Self-Expanding Stent Assembly for Aortic Dissection
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Solution Overview
Problem
Current treatments for aortic dissection, a form of aortic aneurysm where blood separates the aorta's wall layers, creating a false lumen, are inadequate in effectively closing off the false lumen and preventing further expansion.
Innovation Solution
A stent assembly comprising self-expanding zig-zag stents linked by flexible threads or fibers, deployed endovascularly to apply pressure on the aortic wall, closing off the false lumen, with a deployment device that includes a catheter, trigger wires, and a sheath to control the stent's expansion and positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stent assembly is deployed to close off the false lumen, then the effectiveness of treating aortic dissection is improved, but the device complexity increases due to the need for multiple stents, link arrangements, and deployment mechanisms
Solution Approach 1:
The stent assembly is divided into multiple individual stents (first stent, second stent, third stent, fourth stent) that are linked together by connection elements. Each stent can be independently positioned and deployed, allowing the false lumen to be closed off in segments along the aorta. This segmentation enables effective treatment of extended dissection areas while maintaining manageable device complexity through modular construction.
Solution Approach 2:
The stent assembly is nested within a delivery catheter system during deployment. The multiple stents and their link arrangements are contained within the catheter, which guides them to the target location. This nesting principle allows the complex multi-component assembly to be delivered through a single access point and deployed in a controlled manner, reducing the operational complexity despite the high structural complexity.
2Reliability
If self-expanding zig-zag stents are used to apply pressure on the aortic wall, then the ability to close off the false lumen is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The stents are designed with self-expanding characteristics that utilize the natural elastic recovery of the material. When deployed, the stents automatically expand from a compressed state to a larger diameter, applying radial pressure against the aortic wall. This self-expanding mechanism reduces the need for complex external expansion mechanisms and achieves consistent positioning through the material's inherent elastic properties rather than requiring high-precision mechanical control systems.
Solution Approach 2:
The stents employ a zig-zag curved geometry that transforms when expanded. The curved struts form a three-dimensional structure that naturally conforms to the cylindrical aortic geometry. This curved design allows the stent to apply uniform radial pressure around the entire circumference of the aorta, ensuring consistent false lumen closure without requiring high-precision adjustment mechanisms.
3Adaptability or versatility
If flexible links such as suture threads are used to connect stents, then the adaptability to aortic geometry is improved, but the strength of the link arrangement may be reduced
Solution Approach 1:
Flexible link elements such as suture threads or thin wire connections are used to join adjacent stents together. These flexible connectors allow the stent assembly to conform to the natural curvature and geometry of the aorta while maintaining sufficient mechanical strength to hold the stents in their relative positions. The flexibility of these thin link elements enables the assembly to adapt to the tortuous aortic path without compromising the overall structural integrity needed to maintain false lumen closure.
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 stent assembly effectively closes off the false lumen, reducing pressure on the aortic wall and promoting blood flow through the true lumen, providing a stable solution for aortic dissection treatment.
Implementation Method 1
self expanding zig zag stents... upon endoluminal placement by endovascular deployment the stent assembly is adapted to provided pressure on the wall of the lumen
Data Source
AI summary
A stent assembly (42) adapted for endoluminal placement by endovascular deployment for the treatment of a false lumen (10) associated with a vascular dissection. The stent assembly has a number of self expanding stents (35) connected together to define an elongate substantially cylindrical lumen wall engaging surface. The stents are adapted to provided pressure on the wall of the lumen adjacent to and extending away from a rupture. A deployment device (40) for the stent assembly includes a sheath (48) and a retention and release arrangement (50) to retain the proximal end (37) of the stent graft to the deployment device. Release of the stent assembly is by withdrawal of the sheath before release of its proximal end by the use of a trigger wire (54) of the retention and release arrangement.