Stent Retrieval Levers for Uniform Radial Contraction
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Solution Overview
Problem
Existing stent retrieval and repositioning systems require user-sensitive techniques and often fail to achieve uniform radial contraction of the stent body, relying on extraction force to overcome frictional resistance within the body lumen.
Innovation Solution
A stent design incorporating repositioning and retrieval levers spaced circumferentially around the open end, extending radially outward and configured to translate a radially inward squeezing force along the stent body, allowing for uniform contraction and easy access for retrieval or repositioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a retrieval suture or wire is used to engage and contract the stent, then the stent can be retrieved or repositioned, but the contraction is limited to a short distance from the engagement point and does not achieve uniform radial contraction along the stent length
Solution Approach 1:
The retrieval system is divided into multiple independent levers distributed circumferentially around the stent. Each lever independently contracts a segment of the stent, and collectively they achieve uniform contraction along the entire stent length. This segmentation allows the contraction force to be distributed evenly rather than concentrated at a single point.
Solution Approach 2:
The retrieval mechanism transitions from a single-point axial pull (one-dimensional) to a multi-point radial compression (three-dimensional). By applying contraction forces from multiple directions simultaneously through circumferentially distributed levers, the system achieves uniform radial contraction throughout the stent body.
2Productivity
If extraction force is applied to overcome frictional resistance between the stent and intimal wall, then the stent can be removed, but user-sensitive techniques are required and the process becomes complex
Solution Approach 1:
The stent's own structure is utilized for retrieval through the integrated levers that are part of the stent framework. The levers engage with the stent's wire structure and translate external compression forces into controlled contraction, allowing the stent to be retrieved through its own structural features rather than requiring external sutures or wires.
Solution Approach 2:
The retrieval mechanism changes the physical state of the stent from expanded to contracted by applying radial compression forces. This parameter change (radial dimension) facilitates retrieval by reducing the stent's profile and overcoming frictional resistance more efficiently than axial pulling alone.
3Device complexity
If the stent is contracted over a short distance from the engagement point, then the retrieval suture or wire can engage the stent, but the majority of the stent length does not reduce in diameter uniformly
Solution Approach 1:
The contraction function is segmented across multiple levers positioned at different circumferential locations. Each lever creates a localized contraction zone, and the superposition of these localized contractions produces uniform radial reduction along the entire stent length, rather than concentrating contraction at a single point.
Solution Approach 2:
The levers serve multiple functions: they provide structural support to the stent, enable radial contraction, and facilitate retrieval. This multi-functionality allows a single structural element to achieve both mechanical support and controlled contraction across the entire stent length.
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 levers facilitate efficient radial contraction of both the stent end and body, providing improved cinching and radial contraction capabilities, reducing the risk of stent damage and enhancing retrieval and repositioning processes.
Implementation Method 1
The repositioning and/or retrieval levers are configured to translate a radially inward squeezing force applied to the repositioning and/or retrieval levers at a location beyond the first open end to a radially inward contracting force along the first and second legs extending along the tubular body
Data Source
AI summary
A braided stent having a plurality of retrieval and/or repositioning levers includes a stent body formed of a plurality of wires interbraided in a braided pattern. The repositioning and/or retrieval levers have a loop portion extending radially away from the stent body and first and second legs extending along the stent body. The levers are configured to be actuated radially inward toward the central longitudinal axis of the stent by a radially inwardly directed force to radially collapse the stent.