Braided Vascular Stent with Thin Strands for Tortuous Vessels
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Solution Overview
Problem
Current flow-diverting stents and braids face challenges in approximating vessel walls across aneurysm necks in curved, twisted, or forked vessels, leading to inadequate porosity and unwanted blockage of blood flow to secondary vessels, especially in cerebral aneurysms.
Innovation Solution
The development of expandable devices with braided or woven strands of diameters less than 0.001 inches, heat-set for improved flexibility and shape retention, allowing for self-expansion across aneurysm necks with reduced oxide layer thickness and controlled porosity to inhibit blood flow into the aneurysm, promoting thrombosis and healing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current flow-diverting stents or braids are used in tortuous vessels, then the device can be positioned across the aneurysm, but the device suffers from crimping or kinking and cannot approximate the vessel wall properly
Solution Approach 1:
The patent changes the physical parameters of the stent by using extremely thin strands (less than 0.001 inches in diameter) and heat-setting the braided structure. This parameter change increases flexibility and shape retention, allowing the device to maintain its configuration in tortuous vessels without crimping or kinking while still approximating the vessel wall effectively.
Solution Approach 2:
The patent employs a composite structure combining heat-set braided metal strands with a porous configuration. This composite design provides both the flexibility needed for tortuous vessels and the structural integrity to maintain shape, resolving the contradiction between positioning reliability and shape retention.
2Reliability
If the stent or braid is expanded to block blood flow into the aneurysm, then embolization is induced, but blood flow to branching or secondary vessels is undesirably blocked
Solution Approach 1:
The patent applies local quality by creating a porous structure with specific pore size distributions that are optimized for flow diversion. The porosity is locally tuned to allow selective blood flow patterns where flow is diverted into the aneurysm sac for embolization while preserving adequate flow to adjacent secondary vessels through controlled pore architecture.
Solution Approach 2:
The patent utilizes porous materials with controlled porosity (between 10-90%) to achieve flow diversion. The porous structure allows blood to be redirected from the parent vessel into the aneurysm sac, promoting thrombosis and embolization while maintaining some blood flow to collateral vessels, thus balancing treatment effectiveness with preserving necessary blood supply.
3Adaptability or versatility
If the device is made with smaller strand diameters to improve flexibility, then the device can navigate tortuous vessels better, but the opening force and shape retention may be compromised
Solution Approach 1:
The patent changes multiple parameters simultaneously: using extremely thin strands (less than 0.001 inches) for flexibility combined with heat-setting the braided structure. This parameter change approach allows the device to achieve both improved flexibility for navigating tortuous vessels and sufficient opening force through the heat-set configuration that locks the strands in place.
Solution Approach 2:
The patent applies preliminary action by heat-setting the braided structure before deployment. This preliminary thermal treatment establishes the shape and configuration of the strands in advance, ensuring that when the device is deployed, it maintains its shape and retains opening force even with the use of extremely thin, flexible strands.
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
These devices achieve improved flexibility, shape retention, and expanded diameter performance, effectively inhibiting blood flow into aneurysms while minimizing interference with adjacent vessels, facilitating effective treatment of aneurysms in complex vascular geometries.
Implementation Method 1
The expandable device has a compressed state and an expanded state, and is self-expandable from the compressed state to the expanded state
Implementation Method 2
The expandable devices disclosed herein have improved flexibility, shape retention, and opening force over a range of expanded diameters. Some aspects of the present technology include expandable devices that have been heat set according to, for example, a novel heat setting process disclosed herein. The resulting expandable devices have a reduced oxide layer thickness and improved shape retention over a range of strand sizes.
Data Source
AI summary
Vascular expandable devices and associated methods are disclosed herein. An expandable vascular device can be implantable across an aneurysm in a blood vessel of a patient. The device can include a generally tubular structure formed of a plurality of braided metallic elements. The device can have a compressed state with a compressed state diameter of 0.027 inches or less and an expanded state with an expanded state diameter of 1.75 mm or more. Each of the plurality of metallic strands can have an oxide layer having a thickness of about 400 angstroms or less. The tubular structure can be configured to self-expand from the compressed state to the expanded state.