Helical Anchor Stent Graft Fixation
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Solution Overview
Problem
Stent grafts face challenges with migration over time due to blood flow forces and pulsatile pressure, and they can block blood flow to side branches, leading to poor sealing and leakage, especially in complex anatomical locations like the thoracic aorta where major arteries are nearby.
Innovation Solution
A stent graft system featuring a helical anchor with a plurality of coils that can be rotated around a guide rail to securely sew the stent graft to the vessel wall, ensuring fixation and sealing while allowing blood flow to side branches by using a guide tether and driver system for precise deployment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If hooks are used to secure the stent graft to the vessel wall, then fixation strength is improved, but the concentration of loading at single points causes hooks to dislodge over time due to hydrodynamic loading
Solution Approach 1:
The fixation function is segmented from single-point hooks to multiple barbs distributed along the stent graft surface. This distributes the hydrodynamic loading across numerous contact points rather than concentrating it at single hooks, preventing dislodgement while maintaining strong fixation.
Solution Approach 2:
The fixation mechanism transitions from point-contact hooks to surface-distributed barbs that engage the vessel wall along a two-dimensional area. This dimensional change from zero-dimensional points to two-dimensional surface engagement distributes loads and improves reliability.
2Device complexity
If hooks are attached at fixed positions around the periphery of the stent graft, then structural simplicity is improved, but poor seal and leakage occurs when hooks are not set to the required depth
Solution Approach 1:
The barbs are designed to be flexible and capable of self-adjustment during deployment. As the stent graft expands, the barbs dynamically penetrate the vessel wall to varying depths based on local tissue characteristics, ensuring reliable sealing without requiring precise pre-setting of fixed positions.
3Reliability
If a stent graft is deployed to treat an aneurysm, then aneurysm exclusion is improved, but blood flow to side branches may be blocked
Solution Approach 1:
The stent graft structure is segmented with dedicated openings or side ports that allow blood flow to pass through to side branches while the main body excludes the aneurysm. This segmentation enables simultaneous aneurysm exclusion and preservation of side branch perfusion.
4Adaptability or versatility
If the vessel wall area for prosthesis fixation is limited above an aneurysm, then anatomical constraints are improved, but secure fixation of the prosthesis becomes more difficult
Solution Approach 1:
The stent graft incorporates localized features such as concentrated barb density or enhanced anchoring structures at specific regions (proximal and distal ends) where fixation is most critical. This local quality enhancement provides strong fixation even when overall vessel wall area is limited.
Data Source
AI summary
A stent graft system and method of use includes a stent graft for fixation at an attachment site with graft material defining at least one opening having an opening perimeter; a support attached to the graft material; a guide rail attached around the opening perimeter; and a helical anchor having a plurality of coils with a point at one end. The plurality of coils are rotatable around the guide rail to cause the pointed end of the coils to penetrate the graft material and the adjacent tissue in contact with the stent graft to sew the stent graft to the attachment site.