Stent-Graft Constraint Arrangement for Precise Positioning
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Solution Overview
Problem
Existing stent-graft deployment systems face challenges in accurately positioning stent-graft features like fenestrations or scallops within the aorta, due to difficulties in repositioning self-expanding stent-grafts once released, and ensuring precise alignment with branch arteries to avoid occlusion.
Innovation Solution
A constraint arrangement for a stent-graft loaded onto a delivery system, utilizing a suture looped around the cannula and secured by a release wire, which allows for precise positioning and releaseable securing of stent-graft features, enabling accurate alignment and deployment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a self-expanding stent-graft is released from the delivery device, then the stent-graft expands and seals against the vessel wall, but it becomes difficult or impossible to reposition
Solution Approach 1:
The constraint arrangement is established before the stent-graft is released and expanded. The suture loop is pre-positioned around the cannula with the positionable region held at the desired location. Only after this preliminary constraint is in place is the stent-graft released to expand, ensuring accurate positioning from the outset while maintaining the ability to adjust if needed.
2Reliability
If the stent-graft diameter is made larger than the vessel diameter, then sealing against the vessel wall is improved, but accurate positioning becomes more difficult
Solution Approach 1:
The constraint arrangement acts as an intermediary mechanism between the delivery system and the stent-graft. The suture loop and release wire system provides precise positional control during delivery, mediating between the need for accurate positioning and the requirement for effective sealing. This intermediary constraint allows the oversized stent-graft to be positioned accurately before deployment.
3Manufacturing precision
If the stent-graft is securely attached to the delivery system, then positioning control is improved, but release and deployment becomes more complex
Solution Approach 1:
The constraint arrangement uses a temporary, disposable constraint mechanism (suture loop with release wire) that is discarded after serving its positioning purpose. The release wire is simply retracted to release the constraint, allowing the stent-graft to deploy without requiring a complex permanent release mechanism. The constraint is recovered (withdrawn) after use.
Data Source
AI summary
A constraint arrangement for a stent-graft loaded onto a delivery system having a suture extending circumferentially around a surface of a graft from a first fixed end fixed to a stent-graft to a positionable region, and through the graft at a first constraining perforation into the lumen and returning out of the lumen to the surface of the graft at a second constraining perforation to a second fixed end fixed to the stent-graft, thereby forming a loop of the suture within a lumen of the graft, the loop wrapped circumferentially around a cannula such that a pair of legs of the loop hold the positionable region with respect to the cannula, wherein a bight of the loop extends through a gap between the legs and wherein the release wire extends through the bight thereby capturing the bight and releaseably securing the loop around the cannula.