Stent Wire Configuration for Microcatheter Passage and Expansion Force
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Solution Overview
Problem
The challenge is to design a stent that maintains a sufficient blood vessel wall expansion force while allowing a microcatheter to pass through its stitch gap, a conflict between the need for a wide stitch gap for the microcatheter and the requirement for a strong blood vessel wall expansion force, without using special materials or structures.
Innovation Solution
The stent features pairs of right-handed and left-handed spiral thin wires wound in a plain weave shape with a minute gap between them, doubling the number of wires per unit area to enhance blood vessel wall expansion force while maintaining a stitch gap size suitable for microcatheter passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the stitch gap is made large to allow microcatheter passage, then the microcatheter can pass through the stent, but the blood vessel wall expansion force decreases
Solution Approach 1:
The stent wire structure is segmented into multiple thin wires grouped in bundles. Instead of using fewer thick wires, the invention uses multiple thinner wires (e.g., 2-4 wires per bundle) arranged in parallel, which allows the stitch gap to remain sufficiently large for microcatheter passage while increasing the total number of wires per unit area to maintain or enhance expansion force.
Solution Approach 2:
The invention changes the parameter of wire thickness by using thinner wires arranged in bundles rather than thicker wires. This parameter change allows the stitch gap dimension to be maintained at a level suitable for microcatheter passage while the increased number of thinner wires compensates for the reduced individual wire thickness, thereby maintaining or enhancing the overall expansion force.
2Force
If the number of superelastic thin wires per unit area is increased to enhance blood vessel wall expansion force, then the expansion force increases, but the stitch gap becomes smaller preventing microcatheter passage
Solution Approach 1:
The wire structure is segmented into bundles of multiple thin wires. This segmentation allows the stitch gap to be determined by the bundle arrangement rather than individual wire density, enabling sufficient space for microcatheter passage while containing multiple wires within each bundle to provide adequate expansion force.
Solution Approach 2:
The invention transitions from considering wire density in a two-dimensional plane to a three-dimensional arrangement where multiple thin wires are stacked in bundles. This dimensional change allows the stitch gap to remain large in the plane relevant for microcatheter passage while accumulating wire mass in the radial dimension to maintain expansion force.
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
This configuration effectively doubles the blood vessel wall expansion force while ensuring the microcatheter can pass through the stitch gap, allowing the stent to be securely placed at the vascular aneurysm site without being swept away by blood flow.
Implementation Method 1
the stent uses a superelastic hose-shaped body that memorizes a predetermined diameter. When the stent is inserted into the blood vessel, the stent is elongated in the axial direction, is released from the extension at the site of the vascular aneurysm and returns to the predetermined diameter and generates a blood vessel wall expansion force
Data Source
AI summary
In this stent, two superelastic fine wires are disposed along the axial direction at a prescribed helical pitch so as to have a prescribed stent inner diameter D0, while a pair is formed between two helical fine wires that are disposed across a micro gap of a size not more than five times the wire diameter of the fine wires in such a manner as to include a mutually contacting state. A prescribed reticulation gap is formed by crossing a clockwise-wound helical fine wire pair and a counterclockwise-wound helical fine wire pair in a plain-woven fashion, so as to have an axial gap equal to [(prescribed helical pitch)−{2×(fine wire diameter)}−(micro gap)] and a circumferential gap equal to [{(stent inner circumferential length corresponding to stent inner diameter)/N}−{2×(fine wire diameter)}−(micro gap