Stent-Graft Stitch Path for Kink Resistance
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Solution Overview
Problem
Existing stent-grafts face challenges in conforming to highly curved or angled blood vessel anatomy, leading to kinking and reduced flexibility, which affects hemodynamic blood flow and implant stability.
Innovation Solution
A stent-graft prosthesis with a sinusoidal stitch path that allows relative longitudinal movement between the stent and the tubular graft, featuring wider stitches over crowns for sliding and narrower stitches over struts to prevent circumferential movement, enhancing flexibility and kink resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the stent-graft uses a rigid stitch path to maintain structural integrity, then strength is improved, but flexibility deteriorates causing kinking in curved anatomy
Solution Approach 1:
The stitch path is designed with variable width segments that allow dynamic adjustment: narrow segments over struts provide rigid constraint for strength, while wide segments over crowns allow longitudinal movement for flexibility. This dynamic design enables the stent-graft to adapt to curved anatomy without kinking while maintaining overall structural integrity.
Solution Approach 2:
Different portions of the stitch path have different widths to provide locally optimized properties: narrow stitch segments over struts provide strong constraint, while wide stitch segments over crowns permit movement. This local differentiation resolves the contradiction between overall strength and local flexibility needs.
2Stability of the object's composition
If the stent is tightly constrained to the graft to prevent movement, then stability is improved, but flexibility deteriorates reducing ability to conform to curved vessels
Solution Approach 1:
The differential width stitch path creates a dynamic coupling system where the stent can move relative to the graft in controlled ways: longitudinal movement is permitted over crowns for conformability, while circumferential stability is maintained over struts. This dynamic design resolves the contradiction between stability and adaptability.
Solution Approach 2:
The stitch path is segmented into different width zones (narrow over struts, wide over crowns) that provide different degrees of freedom. This segmentation allows the stent-graft to achieve both stability and conformability by restricting movement in some regions while allowing it in others.
3Reliability
If the stent-graft maintains a fixed rigid structure for mechanical engagement, then reliability is improved, but adaptability deteriorates causing kinking in highly angled vessels
Solution Approach 1:
The variable width stitch path creates a dynamically adaptable mechanical engagement system that maintains reliability through narrow segments over struts while achieving kink resistance through wide segments over crowns that allow the stent to flex and conform to highly angled vessel anatomy.
Data Source
AI summary
A stent-graft prosthesis includes a tubular graft and a stent coupled to the tubular graft via a plurality of stitches. The stent has a sinusoidal pattern defined by a plurality of crowns and a plurality of struts. The stitches form a stitch path having a sinusoidal pattern that corresponds to the sinusoidal pattern of the stent. A width of curved segments of the stitch path that are disposed over crowns of the stent is configured to permit relative longitudinal movement between the stents and the tubular graft. A width of intermediate segments of the stitch path that are disposed over struts of the stent may be configured to restrict or permit relative circumferential movement between the stents and the tubular graft. The stitch path may include a plurality of transverse stitches in order to prevent exposure of the crowns beyond the stitch path.