Variable Density Braided Stent for Aneurysm Occlusion
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Solution Overview
Problem
Current devices for treating cerebral aneurysms, such as vaso-occlusive coils and stents, face limitations including poor packing density, instability under hydrodynamic pressure, and difficulty in deployment, especially in wide-necked aneurysms, and lack sufficient rotational positioning capability and flexibility to navigate tortuous cerebral blood vessels effectively.
Innovation Solution
A self-expanding resilient permeable shell with a braided structure, comprising elongate filaments of nitinol and radiopaque materials, designed to expand from a low-profile state for delivery through a microcatheter to a globular shape within the aneurysm, providing effective occlusion and anchoring within the vascular defect while being visible under imaging technologies like x-ray and MRI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vaso-occlusive coils are used to treat cerebral aneurysms, then occlusion of the aneurysm is achieved, but packing density is poor and stability under hydrodynamic pressure is insufficient
Solution Approach 1:
The patent employs composite filament construction combining nitinol (providing superelasticity and shape memory) with radiopaque materials (enhancing imaging visibility). This composite approach creates a material that simultaneously achieves mechanical stability under blood flow pressure while maintaining high packing density through controlled expansion patterns.
Solution Approach 2:
The device utilizes dynamic expansion from a compressed delivery state to an expanded treatment state. The nitinol filaments exhibit superelastic deformation during delivery and then recover to a predetermined expanded configuration, providing stable anchoring and high packing density within the aneurysm sac while withstanding hydrodynamic forces.
2Reliability
If multiple coils are deployed to treat wide-necked aneurysms, then occlusion is achieved, but device complexity and difficulty in deployment increase
Solution Approach 1:
The device is segmented into multiple independent filaments woven into a cohesive structure. Each filament can be independently controlled during deployment, allowing the operator to deploy the device as a single unit rather than multiple separate coils, thereby reducing procedural complexity while maintaining effective occlusion through the collective action of all filaments.
Solution Approach 2:
Multiple filaments are combined into a single integrated device structure that functions as one deployable unit. The woven construction merges the individual filaments into a unified mesh that provides both structural stability and effective occlusion, eliminating the need to manually deploy multiple separate coils while achieving the same therapeutic effect.
3Reliability
If stents are made dense to provide structural support, then stability is improved, but flexibility and ability to navigate tortuous vessels deteriorate
Solution Approach 1:
The device exhibits varying local densities within its structure. The filament weave pattern creates regions of different mesh sizes and densities along the device length, allowing certain sections to be more flexible for navigating vessel curvature while other sections provide greater structural support for aneurysm occlusion, thus resolving the contradiction between overall stability and local flexibility.
4Difficulty of detecting and measuring
If the device is made radiopaque for imaging visibility, then detection capability is improved, but device complexity increases
Solution Approach 1:
The device incorporates radiopaque materials (such as platinum, gold, or tantalum) combined with biocompatible structural materials (such as nitinol or stainless steel). This composite construction provides inherent radiopacity for imaging visibility during the procedure while the biocompatible component ensures mechanical performance and biocompatibility, achieving detection capability without excessive complexity.
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 device effectively blocks blood flow into the aneurysm, reduces the risk of rupture, and is easily visualized under imaging, offering a minimally invasive solution with improved stability and flexibility for treating cerebral aneurysms.
Implementation Method 1
a self-expanding resilient permeable shell having a radially constrained elongated state configured for delivery within a catheter lumen, an expanded state with a globular and longitudinally shortened configuration
Implementation Method 2
the plurality of elongate filaments which are woven together... including at least about 40% composite filaments relative to a total number of filaments, the composite filaments including a high strength material and a highly radiopaque material
Data Source
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AI summary
Devices and methods for treatment of a patient's vasculature are described. The devices include implants made of woven braided mesh having a variable mesh density, i.e., the average size of pores in one region are a different than the average size of pores in another region. Additionally, there is a transition zone between the two regions. The implants have a low profile radially constrained state and an expanded state that is axially shortened. Methods of using the device to treat a cerebral aneurysm are also described. Methods of forming a tubular braid are also described. Methods of forming a tubular braid with variable braid densities are described. Methods of forming a tubular braid using a castellated mandrel are also described.