Balloon-Expanded Polymer Stent With Radiopaque Crush-Resistant Cells
Find Innovative SolutionsGenerate Solutions
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 restenosis and are difficult to visualize during deployment.
Innovation Solution
A balloon-expandable polymer scaffold with a specific design that includes a ratio of outer diameter to wall thickness, strut width, and radial stiffness, allowing for high crush recoverability, radial strength, and fluoroscopic visibility, which balances competing design attributes of radial strength, toughness, and compactness for delivery, while incorporating radiopaque markers for improved visualization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polymeric scaffolds are designed with high radial strength to withstand crimping and balloon expansion forces, then structural integrity is improved, but the scaffolds become less flexible and more difficult to deliver through peripheral arteries
Solution Approach 1:
The scaffold utilizes the glass transition temperature parameter of poly(L-lactide) to enable temperature-dependent mechanical property changes. At room temperature, the scaffold is rigid for structural support, but when heated to above Tg during balloon expansion, it becomes flexible and moldable, allowing easy delivery through catheters and proper expansion at the target site
2Difficulty of detecting and measuring
If polymeric scaffolds are made radiopaque for visualization during deployment, then detection capability is improved, but the scaffolds lose their biodegradability and become suitable for long-term use
Solution Approach 1:
Radiopaque markers are applied only at specific locations on the scaffold (such as at the ends or at intervals along the length) rather than throughout the entire structure. This localized approach provides sufficient fluoroscopic visibility for deployment guidance while preserving the biodegradability of the bulk polymeric material
3Reliability
If polymeric scaffolds are designed for high crush recoverability to prevent restenosis, then reliability is improved, but the scaffolds require more complex structural designs that compromise manufacturing simplicity
Solution Approach 1:
The scaffold employs curved and undulating strut designs with specific geometric profiles that inherently provide crush recoverability. The curved geometry allows the scaffold to flex and recover from compression forces without requiring complex mechanical mechanisms, maintaining manufacturing simplicity while achieving high reliability
4Strength
If polymeric scaffolds are designed with optimal wall thickness for radial strength, then structural performance is improved, but the scaffolds become less compliant and more difficult to crimp for delivery
Solution Approach 1:
The wall thickness of the scaffold is designed to optimize the balance between radial strength and crimping flexibility. The specific wall thickness parameter allows the scaffold to maintain adequate structural support while remaining sufficiently compliant for crimping onto delivery balloons and expansion at the target site
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 at least 90% crush recovery and maintains radial strength and stiffness, reducing the risk of restenosis and improving deployment accuracy through enhanced radiopacity, addressing the limitations of existing polymeric scaffolds in peripheral applications.
Implementation Method 1
The tube is plastically deformed in radial and axial directions by a blow molding process
Implementation Method 2
The deformation improves the mechanical properties of the tube before it is formed into the scaffold by orienting polymer chains in radial and/or biaxial directions
Implementation Method 3
The deformation improving the mechanical properties of the tube before it is formed into the scaffold... the degree of crystallinity and type of crystalline formation during the deformation process
Implementation Method 4
At the treatment site within the lumen, the stent is expanded by inflating the balloon
Implementation Method 5
incorporating radiopaque markers for improved visualization
Data Source
AI summary
A medical device includes a polymer stent (or scaffold) crimped to a catheter balloon. The stent, after being expanded from a crimped state by the balloon, provides a crush recovery of about 90% of its expanded diameter after being pinched or crushed by an amount equal to about 50% of the expanded diameter. The stent has a pattern including a W-shaped or W-V shaped closed cell and links connecting the closed cells.