechanism prevents premature or incomplete stent deployment, enhancing implantation precision.

Inventive Principle:

Principle #23Feedback

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 system effectively delivers polymeric tubular implants without damage, reduces stress relaxation, and ensures controlled expansion and secure placement within bodily lumens, improving the safety and efficacy of polymeric stent deployment.

Implementation Method 1

The first expandable member includes a proximal end having a cross-sectional dimension that is less than a diameter of the polymeric tubular implant when the polymeric tubular implant is in an unstressed configuration

Methodology Applied

Scientific EffectRadial compression: Compression

Implementation Method 2

At least a portion of the inner shaft has a diameter less than a diameter of the polymeric tubular implant when it is in an unstressed configuration, such that the implant can fit over that portion of the inner shaft

Methodology Applied

Scientific EffectElastic recovery: Elastic Recovery

Data Source

PatentUS9198783B2Polymeric implant delivery system

Publication Date: 2015.12.01 LYRA THERAPEUTICS INC

AI summary

Delivery systems for a polymeric tubular implant, kits that include such delivery systems, and methods of treating patients by implanting tubular implants using the delivery systems. The delivery systems include an inner shaft, an expandable member slidably disposed about the inner shaft and configured to receive the tubular implant, and a tubular outer shaft disposed about the inner shaft.