Blunted-End Vascular Prosthesis for Safer Stent Tracking
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Solution Overview
Problem
Vascular prostheses, such as stents and stent-grafts, often have sharp or rough edges at their ends due to wire cutting, which can cause damage to blood vessels during deployment, and they need to be trackable without excessive friction and flexible to conform to vessel shapes.
Innovation Solution
The stent ends are terminated with end caps or bent and welded to create smooth edges, and a two-layer structure with an outer layer featuring flared ends and a tie component woven in an over-under pattern to enhance flexibility and tracking, using materials like nitinol or radiopaque materials for imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If wire ends are cut at distal and proximal ends during machine braiding, then the stent structure is complete and strong, but sharp/rough edges are created that can damage blood vessels
Solution Approach 1:
The harmful sharp wire ends are extracted and removed from the stent structure by cutting them off, then replaced with blunted ends or end caps that eliminate the harmful edges while preserving the overall stent integrity
Solution Approach 2:
The wire ends that would normally be sharp and harmful are converted into blunted or capped structures that are safe for vessel contact, transforming a harmful feature into a beneficial one by changing the end geometry
2Strength
If the stent is made with sufficient strength and rigidity to remain expanded and prevent migration, then it can effectively anchor within the blood vessel, but it becomes difficult to track through the delivery catheter without excessive friction
Solution Approach 1:
Different sections of the stent are given different properties: the main body maintains high strength and rigidity for anchoring, while the ends are modified with blunting or cap structures that reduce friction during catheter passage, creating localized quality variations
3Strength
If the stent is made with sufficient strength to prevent migration, then it remains expanded effectively, but it loses flexibility to conform to vessel shape and natural movement
Solution Approach 1:
The stent exhibits local quality variations where the main body provides structural strength for expansion retention, while specific regions (particularly the ends) are designed with flexibility to conform to vessel curvature and movement patterns
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 solution reduces vessel damage, improves tracking through catheters, and ensures flexibility and anchoring, maintaining the stent's position without migration, while providing a strong scaffold for blood flow restoration.
Implementation Method 1
The tie component can be woven in an over-under pattern relative to the multiple layers of the device
Implementation Method 2
a flare cap is used to secure the wire pairs
Implementation Method 3
the wire ends of a stent can be terminated in an end cap or by bending and welding the stent's wires
Data Source
AI summary
A vascular prosthesis is described, having blunted wire ends. The blunted wire ends can take on a variety of configurations including end caps, bent ends, curved ends, or eyelets. The novel ends provide a smooth surface to contact the blood vessel walls thereby reducing the risk of trauma during placement of the prosthesis.