Braided Vascular Stent for Tortuous Aneurysm Navigation
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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 undesired blockage of blood flow to branching 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, shape retention, and reduced oxide layer thickness, allowing for self-expansion across aneurysm necks with controlled porosity to inhibit blood flow and promote thrombosis.
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 neck, but the device suffers from crimping or kinking and cannot approximate the vessel wall adequately
Solution Approach 1:
The device is constructed from multiple individual strands (e.g., 48-144 strands) that are braided together, allowing each strand to independently navigate tortuous vessel paths while maintaining overall structural integrity. This segmentation enables the device to adapt to curved and twisted vessel anatomy without crimping or kinking, resolving the contradiction between positioning reliability and shape retention.
Solution Approach 2:
The device utilizes superelasticity through specific material selection (e.g., NiTi alloy with superelastic properties) and controlled oxide layer thickness (10-400 angstroms) to enable reversible deformation during deployment. This parameter change allows the device to flex through tortuous vessels while maintaining shape memory, solving the contradiction between navigating curved vessels and retaining structural shape.
2Reliability
If the device is expanded to increase porosity for flow diversion, then blood flow into the aneurysm is inhibited, but the device may block blood flow to branching or secondary vessels
Solution Approach 1:
The device employs different porosity characteristics in different regions: higher porosity (lower PPI) in areas requiring flow diversion and lower porosity (higher PPI) near branching vessels. This local quality variation allows selective flow diversion into the aneurysm while preserving collateral circulation to branch vessels, resolving the contradiction between aneurysm treatment effectiveness and preventing collateral ischemia.
Solution Approach 2:
The device provides dynamic flow modulation through its expandable nature, allowing the porosity to be adjusted during deployment. The device can be partially expanded to divert flow into the aneurysm while leaving gaps that allow flow to branch vessels, creating a dynamic balance between treating the aneurysm and preserving collateral circulation.
3Adaptability or versatility
If smaller diameter strands are used to improve flexibility, then the device can navigate tortuous vessels better, but the device may lack sufficient opening force for expansion
Solution Approach 1:
The device uses composite construction with superelastic material (e.g., NiTi) as the core providing flexibility and navigability, combined with a controlled oxide layer (10-400 angstroms) that provides friction reduction and shape retention. This composite approach allows smaller diameter strands to maintain both flexibility for navigating tortuous vessels and sufficient opening force for expansion through the synergistic combination of materials.
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 and shape retention, enabling effective deployment in tortuous vessels with reduced oxide layer friction, ensuring adequate porosity to inhibit blood flow into aneurysms while allowing perfusion to adjacent vessels, facilitating thrombosis and healing.
Implementation Method 1
the expandable device having a compressed state and an expanded state, and being self-expandable from the compressed state to the expanded state
Implementation Method 2
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
Data Source
AI summary
Vascular expandable devices and associated methods are disclosed herein. An expandable vascular device can include a generally tubular sidewall formed of a plurality of braided strands. The device can have a compressed state for delivery in which the device has a compressed state diameter of 0.027 inches or less. The device can have an expanded state in which the device has an expanded state diameter. A full expansion distance of the device corresponds to a longitudinal unconstrained distance at which the distal end of the expandable device attains the expanded state diameter. The full expansion distance can be 20 mm or less.