Stent-Graft Curvature via Suture Tethers for Aortic Apposition
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Solution Overview
Problem
Thoracic aortic aneurysm treatment using stent-grafts often results in endoleaks due to a 'bird-beak' formation, which disrupts fluid dynamics and prevents optimal apposition of the stent-graft to the aortic wall, especially in the aortic arch.
Innovation Solution
An endovascular implant comprising a tubular graft and stent hoops with sinusoidal configuration, connected by sutures that allow the stent-graft to self-adjust and conform to the aortic vessel shape, reducing the gap between the stent-graft and the vessel wall by changing from a linear to a curvilinear configuration upon deployment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a standard stent-graft is used for TAA treatment, then the procedure is less invasive with reduced surgical morbidity and mortality, but endoleaks occur due to lack of apposition to the aortic wall along the inside curve
Solution Approach 1:
The stent-graft incorporates a control arrangement that allows dynamic adjustment of the graft length along the longitudinal axis, enabling the device to transition from a straight configuration during delivery to a curved configuration in situ to match the aortic arch geometry and achieve proper apposition
Solution Approach 2:
The expansion restriction arrangement modifies the physical parameters of the graft by restricting expansion at specific regions, creating predetermined curvature that changes the graft's geometric parameters to conform to the curved aortic lumen
2Ease of manufacture
If the stent-graft is made straight for easy delivery, then catheter delivery is simplified, but the device cannot conform to the curved aortic arch and creates bird-beak formation
Solution Approach 1:
The stent-graft is pre-configured with a control arrangement during manufacturing that enables predetermined curvature formation, allowing the device to be delivered straight through the catheter and then automatically assume the required curved shape upon deployment in the aortic arch
Solution Approach 2:
The control arrangement segments the graft structure into regions with different expansion characteristics, allowing differential expansion that creates the necessary curvature while maintaining overall device integrity during delivery
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 self-adjusting stent-graft effectively mitigates the 'bird-beak' issue, ensuring better apposition to the aortic wall and reducing endoleaks, thereby improving fluid dynamics and treatment efficacy.
Implementation Method 1
The at least one suture connects one apex of one stent hoop to two apices of another stent hoop to reduce the predetermined distance so that in a compressed or crimped configuration (as inside a catheter sheath prior to delivery in a vessel), the stent-graft extends generally linearly as with the typical stent-graft. Yet in a released configuration (unconstrained in a catheter sheath) in a body vessel, the stent-graft is self-adjusting in-situ so as to curve away from the longitudinal axis
Data Source
Figure 1A
Figure 1B~1C
Figure 2
AI summary
Described are various embodiments of an improved endoprosthesis that includes a generally tubular graft, a plurality of independent stent hoops connected to the graft and at least one suture. The at least one suture connects one apex of one stent hoop to two apices of another stent hoop to reduce a predetermined distance between distinct stent hoops so that in a released configuration in a body vessel, the stent-graft is curved away from the longitudinal axis to conform to the body vessel and reduce formation of a gap between one end of the stent-graft with an inner surface of the body vessel.