Stent Conformance Struts for Graft Infolding Prevention
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Solution Overview
Problem
Stent-grafts deployed in vessels face issues with graft material infolding and endoleaks due to inadequate proximal seal and difficulty in conforming to curved vessel walls, leading to potential blood flow obstruction and complications.
Innovation Solution
A stent with conformance struts that transition from a compressed delivery configuration to a deployed configuration, where the struts encircle the graft material, reducing the likelihood of infolding and enhancing conformity to curved vessels, thereby minimizing endoleaks and allowing for smaller delivery profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stent-graft is deployed to treat an aneurysm, then the graft material may be pulled inward by blood flow causing infolding and endoleaks, but adding structural support may increase device complexity
Solution Approach 1:
The stent is divided into different functional segments: proximal conformance struts for sealing and curvature adaptation, and a main body for structural support. This segmentation allows each part to optimize its function without unnecessarily increasing overall device complexity.
Solution Approach 2:
The proximal end of the stent features specialized conformance struts with different geometric properties compared to the main body. These struts are specifically designed with curvature-adapting characteristics to improve sealing at the proximal end where infolding risks are highest.
2Adaptability or versatility
If the proximal end of a stent-graft is deployed in a curved portion of a vessel, then it may be difficult to conform the proximal edge to the curving vessel wall, but increasing conformability may compromise structural integrity
Solution Approach 1:
The stent structure is segmented into proximal conformance struts and a main body, allowing the proximal struts to independently adapt to curved vessel geometries while the main body maintains overall structural integrity and radial strength.
Solution Approach 2:
The proximal conformance struts are designed with inherent curvature-adapting geometry that allows them to conform to the curved vessel wall in the aortic arch or thoracic aorta, improving seal without compromising the structural strength of the main stent body.
3Reliability
If the stent struts are designed to encircle the graft material, then the delivery profile size increases, but using a smaller delivery profile is needed for accessing smaller vessels
Solution Approach 1:
The conformance struts are designed to be dynamic in nature, transitioning from a compressed delivery configuration where they extend beyond the graft to an expanded deployed configuration where they encircle the graft material. This dynamic transformation allows small delivery profile while achieving large sealed configuration.
Solution Approach 2:
In the compressed delivery configuration, the conformance struts are positioned to extend beyond the proximal end of the graft material, allowing the entire assembly to be delivered through a small profile. Upon deployment, the struts encircle the graft material, creating the sealing structure.
4Ease of operation
If self-expanding stents are used, then the stents expand automatically without further mechanical expansion, but the expansion force may be insufficient to achieve optimal proximal seal
Solution Approach 1:
The proximal conformance struts are designed with specific geometric properties and material characteristics that maximize their expansion force and curvature-adapting capability. This local optimization ensures that the self-expanding stent achieves sufficient radial force at the proximal end to create an optimal seal, even without additional mechanical expansion.
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-graft design effectively reduces the risk of endoleaks and improves conformity to curved vessels, ensuring stable blood flow and suitable deployment in smaller vessels, while maintaining structural integrity and patency.
Implementation Method 1
In a stent made of a shape-memory alloy such as nitinol, the shape-memory alloy may be employed to cause the stent to return to a predetermined configuration upon removal of the sheath or other device maintaining the stent in its predeployment configuration.
Data Source
AI summary
A stent includes a main body having proximal and distal ends, and at least one conformance strut coupled to the proximal end of the main body. A portion of the at least one conformance strut extends proximal to a proximal end of a graft material in a compressed delivery configuration, and further is aligned inside the proximal end of the graft material in an expanded deployed configuration. In the deployed configuration, the proximal conformance strut may at least partially encircle the graft material just distal to the proximal end of the graft material, which may reduce the likelihood of infolding at the proximal edge of the graft material and potential endoleaks.