Stent Delivery Sheath Splitting for Biliary Obstruction
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Solution Overview
Problem
Current stent delivery systems face challenges in accurately deploying stents across biliary obstructions and removing the stent delivery system due to size limitations and distance constraints between the access site and the obstruction in the pancreaticobiliary system.
Innovation Solution
A stent deployment system featuring a sheath made from chemically incompatible materials that adhere without forming cross-linked bonds, allowing the sheath to tear along a longitudinal seam, and a guidewire lumen with a distal tip that splits the sheath to deploy the stent, facilitating accurate placement and removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the stent delivery system is made larger to improve stent placement accuracy across biliary obstructions, then the deployment precision is improved, but the difficulty of removing the system through the access site increases
Solution Approach 1:
The sheath is segmented into two chemically incompatible materials that adhere together but can separate. The first material forms the main tubular body while the second material forms a stripe along the longitudinal axis. This segmentation allows the sheath to be sufficiently large for accurate stent placement yet capable of splitting into smaller segments for easy removal through the access site.
Solution Approach 2:
The sheath is constructed from composite materials - specifically, a first material (such as polyether block amide or thermoplastic elastomer) and a second material (such as high-density polyethylene or polyolefin) that are chemically incompatible. These materials adhere together to form a unified structure during deployment but can separate when exposed to body temperature or physiological conditions, enabling both accurate placement and easy removal.
2Object-affected harmful factors
If the access site size is reduced to minimize patient trauma, then the invasiveness is reduced, but the ability to deploy and retrieve the stent delivery system is compromised
Solution Approach 1:
The sheath transitions from a unified structure during deployment to separated segments during removal. The two chemically incompatible materials remain adhered at body temperatures below their melting points during insertion and deployment, but separate when exposed to body temperature or physiological conditions, allowing the system to adapt its structural configuration to different procedural phases.
Solution Approach 2:
The adhesive properties of the two materials change with temperature. At room temperature, the materials adhere strongly for deployment, but at body temperature (or when exposed to physiological fluids), the adhesion weakens or reverses, allowing separation. This parameter change enables the sheath to maintain structural integrity during insertion while facilitating easy removal through a small access site.
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
Enables precise deployment and retrieval of stents across biliary obstructions, improving the accuracy and ease of stent placement within the pancreaticobiliary system by allowing the sheath to split and release the stent, addressing the size and distance limitations of existing systems.
Implementation Method 1
the first material is chemically incompatible with the second material such that the adhesion between the first portion and second portion is free from cross-linked bonds
Data Source
AI summary
Methods, apparatuses and systems are described for deploying a stent into a body lumen. A stent delivery system may include a sheath with a partially-tubular first portion made from a first material and a second portion made from a second material that is adhered to the first portion to form a tubular body. In some cases, the first material may be chemically incompatible with the second material such that the adhesion between the first portion and second portion is free from cross-linked bonds. The stent delivery system may further include a guidewire lumen with a distal tip that may be slidably disposed within the sheath and a tubular stent disposed between the guidewire lumen and an inside surface of the sheath. The sheath may be formed by coextruding the first material and the second material to form a striped tubular body of the sheath.