Expansion Ring for Braided Neurovascular Stents
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Solution Overview
Problem
Existing braided stents face challenges in selectively reinforcing neurovascular defects, particularly in tiny vessels like those in the brain, due to their weakness and non-linear nature, and existing delivery methods are inadequate for vaso-occlusive surgery, risking trauma or rupture to blood vessels.
Innovation Solution
A braided implant with an internally connected expansion ring that imparts outward radial force, formed by a plurality of interconnected support leaves, is connected to the braided implant by positioning it around a tube, everting an end portion, assembling the expansion ring, closing the openings over intersecting wires, trimming ends, and reversing the eversion to position the ring internally, thereby providing selective reinforcement and reducing trauma.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional braided stents are used in neurovascular defects, then they can provide general reinforcement, but they cannot provide selective reinforcement and may cause vessel trauma or rupture due to the weakness and non-linear nature of neurovasculature
Solution Approach 1:
The stent is divided into multiple segments or modules along its length, with each segment independently controllable. This allows selective deployment and reinforcement at specific locations within the neurovascular defect without affecting the entire vessel, thereby providing targeted support while minimizing trauma to healthy vessel sections.
Solution Approach 2:
The stent incorporates regions with different mechanical properties along its length, including softer, more compliant sections for healthy vessel areas and stiffer, more supportive sections for the defect location. This local variation in material properties enables selective reinforcement at the defect site while maintaining vessel compliance elsewhere, reducing the risk of trauma or rupture.
2Ease of operation
If delivery methods are simplified for ease of use, then deployment becomes easier, but precision and control in tiny brain vessels are compromised
Solution Approach 1:
The stent is designed with a nested or telescoping structure that allows it to be compacted into a small delivery catheter for navigation through tiny brain vessels. Once positioned at the target site, the stent can be sequentially deployed or expanded in a controlled manner, maintaining precision while facilitating ease of delivery through complex vasculature.
Solution Approach 2:
A delivery catheter or guide wire system serves as an intermediary between the operator and the stent. This intermediary provides mechanical advantage and precise positioning control, allowing the operator to accurately place the stent in tiny brain vessels while the stent itself remains simple in design for ease of deployment.
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 solution enables effective flow diversion and selective reinforcement in neurovascular defects with reduced risk of vessel trauma, enhancing the applicability of braided stents in vaso-occlusive treatments by providing a stable and trauma-reducing mechanism for deployment.
Implementation Method 1
The expansion ring can include a frame defined by a plurality of interconnected support leaves that are selectively positioned to impart an outwardly expanding radial force to the braided implant
Data Source
AI summary
A method of connecting an expansion ring to at least one end of a braided implant, the method including positioning the braided implant about a tube; everting an end portion of the braided implant over a first end of the tube; assembling an expansion ring to the braided implant, the expansion ring being a multi-leaved expansion ring comprising clips terminating with an open-ended coupling opening, wherein the openings are pushed over a set of intersecting wires of the braided implant at respective circumferential locations on or adjacent the first end of the tube; closing the openings over the set of intersecting wire; trimming ends of the braided implant; and reversing eversion of the braided implant thereby positioning the expansion ring internal to the braided implant.