Self-Expanding Stent With Radial Anti-Migration Supports
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Solution Overview
Problem
Existing stents face challenges in accurately and repeatedly forming anti-migration features, which are crucial for anchoring them in place within body lumens, particularly in applications like the esophagus, where peristaltic forces can cause unwanted migration.
Innovation Solution
A self-expanding stent with an expandable framework and polymeric outer sleeve, featuring anti-migration supports or loops that extend radially outward and are hingedly attached, allowing them to deflect inward under peristaltic forces while maintaining a constant inner diameter, thereby enhancing anchoring and preventing axial migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If anti-migration features are added to anchor the stent in place, then the stent's resistance to axial migration is improved, but the manufacturing complexity and difficulty of accurate formation increase
Solution Approach 1:
The anti-migration feature is segmented into multiple discrete protrusions distributed around the stent circumference rather than a continuous complex structure. Each protrusion is formed by localized radial expansion of the balloon at specific segments, simplifying the overall manufacturing process while providing effective anchoring through multiple contact points with the body lumen wall.
Solution Approach 2:
The anti-migration protrusions are formed during the stent deployment process itself through preliminary radial expansion of the balloon at specific locations. This preliminary action creates the anchoring features in-situ during manufacturing, eliminating the need for separate complex formation steps and ensuring precise geometric control.
2Reliability
If the stent is designed to resist peristaltic forces, then the stent's stability in the esophagus is improved, but the structural complexity increases
Solution Approach 1:
The anti-migration protrusions act as counterbalancing elements that generate radial outward force to counteract the axial peristaltic forces. When the esophagus contracts axially, the protrusions engage with the lumen wall and convert the axial motion into radial pressure, creating a mechanical counterbalance that prevents stent migration without requiring complex active control mechanisms.
Solution Approach 2:
The stent structure incorporates dynamic elements where the anti-migration protrusions can flex and deform in response to peristaltic forces. The balloon material and stent framework are designed with appropriate compliance to allow controlled deformation during esophageal contraction, enabling the structure to adapt dynamically to physiological conditions while maintaining anchoring effectiveness.
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 resists axial migration within body lumens by transmitting axial forces radially outward through anti-migration supports, reducing the impact of peristaltic forces, and ensuring stable placement.
Implementation Method 1
the expandable framework is configured to self-expand from the radially collapsed configuration to the radially expanded configuration when unconstrained
Implementation Method 2
The anti-migration loops are configured to deflect radially inward at the base when subjected to a radially inward force
Implementation Method 3
The stent effectively resists axial migration within body lumens by transmitting axial forces radially outward through anti-migration supports
Data Source
AI summary
An esophageal stent may include an expandable framework having a first end, a second end, and a central longitudinal axis extending from the first end to the second end, the expandable framework being configured to expand from a radially collapsed configuration to a radially expanded configuration, and a polymeric outer sleeve disposed radially outward of and spaced apart from a body region of the expandable framework. The expandable framework may include a plurality of anti-migration supports extending radially outward from the body region of the expandable framework toward the polymeric outer sleeve.