Segmented Stent-Graft Hinged Graft for Tortuous Vessels
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Solution Overview
Problem
Current stent-grafts face challenges in maintaining flexibility, kink resistance, and strength under high stress/fatigue environments, particularly when navigating varying blood vessel sizes and tortuosity.
Innovation Solution
A stent-graft design featuring a longitudinally compressed tubular substrate with expandable segments and a graft member having a network of cells and hinges, connected by filaments, which enhances flexibility and resistance to kinking while maintaining structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a stent-graft is designed with a continuous tubular structure to maintain strength, then radial strength is improved, but flexibility and kink resistance deteriorate
Solution Approach 1:
The stent-graft is divided into multiple expandable segments spaced apart along the longitudinal axis, with gaps between them. This segmentation allows the structure to bend and flex more easily while maintaining radial strength through the expandable segments, directly resolving the contradiction between continuous strength and flexibility.
2Adaptability or versatility
If the stent-graft is made more flexible to navigate tortuous vessels, then adaptability is improved, but kink resistance deteriorates
Solution Approach 1:
The graft member is constructed with a network of cells and hinges forming a flexible yet structurally sound configuration. The hinge connections between cells allow controlled bending while preventing kinking, enabling the stent-graft to navigate tortuous vessels without compromising kink resistance.
3Strength
If the stent struts are closely spaced to enhance strength, then radial strength is improved, but flexibility deteriorates
Solution Approach 1:
Instead of continuous closely-spaced struts, the invention uses discrete expandable segments with gaps between them. This segmentation maintains radial strength through the expanded segments while the gaps provide flexibility and reduce rotational inertia, allowing the stent-graft to bend more easily.
4Ease of manufacture
If the stent-graft is designed as a single continuous structure, then manufacturing simplicity is improved, but ability to withstand stress and fatigue deteriorates
Solution Approach 1:
The stent-graft comprises multiple discrete expandable segments spaced along the longitudinal axis rather than a continuous structure. This segmentation reduces stress concentration at any single location and prevents crack propagation along the entire length, improving fatigue resistance while remaining manufacturable through modular assembly.
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 design achieves increased flexibility and kink resistance, allowing the stent-graft to navigate tortuous blood vessels without kinking, while maintaining radial strength and durability through the use of shape memory materials and bio-compatible polymers like ePTFE.
Implementation Method 1
self-expanding stents are delivered to a blood vessel in a collapsed condition and expand in vivo following the removal of a constraining force and/or in the presence of an elevated temperature (due to material properties thereof)
Implementation Method 2
Grafts formed of ePTFE include a microstructure characterized by spaced apart nodes connected by fibrils
Data Source
AI summary
An implantable prosthesis including a longitudinally compressed generally tubular substrate defining a longitudinal axis, a plurality of expandable segments disposed over the substrate and spaced apart along the longitudinal axis, and a graft member positioned over the segments. The graft member may include a lattice structure. Adjacent expandable segments may be connected by one or more filaments.