Spiral-Reinforced Bile Duct Stent for Conformability and Retrieval
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Solution Overview
Problem
Existing bile duct stents face challenges in conforming to the shape of the bile duct, particularly when a stenosis occurs in the upper portion, leading to difficulty in placement and retrieval due to regions of varying rigidity.
Innovation Solution
A medical stent with a tubular member and a reinforcing material wound in a spiral shape, featuring regions with different winding pitches, allowing it to conform to the bile duct shape during placement and facilitating easy retrieval by collapsing low-rigidity regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the stent has a long region with greater rigidity to maintain sufficient space at the stenosis portion, then the space-maintaining capability is improved, but the ability to conform to the bile duct shape at non-stenosis portions deteriorates
Solution Approach 1:
The stent applies local quality by creating distinct regions with different rigidity characteristics. The first region (with smaller winding pitch) provides high rigidity for space maintenance at the stenosis portion, while the second region (with larger winding pitch) provides lower rigidity for conformability to the bile duct shape at non-stenosis portions. This spatial variation in material properties resolves the contradiction between needing strength at specific locations and adaptability at others.
2Ease of operation
If the stent has a region with lower rigidity to facilitate smooth retrieval through the channel, then the ease of retrieval is improved, but the space-maintaining capability at the stenosis portion deteriorates
Solution Approach 1:
The stent is segmented into functionally distinct regions: the first region with smaller winding pitch maintains high rigidity for space support at the stenosis portion, while the second region with larger winding pitch has lower rigidity that enables easy collapse and smooth retrieval through the endoscope channel. This segmentation allows each region to independently fulfill its specific function without compromising the other.
3Ease of operation
If the end portion of the stent is held and drawn into the channel for retrieval, then the retrieval process is initiated, but the end portion bends and overlaps requiring additional collapse action
Solution Approach 1:
The stent utilizes parameter changes in rigidity along its length to simplify the retrieval process. The second region's larger winding pitch creates a lower rigidity parameter that allows the stent to collapse easily when pulled, preventing bending and overlapping of the end portion. This parameter variation eliminates the need for additional collapse actions during retrieval.
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 stent effectively conforms to the bile duct shape during placement and can be easily retrieved by collapsing low-rigidity regions, ensuring proper fit and smooth removal without kinking or buckling.
Implementation Method 1
a reinforcing material wound in a spiral shape around a longitudinal axis extending in the longitudinal direction and embedded between an inner circumferential surface of the tubular member and an outer circumferential surface of the tubular member
Data Source
AI summary
What is provided are a medical stent and a stent delivery device that can be placed in a bile duct while they sufficiently conform to a shape of the bile duct.The medical stent includes a main body including a tubular member configured to extend in a longitudinal direction, and a reinforcing material wound in a spiral shape around a longitudinal axis extending in the longitudinal direction and embedded between an inner circumferential surface of the tubular member and an outer circumferential surface of the tubular member, wherein the main body has a first region and a second region in which winding pitches of the reinforcing material are different from each other, and the second region is a region in which the reinforcing material is wound in a spiral shape at a winding pitch larger than that of the first region, and is longer than the first region in the longitudinal direction.