Multilayered Stent Graft with Elastomeric Cell Barrier

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Solution Overview

Problem

Current stent grafts face challenges in preventing cellular migration and occlusion within body lumens, as existing materials are not adequately impermeable to cells, leading to reduced durability and effectiveness in maintaining lumen patency.

Innovation Solution

A stent graft design featuring a multilayered structure with a rotationally spun PTFE first layer for endothelial cell growth, a cell-impermeable elastomeric polymer second layer to inhibit cellular migration, and a third layer of ePTFE for strength, configured to maintain impermeability and expandability without compromising biocompatibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a porous material is used to allow endothelial cell growth, then biocompatibility is improved, but cellular impermeability deteriorates

Engineering Contradiction:

ImprovebiocompatibilityVSAvoidcellular migration

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The stent graft is divided into multiple functional layers: a first layer (e.g., PTFE) that is porous to allow endothelial cell growth and biocompatibility, and a second layer (e.g., elastomeric polymer) that is impermeable to prevent cellular migration. This segmentation allows each layer to perform its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The stent graft uses a composite structure combining different materials with complementary properties. The first layer uses biocompatible porous material for endothelialization, while the second layer uses impermeable elastomeric polymer for cellular barrier function. The composite structure achieves both biocompatibility and cellular impermeability simultaneously.

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If an impermeable layer is added to prevent cellular migration, then cellular impermeability is improved, but device complexity increases

Engineering Contradiction:

Improvecellular migrationVSAvoidmultilayered structure

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The device is segmented into distinct functional layers, with each layer having a specific thickness and material composition optimized for its function. The impermeable second layer is positioned strategically to provide cellular barrier function while maintaining overall device simplicity through clear functional division.

Inventive Principle:

Principle #1Segmentation

3Reliability

If the stent graft is made expandable to maintain lumen patency, then effectiveness is improved, but manufacturing precision requirements increase

Engineering Contradiction:

Improvelumen patencyVSAvoidlayer alignment

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The stent graft uses flexible thin film layers that can be crimped for delivery and then expanded at the implantation site. The elastomeric polymer second layer provides flexibility and elastic recovery, allowing the device to be compressed for delivery through catheters and then expand to maintain lumen patency while the layers remain properly aligned.

Inventive Principle:

Principle #30Flexible shells and thin films

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 multilayered stent graft effectively prevents cellular migration and occlusion, extending its lifespan and maintaining lumen patency by combining endothelial compatibility with cellular impermeability and structural integrity.

Implementation Method 1

a rotationally spun PTFE first layer for endothelial cell growth

Methodology Applied

Scientific EffectEndothelial cell growth:

Implementation Method 2

a cell-impermeable elastomeric polymer second layer to inhibit cellular migration

Methodology Applied

Scientific EffectCellular impermeability:

Implementation Method 3

configured to maintain impermeability and expandability without compromising biocompatibility

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS20230293774A1Stent graft with elastomeric impermeable layer

Publication Date: 2023.09.21 MERIT MEDICAL SYSTEMS INC

AI summary

Medical appliances, such as stent grafts, may be formed of a cover and a scaffolding. The cover is composed of multiple layers of polymeric materials. A luminal layer is formed of rotational spun fibers of polytetrafluoroethylene. An abluminal layer is formed of expanded polytetrafluoroethylene. The scaffolding is disposed between the luminal layer and the abluminal layer. A cell impermeable layer is also disposed between the luminal layer and the abluminal layer. The cell impermeable layer is formed of an elastomeric material. The cell impermeable layer is impervious to cell migration across the layer when the stent graft is in a nominal state and in an expanded state. The stent graft is free of pleats or wrinkles when the stent graft is in the nominal state and in the expanded state.