Expandable Tube for Intracranial Aneurysm Flow Diversion
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Solution Overview
Problem
Current methods for treating intracranial aneurysms, such as surgical clipping and endovascular coiling, are invasive, risky, and ineffective for wide-necked aneurysms, and existing stents lack the necessary flexibility and radial strength to safely redirect blood flow away from aneurysms while minimizing tissue pressure.
Innovation Solution
An expandable tube with a frame that elongates during radial contraction, featuring longitudinally overlapping closed rings and deformable elements, allowing for high radial strength and controlled deployment, suitable for small delivery catheters, and capable of switching between radially expanded and contracted states without excessive strain, providing tailored surface coverage and preventing blockage of branch blood vessels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stent is designed with high radial strength and low porosity to redirect blood flow away from aneurysm, then flow diversion effectiveness is improved, but the stent becomes too rigid to navigate tortuous blood vessels
Solution Approach 1:
The stent is designed with dynamic properties that allow it to transition from a flexible, compressed state for navigation to a rigid, expanded state for flow diversion. The self-expanding mechanism enables the stent to adapt its mechanical properties: when delivered, it is flexible enough to navigate tortuous vessels, and upon deployment, it expands to provide the necessary radial strength and low porosity for effective blood flow redirection away from the aneurysm.
Solution Approach 2:
The stent utilizes changes in physical parameters (radial dimension, porosity, rigidity) between its compressed and expanded states. In the compressed state, it has high porosity and low rigidity for vessel navigation; upon self-expansion, it transitions to low porosity and high rigidity to achieve effective flow diversion and provide structural support to redirect blood flow away from the aneurysm.
2Reliability
If coils are used to fill the aneurysm sac, then the aneurysm is packed and thrombus is triggered, but the aneurysm remains its original size and pressure on surrounding tissue is not removed
Solution Approach 1:
The stent extracts or removes the mass effect and pressure from surrounding tissues by providing a structural framework that redirects blood flow away from the aneurysm sac. Unlike coils that merely pack the sac, the stent actively diverts flow through its low porosity structure, allowing the aneurysm to gradually shrink as thrombus is absorbed, thereby removing the mass effect and pressure on adjacent brain structures.
Solution Approach 2:
The stent acts as an intermediary structure between the blood flow and the aneurysm sac. It provides a controlled barrier that redirects flow away from the aneurysm while allowing gradual thrombus formation and absorption. This intermediary structure enables the aneurysm to shrink over time, progressively removing pressure on surrounding tissues, unlike coils that maintain the aneurysm's original size.
3Ease of operation
If a tube is made flexible to pass through tortuous blood vessels, then deliverability is improved, but it cannot provide sufficient coverage to redirect blood flow away from aneurysm
Solution Approach 1:
The tube exhibits dynamic mechanical properties that allow it to be flexible during delivery and rigid during function. In the compressed delivery state, the tube is flexible and conformable to navigate tortuous vasculature. Upon self-expansion at the target site, it transitions to a rigid structure with sufficient coverage and low porosity to effectively redirect blood flow away from the aneurysm, thus achieving both deliverability and functional reliability.
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
This solution enables a minimally invasive, safer treatment with lower morbidity and mortality rates, effective for both saccular and fusiform aneurysms, allowing for reduced aneurysm mass and pressure on surrounding tissues, and is suitable for use in tortuous blood vessels.
Implementation Method 1
an elongate frame which can be switched reversibly from a radially expanded and longitudinally contracted state in which the frame presents a low porosity to a radially contracted and longitudinally expanded state
Implementation Method 2
The frame comprises a plurality of closed rings of circumferentially deformable elements
Implementation Method 3
an elongate frame which can be switched reversibly from a radially expanded and longitudinally contracted state to a radially contracted and longitudinally expanded state
Data Source
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AI summary
An expandabletube for deployment within a blood vessel is disclosed. In one arrangement, the tube comprises an elongate frame that is reversibly switchable from a radially expanded and longitudinally contracted state to a radially contracted and longitudinally expanded state. The frame comprises a plurality of longitudinally deformable elements for providing longitudinal expansion and contraction of the frame and a plurality of circumferentially deformable elements for providing radial expansion and contraction of the frame. Thelongitudinally deformable elements can be expanded or contracted longitudinally substantially without any change in the shape of the circumferentially deformable elements. The plurality of circumferentially deformable elements comprises a plurality of sets of circumferentially deformable elements. Eachset of circumferentially deformable elements forms a closed ring around an axis of elongation of the frame. Each closed ring consisting exclusively of the circumferentially deformable elements. At least two of the closed rings occupy overlapping ranges of longitudinal positions when the frame is in the radially expanded and longitudinally contracted state and occupy non-overlapping ranges of longitudinal positions when the frame is in the radially contracted and longitudinally expanded state.