Axially Compressible Bare Stent for Aortic Support and Low Permeability
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Solution Overview
Problem
Existing stents for treating aortic dissections and aneurysms, particularly type A lesions, face challenges in being radially compressed to a suitable diameter for delivery through the femoral artery and maintaining sufficient radial support force and low fluid permeability, especially when applied to the ascending aorta.
Innovation Solution
A bare stent formed by overlapping and interweaving wires with different diameters, allowing for partial axial compression to enhance radial support force and reduce fluid permeability, with varying metal coverage and compression ratios along the stent length to address specific treatment sites.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a dense mesh stent is used to treat aortic dissection, then radial support force is improved, but the stent cannot be radially compressed to a suitable diameter for delivery through the femoral artery
Solution Approach 1:
The stent is designed with dynamic compressibility along the axial direction, allowing it to be compressed during delivery and then expand to provide radial support force after implantation. This dynamic behavior resolves the contradiction between needing high radial support force and being able to compress to a small delivery diameter.
Solution Approach 2:
Instead of compressing the stent radially to reduce its diameter for delivery, the invention utilizes axial compression to achieve the same goal. By compressing along the axial dimension, the stent can be delivered through the femoral artery and then expand axially to provide radial support force, effectively using another dimension to resolve the size contradiction.
2Reliability
If a stent with high metal coverage is used to reduce fluid permeability, then obstruction of the tearing site is improved, but delivery through conventional delivery system becomes difficult
Solution Approach 1:
The stent structure allows for dynamic adjustment of metal coverage through axial compression. In the compressed delivery state, the stent has lower effective metal coverage for easier delivery, while in the expanded implantation state, it achieves high metal coverage (30%-60%) for effective obstruction and low fluid permeability.
3Strength
If axial compression is applied to enhance radial support force, then radial support force is improved, but stent length is reduced
Solution Approach 1:
The invention utilizes parameter changes in the compression ratio along the axial direction to achieve different radial support forces. By varying the compression ratio, the stent can provide enhanced radial support force at specific locations while maintaining appropriate length coverage for the aortic lesion.
4Reliability
If the stent is designed for type A aortic lesion treatment, then treatment effectiveness is improved, but delivery through femoral artery becomes challenging
Solution Approach 1:
The invention uses axial compression instead of radial compression to reduce the stent delivery profile. This allows the stent to be delivered through the femoral artery and then expand axially to treat type A aortic lesions effectively, using a different dimensional approach to resolve the delivery challenge.
Data Source
AI summary
An axially compressible bare stent for an aorta, formed by interleaving at least two wires having different diameters, i.e., a first wire and a second wire, in an overlapping manner. In a natural release state, the bare stent has a metal coverage of at least 30%. The first wire has a diameter of 20-150 μm, and the second wire has a diameter of 150-600 μm. During the use in the treatment of aortic aneurysms and/or aortic dissection lesions, low liquid permeability and a strong radial support force are provided at a desired location in an aorta by means of the axial compressibility of the bare stent.