Aortic Stent Graft Discrete Attachment Areas
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Solution Overview
Problem
Aortic stent grafts face issues with top stent separation due to uneven load distribution, leading to suture tearing through the fabric tube, particularly in aortic aneurism treatments, which existing solutions attempt to address but may increase the cross-sectional area and reduce flow area.
Innovation Solution
The introduction of discrete attachment areas on the fabric tube with a thinner wall thickness, achieved through heat and pressure application, which are permeable and identical in weave or knit to the surrounding graft area, providing enhanced resistance to suture pull-through without adding material, allowing suture ties to penetrate and encircle these areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the graft material is folded onto itself at the proximal end into a double thickness cuff for suture attachment, then suture tearing is reduced, but the cross sectional area of the stent graft increases and the flow area through the proximal end decreases
Solution Approach 1:
The patent applies local quality by creating discrete attachment areas with concentrated material density and altered weave structure at specific locations on the fabric tube, rather than uniformly thickening the entire graft. This localized approach provides enhanced suture attachment strength only where needed, while preserving the flow area of the main graft body.
Solution Approach 2:
The patent changes physical parameters of the fabric tube at attachment sites by altering the weave structure to create regions of different porosity and material density. These parameter changes increase local strength for suture attachment without requiring a uniform increase in wall thickness that would reduce flow area.
2Reliability
If the fabric tube wall thickness is increased at attachment areas to prevent suture pull-through, then attachment durability is improved, but the packing volume and sheath size requirements increase
Solution Approach 1:
The patent implements local quality by modifying the weave structure at discrete attachment areas to create regions of enhanced material density and inter-yarn bonding, rather than uniformly increasing wall thickness throughout the graft. This localized structural modification improves attachment durability without increasing overall packing volume.
Solution Approach 2:
The patent creates a composite structure within the fabric tube by integrating regions of altered weave pattern that combine different yarn orientations and densities. This composite approach at attachment sites provides enhanced mechanical properties for suture resistance while maintaining the original graft wall thickness and packing volume.
3Strength
If the weave structure is altered at attachment areas to concentrate material, then resistance to suture pull-through is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the fabric tube into distinct regions: standard weave areas for the main graft body and discrete attachment areas with modified weave structures. This segmentation allows the complex weave pattern to be localized to small, manageable sections rather than applied throughout the entire graft, simplifying the overall manufacturing process.
Solution Approach 2:
The patent changes local parameters of the weave structure at attachment sites, such as yarn spacing, interlacing frequency, and porosity, while maintaining the overall simplicity of the base weave pattern. These targeted parameter changes enhance pull-through resistance without requiring a complete redesign of the entire weave structure.
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 enhances attachment durability and resistance to tensile loads, reducing the risk of stent graft failure while maintaining the original flow area and packing volume, allowing for effective deployment and implantation without increasing the sheath size.
Implementation Method 1
The weave or the knit of the discrete attachment areas is identical to that of the permeable graft area with an exception that a wall thickness of each of the discrete attachment areas is flattened relative to, and thinner than, a wall thickness of the permeable graft area
Data Source
AI summary
An aortic stent graft includes a stent with a framework attached to a fabric tube by a plurality of suture ties. The fabric tube includes a plurality of discrete attachment areas that are at least partially surrounded by at least one permeable graft area. The fabric tube is one of a weave and a knit of thermoplastic yarn. Each of the suture ties associated with the discrete attachment areas at least one of penetrates through and encircles a respective one of the discrete attachment areas. The weave or knit of the discrete attachment areas is identical to that of the permeable graft area with an exception that a wall thickness of each of the discrete attachment areas is flattened relative to, and thinner than, a wall thickness of the permeable graft area.