Ureteral Stent with Coiled Jacket Gap for Fluid Flow
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Solution Overview
Problem
Current stents for long-term placement in the urinary system, such as ureters, face challenges in maintaining patency and preventing migration, especially when deployed in areas compromised by tumors or growths, and require improved designs for fluid communication and retention.
Innovation Solution
A stent design featuring a coiled wire central portion with a jacket and an elongate gap between coils, allowing fluid communication through spaces between coils, and non-linear end portions with apertures for secure placement, along with a safety wire for stability and biasing to maintain the stent's nominal geometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stent is designed with a coiled wire structure and jacket to maintain patency, then fluid communication is improved, but device complexity increases
Solution Approach 1:
The stent is divided into distinct functional segments: a coiled wire central portion with elongate gap for fluid communication, jacketed side portions for structural support, and end portions with apertures for anchoring. This segmentation allows each part to optimize its specific function while reducing overall complexity through modular design.
Solution Approach 2:
The jacket is disposed over the coiled wire central portion, creating a nested structure where the jacket contains the coils. This nesting provides structural support while allowing the coiled structure to maintain fluid communication pathways, resolving the contradiction between reliability and complexity.
2Stability of the object's composition
If retention structures are added to prevent migration, then stability is improved, but ease of operation deteriorates
Solution Approach 1:
Retention features (apertures and hooks) are localized only at the end portions of the stent rather than along the entire length. This localized approach provides migration prevention where needed while maintaining simplicity in the central portion, balancing stability with ease of operation.
Solution Approach 2:
The end portions are configured with non-linear, curved geometries that naturally engage with the urinary tract anatomy (kidney and bladder walls). These curved retention structures provide stable anchoring through geometric interlocking rather than complex mechanical fasteners, improving stability without significantly increasing operational complexity.
3Ease of operation
If the stent is made flexible for navigation, then ease of operation is improved, but strength deteriorates
Solution Approach 1:
The stent utilizes a flexible jacket structure that can be compressed to a low profile for navigation through the urinary tract. Once deployed, the jacket's elastic properties allow it to expand and maintain structural strength, resolving the contradiction between flexibility for navigation and strength for patency maintenance.
Solution Approach 2:
The stent transitions from a compressed flexible state during delivery to an expanded rigid state during function. The coiled wire structure and jacket are designed to dynamically change their mechanical properties based on deployment status, providing flexibility when needed for navigation and strength when needed for patency.
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 maintains patency and prevents migration by allowing fluid flow through the elongate gap and providing secure retention within the anatomy, while the safety wire ensures the stent returns to its nominal geometry, ensuring effective deployment and functionality.
Implementation Method 1
a safety wire extending through the lumen and fixed with respect to each of the first and second end portions. The stent is configured such that the safety wire provides a restoring force to the stent
Implementation Method 2
neighboring coils are closely aligned... allowing fluid flow through the elongate gap and providing secure retention
Data Source
Figure 1
Figure 1a
Figure 2
AI summary
An elongate medical device is provided. The device includes an elongate member defining a lumen through proximal, central, and distal portions. The central portion of the elongate member is defined from a plurality of closely aligned coils that establish the lumen within the central portion. The central portion further comprises a jacket disposed around a majority of an outer circumference of the plurality of coils, the jacket defining opposing first and second longitudinal edges that extend along the length of the central portion, and an elongate gap between opposing first and second longitudinal edges exposing portions of each of the plurality of coils aligned therewith, wherein the elongate gap allows for fluid communication from within or into the lumen through spaces between neighboring coils and through the elongate gap.