Stent with Localized Structural Differentiation for Vessel Support
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Solution Overview
Problem
Current stents face challenges such as restenosis, abrupt reclosure, and non-uniform expansion, which can lead to increased trauma and biological responses, particularly in areas like coronary vessels, due to their design and material properties, and there is a need for improved flexibility, visibility, and drug delivery capabilities.
Innovation Solution
A radially expandable stent with a filamental structure featuring arcuate crowns and elongated struts with varying widths and radii, designed for enhanced lateral bending and radial expansion, with strain distribution focused at transition regions, and a method for delivering bioactive agents through a coated substrate for improved tissue interaction and reduced restenosis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a stent is designed with uniform structure throughout, then manufacturing is simplified, but it cannot provide different flexibility characteristics needed for different treatment sites
Solution Approach 1:
The stent incorporates different structural characteristics at different locations: the first end portion has a first structural characteristic providing first flexibility, the second end portion has a second structural characteristic providing second flexibility, and the middle portion has a third structural characteristic. This local differentiation allows the stent to adapt to various treatment site requirements while maintaining a relatively simple overall design.
2Reliability
If a stent has rigid structure to prevent restenosis, then vessel support is improved, but trauma at treatment site increases
Solution Approach 1:
The stent applies different structural characteristics to different portions: rigid structures in middle portions provide support to prevent restenosis, while more flexible structures at end portions reduce trauma to the treatment site. This localized differentiation allows simultaneous achievement of both reliability and reduced harm.
3Manufacturing precision
If balloon pressure is increased to achieve uniform stent expansion, then expansion uniformity improves, but trauma at stent ends increases
Solution Approach 1:
The stent's differentiated structural characteristics allow different portions to expand at different rates during balloon inflation. The middle portion with higher radial strength expands later, while end portions with greater flexibility expand earlier, achieving more uniform overall expansion without requiring excessive balloon pressure that would cause end trauma.
4Object-affected harmful factors
If stent ends are made flexible to reduce trauma, then trauma reduction improves, but expansion uniformity deteriorates
Solution Approach 1:
The stent incorporates flexible structures at end portions to reduce trauma while maintaining rigid or semi-rigid structures in middle portions to ensure proper expansion uniformity. This localized structural differentiation allows both objectives to be achieved simultaneously.
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 design provides improved flexibility and uniform expansion, reducing restenosis rates and trauma, while enabling effective drug delivery and enhanced visibility through customized material strain distribution and bioactive agent elution.
Implementation Method 1
The stent undergoes lateral or radial deflection with strain distribution primarily at transition regions between struts and crown shoulders on opposite sides of crown peaks of the stent's filamental pattern
Implementation Method 2
a method for delivering bioactive agents through a coated substrate for improved tissue interaction and reduced restenosis
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 2A~2B
AI summary
An implantable stent includes multiple circumferential segments that surround a bore and are connected in series along a length to form a tubular wall. Multiple adjacent alternating opposite facing crowns arranged along each segment's circumference are bridged by struts. The struts include a series of staggered arcuate edges with limited flats to provide a limited region of maximum width between significantly extended reducing diameter tapers at either end where they transition into the crowns. Connections between adjacent segments are wider and stiffer than the struts and strut-crown transitions in the segments. The crowns include inner and outer radii with off-set centers along a common axis to provide medial crown peaks along the axis that are wider than the narrowed crown shoulders on either side of the axis and from which the tapered struts extend.