Nested Apical Locking Mechanism for Stent Grafts
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Solution Overview
Problem
Current endovascular stent grafts face challenges in securely attaching and sealing modular components, particularly at bifurcation sites, due to reliance on radial force and friction, which can lead to potential separation and endoleaks.
Innovation Solution
A modular stent graft system with self-expanding locking stents, featuring a series of apices that flare into a frusto-conical configuration, securely interlocks at the interface between the main tubular body and leg extensions, enhancing attachment and sealing through a nested apical engagement mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If radial force and friction between graft materials are used for attachment, then the attachment method is simple, but the reliability of connection is insufficient leading to potential separation and endoleaks
Solution Approach 1:
The locking stent is nested within the graft material at the interface region, with the stent's frusto-conical apices interlocking with the graft structure. This nesting arrangement provides secure mechanical anchoring while maintaining a relatively compact and integrated device design.
Solution Approach 2:
The locking stent is divided into multiple discrete apices (typically 3-6) distributed around the circumference, allowing the locking force to be distributed across multiple contact points with the graft material, thereby enhancing overall connection reliability without requiring a single complex anchoring structure.
2Stability of the object's composition
If a secure seal and attachment are achieved at the interface, then the stability of connection is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The locking stent utilizes a frusto-conical geometry with progressively flaring apices, transforming the attachment mechanism from relying on precise dimensional matching to utilizing geometric interlocking. The gradual flare angle and apex configuration provide mechanical engagement that is more tolerant of manufacturing variations while maintaining interface stability.
Solution Approach 2:
The frusto-conical shape of the locking stent creates an asymmetric geometry where the apices flare outward at specific angles, providing directional locking force. This asymmetric design ensures stable attachment by creating mechanical interference fit that resists both axial and radial displacement, reducing sensitivity to manufacturing tolerances.
3Ease of manufacture
If the locking stent is secured only at distal apices, then the ease of manufacture is improved, but the strength of attachment may be compromised
Solution Approach 1:
The locking stent is pre-formed with a frusto-conical configuration and secured at the distal apices to the graft material before deployment. This preliminary anchoring at the distal end provides a stable base that prevents migration, while the proximal apices naturally engage with the opposing graft component during assembly, achieving strong attachment without requiring complex multi-point securing procedures.
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 interlocking mechanism significantly increases the pull-out force required for separation, reducing the risk of endoleaks and ensuring a stable, long-term attachment of stent graft components within the vascular system.
Implementation Method 1
a self-expanding locking stent secured to the internal surface of the first interface region, the locking stent being flared or formed into a frusto-conical configuration
Data Source
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Figure 3
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AI summary
A modular stent graft system (30) and methods of assembly are disclosed. The stent graft assembly (30) comprises a first stent graft (32) having an interface region at its distal end and a first locking stent (64) secured to an internal surface of the interface region. A second stent graft (70) having an interface region at its proximal end is configured to at least partially overlap with the interface region at the distal end of the first stent graft (32). The second stent graft (70) comprises a second locking stent (84) secured to an external surface of the interface region. The first and second locking stents (64, 84) are configured to be engaged such that the second locking stent is nested between the first locking stent and an internal surface of the interface region of the first stent graft thereby interlocking the first and second stent grafts to each other.