Endoluminal Prosthesis Sealing Spring Stent Design
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Solution Overview
Problem
Current stent graft designs face challenges in sealing efficacy, particularly at the proximal end, and are inflexible, making them difficult to deploy in tortuous paths and varying aneurysm geometries, such as short AAA necks, tortuosity, and angulation, and are complex to manufacture, especially for bifurcated models with different limb diameters.
Innovation Solution
The design includes a tubular graft with a suprarenal spring stent and a sealing spring stent connected in specific sinusoidal and M-shaped patterns, allowing for improved sealing, flexibility, and easier deployment by aligning apices and struts to reduce diameter and stress, and accommodating varying anatomies through adjustable iliac spring stents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a suprarenal spring stent is used to seal the stent graft at the lumen wall, then sealing is improved, but flow channels can still form between the graft material and the lumen wall where the stent is not holding the graft material in contact with the lumen wall
Solution Approach 1:
The spring stent is divided into multiple segments or cells along its length, with each segment capable of independently engaging the graft material at different positions. This segmentation allows the stent to maintain contact with the lumen wall across the entire sealing zone, preventing flow channel formation between graft and wall while maintaining overall sealing reliability.
2Adaptability or versatility
If traditional stent graft designs are used, then manufacturing is simplified, but the device cannot accommodate individual abdominal aortic aneurysm geometries such as short AAA neck, tortuosity, or angulation
Solution Approach 1:
The spring stent is designed with dynamic characteristics that allow it to adapt to different anatomical geometries. The sinusoidal pattern with varying wavelengths and amplitudes enables the stent to conform to tortuous paths, angulations, and short necks while maintaining sealing contact. This dynamic adaptability is achieved through the inherent flexibility and elastic properties of the spring structure, allowing it to adjust to individual patient anatomies without requiring completely different device designs.
3Reliability
If body spring stents are placed close together to keep graft material out of the lumen, then sealing is improved, but the stent graft flexibility is reduced and it becomes more difficult to maneuver through tortuous paths
Solution Approach 1:
The spring stent is constructed as a flexible, thin-walled structure that can bend and conform to tortuous vascular paths while maintaining its sealing function. The sinusoidal pattern provides flexibility along the length of the stent, allowing it to navigate angulations and curves. The flexible design enables the stent to be maneuvered through tortuous paths during delivery while still providing adequate sealing engagement when deployed.
4Ease of manufacture
If a regular sinusoidal pattern is used for the spring stent, then manufacturing is simplified, but the apices of the rings line up when crimped, increasing the bulk of material and thereby the diameter of the crimped stent graft
Solution Approach 1:
The spring stent employs an asymmetric sinusoidal pattern where the wavelengths, amplitudes, or phases of the sinusoidal waves vary along the length of the stent. This asymmetry prevents the apices of the rings from lining up when the stent is crimped, distributing the material bulk more evenly and reducing the overall crimped diameter. The asymmetric design maintains manufacturing feasibility while solving the diameter reduction problem.
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 enhanced sealing and flexibility of the endoluminal prosthesis improve blood flow exclusion of aneurysms, reduce stress on the aneurysmal sac, and simplify deployment and manufacturing, making it more effective and versatile for various abdominal aortic aneurysm geometries.
Implementation Method 1
The spring stent can be placed in a compressed state during delivery through a catheter and then expanded at the aneurysm site
Implementation Method 2
suprarenal positive apices and suprarenal negative apices connected in a sinusoidal ring pattern by suprarenal struts; sealing positive apices, sealing negative apices, and intermediate sealing negative apices connected in a ring pattern
Data Source
AI summary
An endoluminal prosthesis including a tubular graft having a proximal end and a distal end; a suprarenal spring stent operably connected to the proximal end, the suprarenal spring stent having suprarenal positive apices and suprarenal negative apices connected in a sinusoidal ring pattern by suprarenal struts; and a sealing spring stent operably connected to the tubular graft, the sealing spring stent having sealing positive apices, sealing negative apices, and intermediate sealing negative apices connected in a ring pattern, the sealing negative apices alternating with the intermediate sealing negative apices between adjacent sealing positive apices, the sealing positive apices being connected to the sealing negative apices by sealing struts, and the sealing positive apices being connected to the intermediate sealing negative apices by intermediate sealing struts. The suprarenal positive apices are axially aligned with the intermediate sealing negative apices.