Differential Dilation Stent for Arteriovenous Fistula Creation
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Solution Overview
Problem
Patients with partial or complete occlusions in leg arteries face challenges such as claudication, difficulty in wound healing, and the risk of amputation due to peripheral vascular disease, where standard bypass procedures are often impossible, especially in diabetes-narrowed arteries, and stent placement is ineffective for small vessels or extensive occlusions.
Innovation Solution
Development of differential dilation stents with a cylindrical mesh body made of superelastic nickel-titanium alloy, coated with PTFE or UHMWPE, featuring regions with varying hoop strengths and diameters to accommodate compressive forces and ensure continuous blood flow, allowing for the creation and maintenance of an arteriovenous fistula between the artery and vein.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stent is deployed in blood vessels to provide structural support and maintain patency, then the reliability of blood flow is improved, but the stent may collapse under compressive forces from surrounding tissue
Solution Approach 1:
The stent incorporates varying wall thicknesses at different locations along its length, with thicker sections positioned at areas subject to higher compressive forces. This non-uniform thickness distribution provides localized structural reinforcement where needed while maintaining overall flexibility and blood flow characteristics.
Solution Approach 2:
The stent is constructed from composite materials combining metallic scaffold structures with polymer coatings or fabric layers. This composite construction provides both mechanical strength to resist compression and surface properties that promote endothelialization and blood compatibility.
2Adaptability or versatility
If the stent diameter is reduced to pass through small vessels, then the adaptability to different vessel sizes is improved, but the stent strength decreases making it more susceptible to collapse
Solution Approach 1:
The stent features variable wall thickness and reinforced sections at critical locations, allowing smaller overall diameter for vessel compatibility while maintaining local strength where compressive forces are highest. The non-uniform structure provides enhanced load-bearing capacity without increasing overall stent profile.
Solution Approach 2:
The stent is divided into multiple segments or cells with varying structural characteristics. Certain segments have enhanced wall thickness or structural reinforcement to provide localized strength, while other segments maintain smaller dimensions for vessel compatibility. This segmentation allows the stent to achieve both small overall size and sufficient structural strength.
3Strength
If the stent is made more rigid to prevent collapse, then the strength is improved, but the ability to conform to vessel curvature and promote cellular in-growth decreases
Solution Approach 1:
The stent incorporates flexible polymer coatings or thin film layers that conform to the vessel wall curvature while the underlying metallic scaffold provides structural support. This layered construction allows the stent to be rigid enough to prevent collapse yet flexible enough to adapt to vessel geometry and promote endothelial cell growth along the surface.
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 stents effectively bypass arterial occlusions by providing a stable pathway for blood flow, reducing the risk of stent collapse and promoting cellular ingrowth, thus improving blood circulation and reducing the need for amputation in patients with peripheral vascular disease.
Implementation Method 1
The inner stent or scaffold component may be formed from either balloon-expandable materials and self-expandable materials. Preferably, however, the stent or scaffold will be in the form of a super elastic metal, such as nickel titanium alloy.
Implementation Method 2
small holes, such as laser-drilled holes, may be formed through the material in order to promote cellular in-growth
Data Source
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AI summary
Embodiments herein provide differential dilation stents for use in percutaneous interventions, such as transluminal bypass procedures. In some embodiments, the stents may be used in the process of creating an arteriovenous (AV) fistula during a percutaneous bypass procedure, and such stents may have two or more specialized regions that are configured to adopt a predetermined diameter, shape, and/or tensile strength upon insertion in order to suit the needs of the vessel or procedure. The disclosed stents may be used for creating and/or maintaining an arterial/venous fistula for bypass of an occlusion in a cardiac artery using a cardiac vein, or the femoral artery, for example using the tibial or popliteal vein