Crush-Recoverable Polymer Scaffolds for Peripheral Vessels
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Solution Overview
Problem
Current polymeric scaffolds for peripheral blood vessels face challenges in maintaining structural integrity and radial strength under external loads, such as crimping and balloon expansion forces, and lack radiopacity, making them unsuitable for long-term use in peripheral arteries where they can cause chronic outward force and restenosis.
Innovation Solution
A crush-recoverable polymer scaffold is developed using a process that involves biaxially expanding a polymer precursor to form a scaffold with specific strut and link dimensions, crimping it to a balloon-catheter at a controlled temperature, and incorporating radiopaque markers for improved visibility during deployment, allowing for high radial stiffness, fracture toughness, and minimal profile while maintaining structural integrity under crushing and radial loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If polymeric scaffolds are made to be biodegradable and bioabsorbable, then the scaffold can be temporary and allow vessel remodeling, but the scaffold lacks radiopacity and cannot be visualized under fluoroscopy for precise placement
Solution Approach 1:
The patent combines biodegradable polymeric material with radiopaque materials to create a composite scaffold structure. The radiopaque markers or coatings are integrated into the polymer scaffold, allowing the scaffold to maintain its biodegradable properties while gaining the ability to be visualized under fluoroscopy for precise placement and monitoring.
2Strength
If the scaffold is made with high radial stiffness to maintain vessel diameter, then the scaffold can prevent restenosis, but the scaffold cannot be crimped to a small profile for delivery through catheters
Solution Approach 1:
The patent utilizes temperature-dependent parameter changes in the polymeric material. The scaffold is crimped at elevated temperatures where the polymer becomes more compliant and can be compressed to a small profile. After cooling to body temperature, the polymer regains its radial stiffness to maintain vessel diameter and prevent restenosis.
Solution Approach 2:
The patent exploits the phase transition of the polymeric material between a compliant state at elevated temperatures and a rigid state at lower temperatures. This phase transition enables the scaffold to be delivered in a compressed state and then expand to provide the necessary radial support after implantation.
3Volume of moving object
If the scaffold is crimped tightly onto the balloon for delivery, then the scaffold achieves a compact profile, but the scaffold suffers structural damage and loses radial strength
Solution Approach 1:
The patent changes the temperature parameter during the crimping process to prevent structural damage. By performing crimping at elevated temperatures where the polymer is more ductile and less brittle, the scaffold can be compressed to a compact delivery profile without suffering the structural damage that would occur at room temperature, thereby preserving its radial yield strength.
4Stability of the object's composition
If the scaffold uses brittle polymeric materials for structural integrity, then the scaffold maintains shape, but the scaffold is prone to fracture during crimping and deployment
Solution Approach 1:
The patent changes the temperature parameter to transform the mechanical properties of the polymeric material. At elevated temperatures during crimping and deployment, the polymer exhibits increased ductility and fracture resistance. After deployment, cooling to body temperature restores the polymer's shape stability while maintaining adequate fracture resistance for in-vivo performance.
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 scaffold achieves over 90% crush recovery and maintains radial strength and stiffness, reducing the risk of restenosis and chronic outward force, while being compact enough for delivery and easily visualizable under fluoroscopy for precise placement.
Implementation Method 1
biaxially expanding a polymer precursor to form a scaffold
Implementation Method 2
crimping it to a balloon-catheter at a controlled temperature
Implementation Method 3
crimping it to a balloon-catheter at a controlled temperature
Implementation Method 4
the scaffold achieves over 90% crush recovery and maintains radial strength and stiffness
Data Source
AI summary
Methods for making scaffolds for delivery via a balloon catheter are described. The scaffold, after being deployed by the balloon, provides a crush recovery of about 90% after the diameter of the scaffold has been pinched or crushed by 50%. The scaffold structure has patterns that include an asymmetric or symmetric closed cell, and links connecting such closed cells.