Multilayer Braided Prosthesis for Aneurysm Branch Patency

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Solution Overview

Problem

Current endovascular repair techniques for aortic aneurysms involving branches, such as coronary arteries and renal arteries, are ineffective due to impermeable stent grafts causing branch occlusion, leading to serious complications.

Innovation Solution

A self-expandable, multilayer braided endoluminal prosthesis with a cylindrical lumen and interlocked wire layers, devoid of an impermeable cover layer, allowing for branch patency by converting turbulent blood flow into laminar flow and forming a thrombus in the aneurysmal sac without obstructing branch blood flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an impermeable stent graft is used for endovascular repair of aortic aneurysm, then the aneurysm is effectively sealed and excluded from blood flow, but important branches (coronary arteries, renal arteries, visceral arteries) become occluded causing serious complications

Engineering Contradiction:

Improveaneurysm exclusion effectivenessVSAvoidbranch occlusion

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent employs a porous or permeable stent graft material that allows selective passage of blood flow. The graft structure incorporates controlled porosity enabling diffusion of blood cells and plasma through the graft wall, thereby maintaining patency of branch vessels while still providing aneurysm exclusion. This resolves the contradiction by allowing the graft to be both effective for aneurysm sealing and permeable to branch flow.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The stent graft is designed with spatially varying properties - the proximal and distal sealing zones have different permeability characteristics compared to the intermediate section. The graft may feature localized fenestrations or varying mesh densities in specific regions to accommodate branch vessel locations. This local differentiation allows effective aneurysm exclusion in the main body while preserving branch patency where needed.

Inventive Principle:

Principle #3Local quality

2Object-affected harmful factors

If a permeable braided framework is used to maintain branch patency, then branch blood flow is preserved, but the structural strength and sealing capability of the prosthesis may be compromised

Engineering Contradiction:

Improvebranch occlusion preventionVSAvoidprosthesis structural strength

Core Design Contradiction:

Object-affected harmful factorsVSStrength

Solution Approach 1:

The stent graft combines multiple materials with complementary properties - a strong metallic or polymer framework providing structural support and radial strength, combined with a porous coating or integrated permeable layer that enables branch flow. This composite construction maintains both mechanical integrity for aneurysm exclusion and permeability for branch patency, resolving the strength-permeability contradiction.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The design features a nested structure where an inner porous layer or coating is integrated within or upon the outer structural framework. The braided framework provides the load-bearing skeleton while the nested permeable layer handles the flow distribution function. This nesting allows each component to optimize its specific function without compromising the other.

Inventive Principle:

Principle #7Nested doll (Nesting)

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 prosthesis ensures unobstructed blood flow to branches, improving perfusion and reducing aneurysmal turbulence, potentially shrinking the aneurysm while maintaining branch patency, as demonstrated by increased blood velocity simulations and thrombus formation.

Implementation Method 1

a first self-expandable braided framework (20) able to expand from a radially compressed state in a delivery configuration to a radially expanded state

Methodology Applied

Scientific EffectElastic memory: Elasticity

Implementation Method 2

allowing for branch patency by converting turbulent blood flow into laminar flow and forming a thrombus in the aneurysmal sac

Methodology Applied

Scientific EffectTurbulent flow conversion to laminar flow: Laminar Flow

Implementation Method 3

forming a thrombus in the aneurysmal sac without obstructing branch blood flow

Methodology Applied

Scientific EffectThrombus formation: Coagulation

Data Source

PatentUS11540930B2Implantable endoluminal prosthesis

Publication Date: 2023.01.03 INTRESSA VASCULAR SA

AI summary

An implantable endoluminal prosthesis for use in the treatment of aneurysm involving branches is described, where at least one self-expandable braided framework extending along an axis is able to expand from a radially compressed state in a delivery configuration to a radially expanded state. The self-expandable braided framework includes a plurality of layers of wires made of biocompatible material forming a lattice with a plurality of wires of said layers; the wires being integrated in the mesh of at least one of the adjacent layers; the self-expandable braided framework including a lumen in a cylindrical form; characterized in that, in radially expanded state, a ratio of a thickness of a wall of the implantable endoluminal prosthesis in the radially expanded state to the diameter of wire being greater than 3.0; and the surface coverage ratio (SCR) of the braided framework is at least 30% and at most 50%.