Dual-Segment Renal Stent for Ostial Placement

Solution Overview

Problem

Conventional stents designed for long cylindrical vessels are challenging to deploy at the ostium of short renal arteries, causing disruption of blood flow and embolization of arteriosclerotic debris, with existing solutions failing to provide adequate radial strength and vessel wall coverage.

Innovation Solution

A stent comprising a balloon-expandable segment for the renal vessel and a self-expanding segment for the aortic region, with a mechanism to limit axial movement between sections, ensuring high radial strength and conformability to flared ostial and aortic regions, thereby minimizing flow disruption and embolization risk.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional stents are deployed at the ostium of short renal arteries, then the stent can be placed in the vessel, but the stent disrupts laminar blood flow and causes embolization of arteriosclerotic debris

Engineering Contradiction:

Improvestent placement reliabilityVSAvoidflow disruption and embolization

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The stent is divided into three distinct segments: a proximal self-expanding segment for the aorta, a middle balloon-expandable segment for the renal artery, and a distal self-expanding segment. This segmentation allows each portion to be optimized for its specific location and function, with the balloon-expandable middle section providing a transition zone that maintains flow laminarity while the self-expanding portions provide radial strength.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different segments of the stent have different expansion characteristics and material properties tailored to local requirements. The balloon-expandable middle segment provides controlled expansion for flow management, while the self-expanding segments provide high radial strength for vessel support. The attachment zones between segments have specific mechanical properties to accommodate differential expansion and movement.

Inventive Principle:

Principle #3Local quality

2Device complexity

If stents are designed for long cylindrical vessels, then the stent structure is simple, but the stent is hard to position consistently at the precise ostial location and extends into the aorta disrupting flow

Engineering Contradiction:

Improvestent structure simplicityVSAvoidostial placement precision

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The stent is divided into three distinct segments: a proximal self-expanding segment for the aorta, a middle balloon-expandable segment for the renal artery, and a distal self-expanding segment. This segmentation allows each portion to be optimized for its specific location and function, with the balloon-expandable middle section providing a transition zone that maintains flow laminarity while the self-expanding portions provide radial strength.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The balloon-expandable middle segment acts as an intermediary between the two self-expanding segments, providing a controlled transition zone that manages the expansion forces and maintains flow laminarity. This intermediate section absorbs the differential expansion and prevents direct contact between the self-expanding segments that would cause flow disruption.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If stent struts are expanded to cover vessel wall, then vessel wall coverage is improved, but radial strength is reduced making flaring difficult

Engineering Contradiction:

Improvevessel wall coverageVSAvoidradial strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The stent is divided into three distinct segments: a proximal self-expanding segment for the aorta, a middle balloon-expandable segment for the renal artery, and a distal self-expanding segment. This segmentation allows each portion to be optimized for its specific location and function, with the balloon-expandable middle section providing a transition zone that maintains flow laminarity while the self-expanding portions provide radial strength.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different segments of the stent have different expansion characteristics and material properties tailored to local requirements. The balloon-expandable middle segment provides controlled expansion for flow management, while the self-expanding segments provide high radial strength for vessel support. The attachment zones between segments have specific mechanical properties to accommodate differential expansion and movement.

Inventive Principle:

Principle #3Local quality

4Object-affected harmful factors

If a flared stent end is created to minimize flow disruption, then flow pattern at ostium is improved, but stent radial strength is reduced

Engineering Contradiction:

Improveflow pattern disruptionVSAvoidstent radial strength

Core Design Contradiction:

Object-affected harmful factorsVSStrength

Solution Approach 1:

The stent is divided into three distinct segments: a proximal self-expanding segment for the aorta, a middle balloon-expandable segment for the renal artery, and a distal self-expanding segment. This segmentation allows each portion to be optimized for its specific location and function, with the balloon-expandable middle section providing a transition zone that maintains flow laminarity while the self-expanding portions provide radial strength.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different segments of the stent have different expansion characteristics and material properties tailored to local requirements. The balloon-expandable middle segment provides controlled expansion for flow management, while the self-expanding segments provide high radial strength for vessel support. The attachment zones between segments have specific mechanical properties to accommodate differential expansion and movement.

Inventive Principle:

Principle #3Local quality

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 dual-segment stent design provides superior radial strength and high vessel wall coverage, reducing flow disruption and embolization risk during deployment, while ensuring consistent placement and reduced debris generation.

Implementation Method 1

a balloon expandable segment which is deployed in the renal vessel

Methodology Applied

Scientific EffectBalloon expansion: Pressure Increase

Implementation Method 2

a self expanding segment which is deployed in the aortic segment

Methodology Applied

Scientific EffectSelf-expansion: Elastic Recovery

Data Source

PatentUS7632302B2Stent and stent delivery system for ostial locations in a conduit

Publication Date: 2009.12.15 EV3 INC

AI summary

A renal stent includes a balloon expandable segment intended for deployment in the renal vessel and a self expanding segment intended for deployment in the aortic segment. One or both of the balloon expandable and self expanding segments can be deployed in the ostial region of the renal vessel, typically the renal artery. The balloon expandable segment provides superior radial strength for maintaining dilated diameter of the renal vessel. The self expanding segment expands to conform to the flared ostial and aortic regions of the vessel. The self expanding segment can be balloon dilated to enhance conformance of the self expanding stented segment to the ostial and aortic regions.