Nested Stent Delivery System for Small Introducer Access
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Solution Overview
Problem
The limited introducer space in medical devices restricts the delivery of covered metallic stents to certain regions of the body, such as the duodenal region, due to the small diameter of the working channel, preventing the use of these stents in treating strictures located in these areas.
Innovation Solution
A two-stage delivery system comprising a sleeve member and a metallic stent, where the sleeve member is deployed first to expand within the body lumen, followed by the deployment of the metallic stent within the sleeve member, allowing for the stent to self-expand and exert radial force against the lumen walls, while utilizing a pusher member and outer sheath to facilitate the deployment and positioning of the stent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional introducer with outer sheath and inner sheath is used to deliver covered metallic stents, then the stent can be delivered to accessible regions, but the limited introducer space (maximum 3.3 mm diameter) prevents delivery to the duodenal region and other areas with smaller working channels
Solution Approach 1:
The patent applies nesting by placing the metallic stent inside the expanded sleeve member, which itself is delivered within the introducer. This nested configuration allows the stent to be delivered through a smaller introducer (reducing the 3.3 mm diameter constraint) while still achieving the desired final stent size at the deployment location in the duodenal region or other accessible areas.
Solution Approach 2:
The delivery system is segmented into distinct functional components: the introducer for initial access, the sleeve member that expands first to create a receiving space, and the metallic stent that is deployed second within the sleeve. This segmentation allows each component to be optimized for its specific function and enables delivery through smaller introducers than would be required for a single integrated stent delivery system.
2Ease of operation
If the outer sheath is retracted to enable stent self-expansion, then the stent can be deployed, but the limited introducer space restricts the size and type of stents that can be delivered
Solution Approach 1:
The sleeve member is deployed and expanded within the introducer before the metallic stent is deployed. This preliminary action creates a pre-formed receiving space that facilitates subsequent stent deployment and expansion, enabling the stent to be delivered and deployed through a smaller introducer than would otherwise be possible.
Solution Approach 2:
The metallic stent is nested within the expanded sleeve member during the deployment process. This nested arrangement allows the stent to be contained within a smaller overall envelope during delivery through the introducer, while still achieving full expansion and functionality at the target 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 the successful deployment and expansion of covered metallic stents in regions previously inaccessible due to size constraints, providing effective dilation and maintaining patency of the biliary tree or other lumens, while allowing for easier navigation through body lumens with smaller introducer sizes.
Implementation Method 1
the metallic stent is configured to be deployed within the sleeve member... allowing for the stent to self-expand and exert radial force against the lumen walls
Data Source
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AI summary
A delivery system that is preloaded with a sleeve member and a metallic stent and method of delivery of the sleeve member and stent at a target stricture site are described. The method of delivery occurs in two stages. The first stage involves deployment of the sleeve member and the second stage involves deployment of the metallic stent within the interior region of the sleeve member. The sleeve member may be formed from a shape memory plastic which may also be biodegradable. The delivery system provides a method of deploying a covered stent that would not otherwise be possible because of limited introducer space.